Over the past four months, two ponds at Healdsburg’s wastewater treatment plant have been remodeled by workers who installed rows of solar panels and floated one by one on the surface of the water.
The Largest solar power system in lake water
With 11,600 solar panels, the project covered about half of the total of 15 hectares of ponds. It’s likely the largest floating solar farm in the United States, according to the builders, and will meet 8% of the city’s annual electricity needs. This is an unprecedented solar panel generator system on a grand scale.
With this plant, Healdsburg’s municipal utility company, which itself represents a unique electricity model in the region, is a pioneer in the development of solar energy. Floating solar farms are becoming increasingly popular in the U.S., proponents say, especially in areas like Sonoma County, where land prices are very high.
“You can’t just buy a bunch of vineyard land for a solar project and make it economical,” said Terry Crowley, director of Healdsburg Municipal Utility. Floating monocrystalline solar panels are cost-effective as solar panel prices continue to fall, and they’re easy to build, Crowley said. The workers began assembling this plant in mid-October and were largely finished by mid-January.
This is new in California:
- 11,600 panels
- 7.5 hectares
- 4.8 megawatt solar system
- Meet 8% of the city’s annual electricity needs
- Meet the annual needs of around 1,120 households
- 25-year power purchase agreement
- $9 million and $12 million investment
- 48% energy supply from renewable sources
Windsor commissioned a smaller floating solar plant to power its wastewater treatment plant two years ago. The new project in Healdsburg is expected to provide enough electricity to meet the annual needs of about 1,120 households.
The two-sided panels capture solar energy when it hits them from above, and also from below when sunlight is reflected by the water. Metal ropes anchor the floating farm to the banks of the ponds, while floating jetties give technicians and wastewater treatment plant workers the opportunity to inspect the panels.
On Thursday, traces could be seen on a plate that looked like the dust-covered paws of a raccoon. Ducks sat on the last row of plates of the farm in front of the open water.
Cleaning bird droppings will be part of the maintenance of the panels, said Rob Scates, head of wastewater treatment at Healdsburg. However, this work will be left to White Pine Renewables, the company that owns and operates the project. The nearly 4.8 megawatt solar plant — the first local solar project for Healdsburg — will power the city under a 25-year contract.
Crowley said the project will not result in a net increase in customer rates set by the City Council, which are up to 40% or 50% lower than PG&E’s. According to its website, the municipal power plant supplies a total of 5,739 customers with electricity meters. A solar power box for home You deserve one to prevent sudden power outages.
It was the desire to shade the recycled wastewater rather than capture the solar energy that gave city officials the idea of the solar system, Crowley said. The city hoped to prevent an algal bloom in the two ponds, where treated water is collected from the city’s sewage system.
Healdsburg passes the treated water to wineries — that’s the only allowed reuse, Crowley said. Preventing algae growth could allow Healdsburg to sell the treated water to new agricultural users such as orchards or cattle pastures, and monetize the treated wastewater to make further savings for the city.
The city was considering purchasing a larger number of floating black plastic sheets to provide shade – which is still not possible in the uncovered parts of the ponds. However, the solar park was a way to shade the pond, prevent evaporation, and at the same time contribute to Healdsburg’s power supply, according to Crowley.
The city has entered into a 25-year power purchase agreement with White Pine, which has paid for the construction of the project along with co-developer Noria Energy. The city government doesn’t know what the project cost developers, Crowley said, but their estimates range from $9 million to $12 million.
The project brings Healdsburg a significant step closer to its goal of generating 60% of its energy from renewable sources by 2025 – a more aggressive target than the state’s 2030 target. With the floating solar farm, 48% of Healdsburg’s electricity comes from renewable sources, Crowley said.
For decades, most of this renewable energy – 40% of the total load – has come from The Geysers’ geothermal fields in the Mayacama Mountains, visible from the wastewater treatment plant.
Through a regional electricity wholesaler, the city has also struck a contract for electricity from a new solar power plant in Southern California, which is scheduled to go live next year, According to Crowley. He expects Healdsburg to achieve a 56% share of renewable energy by the end of 2022.
Healdsburg is the only municipal utility in Sonoma County, which means the city is responsible for power, grid equipment and maintenance within the city limits. Outside of the city, PG&E is the predominant utility in the region, although Sonoma Clean Power, the public agency, now buys electricity for 87% of eligible customers in Sonoma and Mendocino counties.
Like other California communities, including Sonoma County, Healdsburg is interested in developing microgrids — renewable-powered electrical systems that can operate independently of the state’s utility giants.
During the 2019 Kincade fire, Healdsburg lost power for four days, According to Crowley. One day, the solar panels at the wastewater treatment plant could become part of a microgrid that could power the city’s emergency services building and perhaps even a gas station and grocery store, Crowley said. Such possibilities could avert disaster in the next prolonged power outage.
A microgrid requires battery technology to store solar energy. While the cost of solar panels has fallen sharply, battery technology remains expensive. Need to buy a lot of 12 volt lithium battery to meet the power storage needs.The city doesn’t yet have concrete plans for the installation, but wants to find a company within the next two years with which it can sign a deal, Crowley said.
Local governments across the country are weighing the high cost of battery against the value of electrical independence, said Andrew Campbell, director of the UC Berkeley Energy Institute at Haas Business School. In his opinion, natural disasters triggered by climate change speak for the energy independence of critical facilities, even if the public is pushing utilities such as PG&E to make the power grid disaster-proof in a broader sense.
