Hydrogen, considered by some to be one of the pillars of the energy transition, would warm the planet much more than previously thought. This is the conclusion of a new study published by the British government.
Hydrogen is an indirect greenhouse gas. It reacts with other greenhouse gases in the atmosphere to increase their global warming potential (GWP, or: global warming potential). Scientists had this knowledge. What they apparently did not know was that the GWP of hydrogen was much higher than previously calculated.
“While hydrogen-induced changes in methane and ozone in the troposphere [the lowest layer of the atmosphere] have previously been taken into account, for the first time we have also taken into account previously ignored changes in stratospheric [the second lowest layer of the atmosphere] water vapor and stratospheric ozone in our calculations of the GWP of hydrogen,” the study authors explain.
The findings were published by the British government, scientists at the National Centre for Atmospheric Sciences and the universities of Cambridge and Reading, and are cited by the website Recharge.
11 times more harmful than CO2
With this new data, the researchers estimate that the GWP(100) of hydrogen – its warming potential over 100 years – is 11 ± 5. This means that 11 is an average, with the score lying somewhere between 6 and 16. By comparison, the GWP(100) of carbon dioxide (CO2) is 1, that of methane (NH4) 8.
11 is about 100 percent higher than previously published calculations, the study authors note. The most cited study to date, dating from 2001, had estimated the GWP(100) of hydrogen at 5.8. “For a time horizon of 20 years, we obtain a GWP(20) for H2 of 33, with a margin of uncertainty of 20 to 44,” the authors further throw in.
Incidentally, the study in question does not take into account the GWP of the hydrogen production process, but only the effect of the H2 released into the atmosphere.
Avoid leakage at all costs
In their 75-page report, the British researchers warn of the importance of preventing hydrogen leakage from plants that are growing in size around the world.
“Any leakage of H2 will lead to indirect global warming, negating the reduction in greenhouse gas emissions achieved by switching from fossil fuels to hydrogen,” it sounds. “Leakage of hydrogen into the atmosphere during production, storage, distribution and use will negate some of the benefits of a hydrogen economy.”
The scientists therefore call for making minimizing leakage a “priority.”
Transport by tanker
Another study, also commissioned by the British government, found that transportation of liquid hydrogen by tanker is the largest contributor to hydrogen leakage, with 13.2 percent of the cargo leaking into the atmosphere. This is followed by above-ground storage of compressed gas (6.52 percent), fuel cells (2.64 percent) and refueling stations (0.89 percent).
At the production level, hydrogen produced by electrolysis would result in the release of 9.2 percent of the hydrogen produced into the atmosphere through “venting and flushing.” This figure would drop to 0.52 percent through additional measures.