Environmental implications of alternative production, distribution, storage, and leakage rates of hydrogen from offshore wind in Norway

Renewable hydrogen offers compelling climate mitigation prospects, with Norway possessing the opportunity to become a main global producer given its unique combination of wind energy potential, available infrastructure, and political motivation. However, comprehensive environmental impact assessments of hydrogen from offshore wind are lacking and hydrogen leakage rates remain uncertain. A life-cycle assessment of hydrogen production from offshore wind farms in Norway is presented, where different combinations of turbines (floating or bottom-fixed), storage options (tank or salt cavern), and distribution methods (trucks or pipelines) are considered. Climate change impacts are assessed across the supply chain using global warming potential 100 (GWP100) and 20 (GWP20) and include hydrogen leakage contributions. The results range from 1.56 ± 0.14–2.28 ± 0.14 kg CO₂-eq/kg H₂ for GWP100 and 2.96 ± 0.76 and 3.75 ± 0.76 kg CO₂-eq/kg H₂ for GWP20 and are on average 55 % and 45 % lower than those of blue hydrogen, respectively. At a default rate of 5 %, hydrogen leakage contributes 50–63 % of the total impact for GWP20 and 25–37 % for GWP100. If higher-end leakage rates from literature are considered, the impacts increase to 3.46 kg CO₂-eq/kg H₂ for GWP100, which is still lower than that of blue hydrogen. The scenario combining bottom-fixed turbines, salt cavern storage, and pipeline distribution presents the lowest environmental impacts. However, while bottom-fixed turbines generally offer lower impacts, floating turbines pose lesser risk to marine biodiversity. Overall, infrastructure represents the main driver of environmental impacts. Mitigation in this area will improve potential benefits.