Sonoma County’s new public electricity supplier is turning to the sun and water — the airspace over treated sewage ponds, specifically — to generate power for local homes and businesses.
Under a deal signed Thursday with a San Francisco-based renewable energy developer, officials with Sonoma Clean Power, now the default electricity provider in Sonoma County, unveiled a plan to install a 12.5-megawatt solar farm on floating docks atop holding ponds operated by the county Water Agency.
When completed in 2016, the project, which will provide enough electricity to power 3,000 homes, will be the largest solar installation in the county.
It also will help fulfill one of Sonoma Clean Power’s central goals — to develop local sources of renewable energy for its expanding customer base, now taking in more than 160,000 residential and commercial accounts across five cities in the county.
Before its launch last May, and through its first nine months of operation, the public venture faced pointed questions as to how quickly it would be able to spearhead local energy projects given constraints on rural land use and the comparatively higher price of power from smaller systems versus large, far-flung industrial sources.
Sonoma Clean Power officials said the planned solar installation served as a key early benchmark of progress in the agency’s rollout.
“To be doing it this early is just exciting,” said Sonoma Clean Power CEO Geof Syphers.
Pristine Sun, the solar farm developer, will build the project on six Water Agency ponds — four in the Sonoma Valley and two just north of Santa Rosa.
The new technology, which is gaining popularity in Japan where real estate is at a premium, allows for large solar installations on man-made reservoirs, preserving land for agriculture, open space or other uses.
The purchase deal with Sonoma Clean Power will allow Pristine Sun to finance and build the project. Syphers declined to give the power purchase price, but he said that it is comparable to a contract the agency has for 70 megawatts of solar power from a development in the Central Valley. Pristine Sun is leasing the ponds from the Water Agency for about $30,000 per year.
The deal comes after the Water Agency last year studied using its recycled wastewater ponds to host the floating solar panels. Cordel Stillman, deputy chief engineer at the Water Agency, said the project meets the agency’s environmental goals by encouraging renewable energy, and it allows the agency to get a secondary use out of the ponds.
The project will represent 15 percent of all the existing solar energy development in Sonoma County and will be more than six times the size of the next-largest project, a 1.8-megawatt solar farm on a former landfill in Cloverdale. The Dry Creek Band of Pomo Indians in November announced plans for a 5 megawatt solar plant near Lake Sonoma.
The Water Agency has its own solar installations and will not use power generated from the project, Stillman said. A side benefit from covering the two ponds just north of the Charles M. Schulz-Sonoma County Airport with panels is that it will reduce the number of ducks and other water fowl that congregate around the airport — a priority for federal aviation regulators, Stillman said.