An electric motor converts electrical energy into mechanical energy (motion energy). The reverse function, converting mechanical energy into electrical energy, is accomplished by a single generator. Engines, for example, used for cars, trucks and electric locomotives often have the dual task when they generate power when braking. In households, electric motors are used for fans and washing machines.
The electric cars are sold with the biggest argument that they are more environmentally friendly than for example. gasoline and diesel, in addition to this, the car is completely quiet and has almost no wear parts requiring maintenance anything a conventional car has. Electric cars reduce the consumption of fossil fuels and, consequently, carbon dioxide (CO2) emissions, provided that electricity production produces lower emissions than the corresponding internal combustion engines in cars. In Sweden, the majority of electricity comes from hydropower, nuclear power and a small part from other renewable sources. Electric cars can also help to balance the consumption of electricity over the day by allowing charging to be controlled at times when total electricity usage is low. However, depending on the battery type, the batteries may contain some environmentally hazardous substances, and they should therefore be recycled in a controlled manner when consumed.