Hydrogen ‘twice as powerful a greenhouse gas as previously thought’: UK government study
Report highlights importance of preventing leakage from future H2 infrastructure
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.
Hydrogen: hype, hope and the hard truths around its role in the energy transition
“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.”
The report, which was commissioned by BEIS, continues: “The majority of uncertainty in the GWP arises from uncertainty with regard to the natural budget of atmospheric hydrogen, where the magnitude of the soil sink for hydrogen is the most uncertain factor. Future work is required to resolve these atmospheric uncertainties.”
This all means that leaks from hydrogen pipes and equipment must kept to a minimum.
“Leakage of hydrogen into the atmosphere during production, storage, distribution and use will partially offset some of the benefits of a hydrogen-based economy,” the study explains.
“Minimisation of leaks needs to be a priority if hydrogen is adopted as a major energy source."
Study calculates emissions savings, but based on a dubious scenario
The first study sets out calculations of hydrogen emissions based on leakage rates of 1-10%, but uses a scenario in which all fossil fuels used for heat and cooking in buildings today is switched to pure hydrogen.
“In our illustrative future global hydrogen economy scenario, we estimate additional H2 emissions of between 9 and 95 Tg [million tonnes] per year [from leakage rates of 1-10%]. Using a H2 GWP(100) of 11, this is equivalent to… carbon dioxide emissions of about 100 and 1,050Tg per year, respectively.”
This scenario is based on an unlikely world in which “100% of the final energy consumption of fossil fuels in the buildings sector switches to H2, along with 50% of the final energy consumption of fossil fuels in the transport sector and 10% of the final energy consumption of fossil fuels in the power generation sector”.
At least 16 independent studies have shown that heat pumps are a far better alternative to hydrogen when it comes to heating homes.
The report adds that H2 replacement of fossil fuels, under this unrealistic scenario, would lead to an expected GHG reduction of about 26 billion tonnes per year, with a further reduction of about 1.2 billion tonnes annually due to reduced methane emissions.
“Therefore, in this global scenario, the increase in equivalent CO2 emissions based on 1% and 10% H2 leakage rate offsets approximately 0.4 and 4% of the total equivalent CO2 emission reductions respectively.”