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U.S. Department of Energy Energy Efficiency and Renewable Energy

Hydrogen Fuel Cell Vehicle Emissions

Hydrogen fuel cell electric vehicles emit only water vapor, warm air, and some hydrogen, which are not concerns for air quality. Similar to electricity, hydrogen is an energy carrier that can be produced from various feedstocks. These feedstocks and production methods should be considered when evaluating hydrogen emissions.

Argonne National Laboratory's (ANL) report, Fuel Choices for Fuel Cell Vehicles: Well-to-Wheels Energy and Emission Impacts analyzed greenhouse gas (GHG) emissions for 10 of the most common hydrogen production and distribution pathways. ANL found that gaseous hydrogen produces fewer GHGs than liquid hydrogen in most cases. ANL also investigated hydrogen's effects on petroleum use and found that using hydrogen as a fuel reduced petroleum use by nearly 100% regardless of fuel pathway.

Chart showing the percent changes in greenhouse gas emissions (relative to baseline gasoline vehicles) for hydrogen fuel cell vehicles. Hydrogen use reduces GHG emissions for all fuel pathways except when the fuel is produced by electrolysis from typical grid electricity.
Relative to gasoline vehicles fueled by reformulated gasoline, hydrogen production for all fuel pathways creates fewer GHG emissions except when the fuel is produced by electrolysis from typical grid electricity.

The California Energy Commission (CEC) study Fuel Cycle Assessment: Well-to-Wheels Energy Inputs, Emissions, and Water Impacts examined GHG emissions from various hydrogen pathways. The CEC found gaseous hydrogen produced from grid electrolysis creates 33% fewer GHG emissions. Compared to ANL's study, this difference could be because California produces less-polluting electricity or because CEC assumed advancements made in electrolysis efficiency.