Hydrogen leakage is becoming a major concern globally amid the race to scale up output and use, with a new study suggesting electrolysis is the most leakage-prone production route.

However, a lack of consistent data makes it difficult to fully assess the issue, leading to regulatory risk.

When released into the atmosphere, hydrogen acts as an indirect greenhouse gas as it can cause atmosphere perturbations, leading to the increase in the concentrations of methane, ozone and water vapour, thus offsetting climate benefits.

“This leaves the door wide open for regulatory uncertainty” Corbeau, Center on Global Energy Policy

A recent study led by researchers at Italy’s Polytechnic University of Turin estimates hydrogen leakage could nearly triple by 2030 from a current level 1.3mt/yr. It could rise to 22mt/yr by 2050, based on average values, the study said.

Overall leakage rates could range between 2% and 20% by 2050, although “these estimates may be subject to considerable variability, reflecting the challenges in accurately measuring hydrogen leakages rates at the various stages of the supply chain”, the report said.

The analysis, which was funded by the EU under the HYDRA programme and covers all stages of the hydrogen supply chain, shows most of the hydrogen losses take place in the production phases (53.3%), followed by use in the industrial processes (27.2%).

In addition, it found electrolysis is potentially the most leakage-prone production pathway, owing to processes such as purging and stack venting. At the same time, the wide leakage range (0.03–9.2%) might be due to the fact outdated electrolysers are being factored in. In addition, there is “uncertainty related to the impact of purging during the regeneration of hydrogen purification systems”, the report said.

By comparison, the average leakage rates for steam methane reforming (SMR)-based solutions are estimated at 0.73% for SMR with CCUS and 0.75% for conventional SMR.

Boil-off

The research also highlights that, as hydrogen infrastructure develops over the coming decades, liquid hydrogen is expected to become a major contributor to losses, mainly due to boil-off during handling, transport and refuelling operations.

“Hydrogen leakage is a critical issue across the value chain and can significantly impact both the economic viability and environmental integrity of hydrogen as a clean energy carrier,” Mamoun Taher, founder and CTO at Graphmatech, told Hydrogen Economist.

The Swedish technology company has developed polymer-graphene composites to be deployed in hydrogen transport and storage, which it says can help to significantly reduce leakages.

“Leakage tends to be most severe, and therefore most urgent to address, in pipelines and storage infrastructure, particularly as legacy natural gas networks are repurposed for hydrogen,” he explained.

“These systems often involve materials that were never designed to contain hydrogen, resulting in significant leakage potential.”

Global warming potential

Despite the growing research on hydrogen leakage, the severity of the issue remains difficult to quantify.

The EU Delegated Act on Low‑Carbon Hydrogen, adopted on 8 July under the Hydrogen & Gas Market Directive, acknowledges that the “global warming potential of hydrogen has not yet been determined with the level of precision required to be included in the methodology for calculating greenhouse gas emissions”.

22mt/yr – Potential leakage in 2050

It adds: “Relevant values for the global warming potential of hydrogen should be added as soon as scientific evidence has sufficiently matured and is applied to measuring the impact of hydrogen leakage over the whole supply chain in the greenhouse gas emissions accounting methodologies for both low-carbon fuels and renewable fuels on non-biological origin.”

“This leaves the door wide open for regulatory uncertainty,” Anne-Sophie Corbeau, researcher at the Center on Global Energy Policy at Columbia University told Hydrogen Economist.

“When will the EU authorities determine that we have reached enough precision? It would be more useful to make sure we have [robust] data and we act to limit leakages,” she said.

Corbeau co-authored a 2022 report titled Hydrogen Leakage: A Potential Risk for the Hydrogen Economy, which highlighted a lack of data on the phenomenon amid insufficient technologies available for leakage detection and monitoring.

Noting that leakage is expected to grow substantially in the coming decades in line with production expansion and market uptake, the research put forward a number of recommendations to policymakers. These include the need to strengthen data gathering and to deploy monitoring programmes particularly for green hydrogen production projects and fuel-cell vehicles.

“There are very few data on hydrogen leakage, especially because most of the new uses and future production methods of hydrogen do not exist today, or certainly not at scale,” she noted, making it difficult to assess “the leakage from electrolysers, storage, transport, cracking ammonia back into hydrogen and using hydrogen in various applications.”

While availability of data is improving, estimates vary widely between different studies, partly owing to the fact new studies focus on short-term global warming potential (GWP) values, along with the 100-year GWP, she noted. This places an emphasis on the warming footprint of gases such as hydrogen, which have short atmospheric residence times.

Should a significant growth in hydrogen production materialise without the emissions issue being addressed, the problem could threaten the position of hydrogen as a clean fuel. “But we are not at a stage where hydrogen grows that much, so there is plenty of time to require measurements and action in case of high leakage rates,” she added.

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Author: Beatrice Bedeschi