Global warming impacts of the transition from fossil fuel conversion and infrastructure to hydrogen

Emissions from fossil fuel extraction, conveyance, and combustion are among the most significant causes of air pollution and climate change, leading to arguably the most acute crises mankind has ever faced. The transition from fossil fuel-based energy systems to hydrogen is essential for meeting a portion of global decarbonization goals. Hydrogen offers certain features, such as high gravimetric energy density that is required for heavy-duty shipping and freight applications, and chemical properties, such as high temperature combustion and reducing capabilities that are required for steel, chemicals, and fertilizer industries. However, hydrogen that leaks has indirect climate implications, stemming from atmospheric interactions, that are emerging as a critical area of research. This study reviews recent literature on hydrogen's global warming potential (GWP), highlighting its indirect contributions to radiative forcing via methane's extended atmospheric lifetime, tropospheric ozone formation, and stratospheric water vapor formation. The 100-year GWP (GWP100) of hydrogen, estimated to range between 8 and 12.8, underscores the need to minimize leakage throughout the hydrogen supply chain to maximize the climate benefits of using hydrogen instead of fossil fuels. Comparisons with methane reveal hydrogen's shorter atmospheric lifetime and reduced long-term warming effects, establishing it as a viable substitute for fossil fuels in sectors, such as steel, cement, and heavy-duty transport. The analysis emphasizes the importance of accurate leakage assessments, robust policy frameworks, and advanced infrastructure to ensure hydrogen realizes its potential as a sustainable energy carrier that displaces the use of fossil fuels. Future research is recommended to refine climate models, better understand atmospheric sinks and hydrogen leakage phenomena, and develop effective strategies to minimize hydrogen emissions, paving the way for environmentally sound use of hydrogen.