California now gets about 5 percent of its electricity from wind power, according to data released Tuesday by the California Wind Energy Association.

The majority of California's electricity - 42 percent - comes from natural gas, followed by nuclear power and hydropower. According to 2010 figures from the California Energy Commission, wind made up 4.7 percent of the state's electricity mix and solar was 0.3 percent.

But in 2011, wind projects that generate 921 megawatts - enough electricity for more than 400,000 homes - were installed across the state, which the wind association says should put it above the long-sought-after 5 percent threshold. California has set an ambitious goal of getting 33 percent of its power from renewable sources by 2020, and utilities are increasingly signing contracts for renewable projects.

"2011 was a banner year for wind generation in California," said Nancy Rader, executive director of CalWEA, based in Berkeley. "Wind has come a long way and is helping to drive California closer to reaching its goal of 33 percent renewable energy."

In California, the vast majority of wind turbines are clustered in three regions: the Altamont Pass between Livermore and Tracy, Tehachapi near Bakersfield and the San Gorgonio Pass near Palm Springs. While solar panels are visible on homes across the state, massive wind farms tucked away in windy mountain passes that many Californians never see produce much more energy.

"California is one of the strongest wind markets in the nation," said Mark Tholke, vice president of Origination for EnXco, which has several wind projects in Solano County, which is southwest of Sacramento. "The wind industry has been quietly chugging along as the workhorse of renewable energy for the last several years."

NextEra, a Florida-based energy company that has several wind projects nationwide, is in the process of "repowering" hundreds of wind turbines along the Altamont Pass in eastern Alameda and Contra Costa counties, both near Oakland.

Nearly 2,000 wind turbines in the Altamont Pass are being replaced with about 100 huge state-of-the-art turbines that, at 430 feet, stand taller than the tallest coast redwood trees. Each of the new turbines, manufactured by Siemens, generates 2.3 megawatts of electricity. NextEra's repowering project will be done in three phases and is scheduled to be completed by 2015.

Other projects are in the pipeline, including Iberdrola Renewables plans for a 200 megawatt Tule Wind Power Project for eastern San Diego County.

Much of the growth in wind power is because of the federal production tax credit, or PTC. The PTC gives a tax credit for electricity production from utility-scale wind turbines but is scheduled to sunset at the end of 2012. While several wind projects across the country should come online in 2012, developers have been reluctant to go forward with plans for 2013 and beyond over fears the credit will not be extended.

"Wind supports 400 manufacturing facilities in 43 states," said Ellen Carey of the American Wind Energy Association. "The production tax credit enjoys bipartisan support, and we have reason to be optimistic."

(c)2012 the San Jose Mercury News (San Jose, Calif.)

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