Colorado will probe the pairing of solar panels with canals and reservoirs. Can solar integrated into agriculture help solve the San Luis Valley’s water woes?
by Allen Best
Agrivoltaics—the marriage of solar photovoltaics and agriculture production— has been filtering into public consciousness, if still more as an abstraction than as a reality. In Colorado, other than Jack’s Solar Garden near Longmont, there’s little to see.
Aquavoltics? The idea of putting solar panels above water? Similarly thin. You have to travel to North Park to see the solar panels above the small water-treatment pond for Walden.
SB23-092, a bill passed on the final day of Colorado’s 2023 legislative session, orders study of both concepts. In the case of aquavoltaics, the bill headed toward the desk of Gov. Jared Polis authorizes the Colorado Water Conservation Board to study the feasibility of using solar panels over or floating on, irrigation canals or reservoirs. The bill also authorizes the state’s Department of Agriculture to award grants for new or ongoing agrivoltaics demonstration projects.
Still another section requires the Colorado Department of Agriculture, in consultation with related state agencies, to begin examining how farmers and ranchers can be integrated into carbon markets. The specific assignment is to “examine greenhouse gas sequestration opportunities in the agricultural sector, including the use of dry digesters, and the potential for creating and offering a certified greenhouse gas offset program and credit instruments.”
While Democrats and Republicans got angry with each other in some cases, in this case there was broad comity. The primary Democratic sponsors were from Denver and Boulder County, and the Republicans from the San Luis Valley and Delta. Votes were lopsided in favor.
The agrivoltaics idea was originally included in the 2022 session in a big suitcase of ideas sponsored by Sen. Chris Hansen, a Democrat from Denver. It fell just short of getting across the finish line.
This past summer, Sen. Cleve Simpson, a Republican from the San Luis Valley whose district now sprawls across southwestern Colorado, took keen interest—and for very good reason. A fourth-generation native of the San Luis Valley, his day job there is general manager of the Rio Grande Water Conservation District, whose farming members must cut back water use so that Colorado can comply with the Rio Grande Compact with New Mexico and Texas. It will be a tough challenge—and he’s trying to figure out how to leave his communities as economically whole as might be possible.
The aquavoltaics idea is new to this year’s bill, though.
Hansen, who grew up along the edge of the declining Ogallala Aquifer in Kansas, 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 said in an April interview, produces a “huge number of compounded value streams.”
Covering the water can reduce evaporation by 5% to 10%, he explained, 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 pumping costs.
Solar panels in cooler climates can actually produce electricity more efficiently, which is why solar developers have looked eagerly at 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 location to deploy solar panels above a small pond used in conjunction 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 the $400,000 cost, with a state grant covering the other.
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.
Hansen said he believes Colorado has significant potential for deploying floating solar panels on reservoirs or panels installed 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.”
Bighorn, Colorado’s largest solar project, has a 300-megawatt generating capacity on land in Pueblo adjacent to the Rocky Mountain Steel plant Comanche’s two remaining units have a combined capacity of 1,250 megawatts, although both are scheduled to be retired by 2031.
Why now and not a decade ago for aquavoltaics? Because, says Hansen, most of the best sites for solar were still available. Because aquavoltaics has an incremental cost, land-based solar was the low-hanging fruit.
Now, as land sites are taken, the economics look better, says Hansen, who has a degree in economics. Plus, with solar prices dropping 10% annually, the economics look even better. The Inflation Reduction Act passed by Congress in August 2022 delivers even more incentives. “I think there will be more and more aquavoltaic projects that will pencil out,” he said.
Arizona water providers have resisted aquavoltaics but are now taking a second look. The Gila River Indian Community announced last year that it is building a canal-covering pilot project south of Phoenix with aid of the U.S. Army Corps 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-covered 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 Turklock Irrigation District are preceded by examples in India.
Officials with the Central Arizona Project, the largest consumer of electricity in Arizona, responsible for delivering Colorado River water through 336 miles of canals to Phoenix and Tucson, will be following closely the new projects in Arizona and California, according to a report in the Arizona Republic.
In its final legislative committee hearing in late April, the bill got robust support. Both the Colorado Farm Bureau and the Rocky Mountain Farmers Union voiced support.
So did a Nature Conservancy representative. “If we want to solve the climate crisis while at the same time not exacerbating biodiversity and farmland loss, we have to think creatively,” testified Duncan Gilchrist.
“This bill has nothing but winners,” said Jan Rose, representing the Colorado Coalition for a Livable Climate.
The most probing questions were directed to Byron Kominek, the owner and manager of Jack’s Solar Garden. There for the last several summers, vegetable row crops have been grown in conjunction with dozens of solar arrays assembled on a portion of the 24-acre farm. He readily receives reporters and all others, casting the seeds of this idea across Colorado and beyond.
The questions were directed by State Sen. Rod Pelton, whose one district covers close to a quarter of all of Colorado’s landscape, the thinly populated southeast quadrant. A farmer and rancher from the Cheyenne Wells area, Pelton wondered how high off the ground the panels were and what kind of racking system was high enough to address the issue of cattle rubbing against them?
The question, though, jibes with what Mike Kruger, chief executive of the Colorado Solar and Storage Association, sees for agrivoltaics. “I don’t think it will ever be ‘amber waves of grain’ under panels,” he said in April. “It will more likely be cattle and sheep grazing.”
Hansen, in his wrap-up comments before the committee in April, talked about different places needing different approaches depending upon climate zones, topography, growing conditions and other factors. That, he said, was the intent of the studies: to figure out how to maximize potential, to get it right.