Comparison of the emissions intensity of different hydrogen production routes, 2021

Notes

BAT = best available technology; CCS = carbon capture and storage; SMR = steam methane reforming; POx = partial oxidation; Median upstr. emis. = global median value of upstream and midstream emissions in 2021; BAT upstr. emis. = best available technology today to address upstream and midstream emissions. Upstream and midstream emissions include CO2 and methane emissions occurring during the extraction, processing, and supply of fuels (coal, natural gas) or production, processing, and transport of biomass. Error bars for natural gas and coal represent the impact of the observed range of upstream and midstream emissions today on emissions intensities. For natural gas, the lower bound corresponds to best available technology today (4.5 kg CO2-eq/GJ), and the upper bound to the 95% percentile of the world range (28 kg CO2-eq/GJ). For coal, the lower bound corresponds to the 5% percentile (6 kg CO2-eq/GJ) and the upper bound to the 95% percentile (23 kg CO2-eq/GJ) of global upstream and midstream emissions of coal supply. The 2021 world grid average is based on a generation-weighted global average of the grid electricity intensity, with the error bars representing the 10% percentile (50 g CO2-eq/kWh) and 90% percentile (700 g CO2-eq/kWh) across countries. The grid electricity intensities include direct CO2, CH4 and N2O emissions at the power plants, but not upstream and midstream emissions for the fuels used in the power plants. Dashed lines refer to the embedded emissions occurring during the production of onshore wind turbines (12 g CO2-eq/kWh) and solar PV systems (27 g CO2-eq/kWh). These embedded emissions are not included in the IPHE methodology and shown here only for illustrative purposes. Electrolysis refers to low-temperature water electrolysis with an assumed overall electricity demand of 50 kWh/kg H2, including compression to 30 bar. Hydrogen production from natural gas via SMR is based on 44.5 kWh/kg H2 for natural gas in the case of no CO2 capture, on 45.0 kWh/kg H2 for natural gas in the case of 60% capture rate, and on 49 kWh/kg H2 for natural gas and 0.8 kWh/kg H2 for electricity in the case of a 93% capture rate. Hydrogen production from natural gas via POx is based on demands of 41 kWh/kg H2 for natural gas and 0.6 kWh/kg H2 for electricity in the case of a 99% capture rate. Hydrogen production from coal is based on gasification, with demands for coal of 57 kWh/kg H2 and for electricity of 0.7 kWh/kg H2 in the case of no CO2 capture, demands for coal of 59 kWh/kg H2 for a CO2 capture rate of 93% and demands for coal of 60 kWh/kg H2 for a CO2 capture rate of 98%.