Long term management of electric vehicle charging requires smart grid technologies


Washington, DC, U.S.A. — (METERING.COM) — January 21, 2009 – The long term, successful management of plug-in hybrid electric vehicle (PHEV) charging will require significant deployment of smart grid technologies, which will take time to design and implement, according to the U.S. Electricity Advisory Committee (EAC) in a new report for the Department of Energy (DOE) on energy storage in the grid.

The report, “Bottling electricity: Storage as a strategic tool for managing variability and capacity concerns in the modern grid,” reviews the potential impact of a significant penetration of PHEVs both in terms of increased demand on the electric power delivery system as well as the possible benefits of the distributed energy storage this technology can offer.

PHEVs are expected to come on to the U.S. market in 2010, with several manufacturers expected to launch the vehicles in that year. However, growth projections are mixed and for example one study estimates that there will be around 2 million PHEVs on the nation’s roads by 2016.

The report says that at present, most experts agree that the adoption of PHEVs will begin in the short term with vehicle charging managed by pricing that encourages charging in off-peak times. This grid-to-vehicle concept gives cost benefits to those agreeing to charge their vehicles at night, thus filling in the load valley, and penalizes those charging during the day. However, there are only about 54 million garages for the 247 million registered passenger vehicles in the U.S. today. Because most consumers without garages do not have a way to charge a plug-in vehicle, there is a substantial amount of infrastructure that will have to be built.

The report proposes a three phase approach to PHEV infrastructure development, with phase 1 limited to vehicle owners who can provide a nightly parking location with access to a power outlet. Owning a PHEV and recharging it every night for a minimum charge would increase the average U.S. consumer’s electric consumption by approximately 50 percent, or 420 kW, assuming a maximum consumption of 14 kWh for a 40-mile range PHEV.

Moreover in addition to being an energy load, the PHEV is also a potential source of energy storage, which could be utilized for peak shaving, valley filling, and reserve spinning. Assuming a uniform distribution of battery charge, that automobiles are driven on average two hours per day, and that the automobiles are available for use by a utility when they are not being driven, the average energy storage available for discharge or charge would be 417 billion kWh.

Phase 2 would be the next logical stage of infrastructure development with the vehicle-to-home (V2H) and/or the vehicle-to-building (V2B) concept. Here, a PHEV would have the ability to communicate with the home or a small business. The PHEV battery might be operated in a way that makes it available for emergency backup for the home or business in addition to allowing the home to manage its charge/discharge schedule.

Then in phase 3 in the long term, the envisioned V2G concept would allow for full bidirectional controlled flow between the vehicle and the grid. Control of the bidirectional electric flow could include payments to owners for use of their automobile batteries for load leveling or regulation and for spinning reserve (the cashback hybrid incentive). Because the flow of energy is bidirectional, electric service providers also can benefit by controlling or at least monitoring the flow between PHEVs and the grid. Possible benefits to utilities include the ancillary services above, demand response/load management assistance from PHEVs, and green power credits.

The report says that to support this model considerable work must be undertaken to develop the market protocols, information exchange standards, and possibly the electronic interfaces that will govern vehicle-to-grid (V2G) integration and interaction,

“PHEVs will bring together the entire value chains of the automotive/transport sectors and the electric supply sectors, which currently do not share common standards or standards bodies,” says the report.