The analysis of hydrogen’s role in mitigating climate impacts reveals both significant challenges and promising opportunities. Hydrogen, widely acknowledged for its potential to decarbonize hard-to-abate sectors, is free from direct carbon emissions when combusted. However, its indirect warming effects complicate its status as a clean energy solution. The primary determinants of hydrogen’s life cycle climate impacts include the production method and feedstock emissions. A comprehensive assessment indicates that while hydrogen leakage contributes to the greenhouse effect, its impact is secondary to the carbon intensity associated with hydrogen production and electricity use.
An examination of hydrogen production pathways—such as electrolysis and steam methane reforming (SMR)—showcases variability in emissions based on the production method used. The potential reduction in greenhouse gas emissions is significant in hydrogen-based steel production and heavy-duty transport compared to traditional fossil fuel methods. A reduction of up to 1400 kg carbon dioxide equivalent per tonne of steel production and substantial decreases in emissions for hydrogen-fueled transportation (up to 0.17 kg per tonne-kilometer) highlight its potential benefits.
Despite the indirect warming effects from atmospheric hydrogen releases, the increase in carbon intensity of hydrogen production remains marginal when compared to total emissions. Data show that hydrogen’s indirect warming potential contributes less than 15% to the emission increases for the considered production pathways, highlighting the efficacy of renewable energy sources like wind power in minimizing emissions. Electrolysis with wind consistently reduces emissions, whereas electrolysis using solar energy approaches the clean hydrogen threshold, depending on hydrogen leakage rates.
Market dynamics predict a surge in hydrogen production and consumption, from under 100 Megatonnes in 2022 to potentially over 650 Mt by 2050. This growth is underpinned by substantial investments in hydrogen infrastructure and production, guided by national strategies and policies like the United States’ Inflation Reduction Act. The act incentivizes reduced life cycle emissions (below 4 kgCO2e/kgH2) to qualify for tax credits, driving innovation and clean energy transitions.
Hydrogen’s interaction with hydroxyl radicals, subsequently increasing methane atmospheric lifetime, is a critical point of concern. These interactions exacerbate greenhouse gas effects, presenting additional layers of complexity to hydrogen’s climate impact. However, empirical data on global hydrogen leakage and its precise impacts remain sparse, introducing an element of uncertainty into emission projections. The U.S. Department of Energy’s funding to advance hydrogen leakage detection technology highlights a proactive approach to address these knowledge gaps.
Life Cycle Assessments (LCAs) further elucidate hydrogen’s decarbonization potential, especially when compared against fossil fuel pathways. While hydrogen facilitates emission reductions across several sectors, its contribution to climate goals is contingent upon careful selection of production pathways and end-use applications. Specifically in the steel industry, hydrogen holds clear emission reduction advantages regardless of production pathways—underscoring its role in existing production process revisions.
Further research is necessary to refine our understanding of hydrogen emissions and to develop comprehensive, data-rich models for future applications. The findings underscore the delineation required in deploying hydrogen effectively across different sectors, particularly those with high emission abatement potentials. Such nuanced strategies are imperative for leveraging hydrogen’s full potential in addressing global climate objectives.
