Delft Seminars on Building Technology Parabolic Algae RoofThe parabolic mirror supported tubular photobioreactor algae growing roof farm.

1353640, Anton ZoetmulderTutor: Hans Voller

AR1A075 2012-Q1/2

mark

Fig. 1.1 Fig. 1.2

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Fig. 1.1 Parabolic algae roof in summer situation, sun on 62 degrees (Source: own work).

Fig. 1.2 Parabolic algae roof in winter situation, sun on 14 degrees (Source: own work).

Fig. 1.3 Susan of the Google Sketch-Up team is maintain-ing the parabolic algae installation (Source: own work).

Parabolic algae roof.The Parabolic mirror supported tubular photobioreactor algae growing roof farmAnton Zoetmulder, 1353640

Amount of words: 3.586

1. AbstractAlgae grow 7 to 30 ti mes faster than the next biomass creati ng crop and have huge po-tenti al in providing the world with energy. Algae need a few simple conditi ons to grow; suffi cient sunlight, fl owing water and nutrients. An additi onal advantage is that the algae consume a large fracti on of CO2 while growing, thus cleaning the surrounding air. In this redesign I integrated a tubular photobioreactor for growing algae on the roof of the Kunsthal. The algae will provide biomass, which will be converted into biogas, which in turn will be used to generate enough clean energy for the enti re Kunsthal. To provide op-ti mal conditi ons for the algaes to grow rapidly I used a parabolic mirror that is closed off with a glass panel. The parabolic mirror focuses sunrays on the algae tubes to increase the sunlight they obtain. Closing off the system with a glass panel creates a small scale greenhouse around the algae, which makes it possible to maintain the ideal temperature for the algae throughout the year. Through obtaining more sunlight and guaranteeing the ideal temperature the algae growing rate will be boosted.

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Fig. 2.1 The Kunsthal in bird eyes view, with the chosen sloped roof fragment with triangular shaped roof lights on the up side in pink (Source: edited from Schwarz).

Fig. 2.2 View from the Kunsthal roof, with left the sloped roof, middle the roofgarden and the tower and to the right the fl at roof (Source: Schwarz)

1. Schwartz, Ineke, Koolhaas, Rem. Kunsthal Rotterdam, magazine a+t, issue number 2, 2002.

2. The fragment chosenThe fragment I have chosen is the roof above the main expositi on hall of the Kunsthal in Rott erdam by OMA. In the original plan the roof was made accessible, it functi oned as the endpoint of the much famed routi ng that leads through the enti re building. Nowa-days the entrance to the roof is closed because of fi re and safety constraints. This is regretf ul because the routi ng is the most exquisite feature of the Kunsthal and in parti cu-lar the characteristi c that made it so famous. At the moment this routi ng misses a clear climax. The re-opening and re-design of the roof could provide this climax. The unused roofscape of 60 x 60 meter is entered through a fl ight of gently sloped stairs. Next to the stairs, in the middle of the building is a sloped roofgarden including pear trees. The stairs end up onto a long and narrow roof terrace made of perforated steel. The terrace is separated from the rest of the roof through a big orange steel beam and the tower. The tower stands in the middle of the roof and is made of a steel con-structi on clad with corrugated plasti c sheets and perforated metal sheets. Also there is a billboard mounted to the tower. In the tower there are additi onal stairs and some climate installati ons situated. The rest of the roof consists of two parts; one part is fl at and covered by regular bitumen roof cover and another big orange steel beam. The other part is slightly sloped and has long triangular shaped roof lights and is covered by a cor-rugated sheet. On the roof there are also two statues present. My redesign will focus on the sloped part of the roof that is situated above the main expositi on hall.

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Fig. 4.1 Roof farming on top of a skyscraper in the middle of the city of Chicago (Source: Sulin).

Fig. 4.2 Tubular photobioreactor for growing algae (Source: CALPOLY).

Fig. 4.3 Parabolic mirror focus’ sunrays on Photovoltaic cell (Source: SkyFuel).

1. Sulin, Otto. Hanging gardens of Babylon, 2001, http://www.openideo.com, 22 Jan. 2013

2.CALPOLY, ’’Biofuels’’, San Luis: CEA energy working group, http://www.brae.calpoly.edu/CEAE/biofuels.html, 22 Jan. 2013

3. SkyFuel, Proven Track Record, Innovative Design, http://www.skyfuel.com/index_main.html#/OUR%20PROD-UCTS/SKYTROUGH/, 22 Jan. 2013

4. Hossain, Sharif A.B.M., et al.’’Biodiesel fuel produc-tion from algae as renewable energy’’ American journal of biochemistry and biotechnology 4 (2008) Science Publica-tions 5. Durrant, Aimee, Boyd, Bryan, Introduction to Algae. Westminster: westminstercollege.edu, 2003

6. Demirbas, Ayhan. ‘’Use of algae as biofuel sources.’’ Energy Conversion and Management 51 (2010)

7. Chisti, Yusuf. ‘’Biodiesel from microalgae beats bioetha-nol’’ Trends in Biotechnology Vol.26 No.3 (2008)

3. The research questi on The main research questi on of this arti cle will be: How can the growing of algae on the roof of the Kunsthal add to the existi ng building in a sustainable way as well as in an ar-chitectural way?

To answer this main research questi on I composed several sub-questi ons: - What ways are there to grow algae? - Which ways are there to create energy out of the algae? - How can the growing of algae be improved, so it can be used for applicati on on the roof of a building? - How can the process of creati ng energy out of algae be improved, so it can be used for applicati on on the roof of a building?

4. Reference ProjectMy redesign is based upon the combinati on of three reference projects; the new phe-nomena of roof farming, the technology concerning algae farms and the use of a para-bolic mirror to focus sunrays into one point.

Roof farmingRoof farming is the practi ce of culti vati ng food on the rooft op of buildings . It became popular in American citi es like Chicago and New York and the phenomenom is now enter-ing the Netherlands. The fi rst projects are being realized in Rott erdam and Amsterdam.

Algae farmsThe technology concerning algae growth is rapidly developing. Algae grow 7 to 30 ti mes faster than the next biomass creati ng crop and have huge potenti al in supplying the world with energy (Hossain). Algae grow using photosynthesis and therefore only need sunlight, fl owing water, the right temperature and some nutrients to grow (Durrant et al.). The algae also consume a large fracti on of CO2 while growing, thus cleaning the sur-rounding air. In the world there are already some examples of large scale algae farms. At the moment there are three major ways of growing algae; algae ponds, photobioreactor using tubes and photobioreactor using sacks (Demirbas et al.). The algae pond is an open system consisti ng of horizontally placed ponds fi lled with shallow water and algae. This system is relati vely easy to construct and operate. Major limitati ons are poor light uti liza-ti on by the cells, evaporati on losses, diff usion of CO2 to the atmosphere, risk of contami-nati on and requirement of large areas. The photobioreactor is a closed system where the supply of light, nutrients, CO2, air, and temperature can be regulated. The algae can either be grown in soft plasti c sacks or hard plasti c tubes. The sacks are cheaper but more vulnerable, and are only used inside (a greenhouse) in a fully controlled environment. The tubes are more expensive but less vulnerable, and can be used outside in a semi-con-trolled environment (Chisti ). For creati ng an algae farm on the roof of the Kunsthal each of the growing methods could be used, each having a diff erent architectural soluti on.

Parabolic mirrorParabolic mirrors are used to focus sunrays into one point. This advantage is nowadays used to focus sunrays onto photovoltaic cells, in order to heighten the effi ciency and producti on. Parabolic mirrors could also be used to focus sunrays onto an algae tube to heighten its growth rate. When combining these three references you could get a parabolic mirror sup-ported algae growing roof farm.

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Fig. 1 Different ways of placing a tubular algae photobiore-actor on the roof of the Kunsthal.

Fig. 2 First idea of a tubular algae photobioreactor inte-grated in the sloped roof of the Kunsthal.

Fig. 3 Further developed design of tubular algae photo-bioreactor with additional (small) parabolic mirrors and openable fl at glass roof.

Fig. 4 Design proposal with tubular algae photobioreactor, larger parabolic mirrors, greenhouse like glass roof and suggestions of rotating mechanism.

Fig. 5 More detailed fragment of design proposal with tubular algae photobioreactor, larger parabolic mirrors, greenhouse like glass roof and suggestions of rotating mechanism.With dimensions and wrongly orientated parabolic mirror.

Fig. 6 Design of closed off parabolic mirror with scheme of rotating mechanism.

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Fig. 5 Fig. 6

ALGAEWater (H20)

CO2

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(sun)lightAlgae Sludge Waste Sludge

Aggregate

Hypoxia Tank

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Annamox reactorGreen gas

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Gas TankGreen gas

ElectricityCO2

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Fig. 5.1

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Fig. 5.1 Algae grow 7 to 30 times faster than the next biomass creating crop; palm oil (Source: Gao).

Fig. 5.2 The proposed process to create greengas out of algae sludge and waste sludge (Source: own work)1. The algae sludge and waste sludge are suffocated in the hypoxia tank. 2. The oxygen free sludge is fed to the anaerobic digester creating biogas. 3. This biogas is fed to the annamox reactor to make the process more continuous (by removing NH4). And to remove the toxic H2S in order to upgrade the biogas to greengas quality. 4.This greengas is stored into a gastank and used to gen-erate electricity in an aggregate.

1. Gao, Yihe, et al. Algae Biodiesel A Feasibility Report, Chicago: BPRO, 2009

2. Hendrikson, Robert, Edwards, Mark. Imagine our algae future; visionary algae architecture and landscape designs. Richmon: Ronore Enterprises, 2012

3. Wiley, Patrick E., Campbell, J. Elliott and McKuin, Brandi. ‘’Production of Biodiesel and Biogas fromAlgae: A Review of Process Train Options’’ Water Environ-ment Research, Volume 83, Number 4 (2011)

4. Salerno, Michael, Nurdogan, Yakup and Lundquist, Tryg J. Biogas Production from Algae Biomass Harvested at Wastewater Treatment Ponds. Seattle; ASABE Confer-ence Presentation, 2009

5.Yen, Hong Wei and Brune, David E. Anaerobic co-digestion of algal sludge and waste paper to produce methane, Bioresource Technology 98 (2007): p. 130–134 6. Kuenen, Gijs, applications of the anammox process, Delft: Life Science Symposium: Evolution & Development, 2010

5. Literature referencesAlgae grow 7 to 30 ti mes faster than the next biomass creati ng crop and have huge potenti al in supplying the world with energy. The biomass that is contained within the algae is most commonly used to produce biofuel. Large scale algae farming is becoming more and more commercially viable. And in recent ti mes the fi rst building designs with integrated algae systems are being produced (Hendriksen). In this paragraph I will fi rstly describe how a tubular photo bioreactor works, then how the process of creati ng biofuel from algae works, aft er that I will argue why this process isn’t suitable for integrati on in an architectural design, fol-lowed by an alternati ve proposal that could be fully integrated in an architectural (re)design.

The process of growing algae in a tubular photobioreactor. The requirements for growing algae properly are; suffi cient sunlight to employ photosynthesis, the right temperature (somewhere between 10-25 degrees, dependent on the species of algae), fl owing water, additi onal nutrients and CO2. A tubular photobioreactor is a closed system consisti ng of small translucent tubes where the supply of light, nutrients, CO2, air, and temperature can be regulated. When you fi rst start growing algae you need a ‘’start-up culture’’, this start-up culture is mixed with moving water and exposed to sunlight. Regularly nutrients and CO2 are added in order to let the algae grow more rapidly. When enough algae have grown you can start harvesti ng regularly. Because of the high growing rate of the algae they consume a large fracti on of CO2, thus cleaning the surrounding air.

The creati on of biofuel. The biomass that is contained within the algae is most commonly used to produce biofuel. There are two factors that are important for the producti on of biofuels from algae. Firstly, the dry mass factor of the algae; this is the percentage of dry biomass in relati on to the fresh biomass. Secondly, the lipid content, this is the percentage of oil in relati on to the dry biomass needed to get it (Wiley et al.). To create biofuel out of the harvested algae the extract is dried unti l there is only dry biomass left . Secondly the lipid, or oily content is extracted from the dry biomass which is then converted into biofuels through a process called fermentati on. This biofuel can then be burned to create electricity.

The disadvantages of creati ng biofuelThe disadvantages of this process are that the creati on of biofuel from algae is very much dependent on the quality (dry mass factor and lipid content) of the algae. This quality should be very precisely monitored. Another disadvantage is that the process to create biofuel out of algae sludge is very extensive, there are a lot of diff erent large scale machineries needed for harvesti ng, monitoring, drying, extracti ng and fermenta-ti on (Wiley et al.). This way of farming algae is more suitable for large scale factory like arrangements and not so much for buildings. Most of the architectural designs with integrated algae systems therefore pro-pose to sell the biomass to an external factory. In this sense the algae system merely adds an iconic feature to the building and doesn’t help the building get more sustainable in any way.

Alternati ve proposalTo really let the algae system be a sustainable additi on to a building design I propose to convert the algae sludge into biogas. This process is less complicated and less quality dependent and can thus be produced in the building itself. To create biogas out of algae sludge, the harvested algae sludge is directly fed to an anaerobic digester (Salerno et al.). Here the algaes are suff ocated in the absence of oxygen (and light). In this way biogas is created, which can be used to create electricity in an aggregate.

Improvements of proposalThe main disadvantage of an anaerobic digester is that the process has to run in absence of oxygen (which takes a lot of energy to remove from the input). Another disadvantage of anaerobic digesti on is that the rate of producti on is slowed down due the creati on of unwanted ammonium (NH4). The fi rst problem is easily solvable when algae sludge and waste sludge (for example containing biodegradable waste from the restaurant, paper waste from the offi ces and sewer sludge) are put together in a closed off tank (Yen et al.). The respirati on of the algae removes the oxygen from the mixture in a process called hypoxia. Only aft er this the resulti ng oxygen free sludge is fed to the anaerobic digester to create the actual biogas. Another advantage of this process is that there is additi onal biomass contained within the waste sludge. The second problem is solvable when the output of the anaerobic digesti on process is led through an anammox reactor where ammonium is fi ltered out to make the anaerobic digesti on process more effi cient and conti nuously (Kuenen). Another advantage of the anammox reactor is that it consumes a large fracti on of the CO2 and removes the toxic H2S to upgrade the biogas to greengas quality. This gas is then stored in a gastank and the major part is used to generate electricity in an aggregate.

Openable glass panel

Tubular photobioreactor tubes

Insulated parabolic mirror

Holding and rotati ng device

Curtain roof system

Walkable insulated gutt er

Existi ng load bearing constructi on

Fig. 6.1

Fig. 6.2

Fig. 6.1 Exploded view of a fragment of the roof construc-tion and tubular photobioreactor with parabolic mirror (Source: own work).

Fig. 6.2 Axonometric projection of a fragment of the roof construction and tubular photobioreactor with parabolic mirror (Source: own work).

6. Redesign 6.1 Structural designFor my redesign I used the existi ng sloped roof constructi on and turned it 180 degrees in order to orientate the slope in the directi on of the sun. The main constructi on details and the integrated venti lati on system stay the same. On the roof structure I placed an aluminum curtain roof system with integrated walkable gutt ers. On the mullions of this curtain roof system the supporti ng aluminum structure of the algae installati on is mount-ed. The climate plan of the Kunsthal itself stays approximately the same, the only diff er-ence is that the energy needed for the climate installati ons is fully provided by the algae system on the roof.

6.2 Constructi on designFirstly the original roof constructi on is disassembled, and then reassembled in the op-posite way. On this structure the aluminum insulated gutt ers are mounted, which in turn carries the mullions of the aluminum curtain roof system. The HR+ glass system is placed in an angle of 3.2 degrees (which is the same angle as the original sloped roof construc-ti on) in order to let the rainwater stream into the gutt ers. The glass system consists of 4mm toughened glass, 12mm cavity fi lled with dry air and 6mm toughened glass with metal coati ng. On the mullions of the curtain roof system the algae installati on is mount-ed. The algae installati on consists of four parts, namely; the supporti ng structure of the algae installati on, the tubular algae photobioreactors, the parabolic mirrors and the machine chamber.

Supporti ng structureThe supporti ng structure of the algae installati on consists of aluminum trussed columns with a height of 500mm. These are bolted to the mullions of the curtain roof system, with a spacing in the length of the tubes of 7500mm and a spacing between the tubes of 1700mm. The columns hold the fi xing mechanism of the algae tubes and the rotati ng device of the parabolic mirror.

Tubular algae photobioreactorThe tubular algae photobioreactor is made out of transparent hard plasti c and is fi xed to the holding device every 7500mm. The tubes have a diameter of 200mm. This large diameter could be achieved because of the parabolic mirror. The conventi onal tube diameter is no larger than 100mm and is restricted by the needed light penetrati on of the sun (that comes from one side only). By installing a parabolic mirror underneath the algae tube the light is refl ected onto all sides of the tube. Therefore we can make the tube twice as large in diameter, thus increasing its circle surface and its content by four (because; Area of circle = pi*r^2). The algae tubes are placed on the sloped roof in order to use some additi onal gravitati onal energy to keep the algaes fl owing.

Parabolic mirrorThe parabolic mirror is positi oned underneath and parti ally around the algae tubes and it is fi xed to the holding and rotati ng device every 7500mm. The parabolic mirror has a maximum width of 1650mm and a maximum height of 560mm, the heart to heart dis-tance between two adjacent mirror is 1700mm. Making it able to let the parabolic mir-rors move separate from each other (for example for maintaining purposes). The para-bolic mirror is insulated and it is closed off by an openable glass panel, thus creati ng a small scale greenhouse around the algae. The parabolic mirror gives three improvements to the tubular algae photobioreactor. Firstly, the diameter of the algae tubes can be en-larged thus exponenti ally increasing its content. Secondly, the parabolic mirror increases the amount of sun the algaes obtain, increasing the photosynthesis possibility, thus mak-

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Fig. 6.3 Azimuth rotary system, 1:20 (Source: own work).1. Rotary engine. 2. Fixing point of parabolic mirror. 3. Rotating part4. Rotating direction of outer edge of parabolic mirror.5. Algae tube

Fig. 6.4 Large scale azimuth rotary device (Source: NRAO).

Fig. 6.5 1:10 section through parabolic mirror system with in elevation the rotary system. (Source: own work)1. Algae tube2. Fixing point of rotary device.3. Aluminum beam4. Openable glasspanel (6mm toughned glass)5. Regulatable ventilation opening6. Mirror fi lm, 50mm insulation, aluminum cladding7. Aluminum welded supporting trussed column.

1. NRAO, National Radio Astronomy Observatory, Antenna mechanics at work, 2009, http://www.vla.nrao.edu/genpub/work/antmech2.shtml, 22 Jan. 2013

ing them grow faster. Thirdly, by creati ng a small scale greenhouse around the algae the ideal growing temperature of the algae can be guaranteed, thus boosti ng its growth rate even further. The parabolic mirror design of the solar power industry can be used with some small alterati ons. The outer shell has to be insulated, an openable glass panel has to be fi xed on top and the rotati ng system will be diff erent. The rotati ng system has to be diff erent because the parabolic mirror systems used in the solar power industry are fi xed to the photovoltaic cells, rotati ng them all at once. This rotati ng system is not applicable for the proposed algae system because the tubes are solidly fi xed and cannot move ac-cordingly. The rotati ng system I propose consists of an azimuth rotary that rotates a fi xed point around a specifi c centre. This centre is ofcourse the centre of the algae tube (the system is represented in fi g. 6.3). The openable parabolic mirror can also protect the algae from overheati ng and/or too much sunlight by opening the glass panel or rotati ng away from the sun.

Machine chamberThe machine chamber is placed on the roof between the start and the end of the algae photobioreactor tubes. It is designed as a small tower in accordance with the existi ng tower of the Kunsthal. In the machine chamber there are several installati ons present. Firstly, the pump to move the algae sludge through the photobioreactor. Secondly, the feeding vessel, that feeds nutrients, CO2 and additi onal water to the algae sludge. Thirdly, a fi ltering system for harvesti ng the fully grown algae. Fourthly, all the installati on need-ed for the extracti on of the gas (as described in Paragraph 5). These are the hypoxia tank, the anaerobic digester, the annamox reactor, the gastank and the aggregate.

6.3 Climate designThe climate design of the Kunsthal itself stays approximately the same, the only diff er-ence is that the energy needed for the climate installati ons is fully provided by the algae system on the roof (the appurtenant calculati on follows below). The largest part of the algae tubes is separated from outside by an insulated parabolic mirror that is closed off by a glass panel. In this way a small scale greenhouse is created around the algae tube. The climate design of this small scale greenhouse works as follow: because of this green-house the temperature which the algae are exposed to are made controllable. There are small air in- and outlets in the middle, top and bott om of the parabolic mirror to let hot air escape. The openable parabolic mirror can also protect the algae from overheati ng and/or too much sunlight by opening the glass panel or rotati ng away from the sun. Also if maintenance is needed the glass panel is openable. A secondary advantage that the rotati ng parabolic mirrors entail, is that they op-erate as sunshading for the glassroof of the main expositi on hall. The mirrors are always pointed towards the sun, thus letti ng only diff use light pass through and preventi ng over-heati ng of the expositi on hall. The opening between the mirrors is larger in winter, letti ng through more light. This way suffi cient diff use light always enters creati ng ideal circum-stances for an exhibiti on space.

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Winter situa on (sun angle 14 degrees) Summer situa on (sun angle 62 degrees)

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Winter situa on (sun angle 14 degrees) Summer situa on (sun angle 62 degrees)Fig. 6.6

Fig. 6.6 Scaled down 1:20 of the roof elevation, with parabolic mirror in winter and summer situation (Source: own work).

1. Braal, R. de, Rapport Integrale Visie Kunsthal; met een scope van 10-15 jaar, Rotterdam: Stadsontwikkeling afdeling Vastgoed, 2012 (p. 7)

2. Lemos, Mark. ‘’Algae biomass productivity.’’ AU Algae University http://www.algaeu.com/biomass-productivity.html 22 Jan. 2013

3. Leeuw, Kasper de, Zoetmulder, Anton A. The living house concept. Delft: Deltasync, 2010

4.VREG. Hoeveel Kwh gaat er in een m3? http://www.aanbieders.be/energie/faqs/hoeveel-kwh-gaat-er-in-een-m3 22 Jan. 2013

5. BBB; Baltic Biogas Bus. About biogas. 2009 http://www.balticbiogasbus.eu/web/about-biogas.aspx 22 Jan. 2013

Calculati on of the necessary amount of algae tubes needed to provide the Kunsthal with suffi cient energy.

Data:The Kunsthal consumes approximately 1.000.000 Kwh per year (Braal), which come down to 1.000.000/365 = 2740 Kwh per day. A conservati ve esti mati on of the algae to biomass producti vity lies between 1,46 - 1,9 Gram biomass per Liter Algae sludge (Lemos). The biomass to biogas producti vity is approximately 2,3m3 of biogas per kilogram of biomass (Leeuw). The cleansed biogas is of greengas quality; the greengas to energy producti vity lies between 9,5 - 10,7 Kwh of energy per m3 of greengas (VREG)(BBB) . An conservati ve guess about the amount of biodegradable waste and paper waste of the Kunsthal lies be-tween the 5 - 10 kg per day. The tube diameter of the photobioreactor is 200mm = 0,2m, giving a radius of r = 0,1m.

Calculati on of lowest amount: Energy consumpti on per day = 2740 Kwh.gives 2740/9,5 = 288,4 m3 biogas needed,gives 288,4/2,3 = 125,4 kg = 125400 gram biomas needed, of which 5kg coming from biodegradable waste and paper waste.gives 125400 - 5000 = 120400 gram biomas needed from algae,gives 120400/1,46 = 82466,1 L = 82,5 m3 of algae sludge per day.

Surface Atube = pi * r^2 with r = 0,1mgives pi*0,1^2 = 0,0314m2,gives 82,5/0,0314 = 2626,3 m = 2600 m tubes needed.

Calculati on of highest amount: Energy consumpti on per day = 2740 Kwh.gives 2740/10,7 = 256,1 m3 biogas needed,gives 256,1/2,3 = 111,3 kg = 111300 gram biomas needed, of which 10kg coming from biodegradable waste and paper waste.gives 111300 - 10000 = 101300 gram biomas needed from algae,gives 101300/1,9 = 53335,2 L = 53,3 m3 of algae sludge per day.

Surface Atube = pi * r^2 with r = 0,1mgives pi*0,1^2 = 0,0314m2,gives 53,3/0,0314 = 1698,6 m = 1700 m tubes needed.

Proposed system: When the proposed system is only applied to the sloped roof of the Kunsthal (37,5 m x 52,5 m) there will be 36 tubes of 50 meter, gives 36 x 50 = 1800 meter of tubes. This arrangement will only suffi ce when the highest values are achieved (this could however be realisti c because the calculati on does not include the benefi ts which the closed of parabolic mirror entails). When the proposed system is applied to the enti re roof of the Kunsthal (60 m x 60 m) there will be approximately 57 tubes of 57 meter, gives 57 x 57 = 3250 meter of tubes. This arrangement will even suffi ce when the lowest values are achieved.

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Winter situa on (sun angle 14 degrees) Summer situa on (sun angle 62 degrees)

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Fig. 6.7 Scaled down 1:20 of the East-West section, with parabolic mirror in winter and summer situation (Source: own work).

Fig. 6.8 Scaled down 1:20 of the North-South section, with parabolic mirror in winter and summer situation (Source: own work). 1. Algae tube, diameter 200mm2. Holding and rotating device3. Parabolic mirror with openable glass panel4. Glass curtain roof system; consisting of aluminum beams (100x50mm) and HR+ glass; 4mm toughened glass, 12mm cavity fi lled with dry air and 6mm toughened glass with metal coating. In slope of 3,2 degrees5. Walkable insulated aluminum gutter (450x175mm)6. Existing ventilation mechanism7. Lowered ceiling consisting of milk glass.8. (continuation of) Existing facade9. Roof garden

Fig. 6.9 Scaled down 1:5 section of East-West section of curtain roof system (Source: own work).

Fig. 6.10 Scaled down 1:5 section of North-South section of curtain roof system (Source: own work).

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Fig. 6.11 1:20 section of the main functions of the para-bolic mirror (Source: own work)1.The parabolic mirror is positioned towards the sun through an azimuth rotating motor2. The top of the parabolic mirror is openable to prevent overheating and to make maintainance possible.3. Sunrays are focused onto the algae tube by the para-bolic mirror.4. Temperature is controlled within the parabolic mirror by air in- and outlets.

7. Peer ReviewGeorgia Syriopoulou | 4247108The arti cle and the redesign convincingly address the matt er of sustainability trough an energy harvesti ng system from algae to cover the building’s energy demands. It has a strong base on literature and project references that are successfully recomposed to meet the specifi city of the project.There are remarks on specifi c parts of the arti cle:+ Although the descripti on of the roofscape is quite detailed it remains a bit unclear which is the exact chosen fragment. A very simple diagram highlighti ng the area of the redesign would be adequate.+ Concerning the reference projects they are very clear and relevant. Also the literature references provide with a thorough analysis of the systems used and show good knowl-edge on the subject. However I think annotati ons are missing both on the pictures and in the text.+ The descripti on of the redesign is understandable and the diagrams accompanying suc-cessfully showcase the way it works in diff erent climate conditi ons.+ I have a slight objecti on on the details chosen to be drawn in a 1/5 scale since they don’t concern the basic part of the redesign but the structure of the roof that already exists. Although I do understand that the algae system might be too much about mecha-nological installati ons maybe a detail of the mirrors’ base mounted on the roof would be feasible to draw.

Mel Schafer | 4255852An interesti ng and innovati ve soluti ons that maximises the use of the large fl at roof area. Perhaps make use of the space in the research questi on spade to list the questi ons for clearer understanding of your intenti ons. i.e. point form.

I feel with the extent of the redesigned roof there is potenti al for further sustainable cli-mati c soluti ons like heati ng in winter and climati c regulate. (I was thinking about using the water already needed for the algae for other soluti ons - heat storage in additi on to biogas generati on.) Is there possibiliti es to harvest the O2?

8. Self Refl ecti onRegarding the peer review of Georgia Syriopoulou. I improved the text of Paragraph 2 and added a simple diagram indicati ng the sloped roof. Throughout the arti cle I added annotati ons and the correct references. Concerning the chosen details; I can fully un-derstand the objecti on Georgia has against the chosen details. However I discussed this matt er with my tutor before, concluding that a 1:5 detail of the parabolic mirror would indeed be too specifi c to elaborate. I therefore chose to elaborate the curtain roof system to a 1:5 scale. As an extra feature I elaborated the algae system including holding device, parabolic mirror and functi oning of the rotati ng device to a 1:10 scale. This shows materi-alizati ons and functi oning of the system but not the exact fi xing. Regarding the peer review of Mel Schafer. I improved the text regarding the re-search questi on, listi ng the diff erent sub-questi ons. There probably is potenti al in investi -gati ng other climate soluti ons that could accompany the algae growing system. However, I could spend an enti re extra Building Technology course looking into these potenti als. Also, this would probably just distract from the main issue I am trying to touch upon.

Fig. 6.12 Fig. 6.13

Fig.6.14

9. ConclusionIn this arti cle I described a potenti al algae growing system that has a heightened pro-ducti vity and were the biomass contained within the algaes is used to create biogas. The algae growing system consist of a tubular photobioreactor improved with a closed off in-sulated parabolic mirror. This parabolic mirror gives the tubular photobioreactor several advantages; Firstly, the diameter of the algae tubes can be enlarged thus exponenti ally increasing its content. Secondly, the parabolic mirror increases the amount of sun the al-gaes obtain, thus making them grow faster. Thirdly, by creati ng a small scale greenhouse around the algae the ideal growing temperature of the algae can be guaranteed, thus boosti ng its growth rate even further. Also the conversion process from algae to biogas, called anaerobic digesti on, has been improved to heighten effi ciency. This has been done by negati ng the two disadvantages of the anaerobic digesti on process. Firstly, the oxygen is removed from the algae sludge by adding waste sludge, in order to respirate the algaes. Secondly, in order to make the process of biogas creati on more eff ecti ve and conti nuous the created biogas is led through an annamox reactor, which removes NH4, H2S and CO2. Also upgrading the biogas to greengas quality. The proposed improvements of the algae tubes concerning the parabolic mirror is probably feasible, although a lot of specialized designing sti ll has to be done to make the parabolic mirror suitable. Making these improvements myself didn’t seem feasible for this course, so I only got the change to elaborate the system to a 1:10 scale. This way I ended up with 1:5 details of the curtain roof system with integrated walk able gutt er, this system is less important for the functi oning of the algae system itself. But it defi nitely gives an additi onal feature, making the rotati ng mirrors functi on within the lightning concept of the expositi on hall and making maintenance possible at the same ti me. The proposed improvements concerning the conversion from algae to biogas is given further research at this exact moment, giving hopeful results. This process is defi nitely the elect-ed alternati ve of making full integrati on of an algae system within a building possible. Because of the overall diffi culty of even grasping upon the complex matt er of algae growing, harvesti ng and conversion, I didn’t really have suffi cient ti me designing a real architectural soluti on. Someti mes I feel the proposed design is sti ll just a technological masterpiece, instead of architecture. However, I am very happy that I had the change to dig deeper into this fascinati ng matt er.

Fig. 6.12 Parabolic algae roof in summer situation, sun on 62 degrees (Source: own work).

Fig. 6.13 Parabolic algae roof in winter situation, sun on 14 degrees (Source: own work).

Fig. 6.14 Susan of the Google Sketch-Up team is main-taining the parabolic algae installation (Source: own work).The installation shown here is congruent with the scale that would fi t on the sloped roof of the Kunsthal.

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