(659a) Keynote: Solar fuel processing: Research, technology development, and scaling

Solar radiation is the most abundant renewable energy source available but it is distributed and intermittent, thereby necessitating its storage via conversion to a fuel or chemical commodity (e.g. hydrogen or carbohydrates) for practical use. Solar thermo-chemical and photo-electro-chemical approaches (and combinations thereof) provide viable, non-biological routes for the direct synthesis of solar fuels and chemical commodities. Both approaches involve complex interactions between electromagnetic wave propagation, multi-mode heat transfer, multiphase flow, charge transfer, and chemical reactions. The design of practical and scalable reactors and their scaling into solar fuel processing systems is therefore challenging, but considerable advancements have been demonstrated over the last decades. I will describe research and technology development of solar fuel processing devices and systems, and compares the various approaches in terms of efficiency, selectivity, production rate, and stability. One specific example I will discuss, is LRESE’s concentrated photoelectrochemical approach, starting from the underlying idea, the design implementation [1], laboratory-scale demonstration [2] with world-record power density [3], and ongoing scaling into an operational solar fuel processing system utilizing our 7m-diameter solar concentrating dish. Remaining challenges to be addressed at a fundamental research level will be discussed in an outlook.

[1] S. Tembhurne, S. Haussener, Integrated Photo-Electrochemical Solar Fuel Generators under Concentrated Irradiation- Part II: Thermal Management a Crucial Design Consideration, Journal of The Electrochemical Society, 163: H999-H1007, 2016.

[2] S. Tembhurne, F. Nandjou, S. Haussener, A thermally synergistic photo-electrochemical hydrogen generator operating under concentrated solar irradiation, Nature Energy, doi: 10.1038/s41560-019-0373-7, 2019.

[3] http://specdc.epfl.ch