Sustainability assessment of hydrogen production via water electrolysis considering different configurations of solar photovoltaics-battery-grid systems in China

Renewable or “green” hydrogen has emerged as a promising option to help mitigate climate change. Given China's abundant solar resources, hydrogen produced using solar energy could be a viable pathway for the country but at present its sustainability is unknown. Therefore, this study evaluates the life cycle environmental and economic sustainability of renewable hydrogen production via polymer electrolyte membrane water electrolysis (PEMWE) using solar photovoltaics (PV) as the main source of energy. Three PV system configurations are considered: a standalone PV (SPV), an off-grid PV with battery storage (BPV) and a grid-connected PV (GPV). The findings reveal the superior environmental performance of SPV. For instance, it has the lowest climate change impact of 4.3–6.5 t CO 2 eq./t H 2 , representing a 14–30 % reduction on BPV and a substantial 84–90 % decrease relative to GPV. SPV also shows notable reductions (4–78 %) across the other impacts in comparison with BPV. While SPV has higher land use and metal depletion (9–170 %) and similar ecotoxicity impacts to GPV, it achieves significant reductions (16–90 %) in the water, soil and air pollution, fossil depletion, freshwater consumption and non-cancer human toxicity (11 out of 18 categories). However, SPV is the second most expensive configuration, with the life cycle costs of 1581–2412 M$ and levelised costs of hydrogen (LCOH) of 3953–6029 $/t. GPV is the best option for costs (1047–1570 M$ and 2741–4048 $/t), while the costs of BPV are around three times as high (4405–5180 M$ and 11,134–12,951 $/t). Looking ahead to 2050, with prospective changes in the grid composition, GPV offers 18–79 % reductions in the climate change, fossil depletion, water consumption, human toxicity and water, soil and air-pollution related impacts, but increases ionising radiation, land use, metal depletion and ecotoxicity by 2–244 % relative to the current grid mix. Currently, SPV outperforms steam methane reforming in four impacts and coal gasification in nine, including climate change, but has a higher LCOH than both conventional processes (1240–2480 $/t). GPV is currently the only option economically competitive with the conventional routes, but it is suboptimal environmentally compared to SPV. This research provides new insights into the selection of optimal configurations for PEMWE hydrogen production in China across different regions and time horizons and will be of interest to technology developers, investors and policy makers.