Thousands of miles of canals stretch across the U.S. A pilot project on tribal land in Arizona shows the benefits of covering these waterways with solar panels.
The first canal-based solar project in the U.S. is nearing completion on tribal lands south of Phoenix, Arizona.
Native Americans have been using canals to irrigate the Gila River Valley for thousands of years, starting with the Huhugam people. Now at least a small slice of the modern-day system of canals that winds through the area will double as a location for generating solar energy for the Pima and Maricopa tribes.
Thousands of miles of federally owned canals stretch across the country, channeling water to thirsty crops, rural communities, and hydropower plants. Placing solar panels over these canals could create a gigawatt-scale source of clean energy with lower environmental impact than large-scale solar farms, but so far the idea has been slow to catch on.
A canal solar concept was deployed in India about a decade ago, and it inspired Ben Lepley, the founder of engineering firm Tectonicus, to create designs, prototypes, and techno-economic analysis for such a project in the U.S. Those plans have resulted in the soon-to-be-commissioned Casa Blanca installation — a 1.3 megawatt, half-mile-long pilot project located on the Casa Blanca Canal, part of an extensive canal network owned by the Gila River Indian Community.
The pilot received money from a $25 million provision of the Inflation Reduction Act that supplies funding for the U.S. Bureau of Reclamation to design, study, and deploy projects that put solar panels over waterways. Lepley’s firm has also won a Department of Energy Small Business Innovation Research Grant and is working with the California Energy Commission and University of California, Merced on the project.
It’s early days for this technology, but another canal installation, Project Nexus, in California’s Turlock Irrigation District, broke ground in May of this year and has already constructed foundations. Developers expect it to be completed in 2025.
The merits and messiness of solar canals
Gargantuan utility-scale solar systems are facing pushback in states ranging from Ohio to Texas, often from farm communities. Local opponents have argued that big solar installations take farmland out of production, reduce property values, and possibly harm wildlife. Federal efforts to build clean energy on public land also face opposition from advocates concerned about the potential impact on fragile ecosystems or tribal communities.
Erecting solar on top of federally owned canals could be a win-win. The approach limits the disruption to ecosystems, and some studies suggest it actually has the potential to help canals do their jobs better; an over-the-canal design can prevent water from evaporating and inhibit algae growth. The comparatively small installations can also connect clean power directly to the distribution grid, an important distinction as it has become increasingly difficult to connect large projects to the transmission grid.
But while pairing solar with canals has benefits in terms of land use and the environment, deploying solar panels over water infrastructure presents a unique set of building requirements.
Maintenance staff and machinery need unimpeded access to the canals in emergencies, according to Lepley, who is system designer for the project. Crucially, the design of the support structure must allow for easy removal of bovines, Buicks, and La-Z-Boys.
“Cows, cars, and couches somehow always end up in the canal,” said Lepley.
These requirements — plus the added steel and concrete materials — make the systems more expensive and technically complex than conventional ground-mounted solar arrays on trackers.
Along with George Cairo Engineering, the engineer of record for the Casa Blanca Canal solar project, Tectonius has evaluated a number of designs for the over-canal hardware. “We looked at steel use, concrete use, solar panel costs, wind lift and weight, power production, and access,” said Lepley. The engineers ultimately arrived at a patented, modular, and prefabricated design that makes it safe to build over moving water without impeding canal flows or access.
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