Decarbonising electricity systems crucial for green hydrogen to meet climate targets

Green hydrogen risks falling short of its climate promise unless electricity systems are decarbonised and supply chains are redesigned, new modelling from the University of Sheffield concludes.

The paper, published in Communications Sustainability, tests 20 production and transport scenarios for green hydrogen across 14 countries from 2023 to 2050 and finds that the environmental performance of hydrogen is driven overwhelmingly by the carbon intensity of the grids that power its manufacture. According to the report by Communications Sustainability, electrolysis routes, because they consume substantial electricity and entail energy‑intensive manufacturing and maintenance, had the largest global warming footprints in 2023 when grid power remained dominated by oil, gas or coal. The study modelled three electrolysis approaches and two biomass pathways, reflecting the technologies currently most deployed worldwide.

The researchers’ projections show a pathway for substantial emissions reductions by mid‑century, but only where national power sectors are rapidly decarbonised. Industry data in the study indicate that proton exchange membrane (PEM) electrolysers could become among the lowest‑impact options by 2050, provided the supplying grids move decisively away from fossil fuels. In some scenarios the authors report potential cuts in key environmental impacts exceeding 90% compared with present‑day hydrogen production, but those outcomes depend on concurrent progress in renewable generation and clean energy deployment.

The team highlights a plausible low‑impact trade route linking the United Kingdom and the United States. According to the study, manufacturing hydrogen in the U.K. using PEM technology for export to the U.S. could deliver one of the more favourable lifecycle results if both countries meet their clean energy commitments and forge resilient cross‑border supply chains.

The lead author, Professor Lenny Koh of the University of Sheffield Management School, warned of the mismatch between policy ambition and current realities: “Green hydrogen is seen as the answer to the world’s energy crisis in terms of reducing our reliance on imported fossil fuels; however, at present, approximately 96% of hydrogen is made using fossil fuels. We cannot be successful in using hydrogen to reach net zero, if fossil fuels are still playing such a huge role in the hydrogen supply chain.” He stressed the need to match technology choices to regional decarbonisation trajectories if international chains are to be sustainable by 2050.

Dr Moein Shamoushaki, a co‑author, added: “Our research is clear that the sustainability of green hydrogen very much depends on energy mix and supply chains. Any delays in policy implementation or disruptions to renewable energy deployment could substantially alter the relative sustainability of green hydrogen supply chains.” The paper frames those policy and deployment risks as decisive: without timely renewable roll‑out and supply‑chain change, some hydrogen pathways could lock in significant emissions.

The University of Sheffield has been building capability to translate those research findings into industrial practice. According to university materials, its facilities include pilot‑scale hydrogen R&D and a newly commissioned PEM electrolyser at the Sustainable Aviation Fuels Innovation Centre, enabling testing of low‑ and zero‑carbon fuels and supporting industrial partners in decarbonisation efforts. The university is also working with industry, for example in partnership with E.ON to assess hydrogen use in steelmaking, an initiative intended to develop business cases for replacing fossil fuels in high‑temperature processes.

Trade and standards bodies have picked up the central message that supply‑chain emissions matter. The Institute of Materials, Minerals and Mining has highlighted the study’s implication that decarbonising upstream components is essential for credible green hydrogen pathways, while trade coverage notes Sheffield’s expanding role in hydrogen‑enabled sustainable aviation fuel research.

For industrial decarbonisation strategists, the study underlines two practical priorities. First, hydrogen policy and investment decisions must be evaluated in the context of projected national grid emissions over the asset lifetime; early deployment of electrolysis in regions with still‑carbon‑intensive power could yield little climate benefit. Second, companies and governments should coordinate renewable generation plans, electrolyser siting, manufacturing decarbonisation and trade arrangements to avoid simply shifting emissions along international value chains.

The Communications Sustainability paper provides a quantified basis for those priorities, but its authors caution that outcomes are sensitive to policy timing and technology trajectories. For stakeholders in heavy industry and energy-intensive manufacturing, the implication is clear: making hydrogen a tool for deep decarbonisation requires simultaneous action on grids, supply chains and technology selection rather than treating hydrogen as a standalone fix.