Considering\nEmbodied Greenhouse Emissions of Nuclear\nand Renewable Power Plants for Electrolytic Hydrogen and Its Use for\nSynthetic Ammonia, Methanol, Fischer–Tropsch Fuel Production

Recent concerns surrounding climate\nchange and the contribution\nof fossil fuels to greenhouse gas (GHG) emissions have sparked interest\nand advancements in renewable energy sources including wind, solar,\nand hydroelectricity. These energy sources, often referred to as “clean\nenergy”, generate no operational onsite GHG emissions. They\nalso offer the potential for clean hydrogen production through water\nelectrolysis, presenting a viable solution to create an environmentally\nfriendly alternative energy carrier with the potential to decarbonize\nindustrial processes reliant on hydrogen. To conduct a full life cycle\nanalysis, it is crucial to account for the embodied emissions associated\nwith renewable and nuclear power generation plants as they can significantly\nimpact the GHG emissions linked to hydrogen production and its derived\nproducts. In this work, we conducted a comprehensive analysis of the\nembodied emissions associated with solar photovoltaic (PV), wind,\nhydro, and nuclear electricity. We investigated the implications of\nincluding plant-embodied emissions in the overall emission estimates\nof electrolysis hydrogen production and subsequently on the production\nof synthetic ammonia, methanol, and Fischer–Tropsch (FT) fuels.\nResults show that average embodied GHG emissions of solar PV, wind,\nhydro, and nuclear electricity generation in the United States (U.S.)\nwere estimated to be 37, 9.8, 7.2, and 0.3 g CO<sub>2</sub> e/kWh,\nrespectively. Life cycle GHG emissions of electrolytic hydrogen produced\nfrom solar PV, wind, and hydroelectricity were estimated as 2.1, 0.6,\nand 0.4 kg of CO<sub>2</sub> e/kg of H<sub>2</sub>, respectively,\nin contrast to the zero-emissions often used when the embodied emissions\nin their construction were excluded. Average life cycle emission estimates\n(CO<sub>2</sub> e/kg) of synthetic ammonia, methanol, and FT-fuel\nfrom solar PV electricity are increased by 5.5, 16, and 49 times,\nrespectively, compared to the case when embodied emissions are excluded.\nThis change also depends on the local irradiance for solar power,\nwhich can result in a further increase of GHG emissions by 35–41%\nin areas of low irradiance or reduce GHG emissions by 21–25%\nin areas with higher irradiance.