A systematic comparison of the energy and emissions intensity of hydrogen production pathways in the United Kingdom

Meeting climate targets requires profound transformations in the energy system. Most energy uses should be electrified, but where this is not feasible, hydrogen can be part of the solution. However, 98% of global hydrogen production involves greenhouse gas emissions, with an average of 12 kg CO2e/kg H2. Therefore, new hydrogen production pathways are needed in order to make hydrogen production compatible with climate targets. In this work, we fill this gap by systematically comparing the energy and emissions intensity of 173 hydrogen production pathways suitable for the UK. Scenarios include onshore and offshore pathways and the use of repurposed infrastructure. Unlike fossil-fuel based pathways, the results show that electrolytic hydrogen powered by fixed offshore wind could align with proposed emissions standards, either onshore or offshore. However, the embodied and fugitive emissions are important to consider for electrolytic pathways as they result in 10–50% of the total emissions intensity. • Comparison of the emissions intensity and energy intensity onshore and offshore hydrogen production pathways. • Consideration of the whole lifecycle of infrastructure required. • Fugitive hydrogen and methane emissions, and embodied emissions can account for between 10 and 50% of the impact of green hydrogen pathways. • While green hydrogen pathways could align with climate targets on or offshore, blue hydrogen pathways are unlikely to.