Hydrogen leaks continue to worry scientists

According to a recent study by the Environmental Defense Fund, the U.S. environmental protection organization, several measures must be put in place to reduce the negative impact of hydrogen leaks on the environment.

The EDF study assesses the climate impact, on different time scales, of hydrogen deployment by taking into account several leakage rates. Its findings reveal that hydrogen emissions can significantly undermine the climate benefits offered by this energy carrier, especially in the decades following its deployment.

“Numerous hydrogen-related projects are currently being launched around the globe. In the U.S. alone, very large investments are accelerating its future democratization. Nevertheless, the harmful consequences that hydrogen could have on the climate are greatly underestimated. This molecule is indeed very small (nearly eight times smaller than a methane molecule). It can therefore easily escape into the atmosphere,” explain EDF scientists Ilissa Ocko and Steven Hamburg in their paper entitled “Climate Consequences of Hydrogen Emissions” published in the journal Atmospheric Chemistry and Physics.

A new report from the British government also reveals that hydrogen is 11 times more potent than CO2 over a century and 33 times more potent over a 20 year period. This would be because it reacts with other greenhouse gases at the atmospheric level and increases their GWP (global warming potential).

“The subject of hydrogen leakage therefore deserves more attention,” the EDF researchers continue. “This would help advance the study of hydrogen’s indirect effects on the environment and improve the calculation of its emissions from its production to its final application.”

Decreasing the leakage rate

Although the total amount of hydrogen leakage is currently unknown, the U.S. organization estimates that an average leakage rate of 1 percent would be ideal, but could be as high as 10 percent for special cases.

Indeed, the study indicates that by 2050, an average leakage rate of 1% would only add about 0.025°C to global warming. However, the study found that higher leakage rates of 5 or 10 percent would increase average global temperatures by 0.1°C and 0.4°C respectively.

Building rather than converting

Ilissa Ocko and Steven Hamburg also explain that reducing hydrogen leakage is more effective when designing a new system than when retrofitting an existing one, warning about plans to convert existing pipelines.

However, converting old pipelines is much cheaper than building new ones. According to the International Renewable Energy Agency, nearly 12.5 percent of the world’s hydrogen (about 77 million tons annually) will be transported via converted pipelines by 2050.

“Not much hydrogen-related infrastructure and systems have been deployed around the world at this point. So we still have some time to solve this leakage problem,” say the two scientists.

Measures to change the situation

The scientists recommend the implementation of five key measures to reduce the effects of hydrogen on global warming:

• Advance research into the indirect radiative effects of hydrogen and the temperature responses to its emissions by incorporating new parameters into chemical and climate models.
• Employ climate parameters not limited to a 20- or 100-year time horizon, but including both, to study the role hydrogen can play in achieving different net-zero emission goals.
• Improve the assessment of hydrogen leakage rates by developing field-usable technologies that will accurately measure hydrogen emissions at very low detection thresholds.
• Include a probability of hydrogen leaks and consideration of their consequences in decision-making about hydrogen deployment areas and methods.
• Identify leakage mitigation devices prior to infrastructure construction.

“The short- and medium-term climate impacts of these emissions must be considered in order to optimize the climate benefits of replacing fossil fuels with hydrogen,” the EDF researchers conclude. “A scientific approach to understanding the effects of these leaks and addressing them will allow hydrogen to deliver on its environmental preservation promise for all time scales.”

More studies to come

EDF is not the only organization interested in the topic of hydrogen leaks and their impact on the environment. In a note published earlier this year, the France Hydrogen association indicated that this was a point of vigilance “not to be overlooked.” Hydrogen Europe, JRC, the Hydrogen Council, MarcoGas, Gas Infrastructure Europe, and the Clean Hydrogen Partnership also launched a study on the subject in January 2022, the conclusions of which will be released in the coming months.