Life cycle assessment of H2O electrolysis technologies

Electrolyzers for Hydrogen Production: Solid Oxide, Alkaline, and Proton Exchange Membrane

“…Figure 1 shows the typical schematic of an electrolysis cell (Holst et al, 2021). This cell comprises four main components: (a) two metal electrodes-an oxygen electrode where oxygen evolution reaction (OER) occurs (anode), and a hydrogen electrode where hydrogen evolution reaction (HER) occurs (cathode), (b) an electrolyte that ensures ionic conductivity (or ion transfer), and (c) a thin material layer that is ion-conductive, called the separator (Grigoriev et al, 2020;Holst et al, 2021;Zhao et al, 2020). During electrolysis, a large direct current (DC) voltage is applied to the cell along with a simultaneous water supply.…”

“…The global focus on achieving net-zero carbon emission targets to avoid the worst effects of climate change has caused a major increase in the production and use of renewable energy technologies (Gerloff, 2021a;IPCC, 2021;Zhao et al, 2020). While the prime focus has been on wind and solar energy for electricity production, other alternative sources and carriers of energy have emerged in recent years.…”

“…Of these, hydrogen (H2) has emerged as a key carrier with significant potential for use across different sectors involving energy generation and consumption (Holst et al, 2021;Ruth et al, 2021). Given the intermittent nature of wind and solar energy, H2 can be produced using these energy forms, stored in bulk quantities, and used to produce electricity for grid balancing, stability, and backup power needs (Gerloff, 2021b;Ruth et al, 2021;Zhao et al, 2020). H2 produced using renewable energy can replace natural gas-based H2 in current applications such as the production of plastics, chemicals, and fertilizers, and refining of oil and metals (Ruth et al, 2021).…”

“…However, these studies focus primarily on the benefits accrued via the change in the energy source used for H2 production. In contrast, only a handful of studies (Gerloff, 2021b;Patyk et al, 2013;Zhao et al, 2020) focus on GHG emissions during the production stages of water electrolysis technologies. This makes it difficult to (a) evaluate and compare the life cycle GHG emissions of H2 production via water electrolysis technologies with that from SMR-NG, (b) determine the relative ranking of different water electrolysis technologies on their GHG footprint, and (c) assess the relative significance of production stages in life cycle GHG emissions of these technologies.…”

Review and Harmonization of the Life-Cycle Global Warming Impact of PV-Powered Hydrogen Production by Electrolysis

“…The studies were excluded after screening because of the absence of open access data; for instance, the GWP results were not broken down into sub-systems and the FU parameters were not fully quantified (Dincer and Acar, 2015;Bhandari et al, 2014;Valente et al, 2017;Mehmeti et al, 2018;Utgikar and Thiesen, 2006;Hacatoglu et al, 2012;Kalinci et al, 2012;Boyano et al, 2011;Lotrič et al, 2021;Zhao et al, 2020;Kovač et al, 2021;Sharma et al, 2020;Ozawa et al, 2017). Hence, in these cases, it was not possible to convert the original FU to FU har of 1 kg of hydrogen for the desired system boundaries.…”