An electric vehicle is any vehicle propelled by an electric motor, including cars, trains, submarines and spacecraft. They can either partially or fully depend on electricity for power. The electricity used in an electric vehicle can come from the electric power grid or be produced onboard. One advantage of electric vehicles is their ability to use regenerative braking, which stores braking energy for the following moments of acceleration. Current disadvantages include high battery costs and shifted environmental effects.
An electric motor converts electricity into mechanical power. This is done through the interaction of a current flow and a magnetic field. This interaction causes the motor to spin in a process opposite that of an electricity power plant.
In some electric vehicles, electricity is produced on or in the vehicle itself. For example, many submarines generate electricity with a nuclear reactor. In this case, nuclear fuel is reacted to produce heat, which changes water into steam, which in turn drives a turbine generator to make electricity. Producing electricity onboard introduces many levels of inefficiency, however, and is typically only done with large-scale vehicles. Hybrid electric vehicles make a compromise by using a combination of conventional gasoline power and battery-stored electric power.
Other electric vehicles only store electricity onboard and do not actually generate their own. For this to work, the vehicle must have access to external electricity and have a method of energy storage. The electricity grids in developed countries are generally considered adequate for electric vehicle charging and would not need substantial restructuring.
One advantage of the electric vehicle is the possibility of regenerative braking. Conventional brakes work by creating friction with the wheels, which changes a vehicle’s kinetic energy into heat. Heat energy from braking cannot generally be recovered, and thus is wasted from an energy standpoint. Regenerative braking, on the other hand, stores a vehicle’s prior kinetic energy in some kind of battery. Flywheel batteries store this energy in the rotational momentum on onboard flywheels.
Some critics have pointed out the disadvantages of the electric vehicle. First of all, these vehicles may not be as environmentally-friendly as many think. Electricity must be generated somehow, and if fossil fuels are used for this, then electric vehicles may be only shifting emissions elsewhere. Stationary power plants are more efficient than internal combustion engines, but electric vehicles would likely have to use extra electricity to produce interior heating in cold climates. In a conventional car, waste heat from the engine is used to warm the interior.