Grid to Electric Vehicles and Plug-In Hybrids

April 10, 2007 – Vol.12 No.3

GRID TO ELECTRIC VEHICLES AND PLUG-IN HYBRIDS:
A TWO-WAY CONNECTION.

Baseload powerplants operate ‘round the clock whether the electricity they generate is sold - and put to work - or not. If the powerplant is a coal burner, for instance, off-peak, unsold power means emissions for nothing: Polluting and planet damaging exhausts have entered the atmosphere with no work done in society. Energy is defined as having the ability to do work.

Energy generated but not put to work can not only be damaging it’s also lost potential revenue for the power company.

If energy storage devices, such as batteries, were dirt cheap, power companies would save all the unsold energy they generated in off hours, and send it to the grid at peak times when it’s needed. Some power companies do this with facilities like pumped storage - volumes of water stored in ponds and released on demand to generate electricity - but this is not always feasible.

Now there’s another growing possibility for power companies: utilize plug-in hybrid electric vehicles (PHEV) or electric vehicles as distributed energy storage devices.

PHEVs or EVs with their large battery packs, would be able to recharge at anytime, but charging overnight when excess, cheap electricity is available makes the most sense for the pennywise. Stored overnight, power in a battery pack would be used to drive the vehicle for a few dozen miles or so on all-electric power the next day.

But what if the power in the battery pack isn’t used up? What if the driver doesn’t need all the stored power? Through a charging connection from the grid, the flow of electrons could be reversed. The vehicle’s battery could be used to power a house, be used in an emergency, for jobsite power, or even sold back to the grid.

Pacific Gas and Electric has demonstrated this scheme in what it calls Vehicle-to-Grid or V2G. V2G allows for the bidirectional sharing of electric vehicles, plug-in hybrids and the power grid. Using a Toyota Prius converted to a PHEV by Energy CS, PG&E showed attendees of the Silicon Valley Leadership Group Alternative Energy Solutions Summit that the car could be charged from the grid at one moment, then discharged back to the grid the next.

Further, PG&E says with applicable metering the electricity sold back to grid could be a money maker for the PHEV or EV owner. Power purchased overnight is much cheaper than power sold at peak periods. Participating owners would be credited on their monthly electric bill for their sale to the grid.

PHEVs and pure electric vehicles, too, will be able to store renewable energy such as that from wind powerplants that churn in the dead of night. With the V2G scheme, wind power stored in the car or truck could be sold to the grid.

Storing and putting to work unsold power from carbon emitting power plants effectively lowers emissions. With stored electricity, less peak period power would have to be generated. And, in the case of energy stored in PHEVs and EVs, emissions normally associated with driving a combustion engined vehicle are eliminated as the vehicle drives along on clean electric propulsion. Visit Pacific Gas and Electric at http://www.pge.com/