Solar Leaf


A technically brilliant collaboration

Here at Total World Energy, we have covered exciting innovations across varied areas of the energy industry. In our January issue we looked at the Solaroad, a pilot project aimed at testing the technology and potential for power-producing roadways. On the other end of the spectrum, December saw us cover the technological advances being made at Schlumberger with their StingBlade – a faster, more efficient and more cost effective drill bit for the oil and gas sector.

Increased attention globally is being drawn to the need for technological advances in the energy industry that are not only economically viable, but efficient and environmentally friendly also. Just this month, a group of high profile CEO’s including Richard Branson of Virgin and Paul Polman of Unilever called for companies and governments to aim for complete carbon neutrality by 2050. With targets such as these to reach worldwide, it is innovations like the SolarLeaf that are bringing the energy industry one step closer to bringing about the changes that are needed. The SolarLeaf façade pilot project was completed in 2013 and unveiled at the International Building Exhibition (IBA) in Hamburg. It is the world’s first bio-reactor to be incorporated in to a building structure, using microalgae as a means to produce renewable energy in the form of biomass and heat. The process of photosynthesis in the microalgae has the desirable effect of absorbing CO2 – a coup for the pilot project and an exciting precedent for future development. Because of this, the BIQ house is virtually carbon-neutral, as CO2 emissions are reduced by six tons per annum, in addition to the biochemical reactions in the panels actually eliminating 2.5 tons of CO2 per annum also.


Solarleaf is the result of a collaborative effort between architects, Spittelwerk, consulting engineers Arup, Strategic Science Consult (SSC) Germany and Colt. The idea has its conception at Spittelwerk architects back in 2009, but required specific technical expertise to realise. Jan Wurm of Arup talks about how the project began: “We were asked by architects Spittelwerk to join their design team. We came up with the idea of getting photo bio-reactors integrated into the exterior skin of the building. There was discussion as to whether that was feasible and at that moment we could identify

SSC Hamburg. Mr. Kerner, he said – forget it, don’t put it on the building because we’d produce so much heat and we’d need to cool it down, it’s much too costly. But then if you think about having that on the building you actually need the heat. So you have the demand of heat and that’s where the synergy comes in and that’s the exciting bit.” Dr Kerner goes in to more detail in the same interview, saying: “He called me three days later and said – you have to have in mind that if you have the façade you do not only cultivate biomass but you have the functionalities of heat production, you have the functionalities of noise reduction, you have insulation and so on and then I was convinced I said okay I will contribute with my technology.” It was after this that Wurm approached Lukas Verlage, Managing Director of Colt International GmbH, in hopes that he would be able to contribute to the system for the house. “I picked up the phone and he told me that he plans a bio-reactor in Hamburg and I was afraid.” Verlage laughs as he recounts his first conversation with Jan Wurm. “What’s a bioreactor? And I saw ‘war’ and said; oh no, we are not involved in that! But, he told me it’s something to do with energy and they need a partner for the façade. After that I was convinced that we will achieve this goal and today we are here and we have achieved something and I think this is a very big step for the future.”


Vertical glass louvres, measuring 2.5m by 0.7m make up the double –skin façade and each of the 129 bio-reactor panels has a capacity of 24 litres and covers an area of 200m² on two sides of the BIQ house. The cavities in the louvres are filled with water which has been infused with nutrients that convert CO2 and sunlight to organic matter through photosynthesis. The microscopically small algae – or microalgae, are the result of this reaction and also the reason for the bright green colour inside the panels. It is this bio-chemical reaction that causes the water to heat up – pretty much your typical solarthermal effects. “The SolarLeaf is a photo bioreactor and that includes an element to cultivate micro-algae,” explains Jan Wurm. “It’s also a solar-thermal collector, so it generates heat and on top of that the solar transmission is changing in relation to the algae content. In that way it’s also a shading device. “So, in principle we are cultivating plants – in this case, microorganisms, algae – in a controlled environment at the façade of the building. We’re harvesting the daylight and we are collecting carbon – carbon emissions. With that we can boost the photosynthesis on the façade and we generate biomass on the one side, and solar-thermal heat on the other. “The heat, we use directly at the building. So, we feed that renewable energy source into the building and we harvest the biomass and use either as a fuel or for selling it to the farming or the food industry,” explains Wurm.


From 2020 onwards, zero energy houses will be obligatory in Germany and some other European countries – every new building will need to produce the same amount of energy as it consumes. The Solarleaf pilot is an example of the kind of innovative thinking that will make that target achievable. The SolarLeaf project has gained recognition for its pioneering design and has recently won a Zumtobel award for ‘Applied Innovation of the Year’. The award “recognises the exceptional sense of collaboration, crossing the fields of design, building engineering” and is an affirmation of the hard work put in by the collaborators. Similarly to the Solaroad pilot project we covered in our January issue, it seems collaboration is definitely key. Bringing together different disciplines in order to come up with new solutions allows the brains of the energy industry to do things differently and think outside of the box. Time will tell how we can apply the technology developed for SolarLeaf in the future. With intermediate results looking very promising and the system producing a net energy gain, the next step is to see how this could be applied on a much larger scale and to see just how lucrative the biomass byproduct will be as an added financial benefit for the system. Jan Wurm goes further, saying the collaborators “really pushed the borders of what is possible. We got out of our box, developed a new system. And in that way I think we do shape a better world, we do develop a technology which is relevant for tomorrow and we’re excited to see what will happen, how it will be adopted by architects and engineers in the near future.”


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