Sonoma Clean Power is adding more wind power to its clean energy portfolio, a move that the power company expects to help stabilize long-term electricity rates and help the county combat climate change.

Sonoma County’s dominant electricity provider this week inked a 20-year deal with the Florida-based wholesale energy provider NextEra Energy Resources to build a new wind farm in the East Bay just east of Livermore, furthering the agency’s goal of boosting its supply of renewable energy and advancing efforts to purchase that power as locally as possible. Once the 46-megawatt project is complete at the end of 2017, an estimated 24 new wind turbines will provide the public electricity provider enough energy to power up to 46,000 homes, according to Geof Syphers, the company’s chief executive officer.

“This is really exciting,” Syphers said. “It’s our first long-term wind contract in California ... It will help us meet our goals for renewables 10 years ahead of schedule.”

State law requires public utility companies regulated by the state, including Sonoma Clean Power and PG&E, to source at least 50 percent of their electricity from renewable sources such as wind, geothermal or solar by 2030.

At present, the agency’s basic service has an energy supply that is 37 percent renewable, from geothermal and wind sources. Contracts for solar projects have been signed, with construction underway on installations inside and outside the county.

“This wind contract is really significant because it will allow us to reach 50 percent renewables by 2020,” Syphers added.

The county’s overall goal is to reduce greenhouse gases to 1990 levels by 2020.

Syphers declined to disclose the power purchase price, citing the possibility of undermining competitive advantages with other utility providers.

Sonoma Clean Power overtook Pacific Gas and Electric Co. nearly two years ago as the default electricity provider for all of Sonoma County except Healdsburg, which has its own municipal power company. At present, Sonoma Clean Power provides electricity to more than 195,000 commercial and residential accounts, representing 88 percent of eligible customers, according to agency officials.

The average residential Sonoma Clean Power customer pays $116.25 on his monthly bill, 1 to 2 percent lower than PG&E, according to the agency. For the average commercial customer, the average monthly bill is $301.92, 1 percent lower than PG&E.

Syphers said the long-term wind contract will help keep rates stable or could even reduce them in the future.

Editor’s note: NextEra Energy Resources will build the new wind farm. The deal to purchase the power was signed with Golden Hills Wind Energy Center in Alameda County, which is owned and operated by a subsidiary of NextEra Energy Resources. This article has been modified to clarify the energy purchase.

You can reach Staff Writer Angela Hart at 526-8503 or angela.hart@pressdemocrat.com. On Twitter @ahartreports.