Impact of energy sources on Global Warming Potential of hydrogen production: Case study of Uruguay

In 2022, Uruguay launched its green hydrogen roadmap, due to its renewable energy potential, water availability, and favorable logistics to position itself as an exporter of green hydrogen and derivatives. The energy source for water electrolysis is a key factor in both the final cost and the environmental impact of hydrogen production. In this context, this study evaluates the environmental impact of hydrogen production via water electrolysis, powered by 150 MW of new power sources (solar, wind, and hybrid farms) in Uruguay, all connected to the national grid. A life cycle assessment (LCA) was conducted using OpenLCA software and the Ecoinvent database, with 1 kg of hydrogen as the functional unit and the system boundaries included power generation and the electrolysis system. The analysis focused on global warming potential (GWP), considering different scenarios for the grid energy mix and the inclusion or exclusion of surplus energy as carbon credits. The wind plant is the option that generates the highest energy output and surplus while requiring the least energy purchase from the Uruguayan grid, due to its higher capacity factor. Regarding GWP, it is also the alternative with the lowest environmental impact, with annual average emissions ranging from 0.84 to 1.02 kg CO2/kg H2 not considering carbon credits (CC) and between 0.2 and -1.87 kg CO2/kg H2 when CC are considered. These values represent emissions based on grid connection during the years with the highest proportion of renewable and fossil sources, respectively.