FEATURE: RESIDUES TO RESOURCES is released as part of a necessary process other than combustion of fossil fuels, explained Friedl, adding that 18 percent of Swiss man-made, unavoidable CO₂ emissions are concentrated in 36 locations and candidates for power-to-methane plants. Incentives needed Delegates called upon politicians to create market incentives to facilitate bringing new CCU technologies to the market. The European Commission (EC) took a first step in this direction with the reform of the “Renewable Energy Directive (RED)”, partially equating CCU fuels with biofuels, as Andreas Pilzecker, DG Climate, reported. A particularly intense discussion ensued on whether a mandatory blend of CCU based kerosene in aviation fuel would be a good route to develop market and capacity as CCU fuels and platform chemicals remain around a factor of 2-3 times more expensive than their fossil counterparts, yet show really low carbon footprints after first life cycle assessments, clearly less than even the best biofuels. CCU state-of-play Hydrogen (H₂) is a key component for most CCU-technologies as it is used to reduce the CO₂. However conventional H₂ production, such as by electrolysis of water, is energy intensive and, as pointed out by Dr Friedl, may defeat the purpose. Several speakers remarked that H₂ production represents over 80 percent of the costs for CO₂ based fuels and chemicals. Lowering the cost of H₂ production is a critical factor and the research race is on. Well-developed CCU technologies on the cusp of industrial-scale commercialisation were presented as well as those still in laboratory or pilot scale. Icelandic company International Carbon Recycling (ICR) is an example of the former with its 4 000 tonne-per-annum renewable methanol plant in Iceland making it the largest CCU plant of its kind. Another pathway has been demonstrated by American company, Joule Fuels Unlimited, with its continuous flow “reverse combustion” CO₂-to-fuel production platform. According to Kees van de Kerk the pilot plant in New Mexico uses sunlight, non-potable water and engineered cyanobacteria that function as living catalysts to produce specific products, ethanol or hydrocarbon fuels that are “inherently compatible” with existing infrastructure. Thomas Heller with MicrobEnergy, owned by Viessmann Group, presented a novel microbiological process set up as a demonstration power-to-gas at a biogas plant in Allendorf (Eder), Germany. The project is part of the German BioPower2Gas subsidy programme. The process combines hydrogen from an external source with the CO₂ generated during fermentation in a biogas plant converting it into methane. A PEM electrolyser built by Carbotech, another Viessmann company, is used to produce hydrogen. – Specialised microorganisms perform the actual methanisation. They absorb the carbon dioxide and the hydrogen in liquid form through their cell walls, ’digesting’ and converting them into methane. The only thing left over after this process is water. Biological methanation impresses due to its optimum flexibility, making it eminently suitable to absorb fluctuating quantities of power produced by wind or solar power, said Heller. 20 Bioenergy Internat ional No 82, 6-2015 Leading in the usage of CO₂ for production of CO₂ based polymers is Covestro, formerly Bayer Material Science and one of the world’s largest polymer producers, which will be the first to produce CO₂ based polyurethane foams in Dormagen, Germany next year. – This should be the start for a new product family based on CO₂ based polyols and polymers, said Dr Christoph Gürtler from Covestro. Also in an advanced state of precommercial deployment are CCU systems that combine electrolysis of water and then from the hydrogen plus CO₂ produce a variety of synthetic fuels and platform chemicals via Fischer-Tropsch processes. This includes for example the technologies from the German company sunfire and the Israeli company NewCO₂Fuels. Artificial photosynthesis Dr Dunwei Wang, Professor from Boston College, US presented the latest update on work to develop cheap low-cost metallic catalysts, which may enable artificial photosynthesis with high efficiency. – The promise held by solar water splitting, however, cannot be materialised unless the process can be carried out using earth-abundant, low-cost materials, said Wang. Wang’s research involves using hematite (alpha phase iron oxide) and addressing the key problems shared by low-cost materials. – Many of these issues are addressable and collectively our improvement strategies demonstrate that the performance of hematite can be improved dramatically, enabling complete solar water splitting without the need for external power input other than the presence of a silicon-based photocathode. These results open up new opportunities toward practical low-cost solar hydrogen generation, said Wang. – The design of highly efficient, non-biological, molecular-level energy conversion “machines” that generate fuels directly from sunlight, water, and carbon dioxide is both a formidable challenge and an opportunity that, if realised, could have a revolutionary impact on our energy system, said Dr Nathan Lewis, Professor at the California Institute of Technology and US Department of Energy Energy Innovation Hub, Joint Center for Artificial Photosynthesis (JCAP). Lewis presented a bold example of mimicry. His research thus far has developed so-called “silicon microwires”, which can split water directly into hydrogen and oxygen with the use of sunlight. These “polymer mats” can be rolled out like a carpet and produce hydrogen from sunlight and humidity. – Basic research has already provided enormous advances in our understanding of the subtle and complex photochemistry behind the natural photosynthetic system, and in the use of inorganic photo-catalytic methods to split water or reduce carbon dioxide – key steps in photosynthesis, Lewis said. In a second step these could be designed to produce synthetic fuels using CO₂ from the air. In other words solar energy could be tapped and transformed into high energy density synthetic fuels and stored in decentralised locations. When could such technologies appear on the market? The next edition of the event, slated to be held in December 2016, is a good place to find out. Text & photos: Alan Sherrard BI82/5065/AS Benedikt Stefánsson ICR explained how power-to-methanol uses power and CO2 from a geothermal plant. Bio-electrocatalytic CO2 reduction with microbes and enzymes, Stefanie Schlager, Johannes Kepler University. Dr Christoph Gürtler, Covestro, revealed production of CO2-based polyurethane foams will start 2016. Christian von Olshausen, sunfire, outlining some of the company’s powerto liquids activities and milestones. Cont. from page 19
Bioenergy no 6 October 2015
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