Comparative life cycle energy and GHG emissions assessment of green hydrogen production with different electrolysers and solar photovoltaics system

Abstract

Electrolysis of water powered by solar photovoltaics is acknowledged as one of a green hydrogen production method. However, the feasibility of large-scale hydrogen production via solar PV powered electrolysis in terms of energy payback and contribution to the decarbonization of the country needs evaluation using a life cycle energy assessment. For specific (per kg) hydrogen production using a solar PV-electrolysis system with PEM and Alkaline Electrolysers, the life cycle embodied specific energy and GHG emissions are calculated as 47.7 MJ/kg H2 and 46 MJ/kg H2 and 3.45 kg CO <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> eq. and 3.33 kg CO <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> eq. respectively. It is observed from the results that the use of power from the Indian electricity grid in an electrolyser for the production of hydrogen results in 12 times more greenhouse gas emissions than electricity generated by solar PV. The energy payback time (EPBT) and energy return on energy investment (EROI) in Indian conditions are calculated as 1.84 years and 12.56 for Solar energy generation, taking into account the system's embodied energy; whereas, the EPBT and EROI for hydrogen production using Solar PV-PEM and Solar PV-alkaline electrolysis is determined to be 7.7 years and 3.0, and 7.45 years and 3.11, respectively.