09.11.17 - Global (mean) power demands of ca. 2×1013 W could be provided from the earth’s ultimate power source, ca. 1.2×1017 W of incident solar radiation, if adequately efficient, durable and economic transducers are developed.

However, the diurnality of solar power requires such transducers to be coupled to energy storage, potentially enabling decarbonising power sources, managing intermittency of renewable power sources and smoothing the dynamics of electrical power demands. This can be achieved if electrons from photovoltaics are used to electrolyse water to form (oxygen and) hydrogen, which can be oxidised subsequently in fuel cells. Alternatively, solar power (ca. 100 - 300 W m-2) can be used directly, and potentially more cheaply, for photo-electrochemical reduction (and oxidation) of water in an environmentally benign route to hydrogen (and oxygen). Hence, extremely large areas of efficient, cheap, environmentally-benign, easily fabricated absorbing materials and devices would need to be deployed to harvest solar power, to displace CO2-emitting fossil fuels and to contribute significantly to meeting global power demands. Photo-electrochemical reactors incorporating semiconducting photo-electrodes will be described, as such systems offer one possible solution.


Geoff Kelsall has been Professor of Electrochemical Engineering at Imperial College London since 1994, except during 1998-2000, when he held the Chair in Electrometallurgy, University of British Columbia, Canada. His research projects involve the conception, modelling, design, performance characterisation and optimisation of novel reactors for electrolytic processes, high temperature fuel cells / electrolysers and prospective photo-electrochemical processes for harvesting and storing solar energy as hydrogen and other fuels.


Geoff Kelsall

Authors:IGM Colloquim, IGM ColloquimSource:Institute of Mechanical Engineering