19 minute read
Energy Purchasing
PURCHASING UTILITIES
For further information on Pöyry Management Consulting visitwww.eibi.co.uk/enquiries and enter ENQUIRY 134
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Embracing the fuel of the future
Hydrogen does not emit any carbon when burned and so it could be considered a zero-carbon energy source, depending on how it is produced. It can be used as a replacement for natural gas in many situations, including power generation, industrial feedstocks, process heat, and domestic heat and cooking. It can also be used with fuel cells to decarbonise transport. In short, hydrogen can help decarbonise sectors where a total electrification solution could be extremely difficult and expensive to achieve.
The energy industry has grasped the potential of hydrogen and many projects are underway to investigate its production and use. These projects vary in scale from smaller investigations into standalone electrolysers, to blending hydrogen with natural gas in existing networks, hydrogen Combined Cycle Gas Turbines (CCGTs) and the grand ambitions of the H21 project in the north of England. H21 North of England aims to convert 3.7m UK homes and businesses from natural gas to hydrogen, making it the world’s largest clean energy project.
For gas producers and network companies, hydrogen provides a possible answer to the existential threat of an all-electric world. If natural gas can be converted into hydrogen with little or no carbon emissions, then the existing gas networks could be repurposed to deliver hydrogen to provide heat to industry and homes. Hydrogen can also be stored in many of the existing natural gas storage facilities and this could allow a form of seasonal storage that renewables alone cannot provide.
Any discussion of hydrogen as a fuel source raises questions about its safety. Hydrogen is highly flammable and so there are concerns around transporting and storing the gas, especially in a domestic environment. Alternative to electrification For industry, hydrogen offers a route to decarbonisation that otherwise could be extremely costly and difficult. It offers an alternative to electrification – which for some may not even be feasible – and an alternative to the installation of carbon capture at individual plants. Converting power to hydrogen allows excess renewable electricity to be used, adding value and creating further revenue for renewables and avoiding curtailment of surplus energy. It also raises the possibility of using hydrogen as a storage medium for electricity. Excess electricity can be used to create hydrogen at times of low demand or price, which can then be stored and converted back into electricity when demand or price increases.
In reality, there are many issues that need to be considered before starting to deploy hydrogen as a fuel-source. First, the hydrogen supply chain will need to be significantly expanded to meet the potential demand, including production, Will we still be purchasing gas in the years to come? Or is hydrogen set to take over? John Williams examines the pros and cons of a hydrogen-based energy future. John Williams is senior principal at Pöyry Management Consulting Electrolysis – electricity is used to separate water into hydrogen and oxygen. If the electricity is renewable the hydrogen is considered zero carbon. This is sometimes called ‘Green’ or ‘Renewable Hydrogen’.
Steam Methane Reformation (SMR) – refers to a chemical synthesis that reacts steam at high pressure to produce hydrogen and carbon dioxide from hydrocarbons such as natural gas. This is sometimes referred to as ‘Grey Hydrogen’.
SMR with Carbon Capture Utilisation and Storage (CCUS) – where CCUS is added to the SMR process to capture and prevent release of the carbon dioxide, the process can be considered as low carbon. This is sometimes referred to as ‘Blue Hydrogen’.
Thermal Methane Pyrolysis (TMP) – this involves natural gas and a low-temperature, high-pressure reaction with no oxygen present to produce hydrogen and solid carbon. This is also ‘Blue Hydrogen’. Methods of producing hydrogen
transport and storage. Unfortunately, there are significant risks to this expansion as there is no certainty that the demand will follow.
Second, there are issues with each of the hydrogen production methods. Grey hydrogen (see box below) is not low carbon and so has little role to play in a decarbonised energy environment. Blue hydrogen needs CCS, and although this is a proven technology, we are not yet at a stage where it can be deployed economically at scale.
Green hydrogen is the most expensive of the production methods and will require very low electricity prices and reductions in the costs of electrolysis to make it a reality. Pyrolysis is not yet proven to be a scalable solution that is competitive with the other production methods. Despite this, if hydrogen is the solution to decarbonising the difficult sectors of residential heat, industrial heat and the heavier end of the transport sector then these issues will need to be overcome. Pöyry’s study ‘Decarbonising Europe’s Energy System by 2050’ compared a zero-carbon gas pathway with an all-electric pathway and examined the potential role for hydrogen for the heat, power and transport sectors. In the zero-carbon gas pathway, hydrogen demand is expected to grow significantly in these three sectors to reach over 2,000TWh by 2050.
Looking at different production costs of hydrogen, the study found that hydrogen production costs from methane reformation were consistently lower than hydrogen produced by electrolysis. This is because by 2050 a flexible demand side made possible by millions of electric vehicles, and high levels of interconnection, mean that there is generally an absence of many very low electricity price periods, which otherwise would support hydrogen production from electrolysis at lower cost than from methane reformation. Subsequently methane reformation is the dominant source of hydrogen production.
The potential of hydrogen is clear, but the route to realising this potential is uncertain. There are numerous barriers that will need to be overcome which include creating a business case, acceptance of CCS, public acceptance of hydrogen at home as well as proving how safe hydrogen is.
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End users could benefit from avoiding £80m of wasted energy
Almost 3 per cent of all energy generated in Europe gets wasted through transformer losses. That’s enough to power Denmark for three years. In the UK, network losses account for 1.5 per cent of the CO2 emissions, 25 per cent of which are caused by distribution transformers. This raises two questions, who pays for this wasted energy and what can we do avoid these losses? The first is a rhetorical question.
Most distribution transformers in the UK were installed when energy wastage was not a crucial problem; technology was focused on access to energy with little regard to how efficiently this was done. According to an FOI request to OFGEM, the average age of a distribution transformer in the UK is 64 years and to put that into perspective, this means that most transformers were installed in the 1950s and have not been replaced since then.
ENA Adaptation to Climate Change First Round Report suggests there are 230,000 11kV to 400/230V distribution substations nationally. If we take a 10 per cent sample of these substation transformers and
assume they were installed in the 1970s, not 1950s, as the statistics show, the saving potential if these transformers were replaced could be enormous.
This puts a strong case for 23,000 distribution transformers to be replaced with new efficient ones. Wilson Power Solutions manufactures the Wilson e3 Ultra Low Loss amorphous transformer that exceeds ECO Design Directives for transformer losses (due to be effective in 2021) and the new reduced transformer losses make it financially feasible and actually a nobrainer to upgrade these networks.
Compared against Ultra Low Loss amorphous transformers, these 23,000 transformers could collectively save 894.8GWh of electricity every year. Taking off the cost of the replacements and considering the total cost of ownership, that results in over £83m savings every year just by doing this single infrastructure upgrade. It’s too obvious to neglect.
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Heat Recovery & Ventilation
For further information on Elta Fans visitwww.eibi.co.uk/enquiriesand enter ENQUIRY No. 135
Paul Harrington is head of residential sales at Elta Fans
Cooling for comfort
Mechanical Ventilation with Heat Recovery is a well-established method of ventilation. However, as Paul Harrington explains, it is crucial that systems start to incorporate cooling technology
The ability to heat incoming air by passing it over a heat exchanger has helped to improve the energy efficiency and comfort of our homes. It ensures that thermal energy remains in the building, without incurring high heating bills.
This has been a successful process for several decades now, especially during the colder months when the outside air is lower than inside. However, advancements in the insulation of our structures, combined with a warmer climate, has presented a significant issue for strategies which incorporate MHVR, particularly during hotter months.
Although widely regarded as an energy efficient way of managing air circulation in a building, it is noticeable that the benefits of MVHR are rarely discussed during the summer months. This is because when the outside air is warmer than inside, this type of ventilation actually raises the internal temperature.
Even the summer bypass function, which is almost universally used across MVHR units, does little to solve this issue. When the incoming air does not need to be heated, the bypass function stops the air from being passed over the heat exchanger. But consider, for example, that the desired temperature within a building is 20 o C. If the outside temperature is anything more than this, then the incoming air will be hotter than inside, regardless of whether the summer bypass is in operation.
Towards a climate emergency It is difficult to avoid the fact that we are heading towards a climate emergency, with action groups and changes to climate change policy ensuring it remains high on the news agenda. Regardless of political stance, temperatures in the UK are getting irrefutably higher, and as a result, our summers are getting longer.
Furthermore, our structures have become increasingly well insulated, which has meant that they retain heat far better than ever before. Although this has had a positive effect on the amount of energy expended in heating buildings, it has meant that the application of MVHR
has decreased in importance. Indeed, overheating as a result of this type of ventilation is a fairly common occurrence.
The combination of a warmer climate and more insulated buildings means that the period of time in which MVHR is viable is shortening, and the need for an alternative system, which is
capable of introducing cooler air into buildings, is increasing.
Mechanical Ventilation with Heating and Coolth Recovery (MVHCR) units, such as Elta Fans’ Vigo and PREMA range, are capable of maintaining thermal comfort within buildings, even during warmer months. By essentially acting in reverse, they are capable of passing outgoing cooler air over the heat exchanger, which helps to ensure the incoming air remains ambient.
This has a very obvious impact on the thermal comfort for occupants, as the desired comfort level can be maintained, whether the outside temperature is warmer or colder than inside. It also has a knock-on effect on the efficiency and effectiveness of air-conditioning, which has itself come under increased scrutiny over the past few years.
Manufacturers of air conditioning units are under pressure to deliver a more environmentally friendly product, in light of the fact that a sizeable proportion of the UK’s energy consumption is linked with the units. MVHR acts in a similar way to opening a car window with the air-con on: the vehicle’s climate control has to work harder to combat the incoming warm air.
MVHCR dovetails extremely effectively with air conditioning, because it prevents the coldness within the air from escaping, and instead transfers it to the warmer incoming air. In doing so, it helps to reduce the amount of work that air conditioning units have to do to keep a building cool, as they work in tandem to achieve the ideal internal temperature.
MVHCR is the year-round solution, capable of improving thermal comfort across all seasons. As our climate becomes progressively warmer, and our structures are increasingly better insulated, the ability to both heat and cool incoming air is vital in achieving thermal comfort within our homes and commercial buildings.
eibi.co.uk/enquiries Enter 15
Heat Recovery & Ventilation
For further information on ebm-papst visitwww.eibi.co.uk/enquiriesand enter ENQUIRY No. 136
Daniel Gebert is in aerodynamics development at ebmpapst Mulfingen
Increasing fan efficiency
The Energy-related Products (ErP) Directive is an essential basis for assessing the efficiency of various components and devices, says Daniel Gebert
The efficiency requirements for fans have been set out since 2013. They were raised in 2015, and there are plans to raise them again in the near future. The effects of the regulation have become impossible to overlook as energy-efficient EC fans are strengthening their position on the market, reducing CO 2 emissions and benefiting the environment. In addition to energy-efficient motors, aerodynamic improvements are primarily responsible for the high efficiency levels of the modern fans.
Proper evaluation of a fan’s efficiency means testing the fan as it will later be used. Otherwise it – and any equipment it is installed in – cannot bear the CE marking. There are good reasons for this. Any slight modification, for example in the design of nozzles or support struts, affects the fan’s efficiency and thus its ErP conformity.
Support struts cause unavoidable blockage of the air flow at the intake or outlet, resulting in efficiency decreases of a few crucial percentage points depending on the operating point.
Nozzle geometry has similar effects, even when the air gap remains unchanged (Fig. 1). The efficiency also decreases by a few percentage points when an axial fan is operated in a short nozzle instead of a full nozzle.
Those wanting to be on the safe side of the fan regulation, should select solutions whose energy efficiency has been determined in the conditions under which they will be used. Otherwise users must prove ErP conformity themselves.
In axial fans, losses typically arise at the gap between the rotating impeller and the stationary fan housing. Possibilities for improvement are rapidly exhausted since the gap will always require a certain size for manufacturing reasons. In addition, there are turbulence losses that arise due to differences in flow speed and losses at the outlet.
Pressure losses at blades In centrifugal fans, gap losses arise because some of the air is transported in a circle through the nozzle gap. There are also pressure losses at the blades, which do not receive optimum air flow in all areas. For both fan types, the greatest potential for improvement is in the outlet, where high outlet speeds lead to losses as the speed and thus the dynamic pressure, go unused.
Much can be achieved by the use of guide vanes or a diffuser on axial fans. Since the rotation of an axial fan’s impeller imparts angular momentum to the expelled air, attaching stationary guide vanes results in a static pressure increase as the kinetic energy conveyed by the angular momentum is converted to static pressure. Diffusers externally mounted at the outlet side offer a means of minimizing outlet pressure losses in larger axial fans.
The AxiBlade series was developed
Fig. 1 Nozzle struts can cause blockage of the air flow
In this way, the axial fans can be optimally designed for a particular application, with an efficiency increase of up to 40 per cent compared with the proven HyBlade series. The version without guide vanes is suitable for low to middle pressure ranges – up to 200 Pa.
In this case, the benefits of the guide vanes don’t come into play. Even without them, the efficiency Fig. 2 A scroll housing can reduce turbulent flow losses Any slight modification of a fan can affect the fan’s efficiency and ErP conformity
and operating noise are much better than the current industry standard. Guide vanes are essential at high back pressures of up to 260 Pa in order to reach high efficiency.
Since the footprint of these axial fans corresponds to the current industry standard, virtually no design changes are necessary to customer equipment.
As requirements regarding the efficiency of ventilation equipment for residential buildings becomes increasingly stringent, ebm-papst has aerodynamically optimised its proven RadiCal centrifugal fans.
To reduce outlet losses, the fans can be combined with a scroll housing that has also been aerodynamically optimised. The scroll housing has an outlet with a round cross section for direct attachment to the pipe fitting on the unit’s air outlet, considerably reducing the usual turbulent flow losses. The characteristic curve becomes very pressure-insensitive, and the efficiency increases by up to 38 per cent compared with centrifugal blowers of the same design (Fig. 2) and noise level decreases by 3.5 dB(A). These fans are also available in a volume-flow-controlled design with a vane anemometer for extremely precise control.
For users, we make it easy to be on the safe side of the ErP Directive without great effort, for both centrifugal and axial fans. Aerodynamic optimisation improves efficiency and noise characteristics, even in differently installed configurations. to ensure that the axial fans work at the best possible efficiency level when installed and operated at application-specific operating points. Its axial fans operate in a wide range of applications at an efficiency of up to 54 per cent with respect to the static pressure increase. At the same time, the noise level can be reduced by up to 8dB(A) compared with the standard range. Using a modular design, the fans can be combined with guide vanes depending on the required pressure ranges.
For further information on products and services visit www.eibi.co.uk/enquiries and enter the appropriate online enquiry number
University entertainment centre benefits from ventilation system
Brunel University London’s Hamilton Centre is home to a host of entertainment facilities, including bars, restaurants, and the student union. With the link between good indoor air quality (IAQ) and concentration levels becoming increasingly well established, optimising the building’s ventilation system was a top priority.
A contra-rotating fan on the roof of the Hamilton Centre, which was directly responsible for ventilating a popular pizza bar in the building, was failing. It had been over specified, which meant it was oversized and using an unnecessary amount of energy.
Marcus Sawkins, co-founder and managing director of GFMS Services Limited, commented: “The existing fan was incurring high running costs and CO2 emissions, neither of which are desirable for an expanding university. Plus, the voltage required to operate the fan was unnecessarily large, which posed a problem as the controls are located in a busy kitchen.”
The decision was made to replace the fan with a more energy efficient model, but it was crucial that performance was not sacrificed. Owing to its reduced running costs,
EC motor, and intuitive controls, Elta Fans’ Revolution SLC EC presented itself as suitable for the application.
The transition from an AC motor to a low energy EC motor negates the need for a mains powered speed controller. As David Millward, product manager at Elta Group explains, this has a two-pronged effect: “The EC motor helps to reduce energy bills by up to 20 per cent, which is crucial for meeting environmental targets as well as lowering the total cost of ownership. It is also a more straightforward installation, allowing contractors to complete projects quicker and with less chance of complications.”
The previous fan was hampered by complicated controls, which meant that end users often neglected using it at all. For those tasked with delivering a high volume of pizza to students, taking time out of their day to operate ventilation was often impossible. Reducing the electrical voltage and offering a simple dial control system has allowed operators to manage the ventilation output more effectively throughout the day.
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New air handling unit with heat recovery for refurbishment projects Swegon has launched another variant of the GLOBAL spacesaving air handling units with heat recovery, a product for light commercial and refurbishment projects.
The GLOBAL LP (low profile) units provide airflows of up to 3,720 m³/h (1,030 l/s) from an extremely compact, low noise product that is designed to be mounted horizontally in the ceiling. They operate at 85 per cent efficiency thanks to the use of a plate heat exchanger for heat recovery, plug-and-play controls, low energy consumption EC fans and highperformance DC motors.
Swegon has developed increasingly effective control strategies with ‘open’ communication via Modbus, TCP/IP, BACnet and KNX to ease integration into the overall management of the building.
GLOBAL LP ventilation units are supplied plug-and-play with the basic functions pre-programmed and most accessories pre-installed, pre-wired and pre-configured in the factory.
The generously sized doors ensure ease of access for maintenance and the enlarged electrical cabinet features an integrated safety switch and better control board access.
The plate heat exchanger complies with standard EN308 and is Eurovent certified and the powerful EC fans ensure that sufficient external pressure is available. The composite fan blades also deliver higher operating efficiency than standard aluminium alternatives – another feature in line with ErP requirements. ONLINE ENQUIRY 138
Ventilation system brings comfort to prime London commercial development
Airflow Developments has supplied a ventilation solution to Adelphi House, a prime listed commercial building in Covent Garden. Spotify occupies four floors, with two other floors currently being redeveloped. This meant there was a requirement for a new ventilation system which Airflow was chosen for.
The specification was met by two Duplexvent Multi-Eco DV1500 and one Duplexvent Multi-Eco DV1100. These indoor units are built accordingly to the project specifications and offer good energy efficiency and performance. They are centralised heat recovery units and reduce energy bills of the premises where installed.
Suitable for commercial and industrial applications, these units are available in a variety of sizes and configurations, they use highly efficient polypropylene plate heat exchangers to recover the heat from the extracted air and use it to pre-warm the incoming cool supply air. Alternatively, for more difficult places to access Airflow offers the compact Duplexvent Rotary thermal wheel range of heat recovery units, which have a smaller overall footprint whilst still achieving high efficiencies with lower specific fan powers.
