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June 13, 2023
California’s massive network of water canals, which totals about 4,000 miles, could be transformed into a renewable energy resource for the state—but not necessarily through hydropower. Rather, power could come from solar panels installed over the canals. Project Nexus, a pilot program funded by California’s state government, was initiated by Solar AquaGrid and is supported by the Turlock Irrigation District and researchers at the University of California, Merced. The goal of this private-public-academic partnership is to try out an innovative tool in California’s fight against climate change and drought: solar canals. The group will install 8,500 feet of solar panels over three sections of water canal in central California to determine the feasibility of installing solar canals across the state.
Canals that have been covered with canopies of solar panels offer multiple benefits. They generate clean energy, of course, which can be fed into the grid or stored in battery systems. They save land, as solar panels are installed over existing infrastructure. And solar canals also reduce water evaporation, since they absorb much of the sunlight that would otherwise heat the water flowing in the canals below. In California, water canals are typically uncovered, leading to strong rates of evaporation, a major problem in a drought-prone state. Project Nexus’s feasibility study estimates that installing solar canals where possible in California could save 63 billion gallons of water annually—enough water to cover the residential needs of 2 million people for a year. Another benefit is the boost to the efficiency of the panels due to the cooling nature of the water underneath (cooler panels generate more electricity). Finally, the shade provided by the panels can help prevent toxic algal blooms spurred by exposure to sunlight.
The electricity benefits that could result from the California project are significant. Project Nexus estimates that state-wide adoption of solar canals could provide up to 13 gigawatts of renewable energy per year, meeting over 50 percent of the new renewable development required to meet the state’s renewable energy goals. Solar canals also provide an opportunity to elegantly address the energy needs of the canal system itself. California’s natural water distribution does not align with the location of its household or agricultural users, so the state spends enormous amounts of electricity pumping water across vast distances. In fact, water activities make up 12 percent of total energy consumption across the state, according to the California Department of Water Resources. Solar canals provide a solution that would use the same infrastructure to offset this electricity consumption.
Additionally, Project Nexus will test the incorporation of battery storage alongside the solar canals. Battery storage, which allows energy produced by renewables to be stored locally, could help reduce demand on the grid as well as contribute to grid stabilization efforts during extreme weather events. Connecting battery storage to utility-scale grids has been successfully implemented in California to prevent blackouts. Local storage could also help to cut down on costly long-distance transmission of electricity. According to Inside Energy, electricity transmission and distribution resulted in energy losses of 2.2 percent to 13.3 percent between 1990 and 2013, and the Institute for Energy Research reports that transmission makes up about 11 percent of the total cost of electricity in the United States. Implementing solar canals and connecting them to local energy users could reduce energy losses and lower costs. This could promote energy equity and increase accessibility for families of color that, according to the American Council for an Energy-Efficient Economy, are most likely to be burdened by high electricity costs because of their lower average household incomes and less energy-efficient homes.
One of the most appealing aspects of solar canals is their use of already-built environments, thus reducing the land needs associated with solar power and potentially avoiding the tensions that can arise from renewable energy development. The installation of large solar farms has become a point of tension between renewable energy developers, farmers, and conservationists. The potential installation of more solar panels across the Mojave desert in southern California is a prime example of how controversial these projects can be.
The Great Plains Institute reports that it takes up to 10 acres of land on a conventional solar farm to produce one megawatt of electricity—enough to power one average U.S. home for about 1.2 months. Lee Walston, a scientist at Argonne National Laboratories, estimates that the United States will require 10 million acres of land to meet solar demand (for comparison, the state of Maryland covers about 7.9 million acres).
Remote, sunny, desertic locations without trees or high buildings that obstruct sunlight are especially suitable for solar farms. But conservationists are increasingly concerned about the impact that solar panels—as well as the infrastructure associated with their installation and maintenance—have on desert ecosystems. The construction process creates significant disruption in delicate desert ecosystems, and the lasting presence of solar panels could create barriers to movement for endangered species such as the Mojave tortoise and Bighorn sheep, further dividing their already-fragmented habitat. University of California, Santa Cruz, researcher Karen Tanner also noted that solar panels affect the temperature and humidity under the panels, potentially throwing micro-habitats out of balance.
In a paper for Environmental Research Letters, scientists noted that “all energy sources will come with a cost to some wildlife. The best mitigation strategy is to avoid developing sensitive and pristine areas.” This is an ethos that solar canals encapsulate well. Solar canals operate on a built environment, and thus provide an opportunity to preserve valuable habitat and reduce the overall land demand for new solar energy.
The potential to mitigate negative impacts to habitat or agricultural lands is a major appeal of Project Nexus, and particularly relevant as Congress continues the process of composing the 2023 Farm Bill. According to a study published by The Nature Conservancy, one-third to one-half of all selected solar projects in the United States could be sited on agricultural land based on current resource assumptions. In addition to preserving agricultural land, solar canals could reduce tensions between renewable energy developers and communities, including agricultural stakeholders and indigenous groups.
Walston pointed to this issue in an interview with EESI, as he emphasized the need to balance solar development with the preservation of agricultural space. The installation of solar canals across California has the potential to preserve 80,000 acres of agricultural or natural land which might otherwise host solar farms. Solar canals, and other “outside the box” solutions for renewable siting, could also prevent land disputes between developers and Indigenous communities. As legislators consider the issues of land use and spiking land prices during the Farm Bill negotiations, solar canals demonstrate that renewable energy can operate alongside agricultural lands without imposing on farmers.
Solar canals come at a higher cost of installation and maintenance because they require customized support structures with galvanized steel to prevent rusting due to increased humidity. Maintenance also requires more trained workers, increasing costs further. However, a peer-reviewed study led by the University of California, Merced and published in Nature Sustainability indicates that these costs would be offset by the benefits of solar canals.
While Project Nexus will be the first large-scale test of solar canals in the United States, the technology is not new. India has been using solar canals since 2014, according to the BBC, supplying electricity for rural areas while taking advantage of lower evaporation rates and improved water quality.
Problems associated with land use were a driving factor in India’s adoption of solar canals. High land prices made it more economical to install solar panels over canals, and these installations demonstrated multiple other benefits. Nilesh Kumar, senior project officer at the Gujarat Energy Research and Management Institute, which oversaw the installation of solar canals in the state of Gujarat, stated in a BBC article that the panels also improve water quality. “With the installation of the solar panels, and absence of direct sunlight, algae growth is drastically minimized,” he said. And algae growth is not just an inconvenience. The Environmental Working Group published a study on the cost of algal blooms in the United States, which found that California spent nearly $53 million to recover from toxic algal blooms between 2010 and 2020.
While solar canals are still in the early stages of development in the United States, Project Nexus provides an opportunity for legislators to observe their potential as a climate solution. Project Nexus also demonstrates the potential of public-private partnerships by bringing together state and industry stakeholders in collaboration.
Federal support is already available for solar canal development. The Infrastructure Investment and Jobs Act (P.L.117-58) provides $8.3 billion for western water infrastructure, as well as $60 million for innovation in solar energy. Solar canal researchers and developers could be eligible to apply for these funds. As Lee Walston puts it, if solar canals are placed intentionally and thoughtfully, “it could really only be a win-win.”
Author: Isabella Millet
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