A plug-in electric vehicle (PEV) is a car, truck, sport utility vehicle or other type of vehicle that is powered entirely by rechargeable electric batteries and recharged by plugging the vehicle into an external electrical source, such as a wall outlet. Plug-in electric vehicles have been at the forefront of alternative fuel options for transportation, which include biodiesel and fuel cell technology. PEVs fall into the category of electric vehicles, which includes all-electric vehicles, hybrids and plug-in hybrid vehicles.
The engine of a plug-in electric vehicle is chargeable from the electrical grid, just like anything one plugs into a wall outlet. This means they are also classified as grid-enabled vehicles (GEVs). Charged batteries are used to drive the wheels. PEVs and hybrids make use of regenerative braking — that is, the brake systems in these cars use kinetic energy from braking to recharge the on-board batteries.
Cars that run off of rechargeable storage batteries that can be replenished from an external electrical source are termed "off-vehicle charge capable” (OVCC) or simply “pluginable”. Much like the fuel tank of a truck running off an internal combustion engine, the batteries of plug-in electric vehicles store the charge provided by the wall socket or charge station. This differentiates them from all-electric cars or battery electric vehicles (BEVs), because BEVs gain their charge from removable batteries recharged outside the car, or, in the case of buses and other public and civic transportation, cables above the roads or grids below the street.
Plug-in hybrid vehicles blend the OVCC traits of the PEV with those of traditional internal combustion engines. Like in hybrid vehicles, the plug-in electric batteries of the car are intended to supplement the gasoline engine, but the larger batteries of the plug-in hybrid allow the car to function in electric-vehicle (EV) mode for extended periods of time. This means that plug-in hybrids are capable of great fuel efficiency during periods of nonstop highway driving.
Traditional internal-combustion engine vehicles (ICEVs) are very inefficient at converting fuel into energy and as such are both expensive to maintain and relatively polluting, because less-efficient conversions leave a lot of waste material behind. Most of the people buying plug-in electric vehicles early in the concept’s realization did so from a strong sense of environmental responsibility — that is to say, a wish to protect the environment from pollution. Should one be motivated to reduce one’s environmental impact, or “carbon footprint,” a PEV might be a good place to start. The purchaser should, however, examine the impact that charging a vehicle from the house’s place on the power grid will have on his or her electricity consumption and utility bill.
Another benefit of plug-in electric vehicles is something called vehicle-to-grid (V2G) systems. These systems are a part of the utilities infrastructure, and they allow the energy stored in the batteries of a parked PEV to be returned to the grid. Electricity flows in the direction of least resistance, so excess power from the idle batteries flows back into the source, just like water. Plug-in vehicle owners in areas offering V2G services can therefore make a useful amount of money selling that residual power back to the city.