Hydrogen blending in industrial heating does not offer greenhouse gas reductions in the near term

Hydrogen as a carbon-free fuel is poised for expansion in the United States as a result of tax subsidies for low-carbon hydrogen production. However, the infrastructure for pure hydrogen storage and transportation is yet to be constructed to accommodate large-scale hydrogen utilization. Therefore, many hydrogen utilization pilot projects blend a small ratio of hydrogen in the natural gas pipelines. Leveraging a recent U.S. national boiler inventory, we assessed the total emissions of powering natural gas-based boilers in the U.S. using pure natural gas versus a 15 vol. % hydrogen and 85 vol. % natural gas blend. Greenhouse gas emissions associated with boiler heating increased by 0.3 ~ 54.7% at this ratio, depending on the hydrogen production feedstock and method. The major contributors to the emissions include grid electricity and natural gas transmission and distribution. This study illustrates the limited role of hydrogen-natural gas blends as boiler fuel in reducing GHG emissions in the near term and the indispensable role of grid decarbonization in clean hydrogen production and utilization, especially for hydrogen generation from water electrolysis.