Colorado lawmakers consider pilot projects that combine solar energy with water conservation

Colorado lawmakers on Thursday, April 13, will hear why Colorado should study the nexus of solar energy and water. Aquavoltaics, as this still-emerging practice is known, positions solar panels above canals and other water bodies.

The marriage, proponents say, can save water by reducing evaporative losses while boosting the amount of electricity solar panels generate.

The proposal is part of a bill, SB23-092, that will be heard by the Senate Transportation and Energy Committee.

That same bill also proposes to nudge development of agrivoltaics, where solar production occurs simultaneously with agricultural production. A similar agrivoltaics bill was introduced last year, but was not passed. Aquavoltaics is new to this year’s bill.

State Sen. Chris Hansen, D-Denver, a principle sponsor of both bills, said his study of water conservation efforts around the world found that aquavoltaics was one of the most advantageous ways to reduce evaporation from canals and reservoirs. Doing so with solar panels, he says, produces a “huge number of compounded value streams.”

Covering the water can reduce evaporation by 5% to 10%, he says, while the cooler water can cause solar panels to produce electricity more efficiently, with a gain of 5% to 10%. Electricity can in turn be used to defray costs of pumping water.

Solar panels in cooler climates produce electricity more efficiently, which is why solar developers have looked eagerly at the potential of Colorado’s San Luis Valley. At more than 7,000 feet in elevation, the valley is high enough to be far cooler than the Arizona deserts but with almost as much sunshine.

Colorado already has limited deployment of aquavoltaics. Walden in 2018 became the state’s first community to deploy solar panels above a small pond used in conjunction with water treatment. The 208 panels provide roughly half the electricity needed to operate the plant. The town of 600 people, which is located at an elevation of 8,100 feet in North Park, paid for half of the $400,000 cost, with a state grant covering the rest.

Other water and sewage treatment plants, including Fort Collins, Boulder and Steamboat Springs, also employ renewable generation, but not necessarily on top of water, as is done with aquavoltaics.

As introduced, the bill would authorize the Colorado Water Conservation Board to “finance a project to study the feasibility of using aquavoltaics.”

Hansen said he believes Colorado has significant potential for deploying floating solar panels on reservoirs or panels above irrigation canals. “There is significant opportunity in just the Denver Water reservoirs,” he said. “Plus you add some of the canals in the state, and there are hundreds of megawatts of opportunity here,” he said.

Other Western states are also eying the technology.

Arizona’s Gila River Indian Community announced last year that it is building a canal-covering pilot project south of Phoenix with the aid of the U.S. Amy Corp of Engineers. “This project will provide an example of new technology that can help the Southwest address the worst drought in over 1,200 years,” said Stephen Roe Lewis, governor of the tribe.

When completed, the canal-covering solar project will be the first in the United States.

But both the Gila and a $20 million pilot project launched this year by California’s Turlock Irrigation District are preceded by examples in India.

Officials with the Central Arizona Project (CAP), a major user of Colorado River water and the largest consumer of electricity in Arizona, will be closely following the pilot projects in Arizona and California, according to a report in the Arizona Republic. In the past, both CAP and the Salt River Project, two of the largest water providers in Arizona, have cited engineering challenges of aquavoltaics.

The new Colorado bill also would authorize the Colorado Agricultural Drought and Climate Resilience Office to award grants for new or ongoing demonstration or research projects that demonstrate or study the use of agrivoltaics. This is to be overseen by a stakeholder group.

Mike Kruger, chief executive of the Colorado Solar and Storage Association, says his members want to see the most expansive definition of eligible projects possible. “I don’t think it will ever be ‘amber waves of grain’ under panels. It will more likely be cattle and sheep grazing,” he says.

That is indeed what will be happening near Delta. There, a solar project was proposed near an electrical substation with the intent of serving the Delta-Montrose Electric Association. Neighbors objected, and the county commissioners rejected it in a 2-to-1 vote. The project developer returned with a revised project, one that calls for sheep grazing to occur amid the solar panels. This revised proposal passed in a 3-to-0 vote.

Hansen says this is exactly the model he expects to see play out in the contest between devoting land for agriculture and for renewable power generation.

“What is clear is that county commissions do not want the fight between solar and agriculture if they can help it,” says Hansen. He cites the Delta County case as a prime example.

“If you combine it with grazing, we are going to say yes, and that’s exactly what the Delta County commissioners did. That is why I see this as one of the ways to address the fight between solar and agriculture.”

Allen Best is a frequent contributor to Fresh Water News. He also publishes Big Pivots, an e-journal that chronicles the energy and water transitions in Colorado and beyond.

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