Hydrogen

The automaker combines an internal combustion engine with a fuel cell system in a race car, seeking to keep the feel of a gasoline engine while eliminating carbon emissions.

Depending on the method used to produce it, hydrogen can be either very polluting or... not at all. And it all comes down to its colors.

ZEMU is the U.S.’s first hydrogen train and is currently being tested in California.

Piedras Pintas Salt Dome could become world’s biggest hydrogen storage facility.