Plug-in hybrid cars combine the benefits of pure electric cars and hybrid cars. Like electric cars, they plug into the electric grid and can be powered by the stored electricity alone. Like hybrid cars, they have engines that enable greater driving range and battery recharging.

What is a Plug-in Hybrid Car?

Plug-in hybrid cars can be charged with electricity like pure electric cars and run under engine power like hybrid cars. The combination offers increased driving range with potentially large fuel and cost savings, emissions reductions, and other benefits.

Plug-in hybrid cars currently do not qualify as alternative fuel cars under the Energy Policy Act of 1992. However, they do qualify for incentives.

How Plug-in Hybrid Cars Work?

Like hybrid cars, plug-in hybrid cars are powered by two energy sources – an energy conversion unit (such as an internal combustion engine or fuel cell) and an energy storage device (usually batteries). 

Schematic of a Plug-in Hybrid Car

The energy conversion unit can be powered by gasoline, diesel, compressed natural gas, hydrogen, or other fuels. The batteries can be charged by plugging into a standard 110-volt electrical outlet – a capability conventional hybrid cars do not have – in addition to being charged by the energy conversion unit when needed.

Plug-in hybrid cars have a larger battery pack than conventional hybrid cars. During typical daily driving, most of a plug-in hybrid cars power comes from the stored electricity. For example, a plug-in hybrid car driver might drive to and from work on all-electric power, plug in the car to charge it at night, and be ready for another all-electric commute in the morning. However, the engine can be used when longer trips are required, and the plug-in hybrid car does not need to be plugged in to operate.

Car-to-Grid Concept

Researchers are developing "car-to-grid" technologies that allow a two-way connection between the plug-in hybrid car and the local utility grid. While the car is plugged in and not in use, the utility could take advantage of the extra electrical storage capacity in the car batteries to help meet peak electricity demand, provide grid support services, or respond to power outages. Plug-in hybrid car owners could get "paid" by the utility for use of their cars, which would only be used when needed and without negative effects on the car battery’s state of charge.

Availability of Plug-in Hybrids