Also a type of electric vehicle, a fuel-cell car takes hydrogen gas and converts it into electricity, while emitting only water vapor.

CNN: Hydrogen fuel-cell cars look to overtake electric autos

The new standard is part of a broader package of regulations to cut vehicle tailpipe emissions and greenhouse cases and could mean 1.4 million electric, fuel cell and plug-in hybrid cars on California freeways by 2025.

FORBES: California Orders Automakers To Sell More Plug-In and Fuel-Cell Cars

The more electric a vehicle is, the more copper it contains (with the exception of completely impractical fuel cell cars).

FORBES: The Environmental Protection Agency Comes-a-Copper