Thirty-four wind turbines at the Vasco Wind Energy Center rise more than 250 feet into the sky from atop the rolling hills of the Altamont in Contra Costa County.
NextEra Energy built the new windmill farm.
Vice President Mike O'Sullivan says the new windmills replace more than 700 old turbines.
O'SULLIVAN: "They're much more efficient, electrically speaking, get much more energy out of these turbines then several hundred of the old ones."
The 34 turbines deliver twice as much power as all the old ones.
PG&E is buying that power, enough to supply almost 20-thousand homes.
PG&E's Fong Wan says the state has mandated that the utility use more renewable power.
WAN: "PG&E currently has about 20 percent of renewable energy, we are on our path to achieve the state's goal of 33 percent by 2020."
The turbines were also designed to lessen the effect of bird deaths, by placing the windmills around thermals where the birds glide, and making the blades easier to see, resulting in 80 percent fewer bird deaths.