A new study reveals that the viability of green hydrogen as a sustainable fuel source hinges on the swift and comprehensive decarbonisation of global energy grids, highlighting the critical link between renewable energy and achieving net-zero emissions.
Green hydrogen, the cornerstone of net zero strategies around the world, could fail in becoming a truly sustainable fuel unless countries rapidly decarbonise their energy grids, according to a new study.
The study published in the journal Nature Communications Sustainability highlighted the decisive role that national energy mixes will play in determining the level of emissions involved in producing the fuel and its impact on the environment.
The researchers, led by Professor Lenny Koh, an expert in supply chains at the University of Sheffield's Management School, evaluated 20 possible scenarios for producing and transporting green hydrogen across 14 countries from 2023 through to 2050.
The countries included were the UK, Japan, China, France, Norway, Canada, Germany, South Korea, the USA, Austria, Ireland, Poland, Italy, and the Netherlands.
The research focused on five different ways of making hydrogen fuel, three of which used electrolysis and two of which used biomass systems, the current main production methods globally.
Results show that in 2023, electrolysis technologies had the highest global warming impacts, mainly due to their energy-intensive operation, maintenance and manufacturing stages, as well as how the electricity used in these systems largely came from grids that were powered by oil, gas or coal.
However, the research suggests that making hydrogen via proton exchange membrane - a type of electrolysis - could be the most sustainable option by 2050, if the grids supplying the electricity have moved away from fossil fuels.
Many of the study's scenarios project substantial reductions in greenhouse gas emissions by 2050, as long as electricity grids become cleaner and countries shift towards renewable energy. In some cases, hydrogen supply chains could reduce key environmental impacts by more than 90 per cent compared with current hydrogen production.
One of the most environmentally-friendly supply chains could involve both the UK and US, should they meet their clean energy ambitions, according to the research.
This scenario is based on manufacturing hydrogen in the United Kingdom using proton exchange membrane, with significant exports to the United States, which could support the US and UK's ambition to transition to a more resilient energy system by 2050.
Professor Lenny Koh, Professor of Operations Management at the University of Sheffield, said: "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 per cent 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."
Koh said the research suggests that hydrogen could still live up to its promise and play a vital role in the clean energy transition, but only if the electricity used to produce it comes from genuinely low-carbon sources and the full supply chain is designed with sustainability in mind.
Dr Moein Shamoushaki, Research Associate at the University of Sheffield's Management School, and co-author of the study, said: "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."