Photos: Hybrids that give back to the grid

Bob Howard of PG&E demonstrates how the vehicle-to-grid Prius can power a projector, a heater and a row of fluorescent lights. The vehicle-to-grid concept could allow owners to sell the electricity they download overnight back to the electrical system during the day when demand--and prices--are high. There are still several challenges to work out, however, including how to identify which car is contributing electricity to the grid and whether people are really interested in this type of model.