Solar Water Splitting by Photovoltaic-electrolysis with a Solar-to-hydrogen Efficiency over 30%


Hydrogen production via electrochemical water splitting is a promising approach for storing solar energy. For this technology to be economically competitive, it is critical to develop water splitting systems with high solar-to-hydrogen (STH) efficiencies. Here we report a photovoltaic-electrolysis system with the highest STH efficiency for any water splitting technology to date, to the best of our knowledge. Our system consists of two polymer electrolyte membrane electrolysers in series with one InGaP/GaAs/GaInNAsSb triple-junction solar cell, which produces a large-enough voltage to drive both electrolysers with no additional energy input. The solar concentration is adjusted such that the maximum power point of the photovoltaic is well matched to the operating capacity of the electrolysers to optimize the system efficiency. The system achieves a 48-h average STH efficiency of 30%. These results demonstrate the potential of photovoltaic-electrolysis systems for cost-effective solar energy storage.

Funding source: This study presents results from an NSF project (award number CBET-1433442) competitively selected under the solicitation ‘NSF 14-15: NSF/Department of Energy Partnership on Advanced Frontiers in Renewable Hydrogen Fuel Production via Solar Water Splitting Technologies’, which was co-sponsored by the National Science Foundation, Division of Chemical, Bioengineering, Environmental and Transport Systems (CBET), and the US Department of Energy, Office of Energy Efficiency and Renewable Energy, Fuel Cell Technologies Office. J.D.B. and J.J. acknowledge support from Stanford Graduate Fellowships. L.C.S. acknowledges support from the DARE Doctoral Fellowship provided by the Vice Provost for Graduate Education at Stanford University. J.D.B. and L.C.S. acknowledge support from the National Science Foundation Graduate Research Fellowship Program
Related subjects: Production & Supply Chain
Countries: United States

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