TY - JOUR
T1 - Thermodynamic and achievable efficiencies for solar-driven electrochemical reduction of carbon dioxide to transportation fuels
AU - Singh, Meenesh R.
AU - Clark, Ezra L.
AU - Bell, Alexis T.
PY - 2015/11/10
Y1 - 2015/11/10
N2 - Thermodynamic, achievable, and realistic efficiency limits of solardriven electrochemical conversion of water and carbon dioxide to fuels are investigated as functions of light-Absorber composition and configuration, and catalyst composition. The maximum thermodynamic efficiency at 1-sun illumination for adiabatic electrochemical synthesis of various solar fuels is in the range of 32-42%. Single-, double-, and triple-junction light absorbers are found to be optimal for electrochemical load ranges of 0-0.9 V, 0.9-1.95 V, and 1.95-3.5 V, respectively. Achievable solar-To-fuel (STF) efficiencies are determined using ideal double-and triple-junction light absorbers and the electrochemical load curves for CO2 reduction on silver and copper cathodes, and water oxidation kinetics over iridium oxide. The maximum achievable STF efficiencies for synthesis gas (H2 and CO) and Hythane (H2 and CH4) are 18.4% and 20.3%, respectively. Whereas the realistic STF efficiency of photoelectrochemical cells (PECs) can be as low as 0.8%, tandem PECs and photovoltaic (PV)-electrolyzers can operate at 7.2% under identical operating conditions. We show that the composition and energy content of solar fuels can also be adjusted by tuning the band-gaps of triple-junction light absorbers and/or the ratio of catalyst-To-PV area, and that the synthesis of liquid products and C2H4 have high profitability indices.
AB - Thermodynamic, achievable, and realistic efficiency limits of solardriven electrochemical conversion of water and carbon dioxide to fuels are investigated as functions of light-Absorber composition and configuration, and catalyst composition. The maximum thermodynamic efficiency at 1-sun illumination for adiabatic electrochemical synthesis of various solar fuels is in the range of 32-42%. Single-, double-, and triple-junction light absorbers are found to be optimal for electrochemical load ranges of 0-0.9 V, 0.9-1.95 V, and 1.95-3.5 V, respectively. Achievable solar-To-fuel (STF) efficiencies are determined using ideal double-and triple-junction light absorbers and the electrochemical load curves for CO2 reduction on silver and copper cathodes, and water oxidation kinetics over iridium oxide. The maximum achievable STF efficiencies for synthesis gas (H2 and CO) and Hythane (H2 and CH4) are 18.4% and 20.3%, respectively. Whereas the realistic STF efficiency of photoelectrochemical cells (PECs) can be as low as 0.8%, tandem PECs and photovoltaic (PV)-electrolyzers can operate at 7.2% under identical operating conditions. We show that the composition and energy content of solar fuels can also be adjusted by tuning the band-gaps of triple-junction light absorbers and/or the ratio of catalyst-To-PV area, and that the synthesis of liquid products and C2H4 have high profitability indices.
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U2 - 10.1073/pnas.1519212112
DO - 10.1073/pnas.1519212112
M3 - Article
AN - SCOPUS:84946763325
SN - 0027-8424
VL - 112
SP - E6111-E6118
JO - Proceedings of the National Academy of Sciences of the United States of America
JF - Proceedings of the National Academy of Sciences of the United States of America
IS - 45
ER -