The European Commission has described hydrogen as an energy carrier with "great potential for clean, efficient power in stationary, portable and transport applications."
The DOE says that a fuel cell — which turns the chemical energy in hydrogen into electricity — combined with an electric motor is "two to three times more efficient" than an internal combustion engine that runs on gasoline.
Hydrogen is already being used in vehicles around the world. To give just one example, a fleet of hydrogen fuel cell buses is currently in operation in the Scottish city of Aberdeen.
In 2016, European airline easyJet revealed plans for a zero emissions hydrogen fuel system. The concept was based around the idea of stowing a hydrogen fuel cell in the hold of the aircraft.
Like the DOE, the European Commission says that when combined with fuel cells, hydrogen can boost energy efficiency in transport. In this way, it can help contribute to mitigating climate change, "especially when produced by renewable primary energy sources."