Potentially, a plug-in hybrid could add more atmospheric Carbon per mile if charged from commercial electric power supplied from a coal-burning power plant.
OTO if charged from a hydro-electric source, the Carbon footprint should be smaller than that of a conventional gasoline burning internal combustion engine (I.C.E.).
Replacing gasoline with Hydrogen seems like a fabulous idea. The "exhaust" is H2O. BUT !
There are problems.
We're having trouble storing Hydrogen. It's a small molecule, and thus easily leaks from pressurized confinement.
Another problem, we can "manufacture", produce Hydrogen with electrolysis of water. BUT !
We only get about 70% of the energy put into that process back out again when such Hydrogen is used as fuel.
We'll need a more efficient means of collecting Hydrogen to render it a viable global automotive fuel.
Yes there are some drawbacks.
What Iceland did was to generate the hydrogen at the filling stations, so the only leaks were from the cars themselves.
Which are not impractical.
A tank of hydrogen takes months to leak out.
While a 30% loss of energy sounds bad, it actually is better than the loses from generating electricity, transmitting it, storing it in batteries, retrieving it from batteries, and then turning it back into kinetic energy.
But a bio fuel like palm oil would be clean because the carbon released is less than the carbon absorbed while the tree grows.
