The green hydrogen express is gathering pace, but it may have a worrying problem with leaks.

As governments and energy companies line up big bets on the much-touted fuel of the future, some scientists say the lack of data on leaks and the potential harm they could cause is a blind spot for the nascent industry.

At least four studies published this year say hydrogen loses its environmental edge when it seeps into the atmosphere. Two scientists told Reuters that if 10% leaks during its production, transportation, storage or use, the benefits of using green hydrogen over fossil fuels would be completely wiped out.

Scientists say the problem with hydrogen is that when it leaks into the atmosphere, it reduces the concentration of molecules that destroy the greenhouse gases already there, potentially contributing to global warming.

They say the lack of technology for monitoring hydrogen leaks means there is a data gap, and more research is needed to calculate its net impact on global warming before final investment decisions are taken.

Columbia University, the Environmental Defense Fund, a joint project by the universities of Cambridge and Reading, and the Frazer-Nash Consultancy have all published studies about the risk of leaks undermining green hydrogen’s climate benefits.

– We need much better data. We need much better devices to measure the leakage, and we need regulation which actually enforces the measurement of the leakage, said Anne-Sophie Corbeau, a researcher at Columbia University’s Center on Global Energy Policy to Reuters.

It estimates that leakage rates could reach up to 5.6 per cent by 2050 when hydrogen is being used more widely.

Norway’s climate research institute Cicero is also working on a three-and-a-half-year study due to conclude in June 2024 on the impact of hydrogen emissions. Maria Sand, who is leading the research, said there was a big gap in the science.

– We need to be aware of the leakages, we need some answers. We simply need to know more before we make the big transition, said Sand.

The chief attraction of using hydrogen as a fuel is that the main by-product is water vapour, along with small amounts of nitrogen oxides, making it far less polluting than fossil fuels – assuming it doesn’t seep out.

Leaks are one of many issues plaguing the adoption of green hydrogen, besides high costs, safety concerns, and the need to invest in enough renewable energy to make it, as well as in the infrastructure to store and transport the colorless gas.

Brussel has called for applications for funding for more research into the risks linked to a large-scale deployment of hydrogen. It asked the research to show how hydrogen could reduce global warming by replacing fossil fuels, but also how it could contribute to global warming in the event of leakages.

The Environmental Defense Fund’s study, meanwhile, urged governments and businesses to gather data on hydrogen leakage rates first, then identify where the risks were highest and how to mitigate them before building the infrastructure needed.

Almost 300 green hydrogen projects are under construction or have started up worldwide, but the vast majority are tiny demonstration plants, International Energy Agency data showed.

Consultancy DNV forecasts that green hydrogen would need to meet about 12 per cent of the world’s energy demand by 2050 to hit Paris climate targets. Based on the current pace of development and DNV’s modelling of future uptake, the world is only on track to reach about 4 per cent, DNV said.

David Cebon, a professor of mechanical engineering at the University of Cambridge, said 4 per cent might be only what’s «manageable», given the huge amount of renewable energy needed to make enough green hydrogen.

– To replace the dirty hydrogen used now in refineries, fertiliser and chemical plants would require almost double the electricity produced by every wind turbine and solar panel worldwide, and that’s before green hydrogen is used for anything else, such as steelmaking, transport or heating, Cebon said.

Still, the EU is considering mandates for green hydrogen’s use in transport, while countries such as South Korea, Japan and China have targets for hydrogen fuel-cell vehicles.