A wind turbine, a rare sight in Sonoma County, was erected Thursday at the Geyserville Sanitation Zone sewage plant, part of the Water Agency's effort to power all of its operations with renewable energy sources.

"This helps us meet our goal of carbon-free water (operations) by 2015," said Dale Roberts, principal engineer for the Sonoma Valley Water Agency. "We meet most of that from power through Warm Springs Dam. We get a lot of power from landfill gas generation facility. We have a number of solar installations and we have explored wind a little bit."

The Water Agency owns and operates the Geyserville facility, which serves the Geyserville community.

The wind turbine is 45 feet above the floor of Alexander Valley, where the annual average wind speed is 9.8 mph and strongest in the spring and summer.

There is not enough wind for a wind farm, but it is enough to generate 5 kilowatts of electricity, which will be 7 percent of the power needs at the plant, Roberts said.

"At a wastewater treatment plant, the power need goes up in the day and drops off at night," Roberts said. "But we wanted something that could generate power at any time."

It is the first wind turbine installed by the water agency, which gets most of the power it uses from the Warm Springs Dam hydro-electric plant, the gas generation facility at the Sonoma County landfill and using solar arrays.

However, the Water Agency is using anemometers to gauge the wind at the Sonoma County central landfill in Cotati and at Tubbs Island near Sears Point, on land the Vallejo Sanitation District owns to dispose of sludge, as possible additional sites.

The Geyserville turbine cost $29,500 and was assembled and erected by Advance Power Inc. of Calpella.

"We didn't want to spend a whole lot, it is somewhat of a demonstration and it is not a place where we have a big power load," Roberts said. "And we didn't want to have a blemish on the landscape."

(You can reach Staff Writer Bob Norberg at 521-5206 or bob.norberg@pressdemocrat.com.)