Prospective life cycle assessment of baseload hydrogen based on solar photovoltaics and wind power including underground hydrogen storage

A prospective life cycle assessment approach is employed to analyse the environmental impacts of green e-hydrogen production from an alkaline electrolyser powered by an off-grid solar photovoltaics-wind power system coupled with underground hydrogen storage. The future environmental impacts of hydrogen production are examined using scenarios based on power sector defossilisation scenarios of the LUT Energy System Transition Model, employing the premise tool and Activity Browser. Finland, Germany, Spain, and Chile are selected as case studies due to their varying regional climate zones and different shares of solar photovoltaics and wind power. Results reveal GWP100 values per kWhH2,LHV decrease from 30.7 to 47.2 g CO2-eq to 12.0 - 16.5 g CO2-eq from 2020 to 2050. Chile, with a very high solar photovoltaics share in the off-grid system, has lower environmental impacts compared to other countries with higher wind power shares such as Finland and Germany. By 2050, the remaining greenhouse gas emissions arise from the production of materials mainly steel, silicon, concrete, and aluminium, and from fossil fuel use in road and maritime transportation and indicate need for improvement in methodology and data. Other environmental indicators exhibit improvements of 20-53% in human health, ecosystem quality, and resource use, while minor increases in acidification and human toxicity are attributable to material production and system operation. Transitioning to 100% renewable energy for materials and transportation could effectively bring these residual emissions to near zero and further enhance environmental impacts.