Modelling UK air quality implications of decarbonisation using hydrogen

Abstract

Many air pollutants are directly or indirectly caused by energy production and consumption. There is concern that decarbonising economies by replacing fossil fuel with hydrogen combustion could lead to higher pollutant emissions than by an electrification strategy. This study examines the implications of adopting hydrogen. Future UK energy scenarios, with varying levels of hydrogen, have been produced using the UK TIMES energy systems model, and a link established to the air pollution model UKIAM (UK Integrated Assessment Model). Using this interface, air pollutant emissions from the energy sector have been derived and superimposed on non-energy contributions to map concentrations and estimate the resulting exposure to PM_2.5 and NO₂ pollution in the UK and associated health benefits. All net zero scenarios achieve a substantial improvement in air quality, with a maximum of 0.3 μg m⁻³ contribution to PM_2.5 population-weighted mean concentrations from hydrogen production and use. This depends on the hydrogen technologies used: as a worst case, hydrogen could eliminate 50% of the economic benefits resulting from improved air quality under net zero measures.

This disbenefit arises despite emission factors for hydrogen production and use meeting potential regulatory limits for NO_x. However technological improvements could possibly reduce emissions very substantially. Attention should turn to understand where hydrogen is used to displace other future or existing energy sources. Other sources of PM_2.5 emissions could be potentially more important for influencing PM_2.5 concentrations, such as road transport non-exhaust emissions and biomass combustion and should be considered carefully in future energy scenarios.