Hydrogen leakage could add to atmospheric methane

The Joint Statement was facilitated by Climate Change ‘High-Level Champions’ – UN nominees that connect governmental work with the voluntary and collaborative initiatives taken by cities, regions, businesses and investors – and non-profit energy organisation, RMI. It was signed by, among others, MAN Energy Solutions, the Aspen Institute, the Global Maritime Forum’s Getting to Zero Coalition, the Green Hydrogen Catapult, InterContinental Energy, and A.P. Moller – Maersk.

However, research from Princeton University and the National Oceanic and Atmospheric Association and published in Nature Communications calls the potential of hydrogen as a clean fuel into question. The hydroxyl radical (OH) present in the atmosphere reacts with hydrogen gas, potentially limiting its availability for breaking down methane which would then be present in the atmosphere for longer extending its warming impacts.

“We have a lot to learn about the consequences of using hydrogen, so the switch to hydrogen, a seemingly clean fuel, doesn’t create new environmental challenges,” said Dr Amilcare Porporato, Professor of Civil and Environmental Engineering at Princeton. He says the effects of a hydrogen spike that might occur as government incentives for hydrogen production expand could have decades-long climate consequences for the planet.

“If you emit some hydrogen into the atmosphere now, it will lead to a progressive buildup of methane in the following years,” said Dr Matteo Bertagni, a researcher on the team. “Even though hydrogen only has a lifespan of around two years in the atmosphere, you’ll still have the methane feedback from that hydrogen 30 years from now.”

The research team identified the tipping point at which hydrogen emissions would lead to an increase in atmospheric methane. If more than 9% of green hydrogen produced leaks into the atmosphere during production or anywhere else along the value chain, atmospheric methane would increase over the next few decades, cancelling out some of the climate benefits of switching away from fossil fuels.

For blue hydrogen produced via methane reforming with subsequent carbon capture and storage, the threshold for emissions is lower, as there is the potential for direct methane leakage in addition to hydrogen leakage. Even with a methane leakage rate as low as 0.5%, hydrogen leakages would have to be kept under around 4.5% to avoid increasing atmospheric methane concentrations.

Bertagni said that in the long term (over the course of a century, for instance), the switch to a hydrogen economy would still likely deliver net benefits to the climate, even if methane and hydrogen leakage levels are high enough to cause near-term warming. Eventually, he said, atmospheric gas concentrations would reach a new equilibrium, and the switch to a hydrogen economy would demonstrate its climate benefits. But before that happens, the potential near-term consequences of hydrogen emissions might lead to irreparable environmental and socioeconomic damage.

The issue has also been raised by other researchers, including a team from Columbia University. Their examination of the scientific literature indicates an economy-wide leakage rate of 2.7% in 2020 and a potential 2050 economy-wide leakage rate of between 2.9% and 5.6%. “This can represent a non-negligible contribution to global warming and up to a $59 billion/year value loss of hydrogen (assuming $2/kg-H2),” concluded the researchers from Columbia’s Center on Global Energy Policy in a 2022 op-ed. They note that the leakage rates for shipping have been extrapolated from road transport for similar fuel-cell based technologies at 2.3%.

“In the future, the real leakage risk will likely be new processes such as green hydrogen production, fuel-cell vehicles, and dedicated hydrogen deliveries. If the goal is to address this potential leakage, monitoring programs will need to be implemented for all new processes at the production, delivery, and end-use stages. Active control of these processes through regulations and policies before they scale up can help reduce risks and potential economic losses associated with the future hydrogen economy.”

They conclude that, presently, with very few exceptions, most aspiring leaders of the emerging global hydrogen market lack the dedicated legislation, regulatory frameworks, and internationally recognized standards to be considered best in class in the global hydrogen economy. “Although international standards for hydrogen use have been developed by the International Organization for Standardization, the International Electrotechnical Commission, and the European Industrial Gases Association, most of the countries that have announced national hydrogen strategies and roadmaps lack comprehensive and robust regulatory frameworks and oversight bodies to support their transition to hydrogen economies.”