A Switch to Hydrogen Could Cause “Non-negligible” Global Warming – Watts Up With That?

Essay by Eric Worrall

Leaks from Hydrogen storage and pipelines will apparently slow down the destruction of atmospheric methane.

New climate chemistry model finds ‘non-negligible’ impacts of potential hydrogen fuel leakage

by Nancy W. Stauffer, Massachusetts Institute of Technology

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But while burning hydrogen won’t emit GHGs, any hydrogen that’s leaked from pipelines or storage or fueling facilities can indirectly cause climate change by affecting other compounds that are GHGs, including tropospheric ozone and methane, with methane impacts being the dominant effect. A much-cited 2022 modeling study analyzing hydrogen’s effects on chemical compounds in the atmosphere concluded that these climate impacts could be considerable.

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Regardless of the process used to make the hydrogen, the fuel itself can threaten the climate. For widespread use, hydrogen will need to be transported, distributed, and stored—in short, there will be many opportunities for leakage.

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Here’s how that feedback works: As the hydrogen decreases the concentration of OH, the cleanup of methane slows down, so the methane concentration increases. However, that methane undergoes chemical reactions that can produce new OH radicals.

“So the methane that’s being produced can make more of the OH detergent,” says Chen. “There’s a small countering effect. Indirectly, the methane helps produce the thing that’s getting rid of it.”

That’s a key difference between their 66-equation model and the four-equation one. “The simple model uses a constant value for the production of OH, so it misses that key OH-production feedback,” she says

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Read more: https://phys.org/news/2024-12-climate-chemistry-negligible-impacts-potential.html

The referenced study;

On the chemistry of the global warming potential of hydrogen

Candice Chen*Susan Solomon Kane Stone

• Department of Earth Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA, United States

Hydrogen (H₂) is considered a promising fuel to contribute to net-zero carbon emission goals. While hydrogen itself is not a greenhouse gas, leakage of hydrogen fuels causes indirect warming due to hydrogen’s influence on methane, tropospheric ozone, and stratospheric water vapor, with the methane term dominating the impact. Some studies consider a simple four-equation box model to explore the climate consequences of leakage from hydrogen fuel use relative to methane, while others have employed much more detailed global photochemical models. Here we use a comprehensive photochemical box model including 66 reactions to show and quantify how the analogous four-equation system is missing a critical OH feedback, leading it to overestimate the time-integrated methane response to a pulse of hydrogen by over 100%. We estimate a hydrogen global warming potential (GWP) relative to carbon dioxide of 28−11+18 on the 20-year time horizon and 10−4+7 on the 100-year time horizon based on the 66-reaction model and information from the literature. GWPs provide a measure of the relative global warming impact of emission of one gas compared to a selected reference gas per unit mass emitted. While CO₂ is generally chosen for the reference, any gas can be used. We present the GWP of H₂ using CH₄ as the reference, as this choice cancels out some uncertainties that are common to both H₂ and CH₄. The GWP for H₂ relative to CH₄ from fossil fuel sources is 0.35−0.06+0.13 on time horizons beyond 15 years; put differently, we find that relative to an equivalent mass of emission of fossil CH₄, hydrogen emission has a climate impact about three times smaller. These global warming potentials underscore that hydrogen leakage does contribute to climate change, emphasizing the importance of limiting both hydrogen and methane leakage if global net-zero greenhouse gas emissions are to be achieved by 2050.

Read more: https://www.frontiersin.org/journals/energy-research/articles/10.3389/fenrg.2024.1463450/full

Good luck stopping hydrogen leaks. Hydrogen is literally the most leak prone substance on Earth, hydrogen molecules are so small they slip through cracks nothing else can escape. You can’t even reliably add odourants to hydrogen to make leaks more obvious – the smelly chemicals which are added to most gasses to provide early warning of leaks get trapped by in the pipe, the larger odourant molecules can’t pass through holes in pipes which freely pass hydrogen.

And of course, hydrogen leaks are a major safety hazard. When hydrogen leaks in quantity it almost instantly catches fire. Though utterly lethal, such fires are almost invisible, because hydrogen in free air burns so hot much of the energy is radiated as pale blue, purple and ultraviolet light.

There is a reason in industry you need a special license to handle industrial hydrogen – handling bulk hydrogen is crazy dangerous.

What can I say? Is there any “green” solution which at scale would not cause a humanitarian or environmental disaster? This latest finding further confirms hydrogen as yet another green non-solution.

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