Hydrogen’s Greenhouse Effect Stronger than Thought

April 11, 2022

The problem is not burning it, but whether significant amounts leak.

ReCharge:

A study released on Friday by the UK government’s Department of Business, Energy and Industrial Strategy (BEIS) has found that hydrogen is twice as powerful a greenhouse gas as previously thought.

The 75-page report, Atmospheric Implications of Increased Hydrogen Use, explains that H2 is an indirect greenhouse gas, which reacts with other greenhouse gases in the atmosphere to increase their global warming potential (GWP).

“While hydrogen-induced changes in methane and ozone in the troposphere [the lowest layer of the atmosphere] have been considered previously, we have also considered, for the first time, previously ignored changes in stratospheric [ie, in the second-lowest layer of the atmosphere] water vapour and stratospheric ozone in our calculations of hydrogen’s GWP,” explain the authors, scientists from the National Centre for Atmospheric Sciences and the universities of Cambridge and Reading.

“We estimate the hydrogen GWP(100) [ie, over a 100-year period] to be 11 ± 5; a value more than 100% larger than previously published calculations.”

In other words, the study says the GWP figure is somewhere between six and 16, with 11 being the average — whereas the GWP of CO2 is one. A previous study from 2001, which has been frequently cited ever since, put the GWP of hydrogen at 5.8.

And perhaps more importantly for the race to net zero, it adds: “For a 20-year time horizon, we obtain a GWP(20) for H2 of 33, with an uncertainty range of 20 to 44.”

University of Cambridge, Atmospheric implications of Increased Hydrogen Use:

Hydrogen leakage will affect the concentration of methane, ozone and water vapour in the atmosphere. The changes in methane and ozone are driven by changes in the hydroxyl radical, OH, which is the major atmospheric oxidant and a key player in the chemistry of the atmosphere. hydrogen acts as a chemical sink for OH, and so increases in hydrogen concentrations lead to a reduction in tropospheric OH, which in turn results in an increase to the methane lifetime. Based on our experiments we conclude that if methane emissions remain constant, increased hydrogen emissions would result in a longer methane lifetime and a higher methane abundance. 

Atmospheric chemists, weigh in.

10 Responses to “Hydrogen’s Greenhouse Effect Stronger than Thought”

  1. Anthony O'Brien Says:

    I am pretty sure buried deep in the longer equation is HONO, which is apparently very important in upper atmospheric chemistry and physics. But I never really understood.

  2. rhymeswithgoalie Says:

    If I read this right, increasing H2 slows the decrease of CH4 in the stratosphere.

    https://upload.wikimedia.org/wikipedia/commons/thumb/7/7c/Atmospheric_Transmission.png/595px-Atmospheric_Transmission.png?20070825092458

    Go here to see the interactive (mouse-over) annotations.
    https://commons.wikimedia.org/wiki/File:Atmospheric_Transmission.png

    Note that adding/sustaining methane (CH4) has more impact because it covers a window in the spectrum that isn’t close to being saturated.

  3. Gingerbaker Says:

    All of this is good information, but to interpret it with meaning requires also an understanding of the half-lives of these gases and their breakdown products.

    Methane and hydrogen appear to have very short half-lives, nitrous oxide medium long, and CO2 the longest of all.

    The way we compare the Greenhouse Warming Potential of all these gases is to superpose a 100-year window on a dynamic system to give relative warming comparisons which distorts the true impact of each gas unless it has an exact 100-year lifespan. Which they do not have.

    Methane, in particular, is distorted because it has only a 10-year lifespan (or half-life, it isn’t clear to me which it is) while CO2, its breakdown product, takes 200,000 years or more before a pulse of it is gone. Using a GWP100 for methane artificially exaggerates its true effect, which is 99% due to CO2.

    So, the effect that a doubling of the hydrogen lifespan may have on methane is virtually nil if we are doing the math faithfully.

    • Gingerbaker Says:

      Plus, the point of green hydrogen is to replace methane use in the first place.

      • rhymeswithgoalie Says:

        Green hydrogen for the many applications that use hydrogen is wonderful.
        However, I’m chary of talk of using it to supplement natgas piped around for fuel in existing pipeline infrastructure (~15% before embrittlement becomes a problem?) because it extends the profitability of extracting natgas.

        Moving electrons will always be more efficient than moving molecules, anyway.

  4. Gingerbaker Says:

    Btw, Mark Jacobson re this study:

    “The article is nonsense and is repudiated by a 2008 study they didn’t even know existed”


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