UC Merced study imagines solar panels atop irrigation canals

An artist rendering shows how solar panels can be placed on California's aqueduct in western Stanislaus County.

An artist rendering shows how solar panels can be placed on California’s aqueduct in western Stanislaus County.

Placing solar panels on the Central Valley’s canals could put the state halfway on its goal of climate-friendly power supply by 2030, according to a new study.

And the panels could reduce enough evaporation from the canals to irrigate about 50,000 acres, the researchers said. They come from the Merced and Santa Cruz locations of the University of California.

The idea has already piqued the interest of the Turlock Irrigation District as one of several ways to increase the solar portion of its power supply.

However, a spokeswoman for the State Department of Water Resources said the panels would affect maintenance of the California Aqueduct, its longest canal.

The study was published last month in the journal Nature Sustainabililty. It was backed by NRG Energy, a Princeton, New Jersey-based company, and Citizen Group, a Berkeley marketing firm.

“It really caught the imagination of many people that this could be a very elegant solution to various problems,” said Jordan Harris, Citizen Group’s senior board advisor, in a telephone interview.

Harris is also the co-founder and CEO of Solar AquaGrid LLC, which was formed to drive the concept forward.

“Decarbonising Our Economy”

Solar is an integral part of the state’s shift away from fossil fuel emissions, which are contributing to overall warming of the planet. According to the California Energy Commission, it accounted for 15.7% of the state’s electricity production in 2019, up from 0.7% in 2010.

The panels are found on roofs, in agricultural fields, as well as in deserts and other natural areas. The study’s authors said channels could significantly increase production without disrupting more land.

They said cables or trusses could hold the panels above the surface of the water and provide enough space for sewer maintenance. The electricity could be fed into the entire grid or used nearby, e.g. B. in the massive pumps along some state and federal channels.

The researchers did not build a model of a canal with solar panels on it. Instead, they rated eight locations in the valley for sunshine, electricity prices, evaporation rates, and other factors. They concluded that it is worth pursuing the idea because of the benefits.

That includes about 13 gigawatts of electrical power, one-sixth of the state’s current generation when all about 4,000 miles of the canal had panels. This is roughly half what the state aims to achieve from all non-carbon sources by 2030.

The evaporation savings could amount to about 193,300 acres per year, enough water for about 55,000 acres, the study says. California has irrigated approximately 9 million acres in total.

The same amount of water could meet the housing needs of around 2 million people.

The next step could be a demonstration project on a mile of actual canal, co-author Roger Bales said in a telephone interview. He is an engineering professor at UC Merced.

“We need solar power across the state to achieve our goal of decarbonizing our economy,” said Bales.

The study found that the canal linings could replace some of the diesel engines that power well pumps, a source of air pollution in the valley. And they said the shading could reduce algae growth in the water, a maintenance expense.

TID has more solar energy in mind

TID and the Modesto Irrigation District supply both urban residents with electricity and farms with water. And some of their channels have transmission lines that may be served by the panels.

TID employees are including channel panels in an analysis of a potential solar project within the district boundaries, spokesman Brandon McMillian said via email. It could go to the board by the end of the year, he said.

“Using existing infrastructure and land may offer financial benefits to our customers, but it also poses potential challenges to the operation and maintenance of our irrigation system,” said McMillan.

TID got 7.4% of its electricity from solar energy as of 2019, much of it from the desert part of Kern County.

MID does not have a sewer project in mind, but is aware of the idea. In 2019, the company got 2.4% of its electricity from solar energy, including an array on North McHenry Avenue.

“The real application of UC Merced’s work is largely unknown and we look forward to carefully analyzing the results of a potential large-scale application in California,” spokeswoman Melissa Williams said via email.

MID and TID each get 17% of their energy from wind, a large part of it from the Pacific Northwest.

State agency sees “enormous costs”

The California Aqueduct supplies water from the Sacramento-San Joaquin Delta to users in the valley and southern California. The study looked at three pumping sites – in counties Western Merced, Fresno, and Kern – where solar panels could be installed.

But DWR spokeswoman Maggie Macias said via email that the idea was impractical.

“Covering the aqueduct would be a huge hassle and make access to the waterway difficult for maintenance or during an unexpected emergency,” she said.

Macias also said that evaporation from the 400-mile aqueduct was “minimal”.

The federal Central Valley project also moves huge amounts of water in the region. The study assessed the canal’s solar potential in Colusa County, the Rancho Seco area near Sacramento, and the Pleasant Valley area west of Fresno.

The US Bureau of Reclamation, which runs the CVP, has not reviewed the study, spokeswoman Mary Lee Knecht said via email.

“However, we are always interested in innovative solutions for renewable energy and managing the changing climate,” she said.

Bales said he was aware of the state agency’s concern about access to maintenance, which would be one of the issues that would be addressed in a pilot project.

The lead author of the study was Brandi McKuin, a postdoctoral fellow at UC Santa Cruz. In a press release, she stated that evaporation savings could be up to 82%.

“This amount of water can make a significant difference in regions with water scarcity,” she said.

NRG Energy, the other study partner, deals with the generation of nuclear power plants and fossil fuels as well as renewable energies.

John Holland covers the latest news and has been with The Modesto Bee since 2000. He has reported on agriculture for the bees and in newspapers in Sonora and Visalia. He was born and raised in San Francisco and graduated from UC Berkeley as a journalist.

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