Urban Energy Flows by Anastasiya Andrukovich

Weidlich / Grajcar, editors

URBAN ENERGY FLOWS Course Research Papers 2017 Urban Energy Flows - Course Research Papers 2017

XQ4 www.blauer-engel.de/uz195

Weidlich / Grajcar, editors Research Efficiency in Architecture and Planning HafenCity Universität Hamburg - Universität für Baukunst und Metropolentwicklung Überseeallee 16 - 20457 Hamburg

Impressum First published 2018 © HafenCity Universität Hamburg Professur REAP Revised by: Maria Grajcar, Ingo Weidlich Design and layout: Pia Schnellberger Print: oeding print GmbH Editors: Univ.-Prof. Dr.-Ing. Ingo Weidlich Dipl.-Ing. Mgr. Maria Grajcar, MA Tel.: +49 (0)40 42827 - 5700 E-Mail:ingo.weidlich@hcu-hamburg.de ISBN: 978-3-941722-64-4

Diese Veröffentlichung ist urheberrechtlich geschützt. Sie darf ohne vorherige Genehmigung der Autoren/ Herausgeber nicht vervielfältigt werden. Alle Angaben dieser Broschüre sind nach bestem Gewissen unter Anwendung aller gebotenen Sorgfalt erstellt worden Trotzdem kann von den Autoren und den Herausgebern keine Haftung für etwaige Fehler übernommen werden. DANKSAGUNG: Die Autoren und Herausgeber danken dem Energieforschungsverbund Hamburg für die Förderung dieser Publikation.

PREFACE

HYDROGEN AND SYNTHETIC METHANE IN THE FUTURE ENERGY SYSTEM

SUSTAINABILITY OF CHP FUEL CELLS

THE SHALE GAS INDUSTRY IN EUROPE: BARRIERS AND OPPORTUNITIES

COMPRESSION CHILLERS: OPERATION CHALLENGES RECOMMENDATIONS TO OPTIMIZE OPERATION

AND

ELECTRIC BUS ANALYSIS FOR BOGOTÁ PUBLIC TRANSPORTATION SYSTEM

ENERGY FROM NORTH TO SOUTH: NEW ELECTRICITY GRIDS FOR GERMANY

REFERENCES

3—

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— Ingo Weidlich, Maria Grajcar This is a collection of the six best research papers that were elaborated by REAP students of the 8th generation in the course Urban Energy Flows (UEF) in 2017. This collection shall give best practice to further generations of REAP students, who will participate in the UEF course and give appreciation to the excellence of the students’ work. When we dived into the lectures of Urban Energy Flows in summer term 2017 we were very curious and motivated but we did not know exactly what to expect. We wanted to transfer as much of our knowledge and professional experience from the energy sector as possible to the students. Time was short and the number of lectures was very limited because we decided to change from collective grades in groups to individual presentations and research papers. This was our concept to increase motivation for

the semester work. Students could choose from a broad range of topics representing the whole Urban Energy Flow – technologies and themes or come up with their own ideas. More than 30 presentations were given and the same amount of research papers was written. Maria Grajcar introduced a new methodology how the students could present their topics. Two options were offered to choose from “conference mode” and “university mode”. “Conference mode” meant something unusual could happen after the first five minutes of the presentation or within five minutes of Discussion section that could disturb the presenter (like in a real conference), while in “university mode” nothing unexpected was foreseen. Most students chose the training option “conference mode” and they learned to deal with impertinent questions, dinner offers, audience looking out of the window,

angry boss, foto shootings, tiny voices, badly translated comments, reckless noise, conversations …. Of course the presenting student did not know in advance what will happen. It was fun! More than 760 pages of research paper had to be reviewed and the results were more than satisfying. We chose the six most excellent ones from our perspective. Without doubt there are more impressive papers written by this generation, so these five only represent the great work of: Feras Abu Diab, Saad Afridi, Ahmed Ahmed, Amir Mohammad Alinaghian, Sindre Andresen, Anastasiya Andrukovich, Animesh Behera, Anda Bufi, Adrian Burduh, Maximilian Busch, Alessandro Caraccini, Elena Chikulaeva, Patricia Dreifus Zaluski, Jonas Falck, Nasimeh Fallahranjbar, Juliane Fritz Benachio, Laura Garcia Rios, Xhelona

Haveriku, Rihab Hlel, Malek Ismail, Delaram Jenab, Noriko Kakue, Nurnida Kemala Ayu, Abdullah Khisraw, Yesim Köroglu, Rodolfo Mesquita Macedo, Comfort Mosha, Mahmoud Moursy Hussein, Gabriel Nießen, Gustavo Pagliari Valerio Dos Santos, Pakdad Pourbozorgi Langroudi, Pragnya Rayaprolu, Kristina Rumiantceva, Pia Schnellberger, Jessica Sellin, Oluwaseun Shittu, Muhammad Shoaib, Tobias Teferra, Mariya Todorova, and Sepideh Yari. Thank you and we want more in the future! Univ.-Prof. Dr.-Ing Ingo Weidlich Dipl.-Ing. Mgr. Maria Grajcar, MA

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INTRODUCTION

— Anastasiya Andrukovich

Anastasiya Andrukovich is an architect and urban planner from Belarus, co-founder of the NGO Minsk urban platform. The main professional focus is a city as a complex organism. Currently, she is a REAP master student at HafenCity University in Hamburg.

KEYWORDS Hydrogen economy, energy carrier, fuel cell, decarbonization, electrolysis, methanation, gasification, green gas, synthetic methane, torrefaction, syngas.

ABSTRACT Climate change driving by constantly increasing energy demand is happening. Certainly, the necessity in transformation of global energy system towards decarbonized economy is recognized. Hydrogen is considered as a possible solution, capable of assisting in issues of environmental emissions, sustainability and energy security. Hydrogen is a green energy carrier which has the potential to ensure energy demand without an impact on the environment, both locally and globally. However, the transition from a carbon-based system to a hydrogen economy requires a significant technological breakthroughs and socio-economic

changes. In this case, synthesis of methane can be an intermediate step capable to solve storage and distribution problems connected with current hydrogen industry. Development of a cross-sectoral system solution power-to-gas solves the problem of fluctuations electricity generation from renewable sources converting electric energy to chemical one and, as a result, obtaining hydrogen and methane. The synergetic technology unifies renewable energy production, mobility, industry, heat supply and power generation.

LIST OF ABBREVIATIONS CHP – combined heat and power GHG – greenhouse gas SNG – substitute natural gas EU – European Union PtG – Power-to-gas

The problem of anthropogenically driven climate change caused by constantly rising energy demand is the main challenge facing humankind. Additionally, in the condition of impending exhaustion of fossil fuel resources the society cannot rely anymore on the current oil orientated economy. Thus, the establishment of carbon-neutral and environmentally friendly energy system is the key task in order to save the world for the next generations. The transformation of economy from fossil fuel-based to renewable sources has three main questions: — Efficient conversion of renewable energy into electricity; — Electricity storage; — Efficient production of a synthetic fuel. Addressing the aforesaid, hydrogen is conceded as one of the most promising energy carriers in the future energy sector. Unlike oil, gas or coal, hydrogen is not a primary source. It does not exist freely in nature and has to be produced from hydrogen-containing sources using energy and then transported for future use where its latent chemical energy can be fully realized (Edwards et al., 2007). On the one hand, accomplishments in fuel cell technology have substantially increased the role of hydrogen in the energy system over the last decade. Combining hydrogen and oxygen, a fuel cell converts chemical potential energy into electrical energy. On the other hand, the development of power-to-gas system offers to convert the electricity from

renewable energy sources into hydrogen or methane and feeding it into the gas infrastructure, or using it directly (German Energy Agency, 2015). Despite that hydrogen can be obtained from diverse sources, both renewable and nonrenewable, there is a wide range of challenges connected with high cost of «green» production, safety, storage and transportation. Moreover, speaking about hydrogen injection directly to the gas grid, maximum hydrogen content in the natural gas infrastructure must be in the range from 0.1 to 10% in EU depending on the grid requirements, and up to 2 % in Germany (German Energy Agency, 2015). Recognizing the growing sector of renewable energy production, the efficient energy storage and delivery are the preconditions for the further hydrogen development. Taking into consideration limitations connected with current hydrogen industry, methanation can be the second step in the PtG system where SNG produced in the reaction of hydrogen and carbon dioxide can be fed in the gas grid without significant restrictions. Thus, development and wide introduction of methanation technologies is transition stage towards hydrogen economy where hydrogen is a major carrier in the energy supply cycle. However, any transitions from a carbonbased to hydrogen-based economy require scientific researches and face technological, socio-economic obstacles. To sum up, hydrogen economy is the alternative direction in order to replace fossil fuel-based economy. PtG technology is central to the hydrogen economy. It is a cross-sectoral

7—

system which creates synergy between renewable energy production, industry, mobility, heat supply and power generation. This paper is dedicated to analysis of the hydrogen and synthetic methane potential for the transition to the decarbonized economy.

—8

Germany in particular are used as a ground for the evaluation of hydrogen and synthetic methane potential in the future energy system.

HYDROGEN IN THE ENERGY SYSTEM

The paper provides the vision of hydrogen

Hydrogen is considered as a clean, flexible energy carrier. Hydrogen utilization is a free of toxic gas formation and GHG emission, can easily be applied in fuel cells for electricity

and synthetic methane role in the future energy system, prospects and challenges in order to achieve decarbonized economy. Hydrogen and synthetic methane production, storage, delivery, safety issues and challenges are analyzed and presented in the chapters 3 and 4. Holistic cross-sectoral system solution

generation. However, there is a significant challenge for the current energy industry. Being the simplest and most abundant element in the Universe, up to 75 % [Periodic Table, 2017], molecular hydrogen (H2) does not occur naturally in the high concentration. Hydrogen is normally bound up with other

unifying renewable energy production, mobility, industry, heat supply and power generation is discussed in the chapter 5. The resent researches and implemented projects from the USA, EU in general and

elements in chemical compounds, for example, water and hydrocarbons are the most common. Therefore, hydrogen can be obtained from hydrogen-containing sources using the diverse technologies.

MATERIALS AND METHODS

Production Hydrogen is produced from wide range sources using different methods: -- From hydrocarbons (natural gas, oil);

coal,

-- From water by electrolysis, photolytic or thermal splitting;

2H2O + energy −> 2H2↑ + O2↑

-- From biomass and municipal waste by fermentation, gasification and pyrolysis.

The reverse of the reaction is employed for electricity generation in the fuel cell:

Such a variety of sources assures the energy security for hydrogen-based economy. The manufacture of hydrogen from fossil fuels using reformation and gasification processes is always accompanied by carbon dioxide emission. Currently, up to 95 % of the produced hydrogen is from coal, oil or natural gas (Hosseini and Wahid, 2015). This fact is explained by more mature mechanisms of hydrogen production from hydrocarbons and high cost of technologies based on renewable sources. However, to achieve the benefits of a truly sustainable hydrogen energy economy, we must clearly move to a situation where hydrogen is produced from non-fossil resources, principal among these being water (J.A. Turner, 2004). Electrolysis of Water

Figure 1: Hydrogen production sources.

a synergy of the renewable energy sector and hydrogen production makes hydrogen a buffer mechanism to cap fluctuations in electricity generation. The process of electrolysis is described by following formula:

Hydrogen can be obtained via electrolysis of water using any electrical source. The water splitting into hydrogen and oxygen using renewable sources of energy is a promising solution for hydrogen production. The process is not only environmentally friendly but also solves the problem of electricity storage from renewable sources transforming PtG. Thus,

2H2 + O2 −> 2H2O + energy The price for hydrogen yield from electrolysis depends on the electricity cost and materials used for electrodes‘ coating, for instance, platinum. Currently, the green production is not cost-competitive with the production from fossil hydrocarbons. Hydrogen from biomass The diverse range of biomass sources is applied for hydrogen production, for instance, wood, agricultural crops, municipal solid waste, waste from food processing. Biomass can easily be converted into a number of liquid fuels, including methanol, ethanol, biodiesel, and pyrolysis oil, which could be transported and used to generate hydrogen on site (Turner, 2004). Methods of hydrogen production from biomass: -- Biological -- Anaerobic digestion -- Fermentation -- Metabolic processing -- Thermo-chemical

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Process

sector and another for stationary applications.

following options:

Cost of Hydrogen (US Dollar per kg), 2015

Cost of Hydrogen (Euro per kg), 2015*

Natural gas reforming

1.03

0.93

restrictions of hydrogen storage are less critical

Natural gas reforming + CO2 capture

1.22

1.1

than those for vehicles; stationary hydrogen

Coal gasification

0.96

0.87

storage systems can occupy a large area,

-- Hydrogen carriers such as solid metal

Coal gasification + CO2 capture

1.03

0.93

operate at high temperatures and pressures

hydride, liquid organic hydrogen carriers

Electrolysis (wind power)

6.64

6.03

and have extra capacity to compensate for

or hydrogen carriers in the form of fuels

Biomass gasification

4.63

4.2

slow kinetics (Edwards et al., 2007).

such as ammonia;

Biomass pyrolysis

3.8

3.45

Currently, there are several probable methods

Nuclear thermal splitting of water

1.63

1.45

for the hydrogen storage (Züttel, 2003):

Gasoline (for reference)

0.93 0.84 * exchange rate US Dollar - Euro is 1.1 (December, 2015)

Table 1: The cost comparison of hydrogen based on various production processes.

-- Gasification -- High pressure aqueous -- Pyrolysis The cost comparison of hydrogen based on various production processes is provided in the table 1 ( Hosseini and Wahid, 2015). Thus, hydrogen production from carbon-free sources with the low price is the long term aim

Secondly, hydrogen is the lightest element and has a very low energy density per unit volume. But even when hydrogen is stored at high pressures, it still does not provide sufficient energy density. Significant high-pressure decentralized storage is required for transport applications due to space constraints (Staffell and Dodds, 2017). At normal conditions, 4 kg

For stationary applications, weight and volume

-- High-pressure gas cylinders (up to 800 bar); -- Liquid hydrogen in cryogenic tanks (-253°C);

-- Tube trailers for compressed gas; -- Tanker trucks for liquefied hydrogen;

-- Natural gas grid injection; -- Hydrogen high-pressure pipeline The current storage and transportation system for conventional fuels cannot be easily transformed for the hydrogen use. Obviously,

-- Absorbed on interstitial sites in a host metal

that infrastructure requires major technological

(at ambient pressure and temperature);

breakthrough in order to impact on the

-- Through oxidation of reactive metals, for example, lithium, sodium, magnesium, aluminum, zinc with water; -- Geological storage.

transition to the hydrogen economy.

SAFETY Safety concerns are the biggest barriers for the widest introduction of hydrogen technologies. Thus, designing facilities and infrastructure

of hydrogen – sufficient amount to drive a fuel cell car up to 500 km – occupies a volume of

Geological storage is one of the most

for its production, storage and delivery a

48 m³ (Edwards et al., 2007).

diverse range of factors have to be taking into

Storage and delivery

promising technologies for large-scale storage

Thirdly, it has to be compressed to liquid

at low cost (Sørensen, 2006). The first option is

consideration.

Hydrogen can be stored as a compressed

state in order to decrease the volume of

deposit in cavities created in salt domes. The

First of all, there is a risk of gas leaks. Hydrogen

gas, cryogenic storage as liquid hydrogen,

storage facilities. Today, liquid hydrogen,

next variation is aquifers in the water carrying

is lighter than air and has a rapid diffusivity, 3.8

metal or chemical hydrides. However, storage

which is the most common form of storage,

layers capped with impermeable layers

times faster than natural gas (Schüth, 2009).

availability and feasibility are crucial and

is hard and expensive to handle because

above into which hydrogen can be pumped

Despite hydrogen is the lightest element in the

the most technically challenging obstacles

hydrogen becomes a liquid only at the ultra-

replacing water. Underground storage is also

universe, it can become a fire hazard being

towards the wide use of hydrogen as an

frigid temperature of -253°C at atmospheric

applicable for compressed gas or liquid

confined in structure containing raising gas.

effective energy carrier.

pressure (Koeneman, 2016).

hydrogen tanks for smaller volume and depth

Hence, the proper design of facilities with

First of all, hydrogen is prone to leakage due

Finally, safety aspects have to be taken into

in order to safe ground space.

ventilation helps hydrogen to escape in case

to small molecules size. Besides, hydrogen

consideration due to hydrogen volatility and

The unique chemical properties that make

of an unexpected release is the precondition

tends to permeate metal. Therefore, storage

flammability.

hydrogen challenging to store, also make it

for infrastructure.

facilities and infrastructure have to be safe,

The hydrogen economy requires two types of

challenging to transport (Koeneman, 2016.).

Secondly, hydrogen is odorless, colorless

durable and fulfilled from reliable materials.

hydrogen storage systems, one for transport

Hydrogen delivery system is presented by

and tasteless. Therefore, human senses

for hydrogen economy establishing.

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SYNTHETIC METHANE IN THE ENERGY SYSTEM

cannot detect the leaks. Thus, industries have

with several physical parameters including

to install sensors in order to distinguish that

temperature and pressure [Rivkin et al., 2015].

problem. At the same time, natural gas also

This characteristic determines limitations in

has no odor, color or taste, but industry adds a

terms of hydrogen concentration in the gas

sulfur-containing odorant to make it detectable

grids. Thus, in Europe the maximum hydrogen

by people. Unfortunately, the same approach

content allowed by national standards for

has obstacles in hydrogen sector because

biomethane injection into the grids generally

odorants contaminate fuel cells.

varies from 0.1 to 10 % in volume depending

Thirdly, hydrogen has high flammability and

on the country (ENEA Consulting, 2016).

might combust in the presence of oxygen.

Finally, the widespread use of hydrogen could,

However, mixtures of hydrogen gas and air do

of course, have unknown environmental effects

not react unless ignited with a flame or spark,

due to increased anthropogenic emissions

Taking into account current immaturity of hydrogen technologies, methanation as a means of producing synthetic natural gas is the next step of wind or solar energy transformation to gas. Methanation is the conversion of carbon oxides to methane through hydrogenation – a chemical reaction between molecular hydrogen and another compound or element, usually in the presence of a catalyst.

resulting in a fire or explosion. Hydrogen can

of molecular hydrogen to the atmosphere

Production

be explosive at concentrations of 18.3 - 59%

(Tromp et al., 2003).

Obtained hydrogen from the electrolysis can be converted to synthetic or substitute natural gas (SNG) using carbon dioxide or carbon

but oxygen must be present in a concentration of at least 10% pure oxygen or 41% air (Schüth, 2009). It is important to emphasize that an

Challenges The current challenges are connected with the

explosion cannot occur in a tank or any

development of hydrogen production, storage,

storage facility that contains only hydrogen.

distribution and utilization technologies. Due

Moreover, there is very little probability that

to the low energy density and volatility, the

hydrogen will combust or explode in open air

design and development of infrastructure

due to its rapid diffusivity and tendency to rise

represents a unique task.

rapidly.

Moreover, economic feasibility is the main

Fourthly, hydrogen can damage storage,

barrier for the wide introduction of hydrogen

piping, and appurtenances materials through

technologies. Firstly, the enormous expenses

processes that are partially a function of the

are

relatively small size of the hydrogen molecule

processes

(Rivkin et al., 2015). Basically, hydrogen

pressure storage and distribution, liquefaction

„attacks“ certain material and this ability is

of hydrogen. Secondly, catalysts, materials

referred to hydrogen embrittlement. Hydrogen

for storage and transportation are significantly

embrittlement is a type of deterioration which

influence the final cost.

can be linked to corrosion processes. As

In addition, safety is not only a technological

a result, metals such as steel become

issue, but also the major psychological and

brittle and fracture due to the introduction

sociological issue facing the adoption of the

and subsequent diffusion of hydrogen into

hydrogen economy [Edwards et al., 2007].

the metal. The mechanisms of hydrogen

In order to integrate hydrogen into energy

embrittlement can be complex and vary

system, it has to be conceded safe by society.

connected such

with as

energy-intensive electrolysis,

high-

Figure 2: PtG, methanation.

monoxide in a methanation process. This methane synthesize can be either a biological or chemically catalyzed reaction: CO2+4H2 −> CH4 + 2H2O CO+3H2 −> CH4 + H2O Catalytic methanation reactors are typically operated at temperatures between 200 °C and 550 °C and at pressures ranging from 1 to 100 bar (Gotz et al., 2015). The methanation is highly exothermic reaction. 165.1 or 206.3 kJ is produced during the catalytic methanation of 1 mol of carbon dioxide or carbon monoxide, respectively (Gotz et al., 2015). Nickel is considered as the optimum catalysts option for the reaction in comparison with other possible metals such as ruthenium, rhodium, and cobalt due to its relatively high

13 —

— 14

activity, methane selectivity up to 100%, and

is more robust against impurities than

To sum up, there are not only economic

catalytic methanation. For instance, relatively

low raw material price (Müller et al., 2013). For

catalytic

that

advantages but also time saving benefits

cheap nickel based catalysts require a high

example, the cost of ruthenium is 1750 euro

catalytic methanation requires high purity

with regard to permission of authorities,

purity of the feed gas. There is a dilemma

per kg and Nickel is 9.75 euro per kg, August

of the feed gas and, as a result, there are

public accepters, design and implementation

between technology, materials and feedstock

2017 (Consensus economist, 2017).

additional expenses connected with refining.

processes.

The required carbon oxides can be obtained

preferences in order to achieve economic

Furthermore, final cost of catalytic methanation

from exhaust and process gases of industries

efficiency.

is influenced by catalysts price. On the other

CHALLENGES

or fossil power plants, biogas plants, or from

On the one hand, methanation solves the

Nevertheless, taking into account obstacles

hand, the efficiency of catalytic methanation is

the atmosphere and sea water but using

higher and the reactors size is much smaller

problem of hydrogen storage and delivery.

connected with the current hydrogen storage

certainly more energy-demandable methods.

for the same volume of supplied gas.

On the other hand, there are a range of

and delivery, synthetic methane production

challenges connected with technological

considered as a bridge technology towards

Storage and delivery

processes and economic feasibility.

hydrogen economy.

The biological methanation is the next option

SNG produced via methanation is nearly

First of all, methanation is the second step

for PtG process chain where microorganisms

identical to fossil natural gas. However, the

work as biocatalysts. The first step is the

remaining sulphur components still have to

hydrolysis of biomass to simple monomers

be removed prior to gas grid injection (Gotz

in a biogas plant. As a result, methane and

et al., 2015). Therefore, SNG can be fed into

carbon dioxide are produced. Then, carbon

natural gas grid without significant limitation

dioxide is converted to methane by feeding

and already existing delivery and storage

hydrogen into the reactor in the presence

gas infrastructure can be applied for the

of microorganisms. Biological methanation

transfer of renewable electricity in the form

proceeds under anaerobic conditions at

of SNG. Thus, investments in construction of

temperatures between 20 and 70 °C and

the new infrastructure for transport, storage

mostly at ambient pressure (Gotz et al., 2015).

and utilization of synthetic methane are not

On the one hand, biological methanation

required.

The methanation waste heat can be applied for further use in a steam power cycle.

methanation.

means

in the PtG process; consequently, additional chemical conversion causes energy losses (Gotz et al., 2015). The efficiency has to be

Future energy system Apparently, the dominating fossil fuel-based energy system can be gradually replaced

improved at the level of electrolysis and then

by the renewable sources-based one. Wide

heat from the methanation reactor has to be

introduction of hydrogen as an energy carrier

utilized.

is considered as a promising vision for the

Secondly,

range

challenges

are

connected with tolerance of impurities in Path

future synergetic energy system. Current technologies

Efficiency (%)

connected

Boundary conditions

Electricity to Gas Electricity −> Hydrogen

54 -72

Including compression to 200 bar

Electricity −> Methane (SNG)

49 - 64

(underground storage working pressure)

Electricity −> Hydrogen

57 - 73

Including compression to 80 bar

Electricity −> Methane (SNG)

50 - 64

(feed in gas grid for transportation)

Electricity −> Hydrogen

64 - 77

Electricity −> Methane (SNG)

51- 65

Without compression

Electricity to Gas to Electricity Gasoline (for reference)

0.93

0.84

Electricity −> Hydrogen −> Electricity

34 - 44

Conversion to electricity:

Electricity −> Methane −> Electricity

30 - 38

60%, compression to 80 bar

Electricity to gas to combined heat and power

Figure 2: Energy losses caused by chemical conversion.

with

Electricity −> Hydrogen −> CHP

48 - 62

40 % electricity and 45% heat,

Electricity −> Methane −> CHP

43 - 54

compression to 80 bar

Table 2: Efficiencies for different Power-to-Gas process chains.

synthetic

15 â&#x20AC;&#x201D;

â&#x20AC;&#x201D; 16

methane production are the transition stage

and reasonable. Secondly, the synergetic

synergy between the renewable energy

methanation, synthetic methane is nearly

towards carbon-free economy.

approach does not allow any waste providing

production and transformation it into chemical

identical to natural one and can be integrated

The future energy system has to be based on

second value for it and integrating into cycle.

energy, mobility, industry, heat and power

in the gas infrastructure without any further

the principle of valorization. It is the productive

Thirdly, all the by-products of the processes

supply.

restrictions.

and efficient use of resources avoiding losses.

have to be applied in the system.

POWER-TO-GAS TECHNOLOGY

However, transition processes within the

First of all, energy consumption has to be smart

PtG technology implements an idea of the

Power-to-gas is a cross-sectoral system solution

unifying

renewable

energy

production, mobility, industry, heat supply and power generation. PtG can be conceded as a storage method which converts electricity from renewable energy sources to hydrogen or methane solving the problem of fluctuations electricity generation from renewable sources. Thus, the over produced electricity is applied for water electrolysis to obtain hydrogen. In the result of electrolysis, water is split into hydrogen and oxygen. The generated oxygen can be released to the atmosphere or applied

Figure 3: Research and pilot PtG projects in Germany.

Power-to-Gas chain are associated with energy losses. The conversion efficiencies can be improved by either technical progress in the single conversion steps, namely water electrolysis and methanation or by synergies with industrial processes which are coupled with the PtG plants (Tichler et al., 2014). The German Energy Agency (DENA) initiated the Strategy Platform to support the use and development of the PtG system solution. Over 20 research and pilot projects in Germany demonstrate technical feasibility of PtG system (German Energy Agency, 2015).

for industrial needs depending on the existing

SYNERGY

demand and synergy level between different

Fluctuating

sectors. At the same time, hydrogen can be

generation in the renewable energy sector

fed either in an own hydrogen distribution grid

poses a huge challenge how to store the

or injected in the natural gas grid, transported

electricity. Transformation of electricity into

by truck and train or stored. This way, electricity

chemistry, PtG technology, might be a solution.

can be stored, distributed and made available

Water is a basic to a PtG installation. Thus,

for various energy usage scenarios (German

hydrogen and oxygen are generated from

Energy Agency, 2015).

water via electrolysis obtaining electricity from

The second possible step in the chain is

renewable sources. Received hydrogen can

methanation. It is a chemically or biologically

be used in the full cell, transport sector, fed

catalyzed reaction of hydrogen and carbon

into the gas greed or applied to the chemical

dioxide resulting to synthetic methane or other

industry as a widely used feedstock. Heat as

words substitute natural gas obtaining. The

a by-product of electrolysis can be fed into the

necessary carbon dioxide can be derived

district or local heating network. In turn, oxygen

from biogenic carbon, for example, biogas,

is the important element in the next value chain,

sewage gas, biomass gasification, breweries,

gasification of biomass. At the base of this

and bioethanol industry or from conventional

process, organic woodstock is transformed

power plants and industrial processes. Via

into biocoal thought torrefaction. Torrefaction is

character

the

electricity

17 —

— 18

CHALLENGES

role in a regenerative, environmentally sound

The idealistic approach unifying renewable

and sustainable energy system. The growing

energy production, mobility, industry, heat supply and power generation have numerous

contributes to technology enhancement.

barriers in the real implementation.

DISCUSSION

Firstly, the possibility to integrate the full value

Broad implementation of hydrogen and

chain between various stakeholders depends on the physical location. For example, oxygen after electrolysis can be used in biogas plant. Taking into consideration that oxygen is usually transported in the liquid condition the distance for supply this by-product to the next

Figure 4: The synergetic model of the energy system.

fraction of renewable energy generation

synthetic methane into energy system is the way towards decarbonized society. Thus, PtG is the promising system solution for the future energy sector. However, the process chain contains the numerous quantities of stages. Thus, the further development has to avoid

value stage has to be minimized or it has to be

unnecessary conversion steps whenever

utilized at the site of electrolysis otherwise the

possible in order to reduce losses and

solution is not technically and economically

increase efficiency. Therefore, economic and

relevant.

technological feasibility will assure benefits of

Secondly, current transformation chain from

the green system in comparison with fossil fuel-

electric energy to chemical and back to

based one. The wide introduction of hydrogen

electric one contains too many steps which

and synthetic methane contributes to the

reduce the efficiency and, consequently, not-

energy security due to multiple sources and

competitive on the market. Thus, the efficiency

production methods. In addition, synergetic

can be increased through technological

model offers numerous options for business

breakthroughs

losses

development due to its technical flexibility and

minimization.Thirdly, the profitable business

the wide range of applications of hydrogen,

a thermal process used to produce high-grade

methane, carbon dioxide, carbon monoxide

solid biofuels from various streams of woody

and it is the source of various gas applications.

biomass or agro residues heating the biomass

Firstly, syngas is a green feedstock for many

to temperatures 250-300°C in a low-oxygen

processes in chemical industry. For example,

condition (Blackwood technology, 2017). The

syngas is applied as an intermediate in

end product is a stable, homogeneous, high

the industrial synthesis of ammonia and

quality solid biofuel with far greater energy

methanol.

models have to be developed in order to

density and calorific value than the original

converted to hydrogen. Thirdly, upgraded to

methane, and sub-products of technology.

establish economy of scale. Optimized

feedstock. The energy value is doubled with

a green gas, synthetic methane, it provides

Moreover, there are also opportunities to create

business models are based on an integrated

innovative new businesses in green industry.

this treatment. In addition, oxygen can be

energy for households, mobility, and industry.

value chain approach for a most beneficial

The transformation process involves not only

used in other industrial production processes,

The gasification process is accompanied with

combination of input and output parameters

technical development but also adjustment of

like the chemical or the metallurgical industry.

the carbon dioxide release. Combining it with

(Breyer et al., 2015).However, in the long-

legal frameworks and formulation of strategies

However, the utilization of oxygen depends

hydrogen, we get synthetic methane again.

term perspective PtG indeed can play a key

at local and international level. —

strongly on the local conditions, particularly

Moreover, carbon dioxide can be captured

the distance to the potential consumers and

from the conventional coal power plants or

the consumer demand (Tichler et al., 2014).

other industries for example cement or steel

The next step is the production of syngas

production. This integration allows reducing

feeding the biocoal into gasification process.

carbon dioxide emissions in the transition

Syngas is the rich mixture of hydrogen,

phase towards hydrogen economy.

Secondly,

syngas

can

towards

transition

19 —

— 20

— Noriko Kakue

Noriko Kakue graduated from San Francisco State University with B.A. Environmental Studies concentrating on the Urban Environment. After working in both governmental and nongovernmental planning and developing sectors in the U.S. and Bangladesh, she entered M.Sc. REAP program with an interest in sustainable infrastructure systems.

KEYWORDS

INTRODUCTION

CHP, Fuel Cell, Heating, Electricity, CO2, Life

Combined Heat and Power (CHP) fuel cell is

Cycle Assessment, Japan, Natural Gas

a power generation system for commercial,

ABSTRACT

industrial and residential buildings, and its

Concerns over climate change shifted the world towards the low-carbon society in the last few decades and energy is one of the most influenced sectors in this challenge. The technology of CHP fuel cell utilizes hydrogen as its primary source that produces no CO2 emission, and also has a high efficiency

hydrogen extraction from natural gas, CHP fuel cells generate no significant emission during electricity or heat generations. There are a few studies conducted to evaluate the overall environmental impact of this emerging technology, despite the fact the mass production of micro-CHP fuel cell for residential home and commercial CHP fuel cells is taking place currently. This paper discusses on the overall sustainability of the CHP fuel cells from its environmental impacts measured from its life cycle assessment and hazardous gas emissions.

METHODOLOGY The argument on this paper is constructed through literature reviews. The data used for this paper is collected from various sources including official reports from government and research institutions. The section, CHP Fuel Cells in Japan, mostly compares the before and after of Fukushima Daiichi nuclear disaster in that these used data are especially time sensitive. All currency such as U.S. Dollar and Japanese Yen are converted in Euro with the average exchange rate of August 2017.

usage is expanding around the world. There are several factors brought CHP fuel cells under the spotlight at the current energy market – for example, the shift in primary energy source due to climate change, price reduction in micro-CHP fuel cells due to technology improvement, and the anti-nuclear movement

by reusing waste heat as a thermal energy

which drove the public more focused on safer

source that it has been under the spotlight as

and reliable power generation.

a stable low-carbon energy solution. While most studies on CHP fuel cells concentrate

CHP fuel cells reuse the waste heat from

on the environment impact at its usage stage,

electricity generation to heating of the building

lifetime impact of the system though life cycle

or water that the total efficiency of the system

assessment has been neglected. Through

is higher than that from other power generation

literature reviews on various international

systems such as combustion, hydroelectric,

researches, this paper concludes that the

and from renewable sources. Although

sustainability of CHP fuel cell is questionable.

CO2 are produced during the process of

Figure.1: (a) Electrolysis of water where electric current separates water into hydrogen and oxygen. (b) Reverse electrolysis where hydrogen and oxygen recombined and an electric current is produced.

21 —

— 22

BASIC TECHNOLOGY OF FUEL CELLS AND CHP FUEL CELLS

Even the most efficient combustion power

There are four types of CHP fuel cells available

plant in the recent years can reach about 60%

in the current market: Low-Temperature (LT)

The technology of CHP fuel cells are applied

of electric efficiency and the rest is discharged

and High-Temperature (HT) Proton Exchange

to commercial, industrial and residential

as waste heat (Ikegami, 2016). Electric

Membrane/Polymer

buildings to provide both electricity and

efficiency can be calculated as the equation

Phosphoric Acid (PAFC), Molten Carbonate

heat. There are various sizes of CHP fuel

below:

(MCFC) and Solid Oxide (SOFC). The

cells systems available depending on the

Electric Efficiency =

difference is based on the material used for its

electricity demand of the building or the

(Eff FPS * H2 Utilization * EffStack * EffPC)* * HHV LHV

complex – typically 200 to 2800kW of capacity is considered for commercial and industrial use and 3 to 10kW for residential and small commercial use (U.S. Environmental Protection

Agency,

2015).

The

basic

principle of the fuel cell system was invented by Sir William Grove in late 1839, where he demonstrated a hydrogen fuel cell (Figure 1). In his demonstration, water (liquid) is being electrolyzed into hydrogen (gas) and oxygen (gas) by passage of an electric current as

Where: Figure 2: Basic structure of fuel cell and its chemical reactions.

when drawing a useful current. In order to produce useful voltage, multiple cells must be connected in series. The connection of such fuel cells is known as a stack (Laeminie and Dicks, 2003). As illustrated in the figure, this chemical reaction discharges only H2O

Eff FPS

= Fuel Processing Subsystem

Efficiency, LLV (LHV of H2 Generated/LHV of

Membrane

(PEMFC),

catalyst electrolyte, and each type has unique strengths and characteristics (Figure 3). All CHP fuel cell systems utilizes hydrogen from hydrocarbon fuels as its primary fuel as shown in the figure above, therefore can be also operated by variety of alternative gaseous fuels including:

Fuel Consumed)

-- Natural gas: methane from the pipeline.

H2 Utilization = % of H2 actually consumed in

-- Liquefied petroleum gas (LPG): propane

the stack EffStack

= (Operating Voltage/Energy

Potential ~1.23 volts)

and butane mixtures. -- Sour gas: unprocessed natural gas as it comes directly from the gas well.

(water) and heat in the end of the process.

EffPC

By using the same structure with different

generated) (auxiliary loads are assumed dc

stack and electrolytes, fuel cell can produce

loads here)

different levels of power and thermal energy

HHV = Higher Heating Value

that currently the technology is utilized to power

LHV = Lower Heating Value

military and space equipment, transportation,

(U.S. Environmental Protection Agency, 2015)

special vehicles, and also as a backup power,

The

portable power and distributed generation

generation is utilized in CHP system for

2H2 + O2 −> 2H2O + e

system (U.S. Department of Energy, 2011).

-- Manufactured gases: typically low- and

heating of the building or the facility, and as a

medium-Btu gas produced as products

Fuel cells function based on this principle. In

CHP fuel cell is based on the same technology

result, the total CHP efficiency can reach 70-

of gasification or pyrolysis processes

order to increase the efficiency of the system,

aside from the fact that the thermal energy

90%. CHP efficiency can be calculated as the

(U.S. Environmental Protection Agency,

thinly layered electrodes and electrolyte are

produced during the reverse electrolysis is

equation below:

2015).

used to maximize the contact area between the

utilized as a heating source. When fossil fuel

CHP Efficiency =

gas, the electrode and the electrolyte, and to

was used for combustion to rotate turbine

minimize the distance between the electrodes

to generate electricity, the chemical energy

(Laeminie and Dicks, 2003) (Figure 2).

cannot be converted 100% electric energy

Energy Used (Natural Gas)

The voltage of a fuel cell is small, about 0.7V

due to the second law of thermodynamics.

(U.S. Environmental Protection Agency, 2015)

shown in the chemical equation below. 2H2O + e− −> 2H2 + O2 When the power supply has been replaced with an ammeter, and a small current flows while recombining hydrogen and oxygen. This reverse electrolysis is where the electricity is produced. −

= AC power delivered/(dc power

heat

-- Biogas: any of combustible gases produced from biological degradation or organic wastes.

produced

during

-- Industrial waste gases: flare gases

electricity

Energy Generated (Electricity + Heat)

and process off-gases from refineries, chemical plants and steel mill.

However, the operations with alternative gaseous fuels require appropriate system design and might cause inefficiency and affect durability of the stack. Therefore, most systems ended up utilizing natural gas, which

23 —

— 24

Type

LT-PEMFC

HT-PEMFC

PAFC

Operating Temperature 60-80°C

110-180°C

160-220°C

Typical Stack Size

< 1kW–

400 kW

100kW

100 kW module

Electric Efficiency

MCFC 600-700°C

SOFC 800-1000°C

300 kW-3MW 1 kW–2 MW

Electrical Efficiency (%)

300 kW

Fuel Input (MMBtu/hr)

module

CHP Efficiency (%)

40-60%

50-60%

36-45%

55-65%

Power to Heat Ratio Net Heat Rate (Btu/kWh)

87-90%

85-90%

85%

90%

Common Electrolyte

Perfluoro

Phosphoric

Solution

Yttria

sulfonic acid

acid soaked

of lithium,

stabilized

in a matrix

sodium, and/ zirconia or potassium soaked in a matrix

Mobile Ion

H+

Fuel Source

Natural gas

CO32-

Natural gas,

O2-

Natural gas

biogas, H2,

H2,

H2, CH4

H2, CH4, CO

methanol/

(external

(internal

ethanol

reformer)

(external

reformer)

Residential,

Commercial

Utilities, large

Commercial

small

buildings-

universities,

buildings-

commercial

baseload

industrial-

baseload

baseload Quick start-

Quick start-

Higher

Variety of

up,

tolerance

catalysts can catalysts can

Sensitive to

to fuel

be used,

fuel impurities fuel impurities impurities,

Variety of

Long start-up Long start-up

Figure 3: Characteristics of different CHP fuel cells.

System 3

System 4

System 5

PEMFC

SOFC

MCFC

PAFC

MCFC

0.7

1.5

300

400

1,400

35.5

54.4

34.3

42.5

0.0068

0.0094

2.2

11.2

0.7

2.78

1.34

0.73

1.08

9,666

6,272

7,260

9,948

8,028

Advantages

Disadvantages

Portable and can be placed both

High initial cost

indoor/outdoor

Low durability of stack (requires stack

replacement in 3-5 years)

Wide range of size of electric generation

and heat generation capacities

No availability during power outage

Low service and maintenance effort

Noise (low-frequency sound)

Less pollution and greenhouse gases

Inefficient operation due to the lack of

user education

High CHP efficiency

High part load efficiency

Quiet operation due to no moving parts

High availability

Longer operating time than batteries

Fuel flexibility

Figure 5: Advantages and disadvantages of CHP fuel cells. CHP Technology

Typical Capacity

Installed Cost (EUR/kW)

CHP Efficiency (%)

Gas Turbine

500kW-300MW

1,011-2,782 (540MW)

66-71

Steam Turbine

50kW < 1000MW

565-927

Microturbine

30kW-250kW

2,108-3,625

63-70

Internal-Combustion

1kW-10MW

1,265-2,445

75-80

5kW-2MW

4,215-5,480

55-80%

be used,

Fuel flexibility, Fuel flexibility, time

System 2

during operation

others

Characteristics

System 1

Figure 4: Typical performance parameters of CHP fuel cells available in the U.S. in 2014 (created by author based on data from U.S. Environmental Protection Agency, 2015).

carbonates,

Typical Application

Fuel Cell Type Nominal Electricity Capacity (kW)

CHP Efficiency

Fuel Compatibility

Performance Characteristics

time

Engine Fuel Cell

Figure 6: CHP capital, engineering cost and efficiency depending on the technology.

25 —

— 26

is the most stable and less contaminated

below shows the comparison between 5

well that every CHP technology has more than

Availability during power outage

fuel among above. The electricity and heat

different CHP fuel cell systems available in

60% efficiency, which is the highest electric

Since the operation of CHP fuel cells is based

demands depend on the use of building.

2014, and the power to heat ratio of CHP fuel

efficiency conventional power plant can

on reverse electrolysis, the system requires

Commonly hotels and hospitals have higher

cell differs greatly to each other depending on

reach (Figure 6). When compared with other

small amount of electricity to start its operation.

heat demand than electricity, and office

the user’s preference while the CHP efficiency

CHP technologies, the efficiency of fuel cells

Commonly available micro-CHP fuel cells are

is similar (Figure 4).

is not considerable. However, these efficiency

programed to shutoff the operation once a

rates are usually at their peak efficiency, in

day in order to keep high efficiency in power

other words, measured at 100% load. CHP

and heat generation. This makes it difficult to

fuel cell systems maintain higher efficient

operate during the long-term power outage.

performance at part loads, below 100% load,

The latest model from Panasonic and Tokyo

than combustion engines in terms of electric

Gas has improved features that enable to

efficiency (Figure 7).

operate CHP fuel cell during the sudden

buildings have higher electricity demand than heat. The demand priority changes

also depending on geographical locations, CHARACTERISTICS seasons and the time of the day. It is difficult

The common characteristics for all types of

to equalize the electricity and heat generation

CHP fuel cells are verified as follows (Figure

ratio and its demand ratio, therefore, there are

5). Among those listed above, this paper

two systems in order to adjust the need of the

focuses on the recent studies conducted on

users: thermal output control and electrical

three aspects (efficiency, cost and availability

output control. Thermal output control operates the CHP unit based on the heat demand and substitute the insufficient electricity by grid or

during power outage) and discusses in depth. Efficiency

Cost

power outage. New stack technology allows 192 hours of continuous power generation

The high cost of CHP fuel cell has been a

performance, which is about twice as long as

barrier for its expansion in both commercial

the previous model. In addition, the system

and residential sectors. In 2011, residential

does not require specialized autonomous

the like, and electrical output control operates

As described in the earlier chapter, CHP fuel

the CHP unit based on the electricity demand

cell utilize both electric and thermal energy from

micro-CHP with the capacity of 0.7 to 1kW was

and substitute insufficient heat by hot water

one system that has a high CHP efficiency. This

startup system, and can be started using

priced between 22,000 to 27,000 Euro (Staffell

boiler or the like (Ikegami, 2016). The figure

commonly available batteries and generators

method applies to other CHP technologies as

and Green, 2011). 6 years later in 2017, the

when the power outage occurs while the

latest model to be released by Panasonic

system is in off mode (ITmedia, 2017). This

and Tokyo Gas reached the price of 12,000

technology could increase the reliability

Euro, the lowest price ever made in Japan,

of CHP fuel cell as an emergency energy

which is 44 to 55% price reduction since 2011.

generation supply, and would be suitable to

The reduction of the price was done by

regions where often experience power outage

simplification of the system components and

due to natural disasters and system failures of

achieving 20% of components reduction

energy suppliers.

compared to the ones currently available on the

CHP FUEL CELLS IN JAPAN

market by the same manufacturers (ITmedia,

The United States, Canada, the United

2017). Also, Tokyo Gas aims for further cost

Figure 7: Comparison of Part Load Efficiency between PAFC fuel cell and natural gas combustion plant.

Kingdom,

Germany,

Spain,

Denmark,

reduction and is currently researching the

and Japan have been the front runners

system design to reach the price under

in the commercial and residential CHP

7,600 Euro per system (Tokyo Gas, 2014).

fuel cell installations and development.

Reduction of price, especially in micro-CHP

Recently influential legislative and technical

fuel cell, could accelerate the popularization of

development are also taking place in South

the system in single family homes and multi-

Africa, Australia, and South Korea (OECD,

family apartment complexes.

2011; Ellamla, et. al., 2015).

27 —

— 28

Japan is considered at the forefront in CHP

117 bcm, where 69.8% was consumed by

homes, Japan aims to install 5.3 million

dropped from 19.4% to 6.2%, ranked 33 out

installation and commercialization among

power generation sector (IEA, 2016). Natural

CHP fuel cells to single family homes and

of 34 OECD countries (Shimizu and Nakano,

above. CHP research development and

gas accounts for 22.7% of the total energy

apartments by 2030 (Tokyo Gas, 2014). Ene-

2017). This is considerably low compared to

demonstration in Japan started in the 1990’s

imports, mostly imported from countries such

Farms is the most common type of micro-

other non-resource-producing nations such

by the government with the development

as Australia, Malaysia, Qatar, United Arab

CHP fuel cell and also its market is rapidly

as Spain (26.7%), Italy (20.1%) and South

of 1 kW PEMFC CHP system for residential

Emirates, and Oman (IEA, 2016; Shimizu

growing in Japan since 2011. Supported by

Korea (17.5%) (METI, 2015). This sudden

homes, and the commercialization began

and Nakano, 2017). Along with the dramatic

the Japanese government’s subsidies, the

drop in of self-sufficiency rate is caused by

in 2009 (Ellamla, et al.., 2015). Before

increase in natural gas availability, the

total number of installation is expected to reach

the exponential increase in natural gas import

installation of CHP fuel cells in commercial,

0.6 million by 2030 (Advanced Cogeneration

as explained earlier. Not all the natural gas is

Japan’s sources for electric energy consisted

industry and residential uses increased.

and Energy Utilization Center, 2017; Tokyo

consumed by CHP fuel cell systems, however,

of 27% coal, 27% nuclear, and 26% natural

METI (2012) reports that 65% of installed CHP

Gas, 2014) (Figure 8). Japanese government

as the number of installation increase, the

gas. Since the incident, Japan has shifted its

systems in Japan are natural gas-base, and

revised the Long-Term Energy Supply and

need for natural gas could become greater

energy dependency on natural gas and its

produce 48% of total electric generation in

ratio rose 24% compared to 2010 (Shimizu

CHP category. 27 TWh of electric power was

and Nakano, 2017). Japan has very limited

produced from CHP in 2016, and Japan aims

natural gas resources that only 2% of the

to increase CHP capacity to 150 TWh in 2030

natural gas demand is met by the domestic

that the increase in installation of CHP fuel

supply in 2015. Compared to 2005, there was

cells in residential, industrial and commercial

44.6% increase in the import of natural gas in

sectors is inevitable (METI, 2011; METI, 2017).

2015, and the volume of import has reached

In terms of micro-CHP fuel cells for residential

Fukushima Daiichi nuclear disaster in 2011,

Figure 8: Annual and total installations of Ene-Farm.

Demand Outlook in 2015. The outlook aims to address mainly four challenges that Japan faces in order to maintain the stable supply

than the current situation.

SUSTAINABILITY

and demand balance: safety, energy security,

CHP fuel cells are considered to have lower

economic efficiency and environment (METI,

direct CO2 emissions and fuel consumption

2015). Among those four challenges, what is

than traditional electricity generation systems.

most intricate for Japan is the energy security.

However, as we see in nuclear technology, the

Improving energy self-sufficiency rate has been

whole life cycle including the manufacturing

Japan’s biggest challenge for over decades.

and disposal of CHP fuel call system must

Due to the country-wide shutdown of nuclear

be considered in order to verify its long-term

power plants after Fukushima Daiichi nuclear

sustainability (Figure 9). As displayed in the

disaster, Japan’s self-sufficiency rate has

previous chapters, CO2 emission at the usage

Figure 9: Life cycle of CHP fuel cells (created by author based on data from Staffell, 2012)

29 —

stage is already proven to be significantly low. Therefore, this chapter focuses on hazardous emissions and material life cycle assessment at the stages of manufacture and disposal. In order to verify the environmental impact at manufacture stage, it is important to verify what

— 30

pipework, electronic control systems, etc.)

Fuel Cell Type

-- An auxiliary boiler to supply peak heat

Nominal Electricity Capacity (kW)

-- A fuel processing system (converts natural gas (or other hydrocarbons) to hydrogen + CO2); -- A grid-tie inverter (to convert low-voltage DC to AC with export ability);

System 5

PEMFC

SOFC

MCFC

PAFC

MCFC

0.7

1.5

300

400

1,400

Negligible

0.005

SOx (kg/MWh)

Negligible

0.00005

Negligible

0.00005

CO (kg/MWh)

Negligible

0.01

Negligible

VOCs (kg/MWh)

Negligible

0.01

Negligible

CO2 (kg/MWh)

513

333

445

476

445

CO2 with heat recovery (kg/MWh)

188

252

236-308

225

236

of the building’s heat demand); -- Control, interaction and feedback: -- Touch-screen LCD interface;

Figure 11: Estimated fuel cell emission characteristics without additional control .

-- Remote control system;

As stated in the previous chapter, CHP fuel

-- Smart-meter for measuring consumption and production; -- Internet-based remote monitoring and control (Staffell and Green, 2013).

-- Heat exchangers (to transfer waste heat

-- The figure below (Figure 10) illustrates

from the exhaust and coolant loops to an

the example of the major inventories of

external system);

producing a SOFC CHP furl cell.

-- Balance of plant (pumps, valves, sensors,

System 4

Negligible

capacity fuel cell can supply the majority

heat, electricity and water);

System 3

NOx (kg/MWh)

this stage. A complete package of a CHP fuel

-- A fuel cell stack (converts hydrogen to

System 2

cell system); -- A high-efficiency heat store (so that a low-

-- The main fuel cell system:

System 1

demands (usually integrated into the fuel

components and processes are included at cell consists of:

Performance Characteristics

-- Additional thermal management:

Emission (usage stage)

cells emit very few pollutants and greenhouse gases that considered as one of the clean energy

solutions.

U.S.

Environmental

Protection Agency conducted a research on the hazardous emission from commonly available CHP fuel cells during its lifetime operation (usage stage) and the result shows that the environmental impact from CHP fuel cell emissions is lower than fossil fuel based power plants such as with coal, which emits 720 to 910 kg/MW (Schlömer, et al.., 2014)

In addition to the pollutants listed above, the primary energy of natural gas CH4, which is 25 times more powerful greenhouse gases than CO2, can also be emitted as a consequences of incomplete combustion or leaks and losses during transportation (Ellamla, et al.., 2015). There are already some CHP fuel cell models utilize alternative gaseous fuels as listed in the previous chapter, and the technology

(Figure 11). Although CHP fuel cells produce

improvement in this field could reduce

no significant amount of hazardous emissions

substantial amount of emissions.

during the operation, the process of reforming

Emission (manufacture stage)

natural gas into usable hydrogen produce about 318 to 408 kg/MWh of CO2 (U.S. Environmental Protection Agency, 2015). A study in 2006 shows that the total life cycle emissions from a 200kW CHP fuel cell used for 85,000 hours are:

Figure 10: Example of an inventory of producing a SOFC CHP fuel cell system. Dashed lines indicate that additional inputs can be considered for every stage.

-- CO2: 9.537 tonnes (Rooijen, 2006).

NOx: 123 kg

CO: 177 kg

In CHP fuel cells, the production of catalyst metals such as nickel and platinum are exceedingly energy intensive. Life cycle emission rate can be calculated when these emissions from manufacturing is included to the lifetime energy output and averaged over. Compared to other electricity supply technologies, the life cycle CO2 emission of CHP fuel cell is even lower than most low

31 —

— 32

Type

Life Cycle CO2 emission (kg/MWh)

Life Cycle CO2 emission -median (kg/MWh)

Residential PEMFC/SOFC

10-20

Wind Onshore

7-56

Wind Offshore

8-35

Nuclear Fusion

Stack Type

PAFC

Stack materials

Assumed lifetime

Units required to operate for 10 years

Major energy consuming stages

Platinum

40-60,000 h

0.67-1

Forming or

Graphite

machining

Silicon Carbide

graphite

3.7-110

Phosphoric Acid

Ocean (tidal and wave)

5.6-28

Hydropower

1-2200

Concentrated Solar Power

8.8-63

Geothermal

6-79

Solar Photovoltaic (rooftop)

26-60

Solar Photovoltaic (utility scale)

18-180

Biomass (from dedicated crops)

130-420

230

Gas (combined cycle)

410-650

490

Strontium

Biomass (cofiring with coal)

620-890

740

Gallium

Coal (pulverized coal)

720-910

820

Yttrium

PTFE Carbon PEMFC

Platinum

20-40,000 h

1-2

Forming or

Ruthenium

machining

Graphite

graphite

PFSA PTFE Carbon SOFC

Nickel Oxide

Negligible

0.005

10-15

0.67-1

0.005

Lanthanum

Zirconium Stainless Steel

Figure 12: Comparison of life cycle CO2 emission in electricity generation technologies.

carbon (renewable) technologies (Figure 12).

Staffell (2012) also states that 55% of

Ellamla (2015) states that manufacturing of a

overall CO2 emission is produced from the

1 kW residential CHP fuel cell emits around

manufacturing is from the stack construction

Fuel processer, inverter & other balance of plant

years

Figure 13: Assumed lifetimes of typical fuel cell stacking technology and other CHP system components. Bolded text indicates that the material is considered as a precious metal.

of information on collection and recycling of

the recycling rate for electric devices is very

Considering most CHP fuel cell types require

CHP fuel cells at the end of their lifetime.

low. Most electronic devices consist precious

system emits 25 to 100 tonnes. On the other

more than one stack in 10 year lifetime of the

hand, a study by Staffell (2012) shows that

Materials

total system, the environmental impact of the

0.5 to 1.0 tonnes of CO2 into the atmosphere,

especially

while manufacturing of a 100 kW commercial

410 to 530 kg of CO2 would be emitted only by construction of typical 1 kW SOFC stack, and combined with inventories for the production

from

the

sintering

process.

stack construction is significant for the CHP fuel cell’s sustainability.

of fuel processor and other balance of plant EMISSION (DISPOSAL STAGE)

Recycling and disposal of CHP fuel cell

metals such as platinum and silver, and common metals such as steel, aluminum, nickel, and copper that could be recycled

systems is another essential stage to verify its

and reused. Statistically, 50% of consumer

long-term sustainability. Although legislations

goods materials are recycled, and the

such as the WEEE Directive in EU raised

remaining 40% are sent to landfill and 10%

components, the complete micro-CHP fuel

There is no study conducted to verify the

awareness and availability of recycling

to incinerator in Europe (Staffell and Ingram,

cell system would emit 1.8 to 2.9 tonnes.

emission from disposal stage due to the lack

options for general public and industries,

2010). There is no specific research being

33 —

conducted to quantify the total amount of CHP fuel cell systems and fuel cell stacks being collected and recycled, however, considering the circumstances stated above, the collection and recycling rates of CHP fuel cell components are assumed to be low as well. The figure below shows the materials composing each type of fuel cell stack (Figure 13). In each CHP fuel cell, there are the average of 1.32g of platinum, 1.2kg of nickel, 6kg of copper and 33kg of steel. If these fuel cell stacks are collected, dismantled and separated properly, the recovering yield for precious metals could reach up to 98%, and 90% for common metals (Staffell and Ingram, 2010). Nevertheless, the collection and recycling of the CHP fuel cell and its parts are not mandated by the manufacturers, and the value of recovered materials do not always meet the cost of the collection and recycling process. Considering the production and installation of CHP fuel cells are increasing exponentially as we see in Japan case, soon the problem of waste from CHP fuel cell could be a major environmental issue when microCHP fuel cells and commercial CHP fuel cells are installed in every building around the world as smart phones and personal computers to our society nowadays.

RECENT RESEARCH In order to improve the sustainability of CHP fuel cell, prolonging the stack lifetime close to the lifetime of the total CHP fuel cell system, reducing the cases if inefficiency due to the lack of user education, and improving the collection and recycling rate would be necessary. The investment in research and development to

— 34

engineer new CHP fuel cell system would be one of the solutions. Recently, there are some researches on alkaline based micro-CHP fuel cell to be commercialized. Alkaline based fuel cells (AFC) are commonly used for power generation in larger facilities such as military base and spacecraft due to its high electrical efficiency (60 to 70%) and wide range in operating temperature (below zero to 230°C ) (U.S. Department of Energy, 2011; Wilberforce etc., 2016). Due to this operating temperature, one study shows also the possibility of using the waste thermal energy to cooling (Zhao, 2015). The advantage of using AFC for CHP system is its lower CO2 emissions in overall life cycle than other CHP fuel cells even though the lifetime of stack is much shorter than other fuel cells that requires 5 to 8 replacements for a 10 years duration of the total CHP system (Staffell and Ingram, 2010). In addition, the low cost on components compared to other CHP fuel cell system is another advantage.

CONCLUSION As many researchers and government officials concluded, the application of CHP fuel cell technology is expanding in various sectors as the technology improves and price becomes affordable. With the primary energy shift from high CO2 emitting sources such as oil and coal, and controversial nuclear, the rise of natural gas usage thus CHP fuel cell technology is inevitable. The World Economic Forum (2015) also recognizes the possibility in further development and expansion of hydrogen technology such as CHP fuel cells, however, concluded that the technology “will not

contribute seriously to decarbonization unless hydrogen taken from carbon-free sources.” As discussed above, the overall sustainability of CHP fuel cell is still unknown. Nevertheless, taking into account that the current system requires finite natural resource, natural gas, as primary energy source, it is questionable to consider current CHP fuel cell system as a sustainable solution. The waste from CHP fuel cell could also accelerate the generation

of e-waste, which is a complicated global issue in the world is facing at the same time with climate change. CHP fuel cell could be a short-term solution for climate change to bridge over the energy transition from fossil fuel base to renewable sources, however, there must be new innovation and technology improvement added to the current system in order to call CHP fuel cell technology sustainable in a long term. —

35 —

— 36

might mark the next step to a carbon neutral

fracturing has been widely practiced in the

future.

United States within the past 15 years. The

INTRODUCTION

USA is the world pioneer in the industry and

Shale gas production refers to the extraction

— Mariya Todorova

and

production

natural

gas

from

sedimentary rocks through the unconventional

Mariya Todorova has graduated in Sociology from the Sofia University “St. Kliment Ohridski, Bulgaria. She has participated into the social impact assessment of the Bulgarian part of the Nabucco Gas Pipeline project. She is currently a student in the Masters Program Resource Efficiency in Architecture and Planning and her area of interest is sustainable urbanism.

method of hydraulic fracturing (fracking or fracturing). Natural gas is geological hydrocarbon formation that occurs after the decomposition of marine sediments and their exposure to specific conditions such as depth, temperature and exposure time. The emerging hydrocarbon formations escape from the source rock and migrate, generally upwards, into porous and permeable strata.

has since set the example for other countries in

both

technological

application

and

scientific research. A study by the U.S. Energy Information

Administration,

suggests

the

potential technical recovery of 203,910 Bcm of shale gas on a global scale (EIA, 2013). Nevertheless, there are only four other countries that produce shale gas on a commercial scale – Canada, China, Argentine and Australia. Following these examples, several countries in Europe have, since 2010, undertaken their first efforts into industry development through legislation establishment and licensing shale

ABSTRACT

prospects and barriers. The topic is explored

Layers of impermeable rock aid as a seal

Speculations about the future of shale gas in

through literature review based on reports

and allow the hydrocarbon accumulation into

issued by the European institutions, peer-

an easily accessible reservoir a few kilometres

reviewed academic articles and online news

below the earth’s surface. Some hydrocarbon

articles. The subject is approached through

accumulations migrate and reach reservoir

a discussion on the management of the

rocks with lower porosity and permeability and

environmental implications of the method of

some stay trapped within the fractures of fine

What brings excitement to the situation is that

production, as well as on a discussion on the

grained shale rocks, called respectively tight

European member states are to explore their

role of natural gas consumption, import and

and shale gas. The terms “conventional” and

natural resources freely, as long as they

production in Europe.

“unconventional” gas extraction do not have

follow the established strict environmental

The paper concludes that the shale gas

a sharp and clear distinction but relate to the

regulations. Controversy in the public and

industry is at an early stage and faces many

overall nature of the reservoir and the method

academic debate is fuelled by, on one hand,

obstacles of economic and legislative matter.

of extraction. “Conventional” gas extraction

the many benefits observed in the USA,

Additionally, further continuous research that

refers to the extraction of natural gas from

such as energy diversification, independent

addresses the many environmental risks

the relatively shallow basins, usually through

development of local resources, political

and concerns in an open public debate is of

vertical drilling, whereas “unconventional”

freedom, a leap from the coal industry into a

led public debates, introduced regulations or

an utter must to the future of the sector. The

implies lower permeability of the source rock

cleaner industry and satisfaction of a market

moratoriums, granted licenses to shale gas

dynamic nature of the innovation field and

and the use of more sophisticated methods

of growing demand, to, on the other hand,

exploration companies or initiated first tests.

the development of new technologies that

such as hydraulic fracturing. Within the group

adverse environmental impacts. Examples

The

the

optimise the wells performance are a source of

of “unconventional” fall the above mentioned

for such are groundwater and surface water

development of the industry in Europe,

optimism. Should technologies such as CCS

tight gas and shale gas extraction (European

contamination, ambient water pollution, land

its current state and the associated future

be massively applied, shale gas production

Parliament, 2011). The method of hydraulic

take, risk to biodiversity, increased seismicity.

Europe are primarily based on the experience collected in the United States. Throughout the past eight years, the US shale gas industry has transformed the hydrocarbon production sector, marking the so called “shale gas revolution”. Several countries have since, taken first steps into commercial production with the promise of the benefits achieved in the USA – energy security, lower energy prices and reduction in the CO2 intensity of the energy production sector. In pursuit of the same goals 11 European Union member states with identified shale gas resources have

following

paper

deals

with

gas exploration projects. The public response triggered varied widely from supportive (Spain, Lithuania), to protests and demonstrations, resulting in moratoriums issued by the corresponding government (France, Bulgaria).

37 â&#x20AC;&#x201D;

â&#x20AC;&#x201D; 38

RESULTS

Several examples of negative effects on the

of shale gas resources globally and in

research attempts about the impacts of

human health are also recorded from the US

Europe (Section 3.1), the paper argues that

hydraulic fracturing are impaired by the lack

experience (European Commission, 2011).

the resource estimates pose as a serious

of systematic baseline monitoring data, lack

All those factors, along with the commitment

argument in favour of considering further shale

of incident rates, as well as lack of data on

to a carbon free economy defined by the

gas exploration. Section 3.2 comments on the

the concentration, behaviour and effects

European Union in the Energy 2020 package

process of shale gas production. It introduces

of the chemicals that are used in the shale

and the Energy 2050 Roadmap shape the

the stages of the development of a shale gas

gas production process. Furthermore, risk

an optimistic future of the sector. With the

contentious debate on the future of shale gas

production site, aiming to situate the topical

assessment needs to take into consideration

progressive depletion of readily accessible

production in Europe (European Commission,

in the European context exploration phase

the difference between the impact of an

gas reserves and the parallel development of

2016). Such debate should, therefore, include

within the life cycle of the basin exploitation.

individual installation and the cumulating

mining technologies, the shale gas industry

both a discussion on the management of the

An overview of the technological process in

effects of multiple installations at different stage

in the USA is on an up rise. The US Energy

environmental implications of the method of

reference to conventional gas production

of the project life. Risk analysis is also to a

Information Administration (EIA) projects that

production, as well as a discussion on the

outlines several barriers to the industry

great extent site specific (Policy Department

the natural gas production from shales will

role of natural gas consumption, import and

development. Those are complemented in

C - Citizens' Rights and Constitutional Affairs,

grow from 21 billion cubic meters (Bcm) per

production in Europe.

3.3 Main adverse environmental impacts

2012). Furthermore, when it comes to the

year as recorded in 2005 (4.1% of all gas

associate with shale gas production and the

research on the state of the industry within

produced in the US) to 561 Bcm per year in

method of hydraulic fracturing, as described

national contexts, European Union data was

2040 (53% of all gas produced). From 2004 to

by the European Commission (European

outdated.

The information in English was

2015, approximately 14,000 unconventional

Commission, 2011) .Section 3.4 explores the

limited which constrained the research to

wells were drilled in the Appalachian Basin,

main conclusions drawn in the Europe 2050

few online news articles with relatively lower

including Pennsylvania, Ohio, and West

Energy Strategy and the trends projected

objectivity.

Virginia. Nearly 9,600 of those were drilled in

Methodology The subject of the following paper is the development of the shale gas industry in Europe. The paper aims to determine what is the current state and future prospects of the shale gas industry in Europe and what are the main barriers that it faces. The focus is on the member states of the European Union that have shale gas resources as estimated by the U.S. Energy Information Administration (EIA, 2013). What makes Europe an even more exciting focus point is the freedom that the individual countries share to explore their own natural resources while taking into account the strict environmental regulations imposed by the European Union. The topic is explored through literature review based on reports issued by the European Parliament and European Commission and peer-reviewed academic articles. Where data was outdated,

Shale gas resources availability globally and in Europe A first look into the shale gas production history of the pioneer in the industry, USA, shows

in the EU Reference Scenario 2016 about the role played by both conventional and unconventional natural gas in the gross inland energy consumption in Europe (European Commission, 2016). It explores the prospects of the shale gas industry in the context of carbon free Europe and the current state of the industry in member states with identified shale gas resources.

Chapter 4. summarises the

main findings of the paper. The final chapter, 5. Outlook, opens a discussion on some future prospects for the industry that could strengthen its role on a European and global scale.

it was complemented with information from

Limitations

online news articles.Analysing the availability

An overview of the available literature suggests

Figure 1: Map of the top ten countries with technically recoverable shale gas resources.

39 —

— 40

Pennsylvania alone (Whitton et al., 2017;

Mexico Australia, South Africa, Russia and

caution. The development of a potential site is

Because of the lower scale of the intervention,

EPRS, 2014). Among the benefits attributed to

Brazil. The consolidated figure for Europe is

usually a long, continuous process in which

this procedure has fewer risks and potential

the robust growth of the industry is the fall in gas

actually even higher than the one for USA,

starting with initial research is followed by an

environmental impacts. Should a EU Member

prices observed on the US market, reduction in

respectively 16,934 Bcm and 16,056 Bcm,

exploration phase and, only if the feasibility

State decide to develop its unconventional

the carbon intensity through substituting coal-

which is an argument in favour of potential

of the basin is proved, production phase

gas resources, the multiplication of all activities

fired with gas-fired power generation, and the

investments in the industry development in

can commence. Even if the exploitation of

increases both the likelihood and magnitude

improvement in the energy independence

Europe. Worldwide, however, as of the end

a site is at a particular point in time not yet

of adverse environmental impacts. Therefore,

and security around the globe through the

of 2015, commercial shale gas production

economically feasible or technically possible,

the understanding and addressing of any

exploitation of new technically recoverable

was observed only in the USA, Argentina,

such should not be entirely ruled out because

risks from this stage is of major importance.

reserves (Middleton et al., 2017).

Canada and China. Taking a closer look into

of the dynamic nature of the sector and the

After the completion of the exploration phase

Preliminary geological assessments suggest

Europe’s resources, 12 out of 28 countries

prospects for technological advancement.

and the both the company and the member

the abundant global distribution of shale gas

stand out with promising shale gas reserves

Therefore,

reveals

state decide to pursue with production, the

around the globe (Figure 1). As per a study

(Figure 2). Among the leaders are Poland,

favourable prospects for the development of

second stage can commence. In this phase

by EIA conducted in 2013, the unproven wet

France and Ukraine with unproved wet shale

shale gas industry in Europe.

the full corresponding infrastructure for the

shale gas technically recoverable resources

gas TTR between approximately 3,600 and

(TTR) worldwide amount to 203,910 Bcm

4,200 Bcm. For a quick reference, Poland’s

(EIA, 2013). The ten countries with largest

2015 natural gas consumption is estimated

technically recoverable shale gas resources are USA, China, Argentina, Algeria, Canada,

resource

availability

The process of shale gas production

production process is constructed and installed. This involves the clearing of the site, the well construction of roads, manoeuvring

to 14.79 Bcm. Naturally, unproved resources

Overview of the stages of an unconventional gas production site development

should, however, be treated with extreme

As already outlined, there is a long path towards

transport of fracking fluid and the construction

social, economic and environmental benefits

of flow-back fluid treatment pits or tanks.

from unconventional natural resources. Before

Depending on the scale of the production

setting into commercial production, a member

site, a natural gas production plant could be

state and/or a licensed company should

present. The drilling equipment is transported

successfully complete the exploration phase

and assembled and the hydraulic fracturing

of a site. The stages that follow it are: moving

process commenced. The third phase,

into production; production and abandonment

production, consists of the maintenance and

of the site. The exploration stage, currently

further development of wells on the site. The

topical in Europe, is a pilot phase aiming to

initial production is expected to decline within

determine the site requirements, presence

the first few months and retain lower levels until

of gas and the sour gas probability, the

the end of the exploitation period (Wynn G.,

characteristics of the geologic structure,

Grant A., 2015). Upon well abandonment,

seismicity of the region and the economic

the equipment is decommissioned and

viability of the undertaking. It consists of the

transported, the well is capped with a surface

construction of 2 or 3 wells and the minimum

plug and the site is restored as far as possible.

needed corresponding infrastructure to service

In the context of that timeline, Europe has a

the well pad - access roads and storage

long way to go before realising the potential of

facilities (The Climate Principles, 2013).

its shale gas resources. Furthermore, because

Figure 2: Unproved wet shale gas technically recoverable resources (TTR), Europe, in billion cubic meters.

sites, storage facilities and the well pad, the

41 â&#x20AC;&#x201D;

â&#x20AC;&#x201D; 42

of the controversy of the method of hydraulic

USA are permitted to retain the composition of

well drilling on a particular site, unconventional

negative impacts, as a thorough review

fracturing, a foul course in the exploration

the chemicals in the fracturing fluid under the

drilling is more area extensive in terms of

would be the subject of a different, focused

phase due to poor practices has the capacity

pretext it is a commercial confidentiality, which

land use. At last but not least, the described

research. The main sources of the overview

to trigger negative public reaction and impair

challenges the assessment of the impact

operation relies extensively on heavy freight

are 2 research papers by the European

any further prospects for the development of

of those chemicals on the environment.

vehicle transport, which is connected with

Commission (2011) and the Policy Department

the sector. Moreover, failure to monitor and

Such is not the case however in the UK,

additional resources and is in short-term not

C - Citizens' Rights and Constitutional Affairs

ensure up-to-standard procedures, poses

where companies are obliged to disclose

contributing to the positive environmental

(2012). Based on the US experience, adverse

immense risks to the environment and human

the chemical composition under the Water

impacts are caused mainly because of

health.

footprint of the operation (AEA 2012).

Resource Act 1991 (Whitton et al., 2017).

Overview of the technology of hydraulic fracturing

Apart from the initial chemical and proppant

Whereas conventional gas production relies mainly on vertical drilling and some internal pressure of the gas within the reservoir, the drilling in unconventional gas production is executed in two stages - vertical drilling in order for the bore to reach the shale layer, and directional drilling, penetrating the shale horizontally. In both situations steel casing pipes are installed into the borehole and

composition, the flow back fluid contains substances

naturally

present

the

reservoir, such as salt, radioactive materials, hydrocarbon, metals (European Parliament, 2011). It is transported into pits or tanks and could be reused or pre-treated and transported to an industrial treatment facility. The well clean-up and testing involves the flaring and monitoring of the well throughout the process.

cemented to the rock formation afterwards.

Depending on the capacity of the site,

After the casing is done, the drilling rig

a centralised compression facility could

is removed. Small explosions along the

be installed for the purpose of the gas

horizontal are created to perforate the casing.

production.

The hydraulic fracturing commences by

between conventional and unconventional

pumping fracturing fluid under high pressure

gas production operations could be drawn.

into the well. This pressure creates fractures

Due to the drilling depth with fracking (up

along the horizontal of the shale rocks

to several kilometres depending on the

(Tagliaferri, Lettieri and Chapman, 2015).

geological structure of the site), the amount

Upon pressure reduction, the wastewater

of water needed for the pumping could be

flows up, mixed with heavy or radioactive

up to 10 times more than in conventional

metals. The proppant in the fracking fluid

production. This is a serious factor in regions

serves as spline and keep the cracks open

under water stress. Another serious challenge

allowing the further gas extraction. The

is the treatment of the waste water, which,

chemicals aid to achieve homogeneous

if done could be energy extensive, and if

distribution of the proppant, reduce friction

skipped poses number of environmental and

and prevent corrosion. Companies in the

health risks. Because of the practice of dense

Several

main

differentiations

Main adverse environmental impacts associated with shale gas production and the method of hydraulic fracturing Unconventional

gas

production

is,

definition, largely dependent on the specific

malpractices and legislation breaches as well as equipment failure and inadequate handling of the operations. The accident rate calculated by the NY State is between 1 and 2% and the Marcellus shale in Pennsylvania registered 1,600 violations on a total of 2,300

geological structure of the site. Therefore, a

wells (European Parliament, 2011).

risk analysis should always combine general

Among the highest risk for groundwater and soil

issues with site-specific aspects. An analysis

is the contamination from naturally occurring

on the general risk ratings on the individual

radioactive elements through existing or

environmental

moderate

artificially created through the process of

to high risk for individual installations and

fracturing pathways in the area of active

predominantly high, cumulative risk for multiple

or abandoned wells. Such contamination

installations (Table 1). The following section

could occur from failed cementing too.

aims to provide an overview on potential

With migration, NORMS can contaminate

aspects

shows

Environmental Aspect

Project Assessment

Cumulative Assessment

Groundwater contamination

High

Surface water contamination

High

Water resources

Moderate

High

Release to air

Moderate

High

Land take

Moderate

High

Risk to biodiversity

Moderate

High

Noise impact

Moderate to High

High

Visual impact

Low to Moderate

Moderate

Seismicity

Low

Traffic

Moderate

High

Groundwater, surface water contamination and water resources Table 1: Overview of preliminary risk assessment of hydraulic fracturing across all project phases.

43 —

— 44

groundwater and in result drinking water

times more water than conventional drilling

Air pollutant emissions such as noise,

within this area could reach up to 6 wells/km2.

supplies. Permeation in the underground is

which is a serious issue in areas already

particulates, SO2, NOx, NMVOC and CO,

Such density increases the occurrence of one

a slow process and hard to observe which

experiencing water stress. Additionally, large

could originate from activities connected to

or more risks (European Commission 2011).

could lead to long-term adverse effects. Prior

portion of the fracking fluid remains in the

the operation of heavy freight vehicles, drilling,

Additionally, that might be agricultural land (as

activity, local geology needs to be analysed

formation – not more than 20% of it flows

natural gas processing and transportation,

in considered during 2011 potential sites in

and monitoring and control should allow zero

back. It is not a common practice that the

waste water ponds evaporation, spills and

Bulgaria and France) and the disruption of the

tolerance for compromises.

water is reused because of the change in

blow outs. US experience recorded many

landscape could pose a threat to biodiversity.

Another source of contamination could be

the chemical composition. Full treatment of

complaints of human illness and several

the chemicals used in the hydraulic fracking

the water is possible but not regarded as

complaints of animal death (Dish, Texas). An

process. Spills of fracking fluid during

economically feasible. Usually, after pre-

independently conducted study registered

treatment wastewater is injected back to the

“the presence in high concentrations of

geological formations, posing a risk of soil

carcinogenic and neurotoxin compounds

salinisation and contamination, as well as

in ambient air and/or residential properties”

increased seismicity (Policy Department C

(European

- Citizens' Rights and Constitutional Affairs,

methane emissions from drilling, flow back,

2012; European Commission, 2011).

fracturing fluids evaporation, valve and

pumping, transportation or due to overflow of the wastewater fluid container are the most commonly occurring accidents. Within the risk mitigation measures is the further research improved mixtures with lower toxicity as well as monitoring and report that prevents accidental spills. Fracturing requires approximately 10

Release to air, noise and traffic

Commission,

2011).

Fugitive

compressor leakage, have huge impact on the greenhouse gas balance. Serious accidents that occurred in the U.S. are the well blow-out resulting in a 16-hour long spewing off 133 cubic meters of wastewater and natural gas into the air (Pennsylvania, 2010), explosion of a well and injuries of several workers (West Virginia, 2010), fire of a waste water storage tank and open pit (Atlas well pad, 2010), (European Commission 2011). Mitigation measures to be undertaken to prevent such scenarios are strict health and

Figure 3: Potential flows of air pollutant emissions, harmful substances into water and soil and naturally occurring radioactive materials (NORM).

Need of further research Although the list of potential negative impacts and risks and the activities during which they might occur, is long, and the registered high accident rate – high, several encouraging arguments with high validity are expressed in the public debate. The main one is that proven accidents and violation are due to poor practices by the servicing companies. State-of-the-art technology along with trained personal, regulations, monitoring and control could effectively prevent large share of those accidents. Furthermore, often reports do not come up with a solid proof of the causality of hydraulic fracturing and the resulting adverse impacts. Hence, future data collection and research could address some of the concerns and lower the remaining risks and negative impacts, allowing shale gas exploration a future in Europe.

safety regulations, monitoring and control. Land take and biodiversity

The role of conventional and unconventional natural gas in the EU

The shale gas production operation is area

Investment and advancement of the industry is

extensive as it requires additional area for

connected with the economic climate and the

storage of technical equipment, trucks with

active legislation within the EU and its member

compressors, chemicals, proppant, water

states. The following section examines the

containers for waste water and others. A

projected role of both conventionally and

typical multi-well site in Pennsylvania is about

unconventionally produced natural gas in

(16,200-20,250 m2). The concentration of wells

Europe.

45 —

— 46

Natural gas consumption projections in the European Union

energy consumption. Because of that, the

decline in conventional production.

described scenarios are also marked with

As illustrated in both graphics, according to the

Within the goals of the Europe 2050 Energy

the close collaboration between decentralised

reference scenario, natural gas is attributed

Strategy is the transition of the European

and centralised power systems and heat

a role limited to a “flexible back-up and

energy system into a carbon neutral one

generation systems. Furthermore, carbon

balancing capacity where renewable energy

(with 80-95% reduction of greenhouse gases

capture and storage (CCS) is expected to

supplies are variable”. A crucial condition for

based on 1990 levels), along with ensuring

play a “pivotal role” in the transformation of

the classification of natural gas as low carbon

competitiveness and security of supply. This

the system. Should CCS be commercialised,

technology is the large-scale application of

is to be achieved following the established

it is to contribute with mitigating up to 32%

CCS technologies (European Commission,

by the European Commission (2011) Energy

of the CO2 emissions in power generation

2011). Successful domestic shale gas

Roadmap. The scenarios in this roadmap

(European Commission, 2011).

production, could compensate for the decline

project a decarbonised system in which

The projections drawn from the EU Reference

in the domestic conventional natural gas

capital expenditures are relatively higher

Scenario 2016 (REF2016) show a drop in

production and minimise the need of import.

and fuel costs, lower. Electricity is expected

the gross inland energy consumption in the

That should however, not compromise the

to play an increasing role, with an almost

EU (Figure 4). Two trends are observed in the

doubled share in final energy demand of up

period from 2005 to 2050 – the decline in the

to 36-39% in 2050, stressing the importance

solid fuels and the oil consumed, and the rise

of a sustainable electricity production. The

of the renewable energy used. The amount

share of renewables is also expected to

of nuclear energy and natural gas used are

rise, reaching at least 55% of the gross final

expected to remain with a stable share.

Figure 4a: Gross inland energy consumption in Europe (EU28) from 2005 to 2050, in ktoe. 2

The projection takes into account the global and EU market trends, along with the already adopted by the EU and its member states energy and climate policies.

Figure 4b: Gross inland energy consumption in Europe (EU28) from 2005 to 2050, in ktoe.

environmental integrity within the member states or pose any risks to human health. It should, additionally prove the long-term GHG

When we take a closer look into the natural

neutrality of unconventional gas production.

gas production, imports and consumption consumption during the period from 2005 to

Positions of the member states with shale gas development prospects towards the method of hydraulic fracturing

2015, followed by projections for a modest

In spite of the shared goals in the Europe 2050

increase in demand during the period from

Energy Strategy, the choice of energy source

2017 to 2021. This is to be explained with

to be developed by the European Member

the expected retirements of several coal and

States remains in their own competence.

nuclear power plants. Additionally, domestic

Although there is no specific EU policy on the

EU gas production is experiencing a gradual

development of shale gas, there is a non-

decline (41% over the past 10 years), leading

binding Recommendation 2014/70/EU on the

to an increase in imports demand. Russia is

use of fracking for the exploration or production

the main gas importer in Europe with 44% of

of shale gas. It addresses the environmental

the EU imports in 2015. Alternatives in gas

aspects of the sector that could produce

supply are recognised in the liquefied natural

cross-border

gas import and the unconventional gas

advocates

production (European Commission, 2016).

whole process and especially the use of

Nevertheless, unconventional gas production

chemicals. Member States that decide to

is predicted to remain below 20 Bcm by 2035

proceed with shale gas explorations are

and will therefore not compensate for the

additionally invited to report their environmental

(Figure 5), we see a drop in the gross inland

impacts. transparency

The

Regulation

concerning

the

47 —

— 48

causing exploration companies to give up

speed of a process supposed to address as

fracking in Spain. Exploratory drilling was also

many of the concerns as possible, might end

approved in Poland , Romania and Lithuania.

up to obstruct the success of the endeavour.

Especially high were the expectations of

While the availability of resources and the

Poland and Romania in replicating the US

industry proficiency are of great importance,

success. Poor results from first tests due to

it is governance that has the potential of being

unfavourable geology in Poland, along with

a deciding factor for the industry’s future.

legislative complications such as the time-

Experience shows that the lack of multi-level

restriction in concessions, led to the drop in

inclusive governance causes high likelihood

concessions and companies pulling out.

of triggering negative public reaction. Both

Announcing their exit from the Romanian,

favouring local economic interests and

where the ban was shortly beforehand lifted,

undermining them while not adequately

the US based shale gas company Chevron

addressing the potential risks the stakeholders

explained that the Black sea state does not

endure, could bring larger environmental and

Figure 5: Indigenous natural gas production, net imports and consumption in EU28 from 2005 to 2050, in ktoe.

compete favourably with other investment

social impacts once the industry advances.

opportunities in the company’s portfolio .

What global experience so far shows is that in

impact measures on an annual basis. Since

(EPRS, 2014). After years of discussion and

Chevron had already departed Lithuania in

lack of scientific knowledge base is among

research, Germany and Netherlands also

2014, citing the inhospitable fiscal regime as

the barriers to the development of the sector,

banned the method of hydraulic fracturing (in

one of the reasons for leaving the country.

the European Commission has established a

2017 and 2015 respectively).

Soon after, in 2015, the government drafted a

High hopes and first fracking attempts in Europe

rate, renewing the interest of the partially owned

European Science and Technology Network on Unconventional Hydrocarbon Extraction (EPRS, 2014). Active debate was led in several

new law with improved base gas extraction tax by Chevron LL Investicijos . Shale gas is also

all the countries, except USA, the growth rate and volumetric magnitudes of the shale gas production were insufficiently low to lead to any positive energy or economic effects (Fukui et al., 2017). Thus, a transparent, inclusive and realistic strategy needs to be developed. The above described examples illustrate that pioneer companies are on the other hand

Spain is among the EU member states

explored in Sweden and Denmark , but the

that regarded high hopes on replicating

limited availability of the resource makes those

the success observed in the US shale gas

shales not that attractive of an investment.

industry. As per a report by the Spanish

Highest hopes are currently regarded on UK’s

Bulgaria was in the process of negotiation

Association of Research, Exploration and

shale gas exploration’s projects, although the

with the US giant Chevron for the exploration

Production, the resources of shale gas in the

industry is still a long way to go . After brief

of site in the Dobrudzha area, a territory

Iberain Peninsula could provide gas supply

seismic activities in initial vertical drilling in

CONCLUSION

with high agricultural significance. After loud

potential equal to 70 years of consumption,

2011, UK had voted moratorium which they

The topic of shale gas exploration in Europe

negative reactions in 2012, the government

thus lowering the import dependence of the

later lifted. First fracking tests are scheduled

stays controversial and the public opinion –

imposed moratorium and revoked licenses

country. Although the National Congress

for 2017 and it is argued that this will be the

divided. Out of the 11 reviewed countries, four

for exploration. Due to the large significance

adopted

2013

most closely observed shale gas exploration

have an active ban on hydraulic fracturing

of the agricultural sector, France also banned

greenlighting shale gas exploration and

project so far, aiming to prove the potential for

(Germany, Netherlands, Bulgaria and France),

fracking, cancelled exploration licenses and

granting

regional

safe hydraulic fracturing. Legal challenges

four have had high hopes but have recently

upheld the ban in their constitutional court

assemblies formed an opposition, eventually

from environmental groups and the slow

lost their initial enthusiasm (Poland, Spain,

European Member States in the last decade. Active ban on hydraulic fracturing. An active ban on hydraulic fracturing is currently present in four European member states.

legislative five

changes

licenses,

several

often discouraged into pursuing long-term investments due to unstable political positions and current low gas prices compromising the economic feasibility of the endeavours at the current state of the available technology.

49 —

— 50

Lithuania, Romania), two have exploration in

(Middleton et al., 2017), concludes that a

place but with limited return projected (Sweden

likely enhancement of well productivity lies in

and Denmark) and one (UK) has upcoming

identifying better performing mechanisms and

exploration activities and optimistic prospects

applying them. Modelling production data

for the industry. The individual stories of the

recognises differences of factor of ten between

member states show that the industry is still

the wells with best and worst performance.

too young and expectations are blinded

Therefore, long-term production should be

by unreasonably optimistic hopes and

considered as a subject of further research and

fierce ideological criticism. Within the main

has a potential to “massively increase shale

barriers that the paper identified are the early

gas extraction and re-revolutionise hydraulic

stage of the industry, the low success rate of

fracturing”. Furthermore, the study argues

exploration activities and the questionable

that refracturing is not negatively impacted

economic feasibility at the current global gas

prices and European regulation. Additionally,

advancement shows a potential for re-

negative public opinion poses a serious

stimulating existing wells, which could be

threat. The data on the risks and impacts

more cost effective and pose a smaller

is still underdeveloped and shows high accident rates and insufficient measures for risk mitigation. This has the potential to fuel the public debate on the long run and obstruct the future of European shale gas production in the long run. However, the promising dynamics of the sector and the continuous role of natural gas provided that carbon capture and storage technology is developed reveals some prospects for the sector in Europe. Success will need to be based on multi-level governance, transparency and a sufficient

production.

— Abdullah Khisraw

Abdullah Khisraw is doing his M.Sc. in REAP with a fully funded scholarship by the prestigious German Academic Exchange program (DAAD). He is graduated with a B.Sc degree from Civil Engineering Faculty of Kabul University. He is the author of two mathematic books in his native language, and worked for more than three years in national and international organizations.

Technological

environmental footprint than developing new shale formations. These findings, if proved and developed have potential to significantly improve the prospects of the shale gas industry in Europe. Furthermore, should CCS technologies become available and applied at a large scale, this could classify shale gas as a low-carbon technology (European Commission, 2011). A recently researched

INTRODUCTION Compression

chillers

in functioning of compression chillers, some are

mechanical

machines used for cooling purposes in

to operation of compression chillers are

commercial areas, industrial areas and

discussed at the end of this paper.

residential units. This paper discusses the

PRINCIPLES

principles upon which compression chillers work, starting from the very basic physics knowledge to understand them, and later gives an insight to the mechanical parts and

approach to reducing the anthropogenic CO2

clarifies how do all parts of the compression

gas recovery (EGR) operations in depleted

cooling. In addition some of the operation

emissions is through coupling of enhanced

of the general recommendations in regards

chillers work together to give a final effect of

To understand the mechanics of how a compression chiller works, it is necessary to understand some of the fundamental thermodynamics principles upon which the system is designed. Here some of the very essential of these principles are discussed in detail:

shale gas reservoirs with long-term CO2

challenges are discussed, mainly challenges and problems associated with compressor

Phase change and latent heat

Along with further research and cost-based

part of the compression chillers, compressor,

The refrigerant we use in compression chillers

economic analysis, CO2-EOR might turn out

being one of the key drivers in compression

experiences phase changes, in order to

chillers is more vulnerable and requires

understand how the process works in this part

The research community is still learning a lot

that could serve the final stages of depleted

proper functioning of all other parts of the

of the paper the latent heat is explained:

about the aspects of shale gas production.

shale gas reservoirs, address some of the

compression chiller to function correctly and

“Latent heat is the quantity of heat which must

Contrary to the established opinion so far, a

concerns of the industry and take the next step

efficiently. Despite all these challenges there

be communicated to a body in a given state

recent research on the 20 years of exploitation

to carbon neutral future. —

are recommendations to minimize faulty

in order to convert it into another state without

operations and to maintain higher efficiency

changing its temperature” (Maxwell, 1970).

set of measures addressing the concerns in ensuring the environmental integrity in the EU Member States.

OUTLOOK

of over 20,000 wells in the Barnett formation

storage operations (Schaef et al., 2014).

to be one of the many revolutionary findings

51 —

— 52

Freezing temperature

0 degree Celsius

it is cold down to 100 °C. Important result of

Refrigerant

Boiling temperature

100 degree Celsius

this analysis is the very high amount of energy

The liquid used inside a compression chiller

Latent heat of fusion

334 J / g

required to evaporate the water compared to

to transfer heat is called refrigerant, usually the

Latent heat of vaporization

2.230 J /g

amount required to melt it. It is vivid the same

refrigerant has a lower boiling point depending

Specific heat capacity of water (cwater)

4.187 J / (kg °C) or 1 cal / (g °C)

amount of energy would be extracted during

on its application different refrigerants are used

Hydropower

2.220 J / (kg °C) or 0.53 cal / (g °C)

condensation. If a gas can be used to cool

for commercial, industrial or residential areas.

Concentrated Solar Power

1.890 J / (kg °C) or 0.45 cal / (g °C)

down another medium, it can absorb more

Depending on requirement of the compression

energy to condense compared to a liquid. In

chiller

compression chillers the similar procedure is

pressure and temperature a proper refrigerant

applied, R-134a as the refrigerant will absorb

is used in compression chillers. Some of the

Table 1: Water properties at 1 atm pressure.

and

mechanical

constraints

Every matter has two sorts of internal energy,

to raise its temperature from 0 °C to 100 °C, Q4

a lot of energy by condensation from the

very common refrigerants are listed in table 3.

one which is sensible in terms of temperature

= 446,000 J to evaporate the 200 g of water

places of higher temperature, transfer it to

It is important to note that refrigerants use are

without raising the temperature, and at the end

places of lower temperature and loses the

bindings between the building blocks of the

Q5 = 3780 J to raise its temperature from 100

energy there. Table 2 summarized some of

matter, this energy is latent and not sensible. In

°C to 110 °C. Figure 1 shows the process of

the R-134a properties (at 1 atm atmospheric

order to undergo a phase change this energy

heat application on this 200 g of ice, and in

pressure).

shall either be taken away from the matter

order to convert the 110 °C steam back to -10

or shall be transferred into it. This amount of

°C ice the same amount of energy should

energy for different matters differ whether it

be extracted. (For step by step calculations

changes from which phase to which. For

please inspect Appendices section at the

example latent heat of vaporization of R134a

end of this paper). From this analysis it is

is 173.1 J/g (Kondou, et al., 2014) while that of

vivid that the biggest amount of energy in

water is 2230 J/g (Halliday, et al., 2011).

phase change is Q4=446000J where water

Heat can act in two different ways on a

evaporates, the same amount of energy

Gay Lussac’s law

substance either it will change the temperature

would be extracted from water steam when

As shown by the French chemist Joseph Louis

and second is the energy affiliated to the

legally challenged depending on their Ozone depletion potential (ODP) and global warming potential (GWP). -- Ozone Depletion Potential (ODP) of a chemical is the relative value that

Freezing temperature

- 96.67 °C

indicates the potential of a substance to

Boiling temperature

- 26.07 °C

destroy ozone gas as compared with the

Table 2: R-134a properties.

potential of chlorofluorocarbon-11 (CFC11) which has a reference value of 1 (Luthra, 2017). -- Global Warming Potential (GWP) is another measure of consideration when a refrigerant use is restricted, it show the

of the substance or it may change state of the

Gay-Lussac (1778–1850) in his experiments,

substance. To further clarify this, water would

the pressure and absolute temperature of a

be considered as an example and will be

fixed volume of a gas are directly proportional

analyzed as it changes from ice to water vapor

to each other.

by applying heat and from vapor back to ice

Based on this law, in compression chillers

by extracting heat under 1atm atmospheric

thermal expansion valve decreases the

pressure. Table 1 shows the properties of

pressure thus decreasing the temperature of

water in 1 atm atmospheric pressure.

the gas, on the other hand the compressor

Assuming 200 g of ice in -10 °C, Q1 = 4440 J

increases the pressure thus increasing

COMPRESSION CHILLERS

of heat is applied to raise the temperature from

the temperature of the gas, which makes

Compression chillers are machines to collect

-10 °C to 0 °C, Q2 = 66,800 J to melt the ice

it possible for the refrigerant to absorb and

heat from places where it is not needed

release the energy.

and dissipate it to places of no objection.

without raising the temperature, Q3 = 83,740 J

Figure 1: Heat graph.

potential of gas that can absorb energy compared to similar mass of CO2, for example if GWP of a gas is 1700 it means the gas is 1700 times stronger than CO2 in terms of energy absorption. It is important to notice that GWP is controversial (EPA, 2017).

53 â&#x20AC;&#x201D;

â&#x20AC;&#x201D; 54

Refrigerant

Ozone Depletion Potential Global Warming Potential

also possible to transfer heat from places of lower temperature to higher temperature only

R-11 Trichlorofluoromethane

1.0

4000

R-12 Dichlorodifluoromethane

1.0

2400

R-13 B1 Bromotrifluoromethane

0.05

1700

650

R-113 Trichlorotrifluoroethane

0.8

4800

R-114 Dichlorotetrafluoroethane

1.0

3.9

R-123 Dichlorotrifluoroethane

0.02

R-124 Chlorotetrafluoroethane

0.02

620

Compression chillers component

R-125 Pentafluoroethane

3400

Compression chillers mainly composed of

R-134a Tetrafluoroethane

1300

4 major components, the compressor, the

R-143a Trifluoroethane

4300

evaporator, the condenser, and the thermal

R-152a Difluoroethane

120

expansion valve. Here the functionality of

R-245a Pentafluoropropane

R-401A (53% R-22, 34% R-124, 13% R-152a)

0.37

1100

R-401B (61% R-22, 28% R-124, 11% R-152a)

0.04

1200

R-402A (38% R-22, 60% R-125, 2% R-290)

0.02

2600

R-404A (44% R-125, 52% R-143a, R-134a)

3300

R-407A (20% R-32, 40% R-125, 40% R-134a)

2000

R-407C (23% R-32, 25% R-125, 52% R-134a)

1600

0.283

4.1

R-507 (45% R-125, 55% R-143)

3300

R-717 Ammonia - NH3

R-718 Water - H2O

R-729 Air

R-744 Carbon Dioxide - CO2

R-22 Chlorodifluoromethane R-32 Difluoromethane

R-502 (48.8% R-22, 51.2% R-115)

Table 3: Refrigerants.

if external work is involved. In compression chillers external work in terms of mechanical work by compression chillers are constantly doing work on the system to make sure that the heat will flow from lower temperature to higher temperature, the basic principle upon which compression chillers are working.

each component is briefly discussed.

Figure 2: Reciprocating Compressor Schematic.

compressors (Figure 2.) refrigerant is sucked by the piston and then pumped back through the discharge chamber by support of series

The compressor

of suction and discharge reeds. It is important

In a compression chiller compressor is the

to mention that reciprocating compressors

main heart of the system driving the machine, it

are easy to build and cost less than rotary

increases the pressure of the vapor refrigerant

compressors, but the issue with reciprocating

circulating the compression chiller, and drives

compressors is its high noise level and high

the refrigerant through different compartments;

vibrations. They can reach up to very high

compressor is responsible for most of the

capacities and despite all above mentioned

energy consumption of the system. The

challenges for applications of more than 1

mechanical work by the compressor increases

Megawatt reciprocating compressors are the

the pressure of the gas thus increasing its

only solution. (Carel, 2017)

temperature as well, based on Gay Lussacs Law. The refrigerant entering the compressor

Rotary Vane Compressors

should be in gaseous state, or else liquids are

The compressor consists of a cylindrical

incompressible. There are different types of

casing with two openings, one for suction of

Compression chillers function based on

cycle is widely used in natural gas plants,

compressors using rotating or reciprocating

the refrigerant and other one for discharging

vapor-compression refrigeration (VCR) cycle

petroleum refineries, food and beverage

systems. Reciprocating compressors feature

the refrigerant. A rotor is positioned in center

through which refrigerant undergoes a phase

processing industries. (Araner, 2017)

reciprocating motion similar to that of a piston

of the cylinder and driven by motor to apply

change. VCR refrigeration is considered to be

A very simple definition of Second law of

to compress the refrigerant while rotary

pressure on the refrigerant, in this chamber

harmful to environment but it is still applicable

thermodynamics states that heat can only

compressors like rotary vane, scroll, screw and

the refrigerant is compressed (Pneumofore,

and the time to switch to an environmentally

spontaneously flow from higher temperature

centrifugal compressors feature a rotational

2017). One of the advantages of rotary vane

friendly solution is not very close. The VCR

to lower temperature (Ben-Naim, 2010). It is

movement. (Carel, 2017). In a reciprocating

compressor is its low cost and compacted

55 â&#x20AC;&#x201D;

â&#x20AC;&#x201D; 56

to 120 kW, scroll compressors are limited

The condenser:

in terms of applications or are at least not

After compressor the refrigerant enters condenser, here the refrigerant releases its energy and condenses back to liquid and partially vapor, the function of a condenser is to make sure that refrigerant releases its energy into condenserâ&#x20AC;&#x2122;s medium either water or air. There are generally two types of mediums for condensers air medium or water medium. For compression chillers mostly water is used (Miller, 2017). If the condenser uses air, it resembles the functionality of a radiator that cools down engine in a car. Radiators use an air blower to force air through wide surface of refrigerant lines, the condenser is designed in way to ensure maximum surface touch between refrigerant and air. Air cooled condensers require outside temperature of 35 degree Celsius or below to operate effectively (Miller, 2017). Water cooled condenser perform similar function as air cooled condensers, and the only difference is that water cooled condensers work in two stages, first in condensing chamber the refrigerant releases its heat and water absorbs the heat (there is no direct contact between refrigerant and water, the heat exchange occurs through the surface of refrigerant pipes inside the condenser), in second step hot water is pumped to cooling tower where again the water is blew by air and excess heat is released to atmosphere, after water is cooled down it is directed back to condenser chamber where it starts back capturing excess energy from refrigerant and repeats the same cycle again.

preferred compared to its competitors, piston and rotary compressors which are preferred for small capacity applications and screw and centrifugal compressors which are preferred for higher capacities. (Carel, 2017) Advantages of scroll compressors are their Figure 3: Rotary van compressor (NPTEL, 2017)

small size and lower weight than medium size reciprocating compressors, albeit higher than

dimension, due to this fact vane compressors

rotary compressors. They also have excellent

are suitable for small commercial uses like

efficiency at a predefined compression ratio.

fridges, freezers, air-conditioners and etc.

They also have lower noise level and reduced

(Carel, 2017). A more advanced version of

vibrations. (Carel, 2017)

rotary vane compressor has double revolving

Screw compressors:

rotors in opposing directions, which in return generates less noise and less vibration. Rotary vane compressors are preferred than scroll compressors which are more expensive and also bulky. Double rotors compressors have also increased energy efficiency and has the same cost as regular ones. They are suitable for applications of up to 50 kW. These compressors can reach up to 7800 rpm while scroll compressor typically achieve 5400 to

Screw compressors are made of two driving screws attached to each other, these screws are joined in a way that the space between them gradually decreases as the screws are rotated and refrigerant is driven toward the outlet of the compressor, due to decrease of space between screws, pressure increases inside the compressor chamber thus compressing the refrigerant. Screw compressors require lubrication and come with built in oil and

6600 rpm (Carel, 2017).

lubrication cooler. (Air compressor guide,

Scroll compressors:

2017)

These compressors use two scrolls, one of

Centrifugal compressors:

them fixed to the body of compressor while

Main part of these compressor is the impeller;

the other one is rotated by the motor, these two

the compressors sucks the refrigerant and

scrolls are designed and positioned in a way

directs it to impeller where it is rotated in high

that rotating scroll pushes the refrigerant thus

speed and gains kinetic energy, later the gas

compressing the refrigerant and discharging.

escapes the impeller and the kinetic energy

(TestEquity LLC, 2017) They are used in

is converted to compression. Centrifugal

homes, commercial air-conditioning systems,

compressors are limited to high cooling

Thermostatic Expansion valve (TXV):

and heat pumps. Capacity ranges from 3

capacities usually large chillers. (Carel, 2017)

Thermostatic expansion valve is the key

Figure 4: Thermal Expansion Valve.

element of refrigeration cycle. It controls the flow of refrigerant and decreases the pressure of refrigerant. Thermal expansion valve uses temperature sensing bulb filled with the similar refrigerant as main refrigeration cycle. The valve has an orifice with a closing cap which is regulated by a moving pin, the pin is connected to a diaphragm and it moves according to pressure increase or decrease of the refrigerant in evaporator and sensing bulb. As the temperature in evaporator increases, it indicates that more refrigerant flow into evaporator is needed. The high temperature at outlet of the evaporator heats up the sensor bulb thus increasing the pressure of bulb, the refrigerant expands and pushes the diaphragm inside the expansion valve, the diaphragm then moves the connected pin and opens the closing cap and allows more refrigerant flow, as more refrigerant flows the temperature at the outlet of evaporator decreases, and the gas inside the sensing bulb cools down. As a

57 â&#x20AC;&#x201D;

â&#x20AC;&#x201D; 58

result the pressure in sensing bulb decreases

like rigidity and safety for the tubes, they

inside cylinder and water inside the tube,

malfunctioning of the system and decrease in

and pulls back the diaphragm and closing

are easy to clean, and helps capture of

it is a flooded type of chillers. (Khemani &

efficiency of the evaporator.

back the refrigerant flow. Inside thermostatic

heat by refrigerant, further they are easy to

Stonecypher, 2010)

expansion valve there is a spring constantly

manufacture and cost less. They can be

pushing the diaphragm and keeping the cap

formed easily into the required shapes, for

close to stop the refrigerant flow, the spring

example box shapes to form closed spaces.

pressure is adjustable which makes it easy to

Plate type evaporators can easily be seen

optimize the function of valve (Whitman, et al.,

in some fridges and freezers. Due to these

2005).

advantages and flexibility they are used

The evaporators

extensively. (ref-wiki.com, 2017)

Evaporator in a chiller is responsible for absorbing heat from warm water and to produce chilled water using the refrigerants capacity to absorb heat from water and evaporate. There are different types of evaporators for various refrigeration applications. They can be classified according to their construction, method of feeding the refrigerant, and etc. There are three types of evaporators based on their construction: bare tube evaporators, plate type evaporators, finned Evaporators, shell and tube evaporators. (Khemani & Stonecypher, 2010) Bare Tube Evaporators: as the name suggests these are evaporators made up of either bare copper tubes or steel pipes. Steel pipes are used for ammonia as refrigerant while copper tubes are used with other refrigerants. The bare tube evaporators are usually used for liquid chilling. They are used in very few applications, but the bare evaporators attached with finned mesh plates are common, called as finned evaporators. (Khemani & Stonecypher, 2010)

Plate type evaporators: In this type of evaporators the tubes are constructed inside the plates, the plates provides advantages

Finned Evaporators: They are the bare tube type evaporators covered with fins. With the bare tube type evaporators, due to few surface contact area less heat is absorbed from the cooling medium either water or air, on the other hand when covered with fins more surface for refrigerant tube is created thus facilitating the absorption of heat. The fined evaporators are more efficient compare to bare tube evaporators. (Khemani & Stonecypher, 2010) Shell and tube evaporators: Almost all of the chillers uses this kind of evaporator. These types of evaporators are composed of single large steel cylinder. Inside this cylinder the warm water tubes which has already collected excessive heat run through it and cools down by dissipating heat to refrigerant. There is no direct connection between the refrigerant and the water tubes the heat exchange occurs through the surface wall of the chilled water tubes. Depending on the direction of flow of refrigerant there are two types of evaporators: Dry expansion type and flooded type chillers. The only difference between both is direction of refrigerant flow, if refrigerant flows alongside the tubes and water alongside the cylinder it is a dry expansion type, if refrigerant flows

Refrigerant loop

Compression chillers operation loops

The refrigeration cycle is the fundamental

Compression chillers have generally three

process

cycle, first the chilled water cycle where it

compression chillers. The refrigeration cycle

collects heat and brings it to evaporator,

consists of following components

second the refrigerant cycle which transfers the heat to condenser, and third is the condenser loop which collects heat from refrigerant and

behind

cooling

effect

the

-- Compressor -- Evaporator

transfers it to place of no objection.

-- Condenser

Chilled water loop

-- Expansion valve

In this cycle chilled water (typically between 4

Just

to 7 degree Celsius, (Brain, et al., 2017)) leaves

refrigerant is liquid, with high pressure and

the evaporator and travels into residential units

high temperature as it passes through the

or offices to collect heat via radiators, next step

expansion valve, due to throttling effect of

it simply brings heat to evaporator where later

expansion valve the pressure decreases and

the water loses the absorbed heat back to

so temperature as well.

refrigerant and it is cooled down, in evaporator

Now after passing the TXV the refrigerant with

chamber there is no direct contact between

low pressure and low temperature enters the

refrigerant and the chilled water, rather the

evaporator in a saturated mixture liquid and

heat is exchanged through skin of meshed

gas refrigerant, the liquid refrigerant boils inside

lines of refrigerant. It is important to keep

the evaporator and absorbs heat from the chill

refrigerant isolated from chilled water to avoid

water cycle, totally evaporating and to be sure

Figure 5: Refrigerant cycle.

before

the

expansion

valve,

the

59 â&#x20AC;&#x201D;

â&#x20AC;&#x201D; 60

that only refrigerant in gas state is entering the

gas by evaporation and in condenser the

compressor, the refrigerant should ideally be

refrigerant phase changes from gas to

superheated (a vapor heated to more than

liquid by condensing. Figure 7 shows the

its boiling temperature) this is regulated and

expansion valve and compressorâ&#x20AC;&#x2122;s function. The TXV changes pressure from high to low and decreases refrigerant temperature on the other hand compressor increases refrigerant pressure from low to high thus increasing the temperature. Condenser loop Water in condenser loop absorbs energy from refrigerant in condenser and condenses the refrigerant, the captured heat is later transferred

Figure 6: Condenser and Evaporator phase change.

to cooling tower, where the transferred heat is

Figure 7: Expansion valve and compressor pressure change.

compressors, if liquid refrigerant enters in

compressing equipment either rotors, screws

large amounts it causes hydraulic shock

or scrolls all are vulnerable to liquids, simply

leading to compressor failures, even in small

because liquids are hardly compressible, so

amounts can simply dilute the oil and destroy

excessive compression by compressing units

compressor bearings. (achrnews, 2005)

in compressors leads to their destruction.

In reciprocating compressors, check valves

98% of the times that a compressor fails is due

COMPRESSION CHILLERS OPERATION too, and the refrigerant is still in gaseous state. CHALLENGES

that control refrigerant inflow and outflow

to a problem in the system that causes the

is a vulnerable part of the system. When

Next step the high pressure, high temperature

compressor to fail. Some of the very common

As mentioned before, compressor acts

operating the compressor, a broken check

gaseous refrigerant travels to condenser,

causes are also listed below (Park, 2009):

as heart of the compression chillers and

valve in suction line allows the compressed

where it meets cooled water coming from

it is the main driver of the system, making it

gas back to suction line, thus increasing the

cooling tower, due to the temperature

also the most vulnerable part of the system.

pressure in suction channel and stopping

difference between the refrigerant and cooled

Compressors operation required continuous

proper flow of refrigerant into compressor,

water, the heat is lost from refrigerant to cooled

inspection and maintenance of not only the

similarly when the diffusion line check valve is

water, as a result the refrigerant is cooled down

compressor but other parts like evaporator,

broken the compressed gas can back flow

and forms saturated mixture of liquid and

condenser, TXV, pumps, radiators, cooling

into the compression chamber and may not

gaseous refrigerant, and leave the condenser

tower, piping, valves, and etc.

only decrease the efficiency of the system but

with same pressure as before heading toward

The oil level in compressors easily lowers and

can cause complete breakdown of the entire

the thermal expansion valve and repeating

decreases the efficiency of the compressor,

system too.

the same cycle again and again. For more

in different compressor designs oil is part of

A challenge in operating compression chillers

clarification see figure 6 and 7.

the requirement for fully functionality of the

is to ensure that compressor receives only

Figure 6 simplifies how evaporator actually

compressors.

refrigerant gas. Liquid refrigerant inside

changes refrigerant phase from liquid to

Liquid refrigerant is another problem for the

compressor could cause destruction of

dissipated into atmosphere either by blowing air or by natural air flow if outside temperature

ensured by the bulb sensor of the TXVs.

is appropriate. The water is cooled in cooling

After absorbing heat, the refrigerants enters the

tower and then driven back to condenser in

compressor, here the compressor increases

order to collect back the heat from refrigerant.

its pressure, thus increasing the temperature

-- Dirty evaporators or condensers -- Improper refrigerant charge -- Miss adjustment of Expansion valves -- Clogged

pipes

and

tubes

inside

condenser -- Pressure loss or malfunctioning of sensor bulb in TXV Refrigerant leakage is one of the worst issues of operating chillers, a leakage not only cause loss of refrigerant but also have significant

environmental

impact

all

61 —

refrigerants are classified according to their impact degree on global warming and ozone depletion potential, some can cause serious environmental impacts. It also requires very careful inspection to first find out a leakage in its early stages, later locating the leakage itself is a challenging job especially if it is inside condenser or evaporator. Important issue with chillers’ evaporators and condensers is the erosion of refrigerant and water channels not only due to corrosive property of refrigerant but also due to a long term significant temperature fluctuation which in presence of the extra corrosive dissolved minerals in water simply forms limescales and masses attached to the pipes and tubes and can even block lines in condensers. Similarly in water cooled systems, the water used in cooling tower is continuously warmed up and cooled down, if not proper precautions are taken, water can form limescale inside condenser units or cooling tower, not only might significantly decrease cooling tower’s efficiency, but might completely block it. In thermal expansion valves the pressure formed by the sensor at very end of evaporator might not always be accurate to control refrigerant flow, to make sure that least liquid refrigerant is allowed into compressor. Maintaining and controlling the correct pressure at both side of the controlling membrane which regulates valve opening is a challenging job. Space requirement for compression chillers is another issue, especially with water cooled systems, which requires additional cooling tower, while air cooled systems requires less

— 62

area and are easier to install too. Similarly, there are a lot of other issues with other mechanical parts of the compression chillers like minor problems with chilled water radiators inside homes, offices or industrial compartments to be cooled, with plumbing of both chilled water loop and condenser loop, with water pumps used to circulate the water in these loops, and etc. These problems are easy to discover and solve compared to problems in refrigeration loop.

RECOMMENDATIONS Compressor as the main mechanical unit of the compression chillers consumes most of the energy required by the entire unit. Operators must ensure that this part of the system is performing efficiently. Continuous monitoring of the compressor could be one of the measure to take for checking any deficiency in performance. It is also important to notice that most compressors do not support easy routine inspections, simply there is no way to inspect them, as discussed in previous sections some are even not able to open. So one way is to consider design modifications to support routine inspection (achrnews, 2005). As discussed previously oil in compressors lower easily and can cause inefficient operation of it. To detect any potential fault in oiling system of the compressor, the oil level should continuously be monitored and checked daily, further the additional routine oil supply of the compressor should be noted every time the compressor oil compartment is refilled, the refilled amount should be cross checked with manufacturer’s guide and design specification to detect any potential

fault in the system. Condenser medium of cooling has its own design requirements as well as operation restrictions, making it hard to generally recommend one. There are always pros and cons with each alternative, a logical trade off can be done considering the restriction and concerns of installation and operating a unit. If life cycle cost of refrigeration and operation costs are matter of concern, the proper option would be to use water cooled system, because in long run water cooled condensers consume less energy than air cooled system due to the fact that water cooled system do not need continuous air blower run by electricity. However, water cooled systems require more initial investment because of numerous pipe installations and the water tower itself. On the other hand if water cost is a major concern, then using an air cooled system is the proper option, because of water losses in water tower due to evaporation or leakages. Initial cost of air cooled system installation is many times less than that of water cooled, because it requires fewer supporting units and plumbing, also its installation is faster and easier. In air cooled chillers, it is also possible to separate the condenser section entirely and put it outdoors, away from the chiller to increase efficiency and performance of condenser. (Miller, 2017) As it is vivid the general procedure by which a compression chiller functions is the proper absorption of heat by evaporator and releasing by compressor. In most compression chillers where both these units are manufactured very close to each other it is a must to

insulate them properly, one might argue that may only insulation of evaporator is needed because this unit absorbs energy from water coming to be chilled and it is necessary to insulate the evaporator to avoid unwanted heat absorption from surroundings of the evaporator, but indeed it is also important to insulate the condenser too, due to the fact that condenser actually hosts high temperature refrigerant and can simply dissipate heat to surroundings easily and in some cases it can directly affect the evaporator and may cause evaporator to capture the dissipated heat this is specifically true when evaporator and condenser are manufactured in single unit close to each other. Generally talking, it is necessary to insulate properly both the condenser and evaporator. On the other hand if the condenser is sufficiently outside that its dissipated heat does not significantly warm up surroundings of evaporator, it would be beneficial to remove the insulation of the condenser to make it easier for the system to get rid of unwanted heat in refrigerant. It is important to mention that all manufacturers currently are aware of this issue and to a very high extent this concern has already been addressed. The water used either in condenser loop or chilled water loop should be initially tested for presence of unwanted corrosive hard minerals which can simply form around the pipes and cause clogging. This can simply be achieved by sampling the water and testing it, if high concentrations of these minerals are detected the water should be replaced and pure water should be charged back into the system.

63 —

— 64

Even without presence of these minerals, it is

loop, and condenser loop. The four main

important to regularly replace chiller waters,

part of the compression chiller are principally

because no matter how precisely a chiller

working in refrigerant loop, while condenser

system is maintained it is always possible

and evaporator shares it with condenser and

for water to corrode the steel pipes due to

chilled water loop respectively too.

dissolved oxygen and mix the fine corrosion

Compressors

particles with itself, consequently decreasing

compression chillers, they are also highly

the efficiency of the relevant loop, and the

responsible for most of the power consumption

entire chiller system too.

of the system, thus making them most

CONCLUSION

vulnerable part of the system too.

are

main

drivers

— Laura Garcia Rios of

the

Laura Garcia Rios is currently making a master focus on Sustainability and Resource Efficiency (M.Sc. REAP) and working as a tutor and research assistant in HafenCity University, Hamburg. She is graduated from Los Andes University from Colombia with B.A. Economics. Her main professional focus is business development and economic consultant of environmental and social projects.

compression

Despite all operation challenges there are

chillers principally uses the high capacity of

specific measures to take in order to optimize

refrigerant’s latent heat of vaporization and

the chiller’s operations which are discussed

phase change to extract heat from one location

as recommendations in last part of this paper.

to another one, leading to a cooling effect.

Generally, best recommendation for proper

Main components of compression chillers are

operation of compression chillers is to make

ABSTRACT

electric bus for Bogotá even thought is a big

compressor, condenser, thermal expansion

sure that compressor is working well, and 98%

This report studies the benefits of switching

challenge; the electric bus could contribute

valve, and evaporator, while there are other

of the times compressor fails because of other

from diesel buses to electric buses for the

parts as well like cooling tower, chilled water

parts of the system not functioning properly,

Bogotá public transportation system. The

circuit water pumps and several other.

so concluding to the fact that best operation

report provides a descriptive analysis of the

There are three main cycles in compression

can be ensured by proper servicing of all

electric buses in the public transport system

chillers, the chilled water loop, refrigerant

other parts of the system too. —

mentioned

previously

and how the technology of electric buses has been developed in the different markets during the last decade. In continuance

APPENDIX

with the study, the benefits that bring by the replacement of the current vehicle fleet with electric buses in the public transportation system in the city of Bogotá are evaluated, in environmental, economic and social terms. Finally, taking into account the descriptive analysis results and the results from the specific case of implementing electric buses in Bogotá, the report finalizes with a discussion

significantly in the Bogota’s inhabitant life quality, especially with improvements such as emission reduction and lower noise level. According to Eurostat European Environment Agency calculations, all sectors have reduced their emissions except the transportation sector; countries such as Germany have reduced their emissions in all sectors by 27 % between 1990 and 2015; however, in the transport sector the reduction has been only 9.8 % (EEA, 2017). The transportation sector is the second largest source of CO2 emissions

from energy use. In 2012, transportation emitted around 10 Gt CO2e and consumed

half the world‘s oil consumption (ICCT, 2012). CO2 emissions from the transportation sector have increased faster than emissions from

and conclusion about the city for future

other sources over the past two decades.

assessments. The main conclusions drawn

Greenhouse gas (GHG) emissions from

by the proposed evaluation process is that the

buses for the year 2015 are forecast to be

65 —

around 700Mt of CO2, with a 50% growth rate expected by 2030 (ICCT, 2012). Using electric buses could further reduce GHG emissions. Nevertheless, the actual data shows that the number of buses, especially in developing countries, is growing rapidly (Frost & Sullivan Report, 2013). It is expected that more than 80% of the buses in 2020 will be acquired in developing countries (Frost & Sullivan Report, 2013), and Colombia is not an exception, where from 2013 to 2016, the buses fleet increased with diesel buses by 53% (Bogotá Mobility Observatory, 2017). Bogotá, the capital of Colombia, is the largest regional economy in Colombia, generates more than 26% of the national GDP and is the third most populous city in Latin America. According to the UN-HABITAT 2012 report, in Latin America, there are 8 mega-cities and Bogota is one of them with almost 8 million inhabitants. In order to process economic dynamics and to attend the needs of its inhabitants, a mega-city has to meet high demands of environmental goods and services, which leads to large amounts of waste and emissions, high financial costs and high impact for human health, undoubtedly generating negative impacts on the environmental, social and economic level. Currently 5,000,000 people, or almost 70% of the city‘s commuters, travel each day by diesel bus. It has been estimated that mobile sources are the main cause of air pollution in major Latin American cities, particularly those located at a high elevation like Bogota, with an annual CO2 of 15.9 million tons, of which 44% is due to transport. SO2, NOx, TSP, CO,

— 66

HC, O3 are some of the prominent elements of its air composition, with a 75% presence of particulate matter, especially PM10 and PM2.5. Similar to other cities, Bogotá can improve its current situation by deploying electric buses in the public transportation system. According to the Automotive District Institute, of the 90,000 mobilized vehicles located in the city of Bogota, approximately 24,000 are public transport buses. The main objective of this research is to analyze the social, economic and environmental impacts and benefits of replacing the current buses with 24,000 public transportation electric buses, considering assumptions that facilitate the study and with the goal to answer the following two research questions; the first one collect information about the main technologies and the global market of electric buses and the second one considers Bogotá as a case study.

RESEARCH QUESTIONS — What are the main electric bus technologies used in the last 10 years in the public transportation sector and how efficient are the electric buses technologies compared to other technologies available in the market? — In Bogotá case, how is the current situation of the city bus fleet, and what are the main benefits in sustainable terms if electric buses are implemented in the public transportation system?

public transport are described. This section summarized information about what the main electric bus technologies used in the last 10 years in public transportation system are, how efficient the electric buses technologies are, the global market for these technologies, and challenges for the future. The second section is the Case Study Evaluation Process, where the benefits of implementation of electric buses in the public transportation system for Bogotá in sustainable terms are estimated. It continues with the evaluation process: a social, environmental and economic level is considered in this section to evaluate the main challenges and benefits at those levels. At the environmental level, CO2, VOC, NOx, PM10 measures from the local environmental observatory are the primary reference. In the economic level comparison of profitability between different technologies including the initial costs, the energy consumption of the electric buses vs. diesel are studied based on the actual prices of the same bus brand. The difference in the national taxes and local fees of a new electric bus fleet vs. a diesel bus fleet and local fuel prices are also taken into account as an assumption for this process.

METHODOLOGY In order to answer the this study is divided into section is the Analytical market and the electric

research question, 3 sections. The first Process, where the bus technology in

Figure 1: Alternative Bus Technology..

The Prescriptive Process, in which critical results, recommendations and challenges are given based on the analytical and evaluation process results. The analytical and evaluation process of this study collect and analyze data based on available information from reliable research projects. The first process is based on numerous documents, however this information is provided by the main bus producers, the main international technical reports and researchers, such as Fraunhofer or ZeUs (Zero emissions Urban bus System) who evaluate the economic, environmental, societal feasibility of electric urban bus systems through operational scenarios across the world. The market research analyses and technology analyses are based on the Frost&Sullivan Research‘s Reports. For the second process, the evaluation is based on prior studies published by the main Colombian Research Institutes and the university leading mobility research. This is due to the fact that since the eighties, the organization of urban transport is a municipal responsibility; the data collection for second process is made through the database of

67 —

the IDU (Urban Development Institute of Bogotá), Secretary of Mobility of Bogotá, Environmental observatory of Bogotá. Furthermore, publications provided for the environmental department from los Andes University focus on mobility emissions and the study “Low carbon technologies can transform Latin America” from Inter-American Develop Bank (IDB) guide for the sustainable evaluation process. This chapter covers technical details related to buses specifically the aspects of charging, energy storage and propulsion system as shown in the figure 1. According to the last ZeUS report, the electric bus can come in different forms, depending on the type of technology used to produce the bus. In contrast with the hybrid or the diesel buses, the electric bus refers to a motor road vehicle emission free at the point of operation, because the battery driven that the buses use to have a lower environmental impact than an internal combustion engine system (2017,

Figure 2: Battery Technology Roadmap.

— 68

ZeUS Report). As is shown in the Figure 1, the electric bus is composed of 3 important technologies: the charging infrastructure, the energy storage system and the propulsion system.

THE CHARGING INFRASTRUCTURE The charging infrastructure can be categorized as one of three types. A plug-in, which refers to the relates to the direct charging, inductive charging, where the bus is charged wirelessly by creating a magnetic field between two inductive plates and overhead charging, that uses the same method that has been applied by trolleybuses since the „Electro motor”, which was the world‘s first trolleybus in Berlin, Germany, 1882. Surprisingly, nowadays the overhead charging is the most expensive system due to costly investment in the city infrastructure.

ENERGY STORAGE SYSTEM The energy storage system can be categorized

Function

Electric Bus

Diesel Bus

Energy source

Battery

Diesel tank

Replenishing energy source

Charger

Diesel pump

Mechanical energy generator

Traction motor

Diesel engine

Speed and acceleration control

Electronic controller

Mechanical carburetor

Power supply accessories

Electronic power converters

Alternator

Regenerative braking

Motor/Generator

CO2 with heat recovery

188

252

(kg/MWh)

Table 1. Equipment comparison between electric buses and diesel buses.

under 3 types of mature technologies. First, ultra-capacitors, which work by mechanically separating the negative and the positive charges on two parallel plates, and connects them electrically via an electrolyte (Fraunhofer, 2014). Compared to batteries, Ultracapacitors have a longer life cycle (Urban Foresight et al. 2014), have a higher power density can be charged and discharged within a shorter period, however these systems are only able to store 10% of the energy that the best battery technology can. Batteries are the most common storage system used, and can currently be found in types of such as Pb, NiCd and NiMH, which are considered mature technology in the following battery technology road-map, figure 2. Other types such as lithium-ion (Lis and Li air) are the most innovative batteries but are currently still in development (Meisenzahl, S., P.-P. Sittig, and M. Höck. 2014). In conclusion, batteries have a broader market and due to the difference in cost, energy density, weight, lifetime, power density, selfdischarge and recycling, it cannot be said that one is better than the others because it

depends on the usage and market maturity, as shown in the figure 2. The third type of energy storage system is fuel cells, which in comparison to batteries need a continuous source of fuel and oxygen to sustain a chemical reaction. Hydrogen has the highest energy density available, but hydrocarbons or alcohols are also suitable as fuels. This type of energy storage system has a low energy density and as a consequence, requires large fuel tanks and has a longer response time. Fuel cells have a high conversion efficiency of fuel to electrical energy, a low noise emission, and almost no greenhouse-gas (GHG) emissions. However, fuel cells are more expensive due to the high price of the main raw material: platinum and palladium. (Fraunhofer, 2014). Fuel cell-powered buses continue to be demonstrated in public transport services around the world. In the last 10 years, demonstration projects have been launched in various stages of implementation. Many have been finished, and some of them are still on process. (Zlatomir Živanović and Zoran Nikolić, 2012).

69 —

— 70

PROPULSION

propulsion system with the electric propulsion

Electric and electric buses. This is followed by

(Albright, Edie, and Al-Hallaj 2012). On the

A Propulsion system refers to the technology

system. Hybrid buses are further classified

the advantages and disadvantages of each

other hand, diesel, CNG, and hybrid buses

into the following segments according to their

segment using data from different research

have higher maintenance requirements and

drive system configuration: the hybrid series,

studies. Although much evidence can be found

costs (Noel and McCormack 2014). Diesel

where the internal combustion engine is solely

to support the benefits in terms of sustainability

maintenance includes frequent oil changes,

connected to the power converter in order to

of electric buses and it is well-established in

filter replacements, periodic tune-ups, exhaust

charge the battery and to propel the electric

the literature that the use of electric buses

system repairs, water pump, fuel pump and

engine, the hybrid parallel which connects

will bring down the overall Greenhouse Gas

alternator replacements, among others.

both engines to the power transmission and is

(GHG) emissions (IEA 2012), the diesel buses

Even though prices can vary within the same

called parallel because the bus can work with

continue as the leaders of the market. This is

segment, as is shown in the comparison

one or both at the same time, and the hybrid

attributed to a mature technology with a well-

table 2. electric bus prices are, on average,

combined, where both other types of hybrid

established supply chain and competitive

5.2 time higher than CNG and diesel buses,

drives are combined connecting the internal

pricing which makes the electric buses not

and electric buses on average can cost 20%

combustion engine to the transmission,

attractive for the consumers. Electric bus

less than a hybrid bus because hybrid buses

helping to recharge the battery, and making

prices are the highest when compared to the

combine 2 types of power source (Electricity

this technology more complex compared to

other four segments, mainly due to battery

& Fuel). Nevertheless, diesel, CNG and hybrid

the hybrids systems (Shen, C., P. Shan, and

costs, the complex design of power train

buses prices as well as electric buses prices

T. Gao. 2011.)

systems and nascent technology. (Delucchi

have been reduced since 2012. On the

2001) (Noel and McCormack 2014).

other hand, the operating costs of the electric

Related to maintenance, electric buses are

buses are less when compared with internal

the segment that has fewest moving parts,

combustion system buses (CNG, Diesel,

making their design the least complicated

Hybrid) due to lower maintenance, cheaper

amongst the four buses segments. Electric

power, and higher fuel efficiency. However,

buses have controllers and chargers, which

the high initial capital costs of the electric bus

are in charge of managing power and stored

and its charging infrastructure make them

energy levels in the battery. Apart from that,

expensive (Global Green Growth Institute

there are no other electronic devices with

2014). Van Hool completed data collection

moving parts and almost no maintenance.

and analysis on nitrogen oxides (NOx)

The batteries used by the electric buses

emissions and Particular matter (PM) of 3

require minimal maintenance and in some

different fleets of buses for 50.000 km per year

cases is better to replace the whole piece

with an average speed 20 km/h, and is shown

that produces thrust to push an object forward. It can come as a motor, hybrid or pure electric type. The motor is the most common and mature technology used around the world. The first commercially successful internal combustion engine was created by Étienne Lenoir around 1859 (Encyclopedia Britannica, 2013). As is showed in the table 1, the equipment between electric buses and diesel buses vary depending on its function, in electric buses the equipment motor/generator take over the function of regenerative breaking, a highly efficient process. While the energy from this process in diesel buses is essentially wasted, in electric buses it saves an energy consumption of approximately 30%. Furthermore, some of the difference in function

BUSES TECHNOLOGY COMPARISON

of the equipment represents the difference in

This section showcases a comparison

efficiency, maintenance, costs, noise, etc. as

matrix among four segments and collects

explained in the comparison section. Hybrids

information from different technology analyses

combine the internal combustion engine

illustrated in the table 2: Diesel, CNG, Hybrid

Parameters

Electric Bus

Hybrid Bus

CNG Bus

Diesel Bus

Power Source

Electricity

Electriicity + Fuel

CNG

Diesel

Power Generator

Battery

Internal

Combustion

Engine + Battery

Engine

Enery Losses

1.02k Wh/km

3.640kWh/km

Investment Costs

5.2 x

6.4 x

Fuel Efficiency

10.2 km / l

1.9 km / l

1.4 km / l

1.6 km / l

Fuel Cost

0.13 € / km

Emissions

zero

low

Noise

minimum

low

Maintenance

low

high

Bus Technology

NOx (per year)

PM (per year)

high (baseline)

100 Diesel Euro III buses

65.5 tons

1.25 tons

high

high (baseline)

100 CNG buses

25 tons

0.25 tons

high

100 Hybrid fuel cell buses

zero

0.17 - 0.22 € / km 0.17 - 0.27 € / km

Table 2. Comparison of different parameters and Bus Technology

0.2 - 0.31 € / km

Table 3. Main parameters matrix among the segments comparison..

71 —

— 72

in the table the results presented; while hybrid

98.3% of the world market. This development

electric buses in 2016-2017, half of them to

Latin-American is expected to have the 21% of

fuel cell buses have zero nitrogen oxides and

is attributed to a strong Chinese government

be fully operational on the day of the COP22

the share of the global urban buses. Europe

zero particular matter, the CNG buses emit 25

policy, with an official program for ‘new energy

climate change conference in November

and North America are only expected to be

tons of NOx and 0,25 tons of PM per year and

buses’ that is looking to produce 1.67 million

2016. In Latin America, it is the same case

part of the market at 8%, with growth rates

the same bus fleet of Diesel segment gives

electric buses and expected to create 1.2

as African development and research: taking

smaller than other regions. Hybrid and electric

approximately 3 times NOx and PM of CNG

million jobs annually for the period 2010-2020.

slow steps and the biggest development has

buses producers like Yutong, Wuzhoulong,

buses emissions.

(ZeEUS eBus Report, 2016).On the other

been done in only a few cities, where there are

Foton, Kinglong and BYD Volvo, ADL and

hand, although the European market is one of

some ongoing pilot projects, like Campinas

Daimler are currently leading the global

the leading regions for electric bus research

(Brazil), Montevideo (Uruguay) and Bogota

market, producers that are primarily from

and development, the Asia-pacific region

(Colombia). (Global Green Growth Institute,

China. (Global Green Growth Institute, 2015)

is the biggest producers of both buses and

2015). On average, the additional cost for

According to Frost &Sullivan data, this market

batteries. Additionally, the infrastructure for

a hybrid bus is in the range of $ 100,000 to

has not been explored completely at a global

charging electric buses is currently weak

$ 150,000 and for an electric bus is from $

level. More than 250 BRT are currently under

in many countries, restricting the growth

250,000 to $ 300,000. According to the ZeEUs

planning, which proves the potential of the

of the electric bus market. (ZeEUS eBus

report, in 2010 about 16 million buses is the

new technology buses. Hybrid and electric

Report,2016). In Africa, even though it is the

number of operating buses, and this number

buses are projected to fill the market with

smallest share in bus production, Marrakech

is expected to grow to 18 million buses in

27,000 units, or a 20% annual rate. In 2012

ELECTRIC BUSES WORLDWIDE The operating costs and the capital cost per bus vary greatly between regions; an electric bus purchased in China is in the price range of a conventional diesel bus in North America or Europe. Additional costs as a percentage of hybrid and electric buses are much higher in low-priced markets such as China, India and Russia, and much lower in high-priced markets such as Europe or North America.

is developing a market with the Morocco’s

The worldwide electric bus fleet is estimated

2020, and to 20 million buses in 2030. In

this percentage was just 6% or 8,000 units

Energy Investment Company (SIE,) where

to have reached approximately 173,000 units

2010, China, South Korea, United States,

sold (Frost &Sullivan, 2014).

launch electric buses were produced in 2017

in 2015 where China is leading this global

Russia, and India were the countries with the

for local and international markets. Marrakech

ELECTRIC BUSES FOR BOGOTÁ

new market, with about 170,000 buses, or

largest operating bus fleets, with 17%, 12%,

has also announced the distribution of 30

6%, 6% and 4% respectively. For 2030, China,

Bogotá Background

India and Korea are expected to be the three

Bogotá is the capital of Colombia and is

leading countries with the largest bus fleets.

located in the geographical center of the

In 2020, 300,000 buses are expected to be

country, in the natural region known as the

sold, and the following figure shows the main

Savannah of Bogota, on the plateau of the

regions of buses consumers. (ZeEUS, 2016).

eastern Andes mountain range. The city has

Asia and Oceania currently have 71% of the

a temperate climate, slightly humid, constant

worldwide bus production and just China is

almost the whole year. Temperatures regularly

expected to have 26% of the global market

range between 5°C and 20°C, with an annual

with 70,000 buses units in 2020. It is proof how

average of 14°C. The city has a height of 2600

China is not only the leader in production, but

meters above sea level. It was founded on

will be also be the leader in implementing

August 6, 1539, in times of conquest. In terms

buses for its local public transportation system.

of economic divisions, in Bogotá there are

The Americas have only 13% of the global

more than a thousand neighborhoods with six

production, inside the region the biggest bus

different strata. The highest strata are located

production is in North-America. However,

in the north and northeast, in residences and

Figure 3. Worldwide bus production by region (2011-2013).

Figure 4. Forecast Global Urban Buses Market 2020.

73 —

— 74

apartment buildings surrounded by wooded

moment. The consumption per transport went

the general population of the city of Bogota,

constitutes a public health problem (Harris,

areas and numerous parks and playgrounds.

from 5,040 Gwh/year in 2000 up to 8,242 Gwh/

the requirements and necessities of the users

1985), and the levels of pollution in Bogotá

The neighborhoods with smaller strata and

year in 2012. (Municipality Bogota, 2012).

as well as mobility behavior. The success

are alarming, according to a study carried

where the greater part of the population lives

In terms of environmental impact, the transport

of electric mobility products depends on the

out in streets where the largest number buses

are located to the south and the south-east.

sector in is responsible for 15% of total CO2

fulfillment of users’ expectations (Pierre et al.

transit. It affirms that the noise levels found are

The middle sectors usually inhabit the central,

emissions in the country, meaning 26M tons

2011, Sammer et al. 2008). However, other

considered high levels within the framework of

western and northwestern portion of the city

per year and depends entirely on fossil fuels

indirect impacts that are not perceived for

the institutions that have dealt with the world-

(DANE, 2016). As a result of poor urban

(diesel). Bogotá is not the exception, where

the inhabitants must also be considered.

wide issue, such as WHO and EPA. The main

distribution, the population has to constantly

the transportation system depends 100% on

Altering the vehicle fleet from diesel to electric

avenue of Bogotá reaches levels considered

move to long distances to access their

fossil fuels, its emissions are 6M tons of CO2

technology will bring benefits to Bogotá in

a public health problem, with probable

workplace, according to the study prepared

per year, 1,400 tons of particulate matter,

terms of air quality, noise level, and public

hearing damage on the population most

by the Bogotá Mobility Observatory, based

54,000 tons of NO2.

health. The highest impact for the inhabitants

exposed to it and even other physiological

is related to the air quality, people in any city,

and

generally care about air pollution only when

González, 2011).

it affects them. When diseases result from

Environmental Evaluation

on the District Mobility Department. The main reasons for traveling are: To the residence, work and study with 43.9%, 25.1% and 13.7% of the total trips made in the city respectively in 2009 (Municipal Bogotá Mobility Observatory, 2012). The city is in constant growth, as a result not only of its own evolution but also of the migration and the displacement of the population due to internal conflicts within the country. At present, it has more than 9.4 million inhabitants, this growth has been uneven and there is urban disorder and a lack of goods and services. Despite this, the capital is notable for its large number of cultural activities In Colombia, the transportation system consumes 38% of the primary energy, and it is expected that by 2030, the energy demand for the transportation sector will increase by 2.2 times. In Bogotá the energy consumption of transport in the last decade seems to be fluctuating, although increasing. This would be associated with, among other things, population, economics, urban growth

Sustainable Evaluation Sustainability has been commonly defined most

often

“Economic

and

social

development that meets the needs of the current generation without undermining the ability of future generations to meet their own needs“ (WCED, 1987). This study focus on the second research question by evaluating the impact of deploying the current bus fleet with electric buses in the public transportation system instead diesel buses, bringing together the three pillars of sustainability; environmental, economic and social development. The following section summarizes prior research in the field of technical tests and studies from the main local institutes and data collectors. For the environmental evaluation, the benefits and impact are estimated based on prior calculations and the economic evaluation is based on financial analysis of the initial investment of the electric bus and the energy consumption.

the pollution on the other hand, as the public health system is funding by national budget, every cost of healthcare associated with these illnesses will in the end affect the inhabitants. This study does not present any information related to number of cases of diseases results from the pollution in Bogotá, due to the lack of data research in this field. However, air pollution is one of the major contributors

psychological

problems

(Ramírez

According to the Bogotá environmental observatory accounts and research made by Los Andes University where the emissions criteria (CO, NOx SOx, PM10, COV) and (CO2,

N2O, CH4) for every vehicle category were estimated, the buses presented the most critical results, and is the category with the biggest contribution to the total emissions in the city. Buses contribute in a high percentage

when it comes to health and life quality in the

of many pollutants: around 30% of the CO

main urban centers around the world. It has

emissions, 40% of NOx emissions, 40% of

been estimated that mobile sources are the

SOx emissions, 50% of PM10 emissions and

main cause of air pollution in major Latin-

20% of CO2 emissions. However, the situation

American cities, particularly those located

is even more critical, considering that buses

at high elevation such as Bogotá (Project,

represent less than 5% of the city‘s vehicle

2017). During the last few years, Bogotá’s air

fleet (Montezuma, R., 2005). According to the

quality has been continuously deteriorating,

same data, in Bogota, the buses contribute

showing noncompliance with air quality

half of the total PM10 emissions, which is

standards. Mobility being one of the top

one of the most harmful pollutants in terms

contributors in it, with its usage of bad quality

of public health (Neuberger et al., 2004). The

and motor vehicle growth, which has varied

Social Evaluation

diesel has resulted in major respiratory and

large share of this category in CO emissions

according to the circumstances of each

The social evaluation considers the benefits of

stress disorders (UNICEF, 2017). Noise also

(30%), is proof of the presence of a significant

75 —

— 76

number of buses that use gasoline as fuel. It is common in many countries, that most vehicles in this category use diesel as the main fuel (Sawyer et al. 2000). In Bogotá, 100% of public transportation buses use diesel as a fuel. (STT Annual Vehicle Report, 2014). It is clear that the quality of the diesel in Bogotá must be improved. According to the latest report of the Bogotá Mobility Observatory 2016, the problem lies in the quality of the fuel used by buses in Bogotá: the fuel contains 1500 ppm sulfur, a higher content compared to other levels in Latin America where cities like Santiago de Chile have only a sulfur level of 50 ppm. This is a serious problem considering that there is a direct relationship between sulfur content in diesel and PM10 emissions. (Durbin, 2003) Actual vehicle Fleet Emission The are models for estimating emissions from different sources, the most used being MOBILE and COPERT, developed by the United States Environmental Protection Agency (USEPA) and the European Environmental Agency (EEA), respectively. The main drawback of these models is that the emissions estimations for different cities, is influenced by conditions and characteristics that each place has in vehicle emission factors. In 2003, the International Vehicle Emissions Model (IVE) was developed, and

since then it has become the most common model used in cities in developing countries. In the case of Bogotá, the inventory of vehicle emissions was carried out with researchers from the University of California and the International Center for Sustainable Systems Research (ISSRC) using the model (IVE).To estimate emissions per day in this study, the results from the ISSRC research were taken into account, and the fleet increased values and the share were used as assumptions, the distance traveled per day was updated with the 2016 size of bus fleet, which is most recent data from the mobility department of Bogota. Taking into account that in Bogota, the buses fleet totals 24,400 and in a year, the buses travel 18.330.000 km (STT,2014), Assuming that the vehicle fleet has increased with the same share, the CO2e emissions have been estimated for the complete buses fleet from Bogotá: 24,400 buses from different categorizes (size, technology, fuel and age). The total emissions for buses for a year are about 866k metric tons of CO2 per day. CO VOC, NOx, PM10 were also estimated.

thermal source for the environment, (CREG,

models, looking at the power supply to

2016). This is a great advantage for a country

massive electric transport systems. The results

whose public transport works with fossil fuels

show that is possible to develop the necessary

and generates unfavorable environmental

infrastructure and reach the energy demand

impacts. Professors such as Mario Rios

for an electric charging system. This is due

from the electric engineering department

primarily to the fact the maximum demand in

in Los Andes University, who focuses his

Bogotá is around 2,500 megawatts (MW) and

research on massive transportation systems,

the power demand of consumption would

affirms that the electric public transportation

be around 20 megawatts in peak hours,

system, is much faster, more comfortable

which indicates that it would not be a very

and safer: „As a citizen you need a mass

high requirement to reach, even if it implies a

transit system to guarantee these three

change in the redistribution of energy since the

conditions to stop using the private vehicle.“

existing substations located on the planned

He also points out that from the point of view

route are with little capacity available, ie at

of electric supply and demand, there is no

full load. Secondly, the company Codensa

impediment to establishing it. Codensa, which

has the capacity to make this redistribution.

ENERGY SOURCE AND FEASIBILITY According to the Energy Generation Commission Regulation (CREG) in Colombia, 70% or 80% of the energy generated is hydraulic, and non-polluting. The rest is produced with natural gas, the least harmful

Total Buses (2016)

km / year

km / day

VOC

NOX

PM10

24.440

1.833.000.000

5.021.918

866

Table 4: Current vehicle fleet emissions estimations.

is a Colombian company, dedicated to the distribution and commercialization of electrical energy, reaches 108 municipalities within Cundinamarca (state of Bogotá) and covers 100% of the capital of the country, “is technically and humanly prepared to implement it, knows what technology is needed and how much

Finally as was previously mentioned in this document, these buses have a technology called regenerative braking, which allows to use the energy generated in braking, saving the energy consumption approximately 30% (Rios, 2016).

electrical power will be demanded. The

Economic Evaluation

only thing that is required is to carry out the

For the economic evaluation comparison of

electrical planning of the distribution network

profitability between different technologies

once the specific points of location of the

including

traction substations are known“. (Rios, 2016)

consumption and the maintenance costs of

In addition, technical analysis have been

the electric buses vs. diesel are studied. The

carried out with distribution planning systems

study is based on the bus model Volvo 7900,

Buses Prices 2016

the

Diesel Bus

initial

costs,

the

Electric Bus

€

Vehicle cost

86.5

96,000

94.1

383,000

National taxes and fees

13.5

15.000

5.9

24.000

Total Cost

100.0

111.000

100.0

407.000

Table 5: Buses technologies prices comparison

energy

77 —

— 78

as it is the same brand and capacity that is

performance of an electric bus in Bogota

development in this field, however cities located

advantages in prices, such as diesel buses.

currently used by the bus fleet of Trasmilenio in

of 12m is 0.88kWh/km while for the case of

in Latin America and Africa are potential clients

For this reason, is indispensable that there

Bogotá (Transmilenio; Public transport system

diesel buses performing the same routes

for those markets. In the second section, this

be the investment of national authorities, in

of Bogotá) (Colombia Transport Ministry

the average performance was 7.3 km/gal.

paper explored the current situation of Bogotá

research and the implementation of legal

2016), Even though the current bus fleet varies

Thus, the electric bus price per km traveled

in order to estimate the impact. Changing

instruments that incentive the implementation

in technology and equipment, in order to

is EUR0.09 while a diesel bus is EUR0.27

diesel buses for electric buses would represent

of clean technologies. On the other hand,

simplify this study, the estimation assumes a

in Colombia. Considering that in Bogotá the

a significant impact, in environmental and

the sales of electric buses is very small

bus fleet of 24400 Volvo 7900 12m vehicles.

current bus fleet (24400 buses) is changed by

social terms, attributed mainly to the high

compared to those of conventional fuel-based

the electric bus model Volvo 7900 and keeping

level of emissions and noise that the public

buses. Despite the fact that we are in an era

transportation system represents. The electric

of globalization, it is difficult to enter a new

bus fleet would benefit not only the users of

country‘s market due to the large requirements

the transport system also the inhabitants of

requested by the national authorities to

CONCLUSIONS

the city, who are currently affected by the

introduce a foreign product to the local market.

compare these two technologies in Bogotá,

The objective of this study is to collect

emissions and noise level, especially in the

Worldwide, there are just a few electric bus

the national taxes were included in the prices.

information about the main technology, the

main avenue where the diesel buses operate.

manufacturers. Only large companies such

In the case of diesel, the national taxes

global market of electric buses, the efficiency

In economic terms, it was found that to offer

as Volvo or Siemens have been able to invest

of those buses technologies compared to

the same service, the city would need to invest

in electric buses developments, and those

diesel buses technology available in the

approximately EUR407,000 including national

market and analyze the social, economic

fees and taxes, meaning 4.2 times the prices

and environmental impact and benefits of

of the current diesel buses.

Investment Price According to the Volvo Price catalog 2016, the Volvo 7900 bus costs approximately EUR383,000. While the same capacity Volvo diesel bus costs EUR96,000. In order to

represent approximately 14% of the total value of the bus, and for electric buses the only 6%. This is due to the national benefit taxation for a clean energy conversion project. Fuel tariff and efficiency. According to the Ministry of Mines and Energy of Colombia, the price of diesel fuel in the capital is approximately EUR2.24/ gal, which is in the average when compared to other cities in Latin America (World Bank

the same distance traveled per day (5 million km per day), this change will represent a savings of more than EUR924,000.

replacing the current public transportation electric buses that are operating in the city. In the first section of this study, the only parameter from the parameter study in that section that has an advantage over the electric bus is the

Data base, 2016).

cost of the available buses in the market and

Fuel Tariff and Efficiency

their mass adoption. The main reason for the

this is the cause of one of the major barriers in

DISCUSSION

companies get the invest capital with the net income from conventional fuel based vehicles sales. Except for BYD, all other electric bus manufacturers have comparatively small production numbers. As a result the demand

Despite the great benefits in sustainable terms

and supply are currently very limited. In the

of implement electric buses in the public

case of Bogota, there have been very little

transportation system, the simplicity of the

research and consultancies that have work

system, the great technological advances

on the field to determine the requirements of

buses and the cities initiatives in new clean

electric buses implementation that have been

alternatives, it is clear that there is still a long

carried out by academic sources. As such, does not achieve a significant interest of the

According to Codensa reports, the main

high costs of electric buses is the battery cost

way to have a complete electric bus fleet

energy distributor company in Bogotá, the

and that the battery industry has not reached

instead of diesel or CNG buses. This is

local authorities. Furthermore, the city budget

price of energy in 2017 is EUR0.2/KWh, ie the

a mature period. Related to the market and

attributed to the obstacles of each market.

is focused on metro implementation, with

price per kilometer traveled is EUR1.22. In the

the main technologies, China is leading in

Currently, the technologies have not yet

the aim to increase the supply of the public

literature review, only two studies of electric

global mass deployment, with more than

reached a maturation period and require large

transport system. However, the metro project

bus performance in Bogotá have been done,

170,000 buses (98.3% of the global total).

investments that only government entities or

does not aim to reduce the environmental

one from the National University and the

This can be attributed to a successful local

great leaders can realize. Creating a new

impact, reduce the number of diesel buses

second one from the Salle University. Both

policy implementation.

European markets,

market, it takes time and even more when

or change the current bus fleet with clean

studies presented similar results, the average

especially Germany, lead the research and

the supplementary product has absolute

alternative technologies. —

79 —

— 80

— Pia Schnellberger

Pia Schnellberger studied Architecture at the Chinese University of Hong Kong and the Universitiy of Applied Science in Stuttgart, where she graduated. With a professional background in the field of sustainable development of natural and built assets, Schnellberger currently studies REAP at HafenCity University Hamburg. Her focus lays on energy production and supply and sustainable urban development, including practical studies in Kazakhstan and Egypt.

RELEVANCE

INTRODUCTION

The integration of renewables is a highly energetic

In a time of resource depletion, energy from wind power plants is highly discussed as an alternative for fossil and nuclear power and as an opportunity for a sustainable energy supply. Wind energy is one of the technical environmental innovation which plays a role in the ecological modernization of economy (Blazejczak et al 1999). Any innovation in any field – be it in chemistry, economy or technology – implies either “a new idea, method, or device” or its introduction (“innovation” in Merriam Webster Dictionary, 2012). The basic idea of generating energy from wind is several centuries old when wind mills were used to perform mechanical work on site. The following idea of using wind force to generate electricity is a development of the working principle of a windmill: As the wind blows, kinetic energy is turned into rotation energy by the sails of a wind mill. In the next and formerly final step, the energy is translated into

topic – not only technically speaking. Political and public discussions about electricity from renewable sources such as off-shore wind parks bear high dynamics as seen in articles like “paradox energy policy” (original title: “Energiepolitik paradox”; Süddeutsche Zeitung, 2014) or „Bavaria electrified” (original title: “Bayern unter Strom”; BR, 2017). Despite the various opinions on renewable energy within Germany, the energy turnaround requires a growing share of these sources within the near future. Especially the high dependence on nuclear power in the south of Germany draws attention on alternative sources of non-atomic and (almost) carbon-free energy. Whilst the federal government strives for the integration of national renewable energy sources, opposing sides suggest the inflow of gas imports. This background led to the consideration of both energy sources, renewables and gas, not as competing but as complementary elements for the development of a reliable electricity grid.

mechanical work by the working shaft inside the mill. Instead of ending the sequence at the point where mechanical work is performed on site for grinding grains or pumping water, rotation energy can be transformed into mechanical energy which finally generates electricity – and thereby opens the boundaries of stationary energy generation towards the generation of transportable electricity. More than one century after the realisation of the first plants to distribute wind energy (Vindmøllenindustrien, 2003), progress of introducing such technical innovations can be traced in Germany. Facing the energy turnaround and its interim and final goals of increasing the share of renewable energy in the German energy mix and decreasing carbon emissions (BMWi, 2016), the implementation of wind energy (and other sustainable sources such as solar energy and biomass) and its distribution as a technical innovation progressed since 2010. One of the core elements to meet the challenges of the energy turnaround is the development of the national electricity grid – the medium for the implementation of technical innovations. Research Question Two research questions underlay the following chapters of this paper: — What are the recent planning and governance influences on the German electricity grid? — Which technological options can be applied to integrate energy from the North into a reliable German electricity grid?

Scope and Delimitation The title „Energy from North to South“ refers to the national transport of energy within Germany only. Its interpretation in a European context, whereas is not further elaborated in the course of this paper. Systems and technologies for the implementation of grid development plans are reviewed from a technical point of view and form the main body of research, thus related market dynamics and influences are not targeted. Time This paper is mainly based on rather recent environmental and electricity related policies and planning from the year 2000 and ongoing. The technical development and statuses are considered from this date and following as well as future development plans for the electricity grids in Germany and the European electricity market. Methodology Within this paper, the focus lays on the evaluation of the current situation of electricity grids and electricity transmission in Germany with a particular emphasis on the transportation of renewable energy from the north to the south. The main data used within this paper is provided by the official statistical data of the German Government and governmental institutions (such as BMWi, Umweltbundesamt, Destatis). General descriptions and technical specifications from governmental sources and operating companies form the basis for the assessment of the current grid conditions and the identification of weaknesses and necessary improvements. In accordance

81 —

to these preceding results, the application of synthetic gas storages is assessed towards a stable electricity grid in compliance with feed in from wind energy farms. The accumulation of results and findings forms the final statement. Keywords Electricity grid; electricity consumption; supply reliability; power to gas; transmission technologies.

ENERGY TRANSFER FROM NORTH TO SOUTH Any kind change and innovation requires an adjustment of the involved technologies. Over the past years, the German electricity grid reached its limits and stands in close relation with the targeted energy turnaround. Amongst targets such as the integration of renewable energy, the maintaining of a high supply reliability and the realisation of a European energy market, a reworked system for electricity transfer - specifically from the north to the south of Germany - is required. These motives are explained as follows: National integration of renewable energies One of the strongest motivation for the integration of renewable energies in Germany is the energy turnaround which aims, amongst other goals, to move away from fossil fuels and nuclear power (BMWi, 2016). This shift of energy sources can be recognized in a share of 31.7 % electricity from renewable sources in the German electricity mix in 2015; in comparison, renewable sources only provided 6.9 % of the gross electric consumption in 2000 (BMWi, 2017). This growth can be traced especially since the

— 82

inception of the Renewable Energy Act (EEG) which introduced the feed-in of regenerative energy sources into the grid. Despite the high share of electricity from renewable sources on a national level, the respective energy mix shows a different constellation of fuel types on a state level. Especially federal states such as Baden-Wuerttemberg or Bavaria in the south of Germany still provide a relatively high share of nuclear energy for electricity consumption of up to 42% in 2015 which is produced within the states’ boundaries (Destatis, 2016). This circumstance can be explained by the topographic and climatic conditions which differ throughout the country: As one example, the so called “Windhöffigkeit” (a measure of wind frequency and speed) assesses the suitability of an area for wind energy generation. The south of Germany shows a relatively low wind speed in different heights which is rated as rather unfavourable for wind power generation (Koch, 2014). In further context with the energy turnaround, the nuclear power plants, which some of the southern Federal States are dependent on, will be shut down by the year 2022 and make it necessary to find alternative sources of supply of energy (Bundesnetzagentur). Lower energy related emissions for electricity generation In relation to the overall energy mix in Germany stands the share of development of CO2-emissions of the German energy mix. The overall energy-related emissions of the German electricity mix decreased by more than 14% since 1990 (Umweltbundesamt, 2017) whilst the share of renewable energy has

decreased in that time period. The generation

stage procedure as a basis for grid

of electricity with a low carbon footprint can

development plans by several researchers.

lead to a further reduction of emissions, hence

On the basis of the Energy Industry act

be beneficiary for the energy turnaround.

(EnWG), the federal government intends the elaboration of grid development plans

Supply Reliability and European Energy Market

(NEP) by the transmission system operators (“Übertragungsnetzbetreiber).

The reliable supply of energy stands in close

These

NEP

resolve in strategies for a needs-oriented

connection to the previous mentioned points.

expansion of the national electricity grid on the

According to data from BMWi, the reliability of

basis of scenario analyses and projections.

supply in Germany is exceptionally high in an international comparison. In the year 2014, the

Projections of Electricity Demand

overall average of electricity disruption was 14

Different factors affect the electricity demand in

minutes, whereas countries as France, Great

Germany: Demographic changes, the overall

Britain or Canada show three to twenty-five

economy, and the industrial sectors are

times this amount (BMWi). To maintain the

fundamental parameters for the projection of

current standard of supply reliability during

the future electricity demand. Furthermore, the

and after the nuclear energy fade-out, the

development and use of recent technology

integration of all types of energy generation into

such as electric mobility, heat pumps or smart

the grid, especially renewables, is targeted by

appliances and the overall energy efficiency

the government (BMWi, 2016). Furthermore,

matter (Übertragungsnetzbetreiber, 2017).

the common European Energy Market plays

The

a role in the steady provision of electricity with

transmission

system

operators

(“Übertragungsnetzbetreiber”) for electricity

the help of grid developments.

are obligated towards the federal government

PARAMETERS FOR ELECTRICITY GRIDS to assess the overall electricity demand as a IN GERMANY basis for the elaboration of grid development Several parameters are revised in a multiNet electricity demand [TWh]

plans (Netzausbau, 2017). The following

2013

A 2030

B 2030

B 2035

C 2030

Net electricity demand incl. grid losses

543

523

510

513

543

Net electricity demand excl. grid losses

523

503

490

493

523

Thereof electric vehicles

0.4

Thereof heat pumps

Thereof further electric appliances

Reduction of net electricity demand by

-42

-66

-76

-63

further influences (e.g. increase in efficiency)

Figure 1 – Net Electricity Demand in Germany. Table based on data from Fraunhofer ISE, 2015.

83 —

table (c.f. Fig. 1) shows the prognosis of total net electricity consumption for immediate future under different scenarios. A scenario is considered an interplay of the mutual influences of the pace of transformation (regarding the energy turnaround) and the degree of innovation (Fraunhofer ISE, 2015): -- Scenario A. The energy turnaround proceeds with moderate pace and only a limited use of new technologies with a rather low degree of innovation. Furthermore, the build-up of wind energy plants and photovoltaic systems is considered moderate within this scenario. -- Scenario B. This scenario reflects the use of various measures and technologies within the development of new plants and a higher use of electric mobility. Scenario B includes a higher convergence between electricity generation and heat generation with technologies such as heat pumps. Simultaneously, a rise in efficiency for existing electric applications and flexibility in load management are expected. -- Scenario C. The accelerated energy turnaround is represented with an intensive use of new technologies and a coupling of the sectors transport, heat and electricity. Scenario C is also characterised by a high energy productivity of PV systems as well as the use of storage options for energy. The use of electric powered vehicles instead of conventional combustion engines is targeted by the Federal Government which indicates a future shift in the consumption sectors regarding

— 84

electricity, projected to increase the electricity demand (Übertragungsnetzbetreiber, 2017). According to data from BMWi (2017), the transport sector represents the biggest consumer of final energy in Germany with 2.619 PJ in 2015. Currently, 94 % of the necessary energy for the transport sector is mineral oil products, which could undergo a change towards the use of more electricity. This assumption considers the governmental plans of introducing one million electric vehicles by the year 2020 (NPE, 2014) and the public discussions about the ban of diesel powered vehicles in 2017. The counterpart to that development can be found in an increasing energy efficiency which is reflected in figure 1. Despite an increasing use of electric appliances such as electric vehicles or heat pumps, an improvement of electric efficiency can reduce the net electricity consumption overall. Another factor that is responsible for a lower electricity consumption is the use of technical devices such as PV panels and batteries at a household level. This share of decentralized energy production and storage can be (in principal) subtracted from the net electricity demand (Fraunhofer ISE, 2015). At this point, especially the projected electricity demand on a state level is emphasised. For further planning actions, regional changes in energy consumption and energy have an influence on the spatial layout of extensions to the electricity grid (Schlemmer, T., Schmidt, U., & Diebels, W., 2017): federal states such as Baden-Württemberg or Bavaria will have difficulties in covering up to 42% of the former share of nuclear energy for electricity

consumption (as of 2015) with their own

Germany (for a technical description c.f.

resources as a consequence of the nuclear

chapter IV) which improves the supply

fadeout. This regional condition mirrors in the

reliability, but possibly mitigates the idea of a

planned expansion of the grid in north south

European energy market. Another possibility

axis (c.f. Fig. 2).

is the use of interconnectors at the interfaces

Primary Energy Emissions

Sources

and

Carbon

On the side of the ÜNB, market relevant factors are considered to assess the feasibility

between neighbouring grids. Instead of a national storage, any energy surplus could be discharged into the European energy grid and vice versa.

of technologies to be applied. The two factors

Public and Political Challenges

primary energy sources and CO2 prices

Besides concerns of technical nature, regional

(related to carbon emissions) are considered

and political challenges add to the complexity

as influencing factors on the final energy prices

of grid expansion in Germany. The national

(Übertragungsnetzbetreiber,

Market

goal for electric mobility or the entry into force

analysis tools aim to model final consumption

of the new Renewable Energies Act are two

prices, including levies and taxes. Besides

examples for legislative influences on the

financial importance, this approach has

parameters for the development of new grids.

an influence on the timing and amount of

Speaking in a federal context, the policies on

renewable energy fed into the grid (thus

a state level need to be mentioned at this point

influences the choice of applied technologies).

as regional, political strategies which have an

The above-mentioned scenarios consider

influence on the development of renewable

2017).

different impacts of the parameter of primary energy sources and carbon emissions

energy generation, thus affect the regional electricity mix. The required protective distances

(Deutscher Bundestag, 2007).

between wind turbines and residential areas

Technical Challenges

example for a regional regulation which has

or protected areas can be considered as one

With an increasing share of electricity from

a direct influence on the ground potential for

renewable sources like wind and sun,

the economical harvesting of wind energy,

challenges such as fluctuations in generation

according to calculations by the Federal

have

respective

Environmental Agency (Umweltbundesamt,

electricity grid. The corresponding factor is

2013). Political obstacles of this kind can

the intermittency of renewable energy sources

lead to delays in the development progress

which stands in close relation with supply

for building new transmission lines or cause

reliability.

an interruption of the whole undertaking

Two systems are applied to ensure the

itself. Further actions on a state level, such

reliability of supply. One option is the storage

as autonomous actions that do not comply

of electricity surplus for later demand in

with the sense of federal decisions, can have

absorbed

the

85 —

a similar effect. In particular, the example of Russian-Bavarian trade relations is mentioned at this point. In the course of assuring a stable energy supply within its territory, the Bavarian Ministry of Economics agreed in 2012 on a common roadmap with the Russian gas supplier “Gazprom” for future natural gas trade (Bayerischer Landtag, 2014). On first sight, these actions might support the idea of a European Energy Market, but could counteract the federal attempts of improving the German electricity grid: In the early

— 86

stages of the development of a national grid development plan after the nuclear disaster of Fukushima in 2011, such actions might undermine endeavours on a national level in the first place. Besides politic strategies, the public acceptance by the society should be mentioned as a factor that can change the initiated use of technology. Its potential influence on the implementation of grid extension plans is further mentioned in chapter IV regarding the appliance and decision of technical systems. The intended connections of

transmission

(overhead

lines

underground cables) are shown in this map based on

BBPlG

These

and

EnLAG

connections

illustrated

are

schematically

which show the direct link between two intended grid nodes, the routing is defined in respective detailed plans (Netzausbau).

In addition to the ÜNB, agencies such as the Federal Network Agency (BNetzA), the Federal Ministry of Economic Affairs and Energy (BMWi) and the platform for sustainable energy grids are substantially involved in the revision and implementation of grid development strategies (“Netzentwicklungsplan”). The elaborated parameters in the previous chapter, amongst others, have a substantial impact on the composition of the electric transmission system. These were analysed by the ÜNB and are revised in the form of implementation drafts by the above-mentioned federal agencies to form (c.f. Figure 2). In the final step, expansion requirement plans are developed in consensus with all involved parties. The basic transmission and storage technologies which are considered in scenario planning as well as in the final action plans are reviewed in the following chapter.

TECHNOLOGIES DEVELOPMENT

FOR

GRID

Technical Electricity Transmission The above-mentioned acts for a specified grid development plan (BBPlG) and the accelerated expansion of electricity transmission technologies (EnLAG) intend the usage of different transmission technologies for its implementation. In general, electricity can be transferred via overhead lines or underground cables in the form of direct or alternating current. Both types of current have specific features when implemented into the transmission system of electricity which translate on the specifications of used cables, such as quality and dimension.

Figure 2 - Transmission Systems in Germany.

Besides different types of current, the voltages of the distributing grid play an important role for the decision on the deployed technology. The German electricity grid contains four levels of voltage between the electricity generators in the beginning and the households at the end of the supply chain. Extra high voltage in a rage from 220 to 380 kV is used to cover longer distances. At this stage, especially nuclear power plants or coal fire power plants currently feed their generated electricity into the grid. Renewable sources whereas tend to connect with high voltage of 110 kV or medium voltage of one to 50 V to the grid. Finally, households can receive electricity after the last transformation to 400 V or the usual 230 V (DIHK, 2015). Not only is the used voltage of consumers responsible for the different voltage levels of transmission but also the transportability of electricity. Over longer distances, energy losses can be minimized with higher voltage levels: Pv = R · I²; from P = V · I and V = I · R with Pv: transmission losses Pv

R · I²

R·P

V·I P V² This formula shows the relation of voltage, intensity and resistance in context with transmission losses. By logic, the denominator (voltage) needs to be as high as possible to minimise transmission losses. Applied on the German electricity grid, this principle leads to the current distribution pattern of higher voltages for higher distances between producer and consumer of electricity (Bundesnetzagentur, 2016 b).

Figure 3: Transmission Technology Analysis.

+ minimal landscape distruption after installation + shielding of electric fields by earth masses + lower transmission losses - no direct access for maintenance and damage assessment - higher costs for transformation from DC to AC (if used)

X 400 V – 230 V

+ low costs and fast construction + easy access for maintenance; direct visibility of damages + flexibility and option of retrofitting - adverse effect on environment by infrastructure intrusions (habitat loss, optical interference) - electric field (no shielding of electric fields) - vulnerable to atmospheric influences Assessment

X 1 – 50 kV

X X

Voltage

110 kV

X X 220 - 380 kV

No change of phases result in an absence of reactive power loads. Preferably used for the transmission of electricity over long distances for lower transmission losses (see previous page). Currently, most of the DC lines are in use as see cables. In comparison to AC masts, DC masts consists of two systems for both negative and positive charge. The electric circuits in the transmission line conductors of AC masts show three phases, whereas DC masts only have one (thus have no reactive power). Type of current DC

Underground cables with alternating current are suitable for low and medium voltages. Higher voltages increase the reactive power (Q) loads and require more compensation measures by phase shifting (φ) of the current. Q = V · I · sinφ Conventional overground lines use alternating current for all voltages. This system does not require a current transformation, thus transmitted electricity can be used directly. The structure of existing masts can be further developed to carry both AC and DC lines (hybrid lines). AC

Masts of up to 80 meters carry the cables for the transmission of electricity. Overground lines are the most common used transmission technology. The resulting heat which is caused by the current flow are cooled by the surrounding air.

Fluctuating electricity loads is one of the challenges that need to be considered for the development of transmission grids (c.f. chapter III). One approach to compensate the variability of solar radiation or wind intensity is to store the surplus as soon as it is available. This can be realized with centralized or decentralized storage units. All development scenarios (c.f. chapter III) assume the further operation of existing centralized storages which are represented by pumped-storage power plants in most cases. A joint study by the grid operators rates these storages as a factor towards more system stability, however new storage technologies are scarcely considered within thei initial assessment by the ÜNB (Übertragungsnetzbetreiber, 2017). On a household-level, decentralized storages such as batteries for small PV systems are increasingly used. This trend has an influence on the load profiles for the electricity grids and was considered for the projection of net

Specfication

Centralized and Decentralised Storage

Overground Lines

Underground Cables

new overground masts or earth cables (Bundesnetzagentur, 2016 b). With respect to the transmission of energy from the north towards the south, the use of buried highvoltage direct current cables seems to carry a high potential. Recent political and public discussions about landscape disruption and loss of natural habitat, especially in the south of Germany, draw attention on the mentioned system combination: Not only is the absence of reactive power loads a striking argument for direct current, a lower visibility can furthermore be convincing for the successful development of connecting lines through Germany.

Transmission Technology

The extra high voltage grid in combination with direct current can be used as a very effective way to transmit electricity over long distances with relatively lower transmission losses. In the range of medium to low voltage, alternating current has the advantage that it can be directly consumed without transformation processes from direct current to alternating current (DIHK, 2015). Especially for the scenario of transporting electricity from the north to the south, direct current lines are foreseen in the grid development plan to overcome these greater distances with as low losses as possible. As a result of public and political discussions (c.f. chapter III), buried DC cables are expected to be promising solutions for electricity transmission that is accepted by the general public. With a voltage of 320 kV, the commonly used cables in Germany show a transmission capacity of 2000 MW. In comparison, the alternating current overhead lines on a basis of 400 kV has a higher transmission capacity. For that reason, a development in the used technology could help overcome this obstacle by introducing another voltage level of 525 kV. An overview over applied transmission technologies in combination with alternating and direct current are illustrated in the following table. The combinations of transmission technologies and type of current can be considered as rather synergetic technologies than competing approaches. The presence of overground masts with alternating current is a factor that induces further thoughts on an additional equipping of existing lines than constructing

— 88

Underground cables are usually buried under 1.5 meters and require specific preparation of trenches. The resulting heat of current transmission is emitted to the surrounding soil, thus natural cooling is not possible.

87 —

89 —

— 90

electricity demand by the network operators

a household-level. The combination

The

in chapter III. Especially developments such

of photovoltaic and battery storage in

have different roles in the development of a

as smart mobility and smart houses promote

particular is rated as a promising solution

stable electricity grid. While batteries, as one

this technology. Additional to the classification

with an impact on the energy market

example, are mostly used for electric mobility

of centralized and decentralized systems, a

(REN21, 2017).

or on a household-level, medium to long-

necessary factor for the integration into the electricity grid is the possible storage time of the different systems. Figure 3 illustrates the storage capacity of applied storage technologies which is further explained as follows using the most commonly used systems in Germany as an example. -- Short-term storage: Batteries represent the most commonly used short-term storage which last up to several weeks. Mobile and stationary applications are possible such as batteries in electric vehicles or storages for produced solar energy on

-- Medium

long-time

storage.

Pumped storages are primarily used to store energy up to several months and are widely used as a medium to longtime storage option. Thereby, energy is stored by pumping water to a higher

above-mentioned

storage

options

time storage options are responsible for the compensation of fluctuations on the electricity market. Besides the relation of given values of discharge time and energy, this illustration of storage capacity of different energy storage systems indirectly implies information about

elevation point (thus making use of

the respective system performances.

potential energy) where it can generate energy again by driving turbines in times

FURTHER ASSESSMENT OF POWER TO GAS TECHNOLOGIES

of demand. Considering losses during

Concerning the overarching title “Energy

that process, this technology recaptures

from North to South”, the compatibility of wind

up to 85% of the initial amount of energy

energy and gas storage is further assessed

(REN21, 2017).

in this chapter as an option for an integrative national electricity supply. It is expected that wind energy provides the highest share of the national energy mix in the future (Übertragungsnetzbetreiber, 2017).

Figure 3 - Storage Capacity of Different Energy Storage Systems.

Figure 4 – Maturity of Energy Storage Systems.

With reference to the goals for the energy turnaround, the federal government projects a share of forty percent electricity from renewable sources (BMWi, 2016), thus a higher share of electricity is affected by intermittency. According to a study by REN21 (2017), this share of renewables in the electricity mix consequentially requires the use of storage technologies to guarantee supply reliability. Researchers from the Fraunhofer Institute for Wind Energy and Energy Systems Technology (IWES), amongst others, have introduced an innovative system for medium to long-time storage. The “power to gas” technology transforms energy surplus from renewable energy – in this case wind energy – to hydrogen by the electrolysis of water. In the next step, the extracted hydrogen reacts with carbon and thus creates methane. This product can finally be stored and distributed any time through the existing gas network (Fraunhofer IWES, 2014). By the combination with regional heat networks, methane cannot

91 —

— 92

only be used for energy supply, but also to

generated surplus electricity and of using it

a different legal landscape could potentially

of carbon which can derive from industry or

provide heat. Another potential of this system

on demand, electricity can be bought on the

lead to more developments.

transport and lead towards a circular energy

lays in the provision of pure carbon for the

common European energy market when the

Environmental innovations generally aim

economy. For the transmission of energy from

creation of methane which is a critical point to

prices are low.

to reduce the strain on the environment as

the north to the south, power to gas storages

well as to avoid additional environmental

can represent an essential stability factor for

tackle at the same time (REN21). With the use of exhaust carbon from industry or transport for the methanation, the power to gas system could be a promising technology for the development of a circular electricity economy. Currently, pilot projects of 1 – 2 MW are installed in Germany, however lacking political or governmental support might be the reason for an insufficient commercialisation (c.f. fig. 4) of this option (REN21, 2017). With regards to political influences, this technology could also be one technical argument in discussions such as to import gas instead of agreeing on the constructions for the implementation of grid development plans in the south of Germany (Süddeutsche Zeitung, 2014). As a final conclusion, a grid system with the option of power to gas bears a high potential

CONCLUSION The shift from fossil to renewable energy sources for the German electricity mix is carried on transmission lines, metaphorically speaking. The proceeding energy turnaround involves high demands on the future use of energy and its distribution: existing conventional supply patterns change with the withdrawal from nuclear energy by 2022 and the aim for a dominating share of renewable energy in the long term. Electricity grids play a significant role in this development, regarding the integration of renewable energy on a national and international level. From a technical point of view, this progress requires evaluation

the of

application parameters.

preliminary Consumption

patterns play an important role on the

to meet the challenges of a reliable supply

projection

system under the aspects of the energy

and allow conclusions on the forthcoming

turnaround. The transportation of energy

implementation of electric mobility or energy

sources with a low carbon foot print such as

storage options. The overall approach of

electricity from wind or sun with the option of

electricity supply grid operators shows that

compensating load fluctuations is a basis

market and pricing is a limiting influence on the

for a reliable grid. In addition to electricity

presumed development speed and feasibility.

transmission, the system of power to gas

The modelled pricing has an impact on the

can also undertake the function as a carbon

amount and speed of renewable energy fed

sink, when provided that exhaust emissions

into the electricity grid, thus is assumed to slow

from industry, transport or biogenic sources

down possible progressive developments.

are used. The integration of such a storage

The assessment of changes in parameters or

option furthermore provides the opportunity for

stronger incentives by the government could

the development of an integrated electricity

consequently be beneficial. Regarding the

market. Besides the option of storing national

development of environmental innovations,

future

electricity

demand

damage in a society and growing economy. By definition, an innovation does not solely refer to a new technical system, it also refers to the progress of implementation of innovative ideas (c.f. chapter I). Power to gas is considered as one of them and was further assessed in this context. It shows, that this storage system lacks political interest which can be assumed to be a reason for its lower

the grid and for the realisation of development plans. Finally, it is given the impression that the federal generation of electricity involves greater effort than the option of importing energy such as gas from countries like Russia. In its nature, a factor of uncertainty is attached to politics and diplomacy. Thus, the advantage of the

degree of maturity. Within the elaborated

implementation of a future-proof electricity grid

scenarios by the electricity grid operators,

from north to south combined with the use

synthetic methane as a storage option is only

of national renewable energy sources is the

considered for the year 2040 or not at all. In

provision for energetic independency and the

its core, the technology allows the storage

higher foreseeability of circumstances. —

93 —

— 94

Cover + background image Cover picture and background image based on: Cb22h, 2013. [image]. Karte der Gewässer in Hamburg. [Accessed 16 January 2018]. Hydrogen and Synthetic Methane in

the

Future

Energy

System,

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