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TID’s Solar-Over-Canals Tackles the Food-Water-Power Connection

By Kristin Withrow posted 01-31-2023 02:21 PM


By Kristin Withrow, CSDA Communications Specialist

When California passed its landmark climate bill AB 32 in 2006, it set a statewide goal to reduce emissions to 1990 levels by 2020.  When that target was achieved in 2016, a more ambitious target of 40% reductions by 2030 was set, followed by an even higher goal to be 100% clean (carbon neutral) by 2045. These targets will require the effort of every sector to modify operations to reduce carbon dependence, conserve energy and modify operations to source renewable energy pathways.  Special districts in the state will be phasing in electric fleet vehicles, exploring operational efficiencies to reduce emissions, and looking to grants and program incentives to aide in the affordability of energy transitions.


Such was the case with Turlock Irrigation District (TID) when it came upon a research paper by an alum of nearby University of California at Merced.  Focused on environmental engineering, Brandi McKuin’s published paper asserted that California could generate a whopping 13 gigawatts of energy, conserve 63 billion gallons of water and make irrigation and water district maintenance operations more efficient by installing solar panels above their irrigation canals.


TID has been an innovator since its creation in 1887.  As the first irrigation district in California, it was founded by innovative thinkers who foresaw the agricultural potential of the land that is now home to over 4700 growers and 150,000 acres of productive land that contributes to the world’s food supply.


Over the years, many have speculated on the possibility of using the airspace over canals to install solar arrays, but none had studied the idea or produced the type of scientifically based calculations in McKuin’s paper.  TID found themselves in the perfect position to forge partnerships around the idea of proving (or disproving) the paper’s theory.  With the state’s declared renewable energy goals, and TID’s dual-purpose role as an irrigation district and a large scale utility provider in a region with 261 days of annual sunshine, they embraced the opportunity to become a research hub to study the efficiency of solar-over-water along two miles of their 250 miles of canals.


The research paper has turned into a partnership between Turlock Irrigation District, California’s Department of Water Resources and the organization providing funding for the project, the project developer Solar AquaGrid, and UC Merced.  They’ve named it Project Nexus to signify the coming together of water and energy and the collaboration of public, private and academic entities seeking climate adaptation strategies.


“We have 250 miles of canals with electrical infrastructure running along the canals. With land in our area valued at $50,000 an acre, the location of this system above existing canals removes those land costs from the project, “ said Turlock Irrigation District External Affairs Department Manager @Josh Weimer. “Having a detailed study of TID’s irrigation system and electric system to see if the scalability makes sense is beneficial to us as we consider future projects.”


With two primary canal types, TID’s existing infrastructure will provide a model for other irrigation districts to follow if the data proves the hypothesized efficiencies are true.  Their secondary canals are about 25’ wide, similar to many irrigation districts in the state.  Their primary canal is 110’ wide, similar to the Department of Water Resources’ California aqueduct system.


Once data is extracted from the program, TID’s engineering and construction processes can be used to scale the project out to the rest of its lines as well as to other districts.


Beyond carbon-free energy production, Project Nexus will also collect water conservation data as well as study whether the water’s presence will spawn increased solar power generation.  The water running under the solar array will provide a cooling effect that allows the panels greater efficiency, shades the surface of the water and shelters it from wind to reduce evaporation.   In addition, the reduction of sunlight on the water will result in less vegetation growing in the canals, thus reducing a burdensome maintenance challenge for the district.


The project is the first of its kind in America to pioneer the engineering needed to retrofit existing irrigation canals with a solar array.  In this case, the solar panels would be anchored above the canals high enough for unimpeded access to the canals. Some guidelines were established early on by the project’s host: Existing operations of the district could not be impeded, to ensure safety nothing could be installed in the canals, maintenance access had to be preserved, including within the canals and along their banks. The engineering team devised a suspension system to satisfy the district’s restrictions while also reducing the amount of steel construction elements, thus providing lowered materials costs.

aerial view of recharge pond surrounded by solar panels over canals“We need to be able to access the canals with specific clearances around the drops and side gates.  There’s also a safety component that comes with capping canals that we were not willing to do,” stated Weimer.

Groundbreaking and installation of the 2 miles of test system will begin early next year with certain key components placed during the irrigation district’s primary maintenance season of October through March, when the canals are not in use.


“Many water agencies have contacted us about the project, most are interested in learning how it’s been engineered, where the challenges have been and how we’ve overcome them.  We are tracking all of it and will be able to report back after the system is in place so others can learn from the project,” stated Weimer.


Turlock Irrigation District is keeping an eye on the numbers, specifically the call to action by the California Energy Commission to hit the ambitious carbon-neutral, renewable energy goals of the state. TID’s system includes hydropower sources from new Don Pedro Dam and “mini-hydros” in the canal system. “Over the course of the years, we have added natural gas, a geothermal stake, wind, solar, and a biomass requirement.  We have a very diverse portfolio of renewable generation and natural gas facilities that provide us the power to meet our load,” said Weimer.  By taking steps today to gather project data to be extrapolated for use by others in the state, TID is carving a path for other special districts to consider as they strive to meet the energy challenges as well.

Follow Project Nexus’ status on the Turlock Irrigation District website at