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ALGAL ENERGY AN

EXPERIMENTAL

S E L F - B U I LT

STUDY

PHOTOBIOREACTOR

AND MICROBIAL FUEL CELL SYSTEM

Jurgen Springer Newcastle University Architecture Dissertation Project

COVER PAGE Algae growth during Photosynthesis Copyright Â© Jurgen Springer

Architecture K100 Newcastle University Dissertation Project submitted in partial fulfillment of Architecture BA Honours Degree, Newcastle University Dissertation Project Copyright ÂŠ Jurgen Springer 170634319 | Newcastle University

Aknowledgements

I would like to express my gratitude and heartfelt thanks to Dr. Huiling Chua who has made it possible for me to pursue my studies at the University of Newcastle. I would like to thank my family for their love and support throughout my time at university. I am particularly fond of the dedicated support that my siblings have given me - I couldnâ&#x20AC;&#x2122;t have done it without you! My thanks also go to my dissertation supervisor, Carlos Calderon, for his continued enthusiasm and interest in my dissertation topic. I have enjoyed working with you. Jurgen

CONTENTS 01 Introduction 02 The Big picture - Algae and Photobioreactors 2.1 An Introduction to algae - Chlorella Vulgaris 2.2 Growing Chlorella Vulgaris 03 Experimental Environment 3.1 The Project in Context 3.2 Cultivating algae in a small vertical column PBR 3.2.1 Aims 3.3 Methodology 3.4 Data Collection and Results 3.5 Discussion 3.6 Cultivating Algae in a large Tubular Photobioreactor 3.6.1 Aims 3.7 Methodology 3.8 Data Collection and Results 3.9 Discussion 04 Using Algae in Microbial Fuel Cells 4.1 Aims 4.2 Methodology 4.3 Data Collection and Results 4.4 Discussion 05 Conclusion 06 References 07 List of Figures 08 Appendecies

CHAPTER 01

01 Introduction

This thesis intends to consolidate the closer integration of renewable energy sources into the architectural realm. The initiative behind this work is to analyse the use of solar energy trapped by aquatic microorganisms, to produce electricity [1, 2] as a sustainable architectural mechanism in the future design of buildings. Present faรงade and curtain wall systems found in urban environments often fail to ecologically benefit the community and act in a sustainable manner to tackle climate change [3]. Through the application of vessel like structures (photobioreactors) capable of cultivating such phototrophic aquatic

microorganisms,

first

steps can be made towards the creation of a greener and more viable economy [4]. Bioenergy is the foundation of architectural technology which will expectantly become a vital component in achieving a net-zero greenhouse gas economy by 2050, as stated by the European Commission in 2018 [5], as well as providing energy security through local energy generation [6]. Photobioreactor systems (PBRs) are receptacles in which water and nutrients circulate in combination with microorganisms (Fig. 2), such as microalgae, which are eukaryotic unicellular photosynthetic organisms [7] (Fig.5) , to absorb light and carbon to generate biomass [8]. A sub class of the currently available PBR frameworks includes vertical column and tubular PBRs. Both of these systems are evident ways to cultivate microalgae species and prove possible architectural solutions. The nutrients used in this experimental evaluation for

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the cultivation of microalgae, more specifically Chlorella Vulgaris, refers back to the BG11 stock which ‘is a universal medium for the cultivation and maintenance of blue-green algae’ compromised of synthetic nitrogen, carbon sources as well as other inorganic salts [9]. The PBRs generated biomass can be harvested for reductive power through the capacity of microbes to perform exoelectrogenic activity, which is ‘the direct and/ or indirect transfer of electrons outside of the cell’ [2]. These bioelectrochemical proceedings take place in a biophotovoltaic system (BPVs), which uses ‘oxygenic photosynthetic organisms to harvest ‘stored light energy and deliver electrical outputs’ [5]. This means that microorganisms, such as Chlorella Vulgaris, absorb light through the process of photosynthesis and can then yield electrical energy through a bioelectrochemical process [2, 10]. For the purpose

of this dissertation the system driving the electrical current is a home-made Microbial Fuel Cell (MFC) which operates by reconstructing bacterial interactions found in nature.

Fig. 2 Schematic diagram of PBR

Currently there is very little research uncovering the architectural application of PBRs and MFCs in combination to generate an electrical output. Furthermore, the availability of resources to construct such PBR and MFC systems in a DIY manner are not widely available or researched. With the use of a self-built PBR and MFC system this dissertation aims to discuss, analyse and prove the feasibility of algae bioenergy and to

contextualise

the

findings

Fig.1 (to the left) External view through Window

architecturally. The experiments summarised in this paper aim to add to existing research, as well as serve as a prerequisite for new elementary guidelines regarding the cultivation of microalgae and their bioenergy potentials. The underlying hypothesis of this work is that microalgae demonstrate extremely valuable and necessary conditions, such as those of self-repair, selfreproduction and energy storage for power generation. Microalgae can perform these tasks efficiently when provided with the right conditions. By conducting three overlapping experiments this work attempts to analyse different factors impacting the cultivation of Chlorella Vulgaris

such as pH, air temperature, cultivation temperature, humidity, light intensity and carbon dioxide levels in a vertical column as well as tubular PBR systems. The results of this study are specific to a student house situated in the North East of the United Kingdom, more specifically Jesmond, Newcastle upon Tyne. Furthermore, this project sets out to demonstrate and discuss the energy potential of Chlorella Vulgaris in an MFC yielding a simple mathematical formula regarding the amount of MFCs needed to provide a given amount of voltage, while also addressing energy losses within PBR and MFC systems.

Fig. 3 Scale drawing of a possible PBR design

Fig. 4 Axonometric drawing of initial possible PBR design

Fig. 5 Schematic Process diagram of an algal cell and Photosynthesis

CHAPTER 02

02 The Big Picture - Algae and Photobioreactors 2.1 An introduction to algae Chlorella Vulgaris The term “algae” is not taxonomically or formally recognised yet it is familiar to most people [11, 12]. Algae are considered as eukaryotic cyanobacteria, ‘oxygenic photosynthetic, nonembryo-producing plants’ [11]. As previously mentioned, they are a diverse group of organisms that absorb light and carbon to generate biomass through using sunlight to turn carbon dioxide into sugars to then later be turned in to chemical energy [8, 7 ,12] (Fig. 5). This dissertation will take a closer look at the sub class Chlorella Vulgaris (Fig. 6) which falls under the phylogenetic tree of the Chlorophyta (Green Algae) [15]. While these aquatic organisms [14 , 15 ,16] may not all be closely related, they distinguish themselves differently from other photosynthetic groups such as

land plants [13]. Photosynthesis takes place in the Chlorophyta through chlorophylls a and b, as well as other carotenoids. Chlorophyll a is the most important, allowing for photosynthesis to take place ‘by passing its energized electrons on to molecules’ to produce sugars in return [17, 18]. This is done through the absorption of violet-blue and orange-red light. Chlorophyll b only occur in green algae and absorbs blue light [23]. These factors play a key role in the cultivation of algae [22] (as seen later in Fig. 37) For the purpose of this project a culture of microalgae C. vulgaris was acquired through Newcastle University. (Fig. 21)

Fig. 6 Drawing of Chlorella Vulgaris

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2.2 Growing Chlorella Vulgaris To obtain biomass from Chlorella Vulgaris, desirable conditions need to be provided under which two main aspects are usually taken in to account; (i) external factors such as ‘temperature, light intensity, pH, aeration and agitation [as well as] (ii) the selection of suitable [nutrients]’ play a vital role in the culture’s growth development [19].

to prevent sedimentation of the algae […] to ensure that all cells of the population are equally exposed to the light and nutrients [21].’

The optimal temperature for algal growth lies between 20 to 30 degrees Celsius [9, 14]. Anything below 16 degrees would reduce the growth rate of the culture [11]. Optimal light conditions of algae lie between 2000 to 3000 lux for the growing of blue green algae cultures [9]. In PBR systems fluorescent lamps are used to emit a spectrum of blue to red light allowing for the cultures a and b chlorophylls to absorb these [20]. A pH range of between 6-9 benefits algal growth [14] and sufficient

To cultivate and grow Chlorella Vulgaris certain Components and nutrients are needed to optimise the growing potential of the culture [9, 23]. BG 11 Agar is an optimised composition for the growth and maintenance of Cyanobacteria. The Agar medium consists of synthetic nitrogen, carbon sources as well as other inorganic salts (Fig. 7) which are important to maximise the growth potential of the algae [9]. This formula can be adjusted and suited to the experimental set up. In a laboratory environment and under optimal conditions all of the 10 components listed in Fig. 8 would be incorporated within the BG 11 medium in addition to dH2O. For the purpose of this dissertation, due to availability, 6 of the 10 common components

aeration/agitation is ‘necessary

were used to make the BG 11

Fig.7 (to the left) The six components used from BG11

Agar medium (Fig. 7) in addition to dH2O. The essential nutrients for algal growth are Nitrogen and CO2. Nitrogen is supplied with NaNO2 and is required ‘to build amino acids, proteins, chlorophyll, nucleic acids, etc’. [23]. Following the guidelines provided by [24] the agar media was prepared by firstly mixing 10mL/L of NaNO3 (Sodium Nitrate), 10mL/L of MgSO4•7H2O (Magnesium

Sulphate Heptahydrate), 10mL/L of Citric Acid•H2O, 10mL/L of Ferric Ammonium Citrate, 10mL/L of Sodium Thiosulfate Pentahydrate in addition to 900ml of distilled water. To bring the medium up to 1L using approx. 50 ml of distilled water. After boiling the agar medium it was then cooled to approximately room temperature before being able to use [19].

Fig. 8 BG 11 Components

Fig.9 (to the right) preparing BG 11 Agar

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CHAPTER 03

03 Experimental Environment 3.1 The Project in Context Fig. 10 Sketch of Room

The experiments were conducted in a student house in Jesmond, Newcastle upon Tyne (Fig. 11, 12) and recorded in a bedroom setting, situated on the North side of the building against the window. (Fig. 10) Due to the importance of sunlight to photosynthesis and the culturing of algae, UV growth lights were used and hung up to make up for the loss of this factor.

Fig. 11 Aerial view of Jesmond, Newcastle

Fig. 12 Aerial view of Oakland road 39, Newcastle

Fig. 13 QR Code to all imperical data gathered

Fig. 14 QR Code to all finalised graphs

Fig. 15 Experimental time line

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3.2 Cultivating algae in a small vertical column PBR 3.2.1 Aims The intention of the following research is: a) to develop two simple vertical column PBRs to start cultivating two Chlorella Vulgaris cultures. b) to create a backup culture, for the experiment outlined in 4.3 c) to analyse algae in different day-to-day situations 3.3 Methodology Using recycled materials in addition to an air pump, air stone, airline control kit and tubing (5mm diameter) this experiment set out to culture algae. Similar experimental research has also been conducted by Lawrence et al. (2019) in their work titled: ‘Big Algae’ [24]. Their work sought to lay the foundation for this

experiment in that it followed a similar DIY remit, the steps of which – as outlined below - have been appropriately adapted for the purposes of this experiment. With the use of four, 2.5L plastic water bottles the PBRs were constructed. To begin with the bottom half of one of the bottles was removed to then turn the remaining upper half of the bottle into the outer body needed for the PBR (Fig. 18). Using a drill, 5mm holes (slightly smaller than the diameter of the tubing) were drilled into the remaining four lids of the bottles, allowing just enough space for the tubing to be pushed through. Then, the air stone was connected and the cap screwed back onto the bottle to finish the main body of the reactor (Fig. 18). This procedure was repeated twice to obtain two PBR bodies. The remaining two bottles were cut in such a way to remove the top quarter and lower quarter of

Fig.16 (to the left) Vertical Column PBR Systems

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Fig. 18 Construction phase 1

Fig. 21 Chlorella Vulgaris Starter Culture

Fig. 19 Construction phase 2

Fig. 22 QR Code: Introduction of 50ml culture

Fig. 20 Construction phase 3

Fig. 23 QR Code: Airline Control Kit System

Fig.17 (previous) Experimental Set up

the bottles respectively. These remaining pieces were needed to create a riser tube within the PBRs to help the culture flow (Fig. 19) Cutting the obtained cylinders in half along the remaining bottleâ&#x20AC;&#x2122;s vertical axis the created ends were pulled inwards to overlap by 4cm and then connected using a hot glue gun. After creating four small incisions along the top of the bottles, around 2cm apart and having folded the tabs outwards to sit on the horizontal axis of the PBRs bodies. The risers could then be inserted in to the PBRs to sit a few centimetres above the PBRâ&#x20AC;&#x2122;s air stones (Fig. 20) Following this, the tubing was then cut around 20cm away from each air stone and an airline control tap was connected. This was to allow for or reduce/shut down airflow in the respective PBRs in case of a culture collapsing (Fig. 23). After the algae was then introduced with the BG11 medium into the PBR systems (Fig. 22), two Fig. 24 Construction phase 4

of the remaining bottom bottle pieces were used as reactor lids to minimise evaporation or over spilling of the culture. (Fig. 24) Illumination was provided by a USB powered growth light. 36 red and 12 blue LEDs were set up to allow for optimum growth conditions. The reactor was then connected to a 230 Volt air pump. (Fig. 25) This was done to allow air flowing through the air stone to prevent sedimentation of the algal cells at the bottom of the PBR systems.

with a Carbon dioxide reader (measuring range of CO2 and temperature: 0 to 3000 ppm; 0Â° C to 50 Â° C). The light intensity was measured with the use of a handheld light intensity measurer. The measurements were taken sporadically. The results listed show the findings of the data collected by measuring the humidity, pH, CO2 levels, Room and Medium Temperatures as well as Light intensity results.

3.4 Data Collection and Results The data for this experiment was noted by hand and then recorded in an excel file (Fig. 13). The room temperature and humidity measurements were taken with the use of an external temperature/humidity sensor. The pH was measured with an electronic pH measuring tool and the CO2 values were read

Fig. 25 Final Construction of Vertical Column PBR

Fig.26 (to the right) Algal Growth in Vertical Column PBR

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Fig. 27 Results Table Exp. 1

3.5 Discussion From the colour and density of the water becoming increasingly greener and darker in colour over the 11-day experimental period, we can conclude that the algae culture definitely grew. The results show a decrease of humidity fluctuating between 67% and 83% over this period with the highest fluctuation within 24 hours occurring on the third day of the experiment with a difference of 16% (Fig. 31) For algae to grow optimally, high humidity and temperature levels are preferred [11].

The small nature of the room in which the experiment was conducted showed fluctuated readings. The majority of high CO2 readings were measured in the evening (Fig. 33). This was most likely due to the increased presence of people within the student flat, as well as the due to the use of kitchen appliances (for example the oven and/ or gas stove). The ongoing presence of a person in the room in which the experiment was conducted also affected the increase of CO2 readings. An average decrease in CO2 throughout the project was noticeable. Further gaps arise within the

Fig.28 (to the right) Algal Growth in Vertical Column PBR by Night

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CO2 results due to a sensor error when the readings went above

lights were kept on constantly. Small increases and decreases

3000ppm. An average of 2078 PPM shows poor air quality and general high CO2 values (Fig. 27, 30)

were noticed in the amount of lux being received due to the window providing more sunlight on certain days and at certain times. Due to a drop in pH (Fig. 32), temperature and a sudden change in colour of the mediums, on the 13th day, it was assumed that the algae had undergone photoinhibition. This reduced the photosynthetic capacity of the algae. In reaction to this the light was turned off on the 10th and 11th day of the project allowing for the algae to recover. (Fig 34.) A study by Pattanaik, Pradhan and Sukla [20] shows that the photoperiod

The Graph, as seen in Fig. 35, shows a close correlation between the temperature measured in both of the mediums as well as with the room temperature. The average temperature for medium A was: 20.4˚C. the average temperature for medium B was: 20.2 ˚C. the average room temperature was: 19.9 ˚C (Fig. 35). The temperature ranged between 17.8˚C and 24.9˚C for all 3 recordings. The light intensity ranged between 5.5 and 1919 lux (Fig. 34). Over the first 9 days the growth

varies from organism to organism and that the optimal period of illumination is 12-15 hours.

Fig. 30 CO2 Air Quality

Fig.29 (to the left) Recording of Results

The air pump allowing for agitation to occur had to remain running at all times or else a backlash through the airline control kit could be noticed. The data for this experiment was noted at different times of the day and big fluctuations seem to be present among the factors measured. In order to receive better information regarding algal growth a more frequent and consistently measured set of results would be able to show and say more about the conditions. This experiment shows that when implementing a PBR system architecturally the accessibility to the growing cultures is extremely important. The algae need to be regularly checked on to allow for their efficiency to be maximised. Furthermore, different reactors implemented within a faรงade system need to work simultaneously, yet independently so that bioenergy can still be produced in the case

of one PBR failing. The possibility of culture failure marks one aspect of the limitations this project poses to the ability of producing bioenergy. In addition to this, even though sometimes very slight, different cultures in different PBR systems can show different growth rates and act differently to the environment even when the same conditions are applied. At the end of the 11 days of investigations the 2L of obtained algae from reactor A were used as a backup culture for the experiment taking place in 3.6. The remaining 2L culture in PBR B was split to then create two new 1L back up cultures: A2 and B2.

Fig.31 (above) Results: Humidity vs Time

Fig.32 (above) Results: pH vs Time

Fig.33 (above) Results: CO2 vs Time

Fig.34 (above) Results: Light Intensity vs Time

Fig.35 (above) Results: Room and Medium Temperature vs Time

3.6 Cultivating algae in a large tubular PBR

conditions of a student house in Newcastle upon Tyne.

3.6.1 Aims

e) to touch on the amount of energy input needed to run the system.

The intention of the following conducted research is:

3.7 Methodology a) to layout the fundamentals of construction for a larger scaled tubular PBR system. b) to create a response to the experiment in Chapter 3.1 by improving data collection through the programming of an Arduino as well as providing a maximum of 12 hours of light a day with the use of a self-timer.

The experimental set-up was constructed to propel and cultivate algae through a system with the goal of obtaining 10L of biomass (Fig. 56), as well as to prove the functionality of a PBR system. (Fig. 42)

d) to further asses the response of

A particular aim of this PBR was to create a response to the previous experimental findings (see section 3.5) as well as to cultivate a culture of Chlorella Vulgaris in a larger, yet different PBR system. The experiment was run over a total of 42 days, which is around when the algae culture has reached its maximum potential. Through photosynthesis the algae culture grew whilst being

Chlorella Vulgaris in the climatic

propelled through a 15m pipe of

c) to develop a basic understanding of how Chlorella Vulgaris grow and to investigate and understand the time scale of its growth in a tubular PBR system from a 2L solution to up to 10L.

Fig.36 (to the right) Arduino sensors

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12.5mm diameter (1840.78cm3) The algae medium was driven by a small pump with a 700 litre per hour output and sat within an enclosed 300mm by 200mm watertight container. Water temperature and pH sensors were bounded to the interior of the PBRs tank. The sensors were controlled by an Arduino Mega board. The PBR rack (length 900mm; width 200mm; height 1000mm) was put together with three 6mm plywood sheets and held up by four steel rods (length 1000mm, width 10mm). 24 steel hex nuts and washers were fixed either side of the plywood sandwiching it to hold it in place. Each of the three plywood sheets had previously been laser cut with 12 holes for tubing to then later pass through.

rack but also keeping the tubing at a sufficient distance, 108mm, to prohibit kinks and bending of the tubing to enhance the flow of the algae medium and preventing excess biomass residue from residing there. (Fig. 39, 40) The algae medium was driven by a 700 litre per hour pump which resided within a glass container (length 300mm; width 200mm; height 300mm). Within the watertight container, the algae medium settled down and collected until it was then recirculated through the PBR system. (Fig. 38)

15000mm of transparent tubing was threaded through all three sheets of plywood not only

Sitting within the watertight container a digital water temperature sensor (WTS) (DS18B20) with a 3000mm cable measured the algae mediums temperature (temperature range of WTS; -55Â°C to +125Â°C) In addition to this an analogue pH sensor monitors the mediums pH. The WTS and pH sensor as well as

strengthening the structure of the

the SD card reader. These were

Fig.37 (previous) Tubular PBR System Experimental Set-up

Fig.38 (to the right) PBR System in Operation

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connected to a breadboard as well as to the ELEGOO Mega2560R3 microcontroller board which was programmed in Arduino. (Fig. 36, Appendix 1) Sedimentation of the algal cells was prohibited at the bottom of the PBR systems using 2 230 Volt aeration pumps connected to air stones. Illumination was provided by 3 USB powered growth lights. 108 red and 36 blue LEDs were set up to allow for optimum growth conditions.

a computer in excel at a later stage. The measurements were programmed to be taken every half an hour. Externally, on an independent monitoring system, a CO2 air quality reader monitored the rooms air temperature as well as CO2 levels (measuring range of CO2 and temperature: 0 to 3000 ppm; 0Â° C to 50 Â° C). These measurements were recorded with the use of an electronic tablet and a time-lapse program. (Fig.43)

3.8 Data Collection and Results

Fig.42 QR Code: Tubular and Column PBR Set-up Fig.41 Results Table Exp. 2

The data was collected through multiple sensors programmed in Arduino (C++) (Appendix 1). The data was recorded via a SD card to then be collated on Fig.43 QR Code: Data Collection through Time-lapse Fig.39/40 (previous/to the left) Transparent 15000 mm Tubing

Fig.44 (above) Results: Room and Medium Temperature vs Time

Fig.45 (above) Results: Medium pH vs Time

Fig.46 (above) Results: CO2 vs Time

Fig.47 (above) Results: Humidity vs Time

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3.9 Discussion The experiment took place over a time period of 42 days. The growth of algae successfully took place in the larger PBR system as well. The success of the growth can be seen in Fig 51 and the increase of greenage found throughout the PBR system. The time period after which algae has generally reached its peak capacity is after 35 days [11]. Analysing the temperature, we can observe that the temperature range throughout the entire project was between 17.25Ë&#x161;C and 25.69Ë&#x161;C (Fig. 44). There were two substantial drops in temperature: between the 26th and 30th November 2019, as well as between the 16th and 19th of December 2020. These mark the dates of a field trip that took place as well as the Christmas break up in which the heating was both turned down. This means that algal growth was

close correlation between the Room Temperature and Medium Temperature. During this period data was monitored through a Webcam. (Fig.54) The Humidity recorded shows a similar trendline to that of the temperature, showing a particularly big drop after the 14th of December 2019. (44, 47) The graph in Fig 45., shows the pH of the first 22 days of the algae growth. While the pH was extremely stable over the first 8 days. A real change in results started occurring from the 1st of December 2019. This shows that the algae did not successfully perform photosynthesis in the first 8 days. After the 1st of December 2019 the PH started to fluctuate in an upwards trend. Lower pH values were recorded in the morning and higher PH values were recorded in the evening/ night times. This fluctuation in pH is specific to algae.

especially affected. There is a

Fig.48 (previous) PBR by Night

Fig.49 (To the right) Algal Sedimentation

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nobit

As already seen in the previous experiment the CO2 levels showed great fluctuations. (Fig. 46) Surprisingly, high CO2 levels were maintained over the period between the 1st December 2019 and the 17th of December 2019. These high results in CO2 show beneficial to the growth of algae. This was also reflected in the pH of the algae where a similar fluctuation occurred when the CO2 levels were high opposed to a stagnant pH between the 22nd of November 2019 and the 1st of December 2019.

values. Unfortunately, this could not be done any differently. A Light dependent resistor was intended to be programmed but would not work after multiple attempts of programming. The hand held apparatus could unfortunately not be kept on in Fig 43.

Furthermore, the data collected could have made a stronger case regarding algae growth if it wouldn’t have been for experimental complications whilst programming the Arduino Sensor as well as the loss of CO2 values caused due to technical difficulties. The measurements of the CO2 are not perfectly consistent. This is due to the available CO2 reader alternating

Ideally a 15 m pipe connected to a Vacuum Chamber degassing system and a 22kW stainless steel heat exchanger would be incorporated as seen in the experimental set up in Fig. 4. With the cultivation of algae, the vacuum chamber serves the purpose of extracting any excess Oxygen (O2) to maintain a pure and more fluid algae culture medium when circulating the system. This is because ‘…any [excess] oxygen produced by the growing cultures can reduce [overall algae] growth’ [4]. Cooling of the PBR could have been optimised with the use of

between temperature and CO2

heat exchanger, yet this seemed

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unnecessary considering the amount of energy used [26]. During construction there were clear difficulties trying to make the Arduino code work effectively, which heavily impacted the pH results. The lack of rigidness of the system equally impacted the lack of CO2 results after the 17th of December 2019. Furthermore, Arduino results were slightly delayed increasing shifting the time when each measurement was taken every time by a few milliseconds. (Fig. 13) Difficulties arose when trying to fill the system with water due to the amount of air in the pipe as seen in Fig. 52. This was later solved by removing all the oxygen out of the system and making sure that the water tank was on a shelf above the PBR itself (Fig. 53)

This experiment once again emphasises the importance of secured and reliable data logging. Although more data was consistently recorded and tells us more about the algaeâ&#x20AC;&#x2122;s growth environment. The backup cultures from the experiment undertaken in chapter 3.1 were not needed in this particular case as the culture did not collapse in the 42 days in which the experiment was undertaken.

Fig.52 QR Code: Difficulties Circulating Water

Further gaps arise within the CO2 results due to a sensor error when the readings went above 3000ppm. Fig.53 QR Code: Successful Circulation of Water Fig.51 (previous) Algae in Tank

Fig.54 (previous) Webcam Monitoring System

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CHAPTER 04

04 Using Algae in Microbial Fuel Cells 4.1 Aims The intention of the following conducted research is: a) to put together and build a fully functional MFC system b) to use an own cultivated culture of Chlorella Vulgaris to obtain an electrical output in an MFC system (Chapter 3.1, 3.6) c) to devise a formula showing the amount of MFCs needed to produce a desired voltage 4.2 Methodology By using the algae cultivated over the course of the previous 2 experiments and around its peak performance in its growth cycle (See chapters 4.2 and 4.3) this experiment sets out to encourage exoelectrogenic output by using an MFC to harvest reductive

power in the form of electric current. Energy can be sourced from organic substrates being catalysed through oxidation, due to the presence of microorganisms [5]. Such a system works with an anode and a cathode. (Fig. 60) The anode is where electrons are lost by the metal electrode (oxidation) and the cathode is where the metal electrode has gained electrons (reduction). The electron transfer takes place via a salt bridge connecting both Anode and Cathode [27]. The apparatus set up for the final experiment of this project was put together primarily with the use of two recycled receptacles, a DIY salt bridge (proton exchange membrane), selfmade electrodes, crocodile clips, copper wires and a voltmeter. To prepare the MFC system a 7.5mm hole was drilled into the sides of both the recycled

Fig.55/56 (previous) iPad Time-lapse recording and Algae Biomass

Fig. 57 Construction phase 1

Fig. 58 Construction phase 2

Fig. 59 Construction phase 3

Fig. 60 Final Construction of MFC

receptacles allowing for the salt bridge to later be threaded through both the holes. The salt bridge was prepared in boiling water with the addition of table salt and then twisted around itself to create a thicker rope. Once damp and cooled off the rope was wrapped in a layer of electrical tape and one layer of duct tape, leaving both ends exposed. Once threaded through the two containers previously drilled holes were then sealed with the use of a hot glue gun. (Fig. 57, 58) A hole was drilled in both of the lids of the recycled containers to thread through the copper wires. A larger hole of diameter 15mm was drilled in to one of the lids, needed for the cathode. This will be used to connect the air pump by threading through a small tube through the hole and connecting an air stone on the opposite side.

Wire Metal Mesh pieces (Diameter 0.4mm, aperture 1mm) 4 times. Copper wire was connected with crocodile clips to the electrodes and to the Voltmeter (Fig. 58, 59). 400ml of water was then used in the cathode and 400ml of the algae was poured in to the anode. 4.3 Data Collection and Results The data for this experiment was recorded using a Multimeter connected to the MFC. The experiment was recorded with the use of an iPad and then the data was plotted in Excel. The full experiment to the results obtained below can be found by following the QR code in Fig. 66 and 67.

In addition to this, electrodes were created by folding 2, 210mm by 300mm, stainless steel Woven

Fig.61 (next) Microbial Fuel Cell Set-up

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Fig.62 (above) Results: Voltage vs Time

Fig.63 (above) Results: Watts vs Time

Fig.64 (above) Results: Current vs Time

Fig.65 (above) Results: Resistance vs Time

4.4 Discussion The recorded data shows a steady drop in voltage over ca. 90 minutes (Fig. 62). The voltage slowly started to stabilise after around 720 seconds. The readings ranged between 0.065 Volt to 0.372 Volt. While the received voltage is extremely low for 1 MFC system - by connecting multiple MFC systems in Series we can obtain a larger Voltage. From this we can deduct a simple formula to calculate the amount of MFCs needed to produce a desired voltage. Formula for algae Microbial Fuel Cell: Number of Volts needed = x â&#x20AC;˘ 0.065, where: Energy Output by algae = 0.065 V and x = Number of MFCs connected in series

over approx. 30 minutes. The graph shows that it is inversely proportional to that of the Voltage (Fig. 64). A sudden decrease and drop in resistance (Fig. 65) can be noticed between 440 and 1360 seconds. This reflects the addition of water which occurred. It is important to mention that due to water leaking from the salt bridge due to not being water tight water was added throughout the experiment to bring the water level above the salt bridge again which caused an increase spike between 400 and 800 seconds when measuring the Current (Fig. 64). This started, stabilising according to the trend between 0 and 400 seconds, after 1360 seconds again. Ideally voltage and resistance would have been tested over a much longer period to understand the bioenergy potential of the MFC much better.

In addition to this, using Ohms law, the Current could be plotted

Using Ohms law, Power = voltage â&#x20AC;˘ current, we deduct that over around 0.5 hours the average energy output of this MFC system is about: 147 Watts (0.0735kWh). It has previously been shown that MFC produce voltages of around 0,5V. When in operation this voltage quickly sinks to 0,2V [12, 28]. The DIY MFC in this experiment yielded just under half of that when in operation. To improve the performance of the system, multiple MFCs can be connected in Series, which would allow for a greater Voltage to be achieved. In addition to this a more stable connection of the salt bridge would have been preferred to prevent leakage of the Anode or Cathode. It would have been beneficial to have recorded MFC results throughout all stages of the algae development. This could have been done in a next step by merging both the MFC and PBR systems.

Fig. 66 QR Code : Experiment 3 measuring Current

Fig. 67 QR Code : Experiment 3 measuring Voltage

CHAPTER 05

05 Conclusion It is possible that algae energy building technologies may make the intensive culture of algae viable in the built environment in the long-term, if the energy efficiency of the system can be correctly tuned with a) more expensive, durable components and b) be constructed and built in an environment beneficial to algal growth. The three experiments summarised here confirm that the number of MFCs needed to supply enough bioenergy through algae to support regular energy consumption is very high. The MFC from the experiment conducted for the purposes of this paper yielded an average of 147 watts over 0.5 hours (0.0735kWh) through the exoelectrogenic processesâ&#x20AC;&#x2122; undertaken by the Chlorella Vulgaris culture. In comparison to this the student house in Jesmond consumed 18368 kWh (Fig. 68) between the 1st October 2019 and the 4th of January 2020, which is

roughly 206.4 kWh per day. This means that 2,808 MFC systems, connected in series, would need to be in use simultaneously to cover the needed electrical output. This does not take into account other energy consumptions such as gas to supply kitchen appliances. This confirms that such a system cannot, in any way, be implemented in a fully sustainable manner yet. While considering this it is also important to note that an high energy input needs to be invested at a constant rate to keep the algae cultures growing through devices such as pumps etc.

Fig. 68: Electrical Readings from Energy Supplier

Algae BPV/PBR faĂ§ade systems must be supplied with the appropriate conditions, such as

the right amount of sunlight to allow for photosynthesis to take place as well as not allowing for excess sunlight to cause photoinhibition of the cells.

Limitations of this study include, but are not limited to, a home DIY environment. The empirical results detailed in this paper

potential drivers and challenges with regards to algae building technology. A logical next step following on from this piece of work would therefore be to consider a demonstration of an algal building panel mounted directly onto the façade of a building [30, 31]. Such a prototype is likely to yield additional empirical evidence in assessing the feasibility of algae BPV/ PBR systems. In addition, other weather conditions may be able to be accounted for in the assessment of algae BPV/PBR systems and their suitability to a variety of climatic conditions. Moreover, while the available literature widely discusses the ‘building with Bio-Intelligent Quotient’ House in Hamburg with an integrated algae façade system, it is one of the only buildings that has since been designed using algae BPV/PBR technology to create bioenergy [32]. It is important to note that most of its energy is supplied through the likes of geothermal energy as well

are thus a sole reflection of the

as the use of photovoltaic system.

Furthermore, algae predictability needs to be monitored over a longer lasting time period through a highly reliable system for energy efficiencies to be optimised and algal cultures to be understood in the broader context of BPR systems. It would have been beneficial to analyse the energy potential with the use of an MFC during different stages of algae growth rather than simply on the day when it was ‘assumed’ that the algae were at its maximum potential to produce the highest amount of voltage.

Few researchers, especially in architecture, have had any direct experience with this technology and their perceptions are thus likely to be based on a limited understanding of algae, its properties and buildings and their experience of applying other newly emerging technologies to the built environment [29, 30, 33, 34]. By minimising the amount of aeration provided for agitation purposes as well as finding an ideal time span in which the pumps need to be kept running the initial energy output can already be reduced. In addition to this using a more reliable and optimised MFC which does not leak and is more efficient can produce a higher voltage output resulting in a higher energy output as these are directly proportionate to each other. It would have been interesting and beneficial to continue further experiments with multiple MFCs and to repeat them to analyse their reliability

in bioenergy production. Equally by experimenting with different solutions on the anode of the MFC the output of voltage may be increased. Currently there are also increasingly more studies regarding the treatment of wastewater and there use in redox reaction at anode in combination with algae biomass at cathode. Finally, this study has resulted in some ‘lessons learned’. However, overall, there are clear divers and challenges for innovation and the development of this technology. This Paper attempted to introduce the knowledge of PBR systems to architects and to reiterate the importance between the scientific findings and their architectural application. In order to tackle the role of sustainability and to tackle current climate challenges it is strongly suggested that this relationship – between science and architecture – continue in tandem to further and to pass on the ‘know-how’.

REFERENCES

LIST OF FIGURES

APPENDICIES

Appendix 1: Arduino Coding