How ‘solar canals’ could help California reach sustainable energy goals

TURLOCK, Calif. — Amid intense heat waves that strained the California energy system this month, attention has been placed on efforts to build on renewable energy in the country’s most populous state. At the state level, California is gradually taking steps to run on carbon-free electricity by 2045, and legislation pushing for that calls on retail and state-run electricity sold to come from renewable sources. The transition has reached the automotive industry, with recent legislation pushing for more electric vehicles to be sold and the slow phasing out of sales of gasoline-powered cars. Large investments in clean energy infrastructure will be needed to meet California’s renewable energy goals, but some, like the state’s oldest irrigation district, are getting creative in how to get there. Irrigation districts are tasked with the distribution and management of water that has beneficial uses like agriculture or drinking.

Last year, a study published in Nature Sustainability by researchers from University of California at Santa Cruz along with UC Merced found that it may be possible to tap into the network of public water delivery canals as a way to both conserve water and advance the state’s renewable energy efforts. The researchers studied the concept of “solar canals,” which includes assembling a canopy of solar panels to prevent evaporation while also generating electric energy. The idea is being put to the test in an experiment called Project Nexus. Brandi McKuin, the lead researcher on the study and current assistant project scientist at UC Merced, said the amount of evaporation from canals in California varies by location and time of year. Placing solar panels over the water channels would not only help reduce a percentage of evaporation, but could also boost energy production, she said, since water cools slower than land.

For now, Project Nexus is starting small and is mainly a test of whether the research can hold true in practice, McKuin said. But the project views the state’s canals as a gold mine for not just energy, but information that can inform future energy projects. Those involved are going in with more questions than answers. The research suggests that covering all of California’s canals – spanning roughly 4,000 miles – with solar panels could save up to 63 billion gallons of water and generate 13 gigawatts of renewable power annually. One gigawatt is equal to the energy consumption of 100 million LEDs, or as others put it, enough to power 750,000 homes.

Other benefits include reducing weed growth in the canals and replacing diesel-powered irrigation pumps with solar-powered engines, which lessens the impact on air quality from nitrogen oxide and tiny particulate matter given off by the diesel pumps. While the solar canal idea is new for the region, it’s a sign that “out-of-the-box” ideas are worth exploring to meet the state’s renewable energy capacity, McKuin said. But she said more research is needed, as well as policy, to drive new types of solutions. “There isn’t a single silver bullet solution to our water crisis,” McKuin told the PBS NewsHour. “California is facing a challenging water future, and it’s our job as researchers to find solutions wherever we can, and solar canals is just one of the solutions that can contribute to drought resilience for the state.” The project has a $20 million backing in the state’s current budget, and construction is expected to be completed in 2023.

Eye on local, statewide benefits

The idea of solar canals struck a chord with the Turlock Irrigation District, which operates about 90 miles north of Fresno. The agency provides both water and electricity – a rare operation in the state. mMost irrigation districts just deliver seasonal water to farms and communities, but the Turlock Irrigation District is one of eight “electric balancing authorities” in the state, which help maintain “consistent electric frequency” of the grid, according to the California Energy Commission. The Turlock district’s venture into electric utility began in 1923 after the Don Pedro Dam was built at the Don Pedro Reservoir in the foothills east of the city of Turlock, giving the district an opportunity to generate its own electricity. The following year, the district supported more than 3,000 customers with electricity. Today, nearly 250,000 customers are provided electricity by the district.

The largest balancing authority in California is the Independent System Operator, providing 80 percent of the state’s power load. During the heat wave in early September, which brought record triple-digit temperatures to much of the West, the California ISO issued a Flex Alert to cellphones calling on consumers to conserve energy by shutting down appliances in order to avert an energy shortage. mThe Turlock Irrigation District also saw historic energy peaks, but it did not issue similar urgent calls to conserve energy, said Josh Weimer, a spokesperson for the district, mainly because the district has been able to carefully manage its own water and power distribution, as it has always done in its 135-year history.

However, in recent years, the district, like many other agencies, has had to reconsider how much water it is able to deliver to its customers as it faces the increasing challenges of drought and heat. Sustained drought in the West has led to dwindling water supply in recent years, leaving key reservoirs like Lake Mead at historically low levels. The growing uncertainties that come with climate change are hitting in many places and pose tough questions about California’s Sierra Nevada snowpack, where the irrigation district’s water begins to form. Forecasts suggest the Sierra will have less snowpack in coming years due to the effects of greenhouse emissions, and rainstorms have the potential to be wetter than usual. Those events could have effects downstream for communities. “We’re not left out of being impacted by a change in climate and multi-year consecutive drought,” Weimer told the NewsHour.

It’s why the idea of placing solar panels over roughly two miles of its more than 250 miles of canals in the middle of California seemed worth exploring, Weimer said. His district could use more water to grow walnuts, peaches and almonds and feed its dairy industry in addition to examining an idea that could potentially improve the district and state’s energy supply. And though the district will be the first in the nation to jump into the solar canals idea, “it’s worth changing the status quo and how we operate our system because of the potential benefit,” Weimer said. The solar canal study suggests conserving water in the canals could reduce groundwater pumping and lead to fewer deserted fields due to water shortages. Communities in the San Joaquin Valley have routinely dealt with unreliable water supply from drought and over pumping. The state’s Department of Water Resources supports the project, and if the test run at the Turlock Irrigation District is able to produce the intended results, the agency will be a crucial body to extend the project to the state’s water systems. “As California prepares for a possible fourth dry year, the state is excited to examine new ways that will improve water conservation, provide a clean energy resource, and build drought resilience,” Karla Nemeth, director of the Department of Water Resources, said in a statement.

Origins of the idea

Inspiration for placing solar panels over canals came from a similar project in Gujarat, India, in 2014. The developers of Project Nexus and founders of Solar AquaGrid LLC commissioned the study of solar canals with support from Texas-based NRG Energy and Bay Area-based Citizen Group. The India project informed U.S. researchers. Jordan Harris, co-founder and CEO of AquaGrid, said the new solar canals can use 50 percent less raw material than the India project, in addition to allowing for more space around the panels for easy maintenance. Project Nexus will include various solar canopies designed for the shapes and sizes of different canals within the experiment to study the impact of each type of canopy, Harris said.

The Turlock district’s operation as a water and electricity provider gave the founders of AquaGrid extra interest because searching for land to build solar farms can be expensive and difficult. Placing solar panels over existing waterways and property is not only cost-effective but removes the possibility of building on unused land that could negatively impact the environment. Solar farms take up a large area, and sometimes the problem is finding enough space to construct them. “There simply isn’t enough land to build that much solar and wind,” Harris said. “So, the idea of looking at already disturbed space [like] in every rooftop, every parking lot and 4,000 miles of canals and reservoirs, is a huge opportunity to solve problems.”

Ultimately, Harris said he hopes a project like Project Nexus in California’s Central Valley will help reimagine the way people think of canals and other infrastructure in the move toward renewable energy. He added the state’s engineering of thousands of miles of canals that divert water to major cities and industries will have a chance to adapt to the changing climate conditions, if the project were expanded. If California were its own country, it would have the fifth-largest economy in the world, but Harris said such prosperity can’t continue if the environment is ignored. “In our quest to satisfy human needs, we’ve often been irresponsible, and built big cities where there aren’t the natural resources, so we figure out how to bring the resources. I think there’s a way to honor the landscape and the land, and show responsibility and respect, and I think that’s what this type of innovation can do,” Harris said.

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