what is v2g?

Vehicle-to-Grid (V2G) technology utilizes the stored energy in electric vehicle batteries to contribute electricity back to the grid when the grid operators request it. Revenue from V2G will reduce the customer cost of electric vehicles; it will also increase the efficiency and reliability of the existing grid today, decreasing petroleum use, and making possible a much larger share of intermittent renewable energies such as wind and solar in the future.


Vehicle to Grid (V2G) allows electric-gasoline hybrids or fully-electric vehicles to provide power back to the grid. Electric-drive vehicles, whether powered by batteries, fuel cells, or gasoline hybrids, have within them the energy source and power electronics capable of producing the 50 Hz or 60 Hz AC electricity that powers our homes and offices. A hybrid designed for overnight charging on any circuit might draw 1.5 kW, the average load of one US house. A fully electric car can draw or produce up to 19 kW, the average power need of 13 US houses. The key to realizing economic value from V2G is making the power available without compromising driving requirements of any one vehicle owner, yet having the aggregate of vehicles meet the time-critical "dispatch" needed by the electric distribution system.


With a plug-in car, you are driving an electrical storage system

The cost of such storage can be shared between the electrical system and the transportation system, making it economically more efficient. The average US car is driven one hour per day, and the electric system could make good use of it the other 23 hours. Using IP or broadcast protocols, utilities grid operators can “talk” to plugged-in cars, buying electricity from car owners when it is needed, and selling it back when demand is lower. 


Expected results include

Increased reliability and efficiency of existing electric grid. V2G cars can take load off over-loaded distribution feeders when energy demands are high. They can supplement or replace spinning reserves and provide regulation up and down as demand fluctuates, and do so a much faster ramp rates than any existing generation.

Provide electrical storage to allow increased use of intermittent renewable energies such as wind power and photovoltaics. Up to a certain percentage of generation, the fluctuations of wind and solar are handled by today’s grid management. To displace large fractions of fossil generation, electrical storage will be needed. Fleets of V2G-capable vehicles constitute such a system, capable of holding MWs of electricity for later use. 


Elements needed for V2G

A plug-in car - Either a plug-in hybrid or pure electric will work. The economic value of V2G is proportional to kW capacity of the power plug. This car has a 19 kW connection at 240 volts, although it can also be run at lower power and 120 volts.

Control Signal from the electric grid - In most areas of the US, the Independent System Operator (ISO) provides an electronic signal to request frequency regulation, reserves, and other forms of fast-response, high value power. Additionally, a local utility may want to signal for other V2G services, such as peak load shedding or relief on targeted parts of the distribution system.

Computing to mediate driver and grid needs - There must be intelligent mediation between driver needs and grid operator needs.

Off the pump. On the plug.

off the pump. on the plug.