Vehicle to grid, also known as V2G, is a term used to describe the energy concept whereby electric cars, and certain plug-in hybrid cars, could not only receive electricity from, but send surplus electricity back into, the electric grid. The concept was developed at the University of Delaware, in the U.S., by Dr. Willett Kempton. Kempton envisioned that electric cars could do more to conserve energy than operate free of fossil fuels; he imagined that they could further save on energy by pumping excess electricity back into the grid. Under this vision, future electric car owners could actually make money by selling electricity back to the grid for use in homes and businesses.
Vehicle to grid would help save electricity that might otherwise be lost energy. The electric grid is designed to hold only as much electricity as is in demand at any given moment. To achieve this, it communicates with energy sources by computer every few seconds, letting generators know exactly the amount of electricity it needs to meet demand. This, however, means that there's a lot of potential surplus electricity that might go unused. Using vehicle to grid technology, car batteries sitting overnight in a garage could store the surplus energy that the grid couldn't immediately use, and then send the electricity back into the grid when it's needed.
Surplus electricity stored in car batteries would have other benefits as well. In the event of a power outage, in which the grid is unable to deliver energy via power lines to homes and businesses, electric cars could act as back-up generators, with the potential to power multiple households. Electric car owners could also benefit financially from vehicle to grid, receiving payments for electricity they've sold back to the grid.
Although the technology is in place to make vehicle to grid a reality, there are numerous hurdles to overcome before electric charge stations replace the corner gas station. Car companies would have to collaborate with utility companies to ensure the car could adequately communicate with the grid. Vehicle to grid cars would also have to be user-friendly. Additionally, electric car owners would have to easily be able to choose exactly how much electricity they wanted to buy and sell, and auto manufacturers would need to ensure batteries would hold the same lifespan even under the constant influx and output of electricity. Perhaps even more importantly, charge stations would need to be readily accessible throughout cities and along highways. And, of course, there must be enough consumer demand to make it successful.
Vehicle to grid researchers have already make tangible steps toward implementing the technology for consumer use. Electric vehicle makers have forged partnerships with vehicle to grid researchers as well as some utility companies and major auto makers to launch pilot programs dedicated to delivering the technology to the market. Legislators have also been working to implement the technology. In 2009, Delaware Governor Jack A. Markell signed a bill — the first of its kind — which mandated that car owners would be paid for electricity sold back to the grid at the same rate they're charged for using it.