A new study led by researchers at the University of Sheffield suggests that without rapid power sector decarbonization and tighter oversight of supply chains, the global push toward green hydrogen could fall short of its climate objectives.
Published in Nature Communications Sustainability, the research evaluates 20 hydrogen production and transport scenarios across 14 countries from 2023 to 2050, including the United States, the United Kingdom, Germany, Japan, and China. The analysis compares five hydrogen production pathways, spanning electrolysis and biomass-based routes, and assesses how electricity sources and transport logistics shape overall environmental performance.
The results point to a structural contradiction at the heart of today’s hydrogen strategies. While electrolysis-based hydrogen is widely framed as a clean alternative, the study finds that it currently carries some of the highest global warming impacts among the pathways analyzed. The reason is straightforward: much of the electricity feeding electrolyzers still comes from carbon-intensive grids. With around 96 percent of global hydrogen production linked to fossil-fueled energy systems, scaling electrolyzers on today’s power mix risks locking in emissions rather than eliminating them.
This creates a problem-solution dynamic that policymakers and project developers have been slow to address. Hydrogen is increasingly positioned as a decarbonization lever for steelmaking, chemicals, and heavy transport, sectors where direct electrification is difficult. Yet the study shows that without clean electricity upstream, hydrogen can shift emissions geographically rather than reduce them. In grids dominated by coal or gas, electrolysis can produce hydrogen with a climate footprint comparable to or worse than conventional gray hydrogen.
The research does not dismiss hydrogen’s long-term potential but reframes it as conditional. Under scenarios where electricity systems are rapidly decarbonized, hydrogen supply chains could cut environmental impacts by more than 90 percent by 2050 compared with current production. That outcome depends less on the choice of electrolyzer technology and more on the pace of renewable deployment and grid cleanup in producing countries.
