Hydrogen Fuel Cell Vehicle Emissions
Hydrogen fuel cell 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.
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.