Global warming consequences of replacing natural gas with hydrogen in the domestic energy sectors of future low-carbon economies in the United Kingdom and the United States of America

Abstract Hydrogen has a potentially important future role as a replacement for natural gas in the domestic sector in a zero-carbon economy for heating homes and cooking. To assess this potential, an understanding is required of the global warming potentials (GWPs) of methane and hydrogen and of the leakage rates of the natural gas distribution system and that of a hydrogen system that would replace it. The GWPs of methane and hydrogen were estimated using a global chemistry-transport model as 29.2 ± 8 and 3.3 ± 1.4, respectively, over a 100-year time horizon. The current natural gas leakage rates from the distribution system have been estimated for the UK by the ethane tracer method to be about 0.64 Tg CH4/year (2.3%) and for the US by literature review to be of the order of 0.69–2.9 Tg CH4/year (0.5–2.1%). On this basis, with the inclusion of carbon dioxide emissions from combustion, replacing natural gas with green hydrogen in the domestic sectors of both countries should reduce substantially the global warming consequences of domestic sector energy use both in the UK and in the US, provided care is taken to reduce hydrogen leakage to a minimum. A perfectly sealed zero-carbon green hydrogen distribution system would save the entire 76 million tonnes CO2 equivalent per year in the UK.