Los Angeles Exploring Plan to Cover Critical Aqueduct With Solar Panels

After enduring another summer of searing heat waves, the intensity of which prompted officials to design a first-in-the-nation ranking system for future hot blasts akin to hurricane warnings, Los Angeles officials are eyeing the relatively new idea of "solar canals" to help conserve water and boost renewable energy efforts. 

Late last month, the Los Angeles City Council voted to examine a motion from councilmember Mitch O'Farrell to place solar panels over the 370-mile Los Angeles Aqueduct. The gravity-fed aqueduct, which delivers water from the Owens River in the Eastern Sierra Nevada Mountains to the city of Los Angeles, is nearly all uncovered and loses an estimated 10%-11% of water to evaporation each year. That's equal to billions of gallons of water—an enormous amount for a lifeline that, from 2013 to 2016, provided nearly 40% (close to 55.5 billion gallons) of L.A.'s drinking water, according to the motion.

"Los Angeles is already doing so much to fight the climate crisis and advance our environmental justice goals, but as we act urgently, we must also think creatively," O'Farrell, who chairs the council's Energy, Climate Change, Environmental Justice, and River committee, said in a release announcing the proposal. "The aqueduct is the reason that modern-day Los Angeles exists, but we're not using it smartly enough. Let's change that, starting with today's action."

In addition to reducing evaporation, O'Farrell's team estimates that the proposed solar installation would eventually also provide clean energy to 1.54 million customers in Los Angeles and 6,000 in the Owens Valley.

Solar Canals: A Young Idea Gaining Traction

While the City Council's plan to cover the L.A. Aqueduct in solar panels is the largest exploratory proposition of its kind in the state, it's not the only solar canal project under consideration. In fact, should any of them move forward, the driving force will likely be the results of a $20-million proof-of-concept called Project Nexus. 

Spearheaded by the California Department of Water Resources, the Turlock Irrigation District (TID), the University of California at Merced, and Solar AquaGrid, a project development firm specializing in advancing solar canopies over waterways, Project Nexus will demonstrate the feasibility of "narrow and wide-span canal coverage of solar panels." Ground breaking is expected early next year on installations over three canal sections totaling 8,500 feet within the Turlock Irrigation District.

"If this is something that works on these first two miles of Project Nexus that we're doing, there's the potential that this could scale to multiple locations," Josh Weimer, Turlock Water & Power's external affairs manager, told Reuters in August. 

The inspiration behind Project Nexus can be traced to two recent advancements in the nascent application of solar panels over canals. In 2014, India pioneered the idea by covering over 2,400 feet of irrigation channels with solar canopies. Since then, similar projects have been commissioned around the country, including a nearly 25-mile, 100 MW stretch over canals branching from the Narmada River (the fifth longest river in the country).

In 2021, researchers from UC Merced decided to apply the idea of solar canals to California's 4,000 miles of public water delivery infrastructure. Their study, published in the journal Nature Sustainability, found annual savings of 63 billion gallons of water coupled with 13 gigawatts of energy production. It’s estimated that one gigawatt of energy alone is capable of powering 750,000 households.

Besides curbing evaporation and producing energy, there were some additional noted benefits. These included a reduction in aquatic weed growth in the canal, which in turn reduces high maintenance costs. Compared to ground-based panels, the cool water running under the solar canopies also creates a microclimate that boosts overall energy production efficiency. In addition, the study found that between 15 and 20 diesel irrigation pumps could be eliminated per MW of installed solar to help improve air quality in the regions surrounding the canals.

One of the biggest advantages, however, is the removal of a roadblock that often stymies renewable energy projects. Since the state already owns the canals and controls easements for access to them, the legal and cost concerns surrounding land use for solar generation could be greatly minimized.

"What we’re seeing here is actually some surprising benefits when you bring water and energy together," senior author and UC Merced environmental studies professor Elliott Campbell said in a release. "Sometimes it leads to a smoother landing in how we transition to better ways of making energy and saving water."

Are Solar Canals Financially Feasible?

While the benefits are clear, is it realistic to expect that California could soon lead the world in the installation of solar canopies over canals? Accordion to the UC Merced study, costs for various over-canal solar array systems average higher than traditional installations. There are also concerns regarding impacts from humidity on structural longevity, as well as the availability of electrical infrastructure to transfer energy to where it’s needed. Ultimately, however, the team’s economic assessment found the cost savings of the many combined benefits "made solar canals financially viable, rather than benefits from reduced evaporation alone."

Project Nexus and its different canal test sites presents a rare opportunity for these conclusions to merge with reality. "It's really exciting to test our hypothesis and the paper we published," UC Merced project scientist Brandi McKuin told Reuters. "We'll have an opportunity to really understand if those benefits pencil out in the real world."

All of which could mean good news for L.A.'s solar aqueduct plans, as well as California’s goal of achieving 60% clean energy generation by 2030.

"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."