Energy Committee "Plug-in hybrids and renewable energy"

A talk by Sherry Boschert, member of the Chapter Energy Committee and author of Plug-in Hybrids: The Cars that Will Recharge America

Thursday, March 8, 7 - 9 pm, third floor, Sierra Club Headquarters, 85 Second Street, San Francisco (near Montgomery BART/Muni station).

The average car gets driven three hours a day; the other 21 hours it could be plugged in to an electrical socket, sopping wind- or solar-generated energy into its storage battery - and ready to feed power back into the grid, if needed, on a hot summer afternoon when thousands of people turn on air conditioners. Assuming, of course, that the car is an electric vehicle or a plug-in hybrid.

General Motors, Toyota, and Nissan have all announced plans for plug-in hybrids, and smaller companies (Tesla Motors and AC Propulsion) are marketing all-electric vehicles. "Vehicle-to-grid" (V2G) technology can integrate the energy and transportation sectors, enabling society to use more clean, renewable power.

V2G would be a bonus for consumers and for the environment. Utilities and car owners would sign V2G contracts, bringing flexibility to the grid for the utility and extra income for the driver. Computer monitoring could make sure that the car's batteries have enough power when the driver gets back to it, or the car could simply drive in gasoline mode. Technology could prevent cars from charging during periods of peak electrical demand. Driving on electricity is cleaner than driving on gasoline, even with today's 50%-coal U.S. grid.

Toyota has been testing a V2G linkage in a Prius with a rural electric cooperative in Oklahoma. AC Propulsion demonstrated V2G in a converted Volkswagen Beetle in 2002 and a VW Jetta conversion in 2003. AC Propulsion estimated in 2001 that one million V2G vehicles could store and return electricity equivalent to 20 average-sized power plants. Wide use of cars and trucks with V2G technology could generate enough power to reduce the need for central power-generation capacity by 20% by 2060, the Electric Power Research Institute (EPRI) estimates. Each V2G vehicle might earn its owner as much as $3,000 per year, and for utilities that's a lot cheaper than building more plants.

Solar power peaks at noon, but the highest demands for electricity come several hours later. University of Delaware researchers calculated that if 26% of the U.S. light-vehicle fleet consisted of electric Toyota RAV4-EVs with V2G capability, the cars would store enough solar energy to handle the peak loads, even if only half the vehicles were plugged in when the grid needed power back.

For large-scale use of wind power, the grid will need more sources of "regulation" power (used to keep the frequency and voltage steady for a few minutes at a time, many times per day). If half of U.S. electricity generation came from wind, the Delaware academics estimated that we'd need only 3% of cars, SUVs, and light trucks to be V2G for grid regulation, again assuming half the vehicles to be available at any one time. U.S. Department of Energy studies suggest that widespread implementation of V2G technology could increase usage of wind power by a factor of three.

PG&E and EPRI are testing a plug-in-hybrid "trouble truck", one of the large trucks with bucket lifts to raise workers up to damaged power lines. The utility expects the plug-in hybrid to improve fuel economy by 30 - 50%, reduce emissions by 50 - 70%, and allow 6 - 8 hours of stationary operation without idling. It will also act as a standby generator for 25 - 30 kW of power in an emergency, and because it will be plugged in at night, recharging aligns with the hours of most wind power in the PG&E area.

BART estimates it could save $260,000 per year with V2G. Plug-in hybrid drivers who park in BART lots would charge for free and agree to let BART draw power from their batteries when needed. BART contracts with PG&E for power in advance of use, and pays a hefty premium if it uses more power than scheduled. In one month studied, it exceeded the schedule during 61 one-hour periods. Tapping plug-in cars through V2G could keep BART within its contracted limits. Drivers would save an estimated $800 - 1,200 per year by running on BART's electricity instead of gasoline much of the time.

The Sacramento Municipal Utility District found that vehicles charged on summertime winds (blowing mainly at night) could power nearly half of SMUD's peak daytime load for an hour and a half. Alternatively, V2G could fill in for 250 MW of wind for eight hours when the wind stops blowing during the day.

Other scholars have found that if the grid temporarily goes down, one vehicle with a 20 kW line connection could power 12 houses at an average load of 1.5 kW per house, though utilities may want to limit distribution to three houses for reasons related to infrastructure.

V2G is in its infancy, but deserves our attention as we move as rapidly as possible toward renewable sources of energy.

For more information about the talk, contact Aaron Israel at (415)515-2683 or email izzinsf@gmail.com

Sherry Boschert