To meet the emission reduction goals put forth by the International Energy Agency, the transportation sector needs major changes. Hydrogen fuel (HF) vehicles, and their zero tailpipe emissions, are poised to help decarbonize transportation. But a recent study highlighted that the carbon use and emission-reduction capabilities of the local power grid play a role in their utility. The study examined the impacts of HF vehicles compared to battery electric (BE) vehicles, which also have zero tailpipe emissions. When a local power grid is reliant on hydrocarbons and uses decentralized electrolyzers to generate HF on-site then the emissions from HF vehicles could exceed even conventional internal combustion engines and were easily higher than BE vehicle emissions. However, if the local grid uses renewable energy sources or carbon capture utilization and storage methods then both HF and BE vehicles approached zero emissions per mile. Thus, countries with carbon-dense power grids or limited emission-reduction methods may not benefit from adopting HF vehicles. This research highlights the interconnected nature of power use systems and the need for more research into energy storage and transport.