Hydrogen leakage 'could reduce climate benefits of green H2 in half': EDF study

Hydrogen leakage 'could reduce climate benefits of green H2 in half'

If many people begin using clean hydrogen, it could have a big impact on the climate. That's because the H2 molecule is smaller than the methane molecule and it's easier for it to escape. A new study by US non-profit Environmental Defense Fund (EDF) found this.

Ilissa Ocko and Steven Hamburg, scientists from the Environmental Defense Fund, wrote a paper that was published in the journal Atmospheric Chemistry and Physics. The paper discusses how billions of US dollars in investments and financial subsidies will speed up the adoption of clean hydrogen. However, they also note that hydrogen has significant climate impacts that are often overlooked or underestimated. Hydrogen is a small molecule that can easily escape into the atmosphere from infrastructure, which can cause climate damage.

According to a recent report by the UK government, hydrogen is about 11 times more powerful a greenhouse gas than CO2 over a 100-year period. This means that when it reacts with other greenhouse gases in the atmosphere, it increases their global warming potential (GWP).

This study evaluates the climate impacts of using clean hydrogen. The study found that if there are any leaks in the system, the benefits of decarbonization strategies that involve clean hydrogen would be reduced. This is especially true in the short term after deployment.

Therefore, this issue deserves more attention. Scientists need to study hydrogen's indirect climate effects more. And we need to make better estimates of hydrogen emissions throughout the entire process, from production to use.

"Leakage from hydrogen systems will be important to reduce if hydrogen is going to be effective in reducing climate change."

The report explains that hydrogen escapes into the atmosphere easily and the amount of emissions from hydrogen systems is unknown. But it estimates that on average, 1% of the hydrogen would escape and this would be a "best-case scenario". However, in some cases, 10% of the hydrogen could escape.

The study says that "green hydrogen applications with higher-end emission rates (10 percent) may only cut climate impacts from fossil fuel technologies in half over the first two decades, which is far from the common perception that green hydrogen energy systems are climate neutral."

"However, over a 100-year period, climate impacts [from fossil fuel technologies] could be reduced by around 80%. On the other hand, if we continue to use low-emission technologies, the impacts on the climate over all timescales would be limited." According to the report, if the average leak rate is 1%, it would only add about 0.025°C to global warming by 2050. However, if the leakage rate is 5% or 10%, it could increase average worldwide temperatures by more than 0.1°C or 0.4°C, respectively.

Getting ahead of the problem

The EDF study found that it would be easier to reduce hydrogen leakage when designing a new system, rather than retrofitting an existing one. However, retrofitting existing natural-gas pipelines is far cheaper than building new hydrogen pipes. According to a recent study by the International Renewable Energy Agency, about one eighth of the world’s hydrogen — about 77 million tonnes annually — would be transported via retrofitted gas pipes by mid-century, in its 1.5°C scenario.

We have the opportunity to get ahead of this issue and prepare for a future hydrogen economy. In order to maximize the climate benefits of a hydrogen economy, we need to take five key actions:

1. Researchers are studying the effects of hydrogen on the climate. They are doing this by looking at how emissions from hydrogen cause changes in temperature. To do this, they are using complex models that account for the interactions between emissions, chemistry and radiation. They are also using simpler models to see if the results from the complex models can be generalized.
2. Employing climate metrics that look at both a 20-year and 100-year time frame can help us understand how hydrogen could play a role in meeting different net-zero goals.
3. Developing technologies that can accurately measure hydrogen emissions, even at very low levels, could help us better understand how much hydrogen is leaking from various sources.
4. Including the possibility of hydrogen leakage and its potential consequences in decisions about where and how to deploy hydrogen - like having production and end-use applications close together - is important.
5. Finding ways to stop water from escaping before building the infrastructure is important.

The study says that "if we want to meet the climate challenge, it is important to look at the different ways we can reduce carbon emissions. We need to use good metrics and data for this."

The study continues by noting that "the short and medium-term climate impacts of hydrogen emissions are greater than people think."

"It is important to take into account the climate benefits of replacing fossil fuel systems with hydrogen in order to get the most out of the switch."

If we want hydrogen to help improve the climate, it's important to take a careful and scientific approach to understanding and dealing with any hydrogen leakage.

The full EDF study can be read here.

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