The Roseville-based Northern California Power Agency (NCPA) – which operates two geothermal power plants at The Geysers steamfields – and SPG Solar of San Rafael said this week that they're joining forces to build solar installation near Clearlake.
NCPA reported that the $8.2 million installation consists of 6,300 solar modules that will produce 2.2 million kilowatt hours of electricity annually, enough to power 300 homes and offsetting nearly 800,000 pounds of carbon dioxide per year.
Mark Dellinger, director of Lake County Special Districts (LACOSAN), explained that the 13-acre solar “array” – the name for a continuous assembly of solar collectors – will be located at LACOSAN's southeast treatment plant, located just north of the City of Clearlake.
“This is all part of our water recycling system that sends our water to The Geysers,” said Dellinger.
The 1 megawatt installation will provide a third of the power to the pumping station, also located at the Clearlake facility, which pumps wastewater from Lake County to the NCPA Geysers Geothermal Energy Plant near Middletown, said Ken Speer, NCPA's assistant general manager for generation services.
During the day's peak hours the solar installation will generate about 1 megawatt of power, said Speer. The facility will still need to buy two-thirds of its power from Pacific Gas and Electric.
LACOSAN has a partnership with NCPA and Calpine for use of the effluent, explained Dellinger.
NCPA and Calpine each get half of the water to use in their geothermal injection operations, added Speer. Calpine will reimburse NCPA for the energy that is provided.
The NCPA Geysers Geothermal Plant uses wastewater from Lake County and injects it into the geothermal reservoir, the agency reported. The reservoir converts the wastewater into steam, which is used by geothermal power plants to produce electricity.
Currently, about 70 percent of steam produced from the reservoir is due to wastewater injection, according to NCPA.
None of the power generated by NCPA actually serves Lake County, said Speers, where PG&E is the chief energy supplier.
County has more solar plans
Dellinger said the pumping station the solar power will service is the largest of four such stations that move water 26 miles to The Geysers, where it's injected into the steamfields in a process to create geothermal energy.
The Clearlake pumping station has seven 300-horsepower pumps that pump between 6,200 and 6,400 gallons a minute, or 8.9 million gallons of wastewater a day, said Dellinger.
The wastewater comes from the Northshore – Upper Lake, Nice, Lucerne, Paradise Valley and Clearlake Oaks – as well as Clearlake, Lower Lake and Middletown, said Dellinger. Those areas constitute the first two phases of the Full Circle Project.
Still not included in the system are Kelseyville and Lakeport, which will be expensive to tie in, Dellinger said.
Speer said the solar installation has been in the planning stages for about eight months, with approval coming three months ago. Final signatures were received Dec. 7.
Dellinger said the Board of Supervisors also had to approve the project, because of the county's joint operation agreement for the pipeline. That agreement had to be amended to accommodate the solar array and its installation on county land.
“We hope to have this thing up and running and producing power by late summer of next year,” said Speer, who called the project “pretty unique.”
Dellinger said the county is due to install seven more acres of solar arrays – for a total of 20 acres – to power the county jail, the new Animal Care and Control facility, and two wastewater treatment plants.
All of the solar arrays are composed of a series of 4-foot by 8-foot flat collectors that sit on an axis, and move to follow the sun throughout the day, said Dellinger. That “tracking” system generates as much as a third more energy than a fixed solar installation.
Dellinger said the county is just starting the environmental review process for those other solar installations, with the reviews expected to be finished by March and construction planned to start in April.
The goal, he said, is to have the facilities operational by this time next year or sooner, said Dellinger, which will help the county take advantage of rebates and financial incentives from PG&E.
E-mail Elizabeth Larson at
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