The additional generation is enough to supply about 120,000 customers, said Fong Wan, vice president of power contracts for San Francisco-based PG&E.

"The addition of these wind energy resources ensures that more than 30 percent of our northern and central California customers´ energy needs will come from renewable energy sources," Wan said.

PG&E supplies 31 percent of its customer load from renewable resources, with 18 percent coming from its large hydroelectric plants.