Abstract:The next likely source of energy for vehicles is electricity. Recent technological innovations—including better batteries and ultracapacitors, better electric motors and motor-control systems, and lightweight materials—are leading to the prospect of vehicles that carry stored electricity, rather than petroleum products, on board. The electric energy can be drawn from many sources, such as renewable solar, wind, geothermal, and hydroelectric as well as conventional fossil-fuel and nuclear sources. Initially it is being stored in batteries that act like gas tanks, carried along in the vehicle as it makes its way.

Many analysts expect that the technological successor to the electric vehicle with on-board electricity storage is most likely to be the fuel-cell vehicle. Fuel cells are fundamentally different from batteries. Instead of merely storing and releasing electricity, they generate it by converting hydrogen gas and oxygen into water via processes that force electrons to flow. Hydrogen can be drawn from an array of different feedstocks—natural gas, methanol, biomass, and even water converted into hydrogen and oxygen by electrolysis. These several options promise that motor vehicles will become less and less reliant on petroleum-based fuels, while also potentially reducing air pollution and greenhouse gases.