Up-scaling solar hydrogen production

Lead Research Organisation: Imperial College London
Department Name: Chemical Engineering

Abstract

'Solar fuels' are synthetic, storable, high energy density chemicals, produced using sunlight as the sole energy source. Solar fuels include hydrogen (termed "golden hydrogen"), which is generated by solar-driven water reduction, and various carbon-based fuels produced through the reduction of carbon dioxide. Fuels synthesised in this way can contribute towards reaching net zero greenhouse gas emissions.

The projected increase in global power demand necessitates urgent decarbonisation of power sources and fuels to limit the release of CO2 into the atmosphere. One major pathway to achieving this goal is to harness and utilise renewable energies. These, however, are intermittent and so require management, for example via energy storage in chemical bonds.

Photoelectrochemical reactors present a potential technological solution for producing solar fuels at scale. Such reactors combine - in a single device - the functions of photovoltaic (PV) panels and electrolysers; the former convert solar energy to electrical energy, while the latter convert electrical energy to chemical energy. In photoelectrochemical reactors, photoabsorbing components are immersed in liquid media. This approach was conceived to lower the capital cost of solar fuel production compared with commercially available PV + electrolyser systems.

The overarching aim of this research is to answer the question 'What might an industrial scale photoelectrochemical reactor system ultimately look like?'. Development of up-scaled reactors is a multidisciplinary challenge, involving material science, (photo)electrochemistry, electrochemical engineering and optics, supplemented by numerical modelling of the complete system to guide its design and optimisation. These many considerations need to be addressed simultaneously. By answering some of these critical questions and developing large-scale prototype reactors, this project will accelerate the development of sustainable hydrogen production using photoelectrochemical devices and bring us closer to the decarbonisation of our energy systems that we urgently need.

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