One of the potentially most beneficial aspects of vehicle to grid (V2G) applications is that electric and plug-in hybrid vehicle batteries could delivery power to the grid during peak times and draw power when it is not in demand.

However, as my new report for Pike Research "Electric Vehicles on the Grid" states, V2G is likely to be limited to small pilot projects through 2015. Auto manufacturers are wary of stressing new and expensive lithium ion batteries for anything other than vehicle locomotion until they have an established track record of performance. Utilities are equally cautious about the new technologies required to control the flow of power up and down and across the grid.

One potential V2G application that could make financial sense down the road is for commuter parking lots to control the power flow of the thousands of vehicles parked during the day to load shift away from peak demand.

Andy Frank, a pioneer in plug-in hybrid development and the Professor, Mechanical and Aeronautical Engineering at the University of California, Davis, ran the numbers on what would be possible if BART, the San Francisco Bay Area Rapid Transit system, were to use vehicle batteries to load balance their electricity draw.

As Dr. Frank explained, BART has to buy electricity in bulk and well in advance (2-3 years) of when it is needed. But the power needed to run its electric trains and facilities increases greatly during rush hour, requiring the organization to "oversubscribe" by buying enough power to satisfy the peak demand that occurs during just a small fraction of the day. BART pays for energy that's never used, and passes the cost onto commuters.

Frank says that by allowing EVs to plug in and having BART charge the batteries with excess power during the slow times, and then draw back a percentage of the power during peak times, BART could save up to $4 million annually. Even at a slow (level 1) speed of delivering power back to the grid, 1000 vehicles could act as a small power plant, delivering about 1.5 megawatts. The transit agency knows how many vehicles park in its lots, so they could predict how much power would be available to buffer its peak demand, and could save money by buying less power.

Even by giving away the power for free and fully charging vehicles before they depart, V2G storage would cost between 10 and 25 percent of the cost of peak power, according to Frank.

This scenario would require vehicle owners to permit their vehicles to be managed, and for two-way wireless or wired communications to relay both the status of the battery and BART's power demand.It also asks BART to morph into a power command center, and puts the agency at risk should something happen to a vehicle during charging, but the point is well taken.

Load balancing and demand management can replace or reduce electricity consumption at a much lower cost than purchasing energy. Vehicle batteries-- after the kinks have been worked out and auto makers and utilities are comfortable -- will likely be play supporting roles to the grid in providing mobile storage. But don't plan on it as being part of your early EV experience.

John Gartner is Editor in Chief of Matter Network and an Industry Analyst for Pike Research