Hydrogen leakage could partially offset the climate benefits of switching energy sources.

In Atmospheric implications of increased hydrogen use, the Department for Business, Energy & Industrial Strategy modelled different scenarios to see how much hydrogen leakage would offset CO2 reductions for global warming.

They modelled a 50% and 300% increase of surface mixing ratios, an increase of 0.25 parts per million (ppm) and 1.5ppm respectively, to try and account for different amounts of hydrogen use and leakage.

They found that hydrogen leakage will ultimately increase the atmospheric lifetime of methane and it's impact on the climate, due to its direct impact on the tropospheric concentration of hydroxyl radicals.

The report stipulates that there is also an increase in tropospheric ozone, if other emissions stay the same, as well as an increase in water vapour.

Accordingly, increases in the tropospheric ozone, water vapour and methane would partially offset the benefits of reducing the climate benefits of switching to hydrogen.

The report accounts for previously ignored changes to stratospheric water vapour and stratospheric ozone to calculate hydrogen's Global Warming Potential (GWP). Hydrogen's GWP over a 100 years is estimated at 11 ± 5, 100% more than previous calculations.

For future policy the Department for Business, Energy & Industrial Strategy wants to focus on reducing emissions that are co-emitted with the production of CO2, such as methane and carbon monoxide.

Extract from IOM3 - read more here

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