The hidden journey behind green hydrogen production
How sustainable is green hydrogen? Professor Lenny Koh is exploring the supply chain decisions that shape its environmental impact.
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Green hydrogen is often promoted as a clean fuel that could help tackle climate change. But new research from the University of Sheffield shows that producing hydrogen with renewable energy is only part of the story.
Professor Lenny Koh and her team are the first to examine how entire international green hydrogen supply chains affect the environment over time.
The findings provide important evidence to help governments and industry make smarter decisions about investing in green hydrogen and building a truly sustainable hydrogen economy.
Hydrogen has a clean energy promise, but the way we produce it tells a different story.
Around 96 per cent of the world's hydrogen is still produced using fossil fuels, making it a significant source of greenhouse gas emissions.
In recent years, green hydrogen has emerged as a cleaner alternative, using renewable electricity from sources such as wind and solar to split water into hydrogen and oxygen.
For industries that rely heavily on hydrogen but are difficult to electrify, this cleaner energy option has been widely seen as a promising way to cut carbon emissions and support the transition to net zero.
However, new research from the University of Sheffield suggests that the sustainability of green hydrogen cannot be judged by how it is produced alone. Led by Professor Lenny Koh from the University of Sheffield’s Management School, the research is the first large-scale international study to assess the environmental impacts of green hydrogen supply chains over time.
Taking a global approach, the team analysed 20 different supply chain scenarios across 14 countries and five hydrogen production technologies, tracing the complete hydrogen journey from production through to transport, storage and delivery.
The findings revealed that decisions made across the supply chain can significantly influence whether green hydrogen delivers the environmental benefits it originally promised.
Why green isn't always green
One of the main challenges with green hydrogen is that it is not always as environmentally friendly as people assume. Most existing research focuses primarily on the methods used to produce hydrogen, often without considering where it is made or how it moves through the supply chain. Because of this, studying green hydrogen projects in isolation can provide an incomplete picture - as their true environmental impact may only become clear when the entire supply chain is taken into account.
“Our research examined whether producing green hydrogen in different regions, each with varying energy mixes and electricity grid characteristics, affects its overall sustainability. The findings show that simply labelling hydrogen as green does not automatically mean it has a low environmental impact”, explains Professor Koh.
The environmental benefits of green hydrogen depend heavily on supply chain design and the energy systems that support it. One of the study's most striking findings is that sustainability can vary significantly between countries and supply chains.
Professor Lenny Koh
Management School, University of Sheffield
“Hydrogen produced in regions with rapidly decarbonising electricity systems delivers much greater environmental benefits than hydrogen produced in countries that remain heavily reliant on fossil fuels. The carbon intensity of national electricity grids emerged as one of the most important determinants of overall performance”, adds Professor Koh.
“Transportation also matters. Moving hydrogen across long distances requires infrastructure and energy, adding to environmental impacts. Manufacturing equipment and maintaining operations further influence outcomes”.
Three key recommendations from the research
Professor Lenny Koh's research revealed three key findings that highlight how the sustainability of hydrogen depends not only on production methods, but also on where and how it is supplied around the world.
A UK–US partnership could offer the strongest long-term pathway
A UK–US green hydrogen supply chain as the most sustainable option by 2050. Under one of the study's scenarios, hydrogen produced in the UK, with half exported to the United States, reduced global warming impacts by 97.9 per cent. This is largely driven by the expected decarbonisation of the UK electricity grid and the relatively low-carbon energy mix projected for the US.
Cleaner electricity is key to cleaner hydrogen
Electrolysis-based hydrogen technologies have the greatest potential to reduce greenhouse gas emissions over time. However, the environmental benefits of these technologies depend heavily on the electricity used to power them. This means that where hydrogen is produced, and the carbon intensity of the local energy system, can be just as important as the technology itself.
The sustainability of hydrogen changes over time
The sustainability of green hydrogen supply chains is not fixed. It evolves over time as energy systems decarbonise, technologies mature and supply chain configurations develop. By using a dynamic spatial-temporal model rather than a static approach, the study was able to uncover future trade-offs and show how decisions about where hydrogen is produced, manufactured and traded can significantly influence environmental outcomes.
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What this means for the future of clean energy
The research project provides valuable evidence for governments, industry leaders, and investors planning the future of green hydrogen.
“Our analysis shows that while PEM electrolysis, a technology that uses electricity to split water into hydrogen and oxygen, currently faces challenges such as high upfront costs and technological maturity constraints, it demonstrates the greatest sustainability improvements over time. This suggests that PEM is likely to be one of the most promising technologies for large-scale green hydrogen production in the future”, explains Professor Koh.
“The research also highlights the importance of policy and infrastructure coordination between the UK and US. A transatlantic hydrogen supply chain will depend on supportive regulation, trade agreements, and investment in infrastructure. These findings can help shape energy policy and strengthen advanced technology partnerships between both countries”.
“In addition, our regional analysis shows that countries with faster electricity grid decarbonisation, such as the UK and US, are likely to gain a first-mover advantage in green hydrogen production. By contrast, regions that remain heavily dependent on fossil fuel-based electricity may see lower sustainability benefits. This emphasises the need to align hydrogen supply chain strategies with national net-zero pathways", adds Professor Koh.
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Next steps for industry and policy makers
The most important next steps for policymakers and industry are to use these findings to make informed decisions about where and how green hydrogen is produced, who to partner with, and which technologies to prioritise.
For policymakers, the research provides evidence to support investment strategies, international partnerships, infrastructure planning, and policies that align with net-zero targets. It also offers a framework for ensuring compliance with environmental regulations while reducing emissions across the hydrogen supply chain.
For industry, the findings help identify the most sustainable production technologies, optimal transportation routes, and resilient supply chain configurations. This can support investment decisions that minimise environmental impacts while maximising long-term reliability and commercial viability.
“Overall the project demonstrates how research at Sheffield can provide practical evidence to support international policy, investment decisions and the transition to net zero. It also reflects the work being undertaken across the University's world-leading energy and sustainability research communities, reinforcing our reputation as a leader in developing practical solutions for a low-carbon future”, concludes Professor Koh.
Connect with Professor Koh on LinkedIn
Written by Anna Blagg (Marketing and Communications Officer, Research)
For further info contact: mediateam@sheffield.ac.uk