From the press release:
V2G technology allows for the bi-directional sharing of electricity between Electric Vehicles [EVs] and Plug-in Electric Hybrid Vehicles [PHEVs] and the electric power grid. The technology turns each vehicle into a power storage system, increasing power reliability and the amount of renewable energy available to the grid during peak power usage.
In addition to reducing energy costs, V2G technology could provide the ability for customers to sell back energy to the utility during hot afternoons when demand is highest and most costly to avoid blackouts. During these periods, energy is worth several times more than overnight when vehicles charge.
Vehicle owners will select a price threshold at which they are willing to sell energy, and when the price reaches this point the utility will be able to automatically draw energy out of the vehicle, leaving enough for the drive home if necessary. The utility's customers would then earn credit in the amount of energy used by the utility toward their monthly energy bill.
V2G technology also serves as a way to increase the amount of renewable energy used during peak energy hours. During times of maximum demand, electrical utilities have to buy power from expensive and less efficient fossil fuel power generating sources. PHEVs will charge their batteries at night when energy is inexpensive and is generated with a larger percentage of renewable resources. When demand is high the next day, instead of turning on a fossil-fuel based generator, the utility can purchase the renewable energy stored in the vehicle batteries.
PG&E's V2G demonstration marks an important milestone for plug-in vehicle technology," said Felix Kramer, Founder of CalCars.org. "Using a grid-connected car's battery as distributed energy storage for homes or businesses expands the economic and environmental benefits of plug-in vehicles.
PG&E's prototype PHEV, converted in partnership with the Bay Area Air Quality Management District and Energy CS, adds a lithium ion battery to a traditional Toyota Prius. The additional battery capacity increases the vehicle's ability to run completely on electricity.
Though each vehicle supplies only a small amount of electricity, harnessing the surplus power stored in hundreds of thousands or millions of vehicles would provide a storage capability that would greatly enhance electric utilities capability to deliver peak power at lower cost.
This technology may be ahead of its time because it requires the deployment of millions of vehicles with extra battery storage and parking locations where the vehicles could be plugged in to return power to the grid. Nonetheless, technology development takes a long time and it is good to demonstrate technology of the future. It is also a good selling point to show that PHEVs and EVs can help lower our energy costs.