Hydrogen leakages across the supply chain: Current estimates and future scenarios

Low-carbon hydrogen is widely acknowledged as a key pillar of the global energy transition. However, because hydrogen acts as an indirect greenhouse gas, estimating its atmospheric leakages across the supply chain is necessary for an accurate evaluation of its overall environmental benefits. As part of the European HYDRA project, this study presents a thorough assessment of hydrogen leakages across the entire supply chain – encompassing production, handling, storage, transport, and end-uses – under current conditions (2023) and projected scenarios for 2030 and 2050. For this purpose, a detailed dataset of hydrogen leakage rates is compiled from the literature, offering both average and minimum–maximum estimates to reflect the inherent uncertainties and provide ready-to-use values for emissions assessments. Results indicate that electrolysis is potentially the most leakage-prone production pathway, owing to processes such as purging and stack venting. Moreover, as hydrogen infrastructure develops over the coming decades, liquid hydrogen is expected to become a major contributor to losses, mainly due to boil-off during handling, transport, and refueling operations. By 2050, overall leakage rates across the supply chain could range from below 2% in optimistic projections to nearly 20% in worst-case scenarios. These findings highlight the importance of accurately quantifying hydrogen emissions and implementing mitigation measures to fully harness the climate benefits of a possible future hydrogen-based economy. By identifying the processes most susceptible to leaks, this analysis offers valuable insights for policymakers, researchers, and industry stakeholders aiming to reduce hydrogen losses and maximize hydrogen-related environmental benefits.