A two-way street with these hybrids

California power companies are salivating at the idea of plug-in hybrid vehicles that would provide extended all-electric travel using bigger batteries that are recharged from the conventional power grid.

For one thing, the utilities would make money selling the extra juice. For another, all that stored power could come in handy when demand for electricity outstrips supply and rolling blackouts are threatened.

Pacific Gas & Electric Co. demonstrated bidirectional, or vehicle-to-grid, technology in San Francisco this month, using a Toyota Motor Corp. Prius modified by Energy CS, a Monrovia firm that develops plug-in hybrid conversions.

After the car’s extra lithium-ion battery was charged, a PG&E; technician flipped a switch and the power in the battery started flowing back onto the grid, causing the electric meter monitoring the activity to start running backward.

If such technology ever made it to mass production, plug-in hybrid owners could recharge their batteries at night, when most electric rates are lower, said PG&E; environmental spokesman Keely Wachs.

Then on hot days, when demand for power soars, owners not using their cars could plug them in and transfer electricity from the batteries to the commercial grid. Utility companies would pay hybrid owners for that power, and at the higher daytime rate.

Plug-in hybrids also could provide their owners with emergency power to run refrigerators, lights or air conditioners during power outages, Wachs said.