Vehicle to grid

Vehicle-to-grid (V2G) describes a system in which plug-in electric vehicles, such as electric cars (BEV) and plug-in hybrids (PHEV), communicate with the power grid to sell demand response services by either returning electricity to the grid or by throttling their charging rate.

Vehicle-to-grid can be used with gridable vehicles, that is, plug-in electric vehicles (BEV and PHEV), with grid capacity. Since at any given time 95 percent of cars are parked, the batteries in electric vehicles could be used to let electricity flow from the car to the electric distribution network and back. This represents an estimated value to the utilities of up to $4,000 per year per car.

The company AC Propulsion Inc. coined the term V2G for vehicle-to-grid.

V2G is a version of battery-to-grid power applied to vehicles. There are three main different versions of the vehicle-to-grid concept, all of which involve an onboard battery:

It should also be noted that besides vehicles which have an onboard battery, vehicles without a large battery, but which connect to/recharge a battery placed at the house (for example being part of an off-the-grid electrical system or net metering system) could in effect form a vehicle-to-grid system. Even a renewable energy source (like wood gas) could be used.

V2G is classified based on the power flow direction: Unidirectional V2G and Bidirectional V2G.

The concept allows V2G vehicles to provide power to help balance loads by "valley filling" (charging at night when demand is low) and "peak shaving" (sending power back to the grid when demand is high, see duck curve). Peak load leveling can enable utilities new ways to provide regulation services (keeping voltage and frequency stable) and provide spinning reserves (meet sudden demands for power). In future development, it has been proposed that such use of electric vehicles could buffer renewable power sources such as wind power, for example, by storing excess energy produced during windy periods and providing it back to the grid during high load periods, thus effectively stabilizing the intermittency of wind power. Some see this application of vehicle-to-grid technology as a renewable energy approach that can penetrate the baseline electric market.

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Wikipedia