Vehicles running on electricity do not necessarily fall in the category of sustainable transport, because they may still use power from fossil or nuclear power plants. Nevertheless, if the share of power from renewable sources increases, electric vehicles (EVs) also become more sustainable. In some cases, EVs could exclusively run on power from renewable sources, for example, when the batteries are charged in a solar-powered filling station.
In general, two types of EVs are being developed. Full-electric vehicles are essentially powered by the grid, by means of storing power in batteries. Trains, subways, trams, and trolley buses are grid-connected and can also be regarded as full-electric transportation.
So-called “hybrids” combine an electric drive system with a conventional engine and batteries; they run on electricity and fuel. Hybrids do not necessarily connect to the grid; special “plug-in” hybrids provide that opportunity.