an essentially zero-emission fuel that produces water vapor when burned. It can be used in electrochemical cells or internal combustion engines to power vehicles or electric devices. It has begun to be used in commercial fuel cell vehicles such as passenger cars, and has been used in fuel cell buses for many years. It is also used as a fuel for the propulsion of spacecraft.
Hugely abundant; can make energy or water
Energy-intense to harvest and store for future use.
Hydrogen is the most likely to replace propane and natural gas, but technology development and investments are needed.