California to test solar panels on canals to save water and boost energy

The Nexus project, which will begin this fall in central California, aims to test water and energy conservation using solar panels. (Photo courtesy of Solar AquaGrid, LLC)

TURLOCK, Calif. — As the most persistent drought conditions on record continue to plague the Southwest, a pilot project in California’s lush Central Valley is seeking to save water and increase energy efficiency.

The Turlock Irrigation District, California Department of Water Resources and university researchers are working together to construct solar panel canopies over existing canals to test and study the benefits of energy saving and of water. They will inaugurate the Nexus project this fall, which focuses on three sections of the district’s 250 miles of canals.

The district says water from the canal is expected to cool the solar panels, increasing their efficiency, while the canopies will shade the water and protect it from the wind, reducing evaporation while reducing aquatic growth that harms water quality. ‘water.

(Audio by Karen Marroquin/Cronkite News)

But what works in the Central Valley won’t work in Arizona, according to the desert state’s water experts, who say the costs would be too high and the savings too low.

The Turlock pilot program is scheduled to end in 2024. But a 2021 study by University of California system researchers found that if California’s 4,000 miles of irrigation canals had solar canopies, 63 billion gallons of water could be saved from evaporation each year. .

In addition to water savings, said Brandi McKuin, a postdoctoral researcher at the University of California, Santa Cruz and one of the study’s authors, the panels should also improve electricity production, increasing it possibly 3%.

“There is a thermal threshold on solar panels – if they get too hot, their performance drops,” she said. “Because water heats up more slowly than land, we believe there could be an increase in the efficiency of electricity from solar panels.”

Using existing canals in the Turlock Irrigation District rather than buying land and digging new canals has both financial and environmental benefits.

“By using already disturbed land,” McKuin said, “we can avoid habitat loss, degradation and fragmentation. occupation of vast stretches of desert.

Josh Weimer, external affairs manager for the irrigation district, said with high land values ​​in California, buying new land would have pushed up the cost of the project.

The Nexus project is the first solar channel project in the United States, but India was the first to experiment with such panels. Since 2015, when the panels were first used on a large scale in the Vadodara district of Gujarat, India, has expanded its solar canals to include a 100 megawatt project in the Narmada River basin, which flows into in the Arabian Sea on the west coast of the country. .

McKuin said the California project has similar ambitions, however, the University of California research team will use a slightly different design.

“We’re really thinking about optimizing the design of this solar canopy so that it’s lighter and more efficient,” she said.

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Although California researchers are optimistic about the project’s possibilities in the Southwest, geographic challenges and high maintenance costs in Arizona and other states outweigh the advantages of solar panels over canals, according to Darrin Francom, deputy general manager of operations, maintenance and engineering for the Central Arizona Project, which brings water from the Colorado River to parts of the state.

The location of the CAP channels is part of the difficulty in installing solar canopies, he said.

“The majority of the Central Arizona Project Canal is in extremely rural areas, and some areas where there is nothing around it for 50 or 100 miles,” Francom said. “It’s a real challenge for a solar system because you have to be able to connect it to a (power) transmission system, and transmission projects are very expensive.”

UC Santa Cruz researchers say one of the main benefits of solar channels is to reduce evaporation. Francom estimates that the CAP system loses about 2% of its water to evaporation each year.

“The extra cost of solar power on the canal is not offset by the water savings,” he said. “Our water saved from a financial perspective is far less than the cost of solar energy.”

The 336-mile Central Arizona Project Canal, which provides water to 80% of the state’s population, was completed in 1993 at a cost of $4 billion. A study by the Bureau of Reclamation found that placing photovoltaic panels above the canal would be approximately 24% more expensive than placing panels next to the canals.

Even so, Weimer believes the Turlock Irrigation District project will show the potential of using solar panels on canals in California and beyond.

“Because of the small size of the pilot, we don’t really expect evaporative savings to really be something we’re going to see in TID with this pilot program,” Weimer said. “But what we hope is that the data that the researchers are able to obtain will prove the possibilities for scalability.”