As electric vehicles become commonplace, will the grid be able to handle the extra load? Too many cars plugging in at once might cause disruptions and necessitate costly infrastructure upgrades....
The V2G Concept: A New Model for Power?
Connecting utility infrastructure and automobiles.
Electric-drive vehicles can be thought of as mobile, self-contained, and - in the aggregate - highly reliable power resources. "Electric-drive vehicles" (EDVs) include three types: battery electric vehicles, the increasingly popular hybrids, and fuel-cell vehicles running on gasoline, natural gas, or hydrogen. All these vehicles have within them power electronics which generate clean, 60 Hz AC power, at power levels from 10kW (for the Honda Insight) to 100kW (for GM's EV1). When vehicle power is fed into the electric grid, we refer to it as "Vehicle-to-Grid" power, or V2G.
Electric utility planners and strategists, when they think about electric-drive vehicles at all, have seen battery vehicles as night-charge (valley-filling) load, and perhaps have seen fuel cell vehicles as possible generation resources for some distant future. In contrast, a recent study we conducted for the California Air Resources Board (CARB) and the Los Angeles Department of Water and Power, shows all three types of EDVs (battery, hybrid, and fuel cell) have potential roles to play as utility resources, and that ancillary services are the most lucrative use for vehicle power.
The electric power resource from vehicles is potentially quite large. In California alone, we calculate that CARB's zero emission vehicle mandates will provide 424 MW of power capacity by 2004, and 2.2 GW by 2008 (Kempton et al., 2001: 22). Looking further into the future, the Electric Power Research Institute (EPRI) predicts that power from electric-drive vehicles could reduce the global requirement for central station generation capacity by up to 20 percent by the year 2050 (EPRI 2001).
Our study assesses the technical requirements, electrical capacity, and economic value of V2G. We examined a range of EDVs to provide four types of power: baseload, peak, spinning reserves, and regulation (up and down). V2G for baseload power does not make sense, as the per-kWh cost is too high and drive train designs assume low operating time (average 1 hour/day). However, the economic value of other forms of V2G appears high, more than enough to offset the initially higher costs of electric-drive vehicles. To realize this potential, however, will require some minor design modifications to current vehicles, and some coordination of vehicle and infrastructure planning.