Installing solar panels over California canals can pay off for water, land, air and climate
The California Aqueduct, which carries water more than 400 miles south of the Sierra Nevada, split when it entered Southern California on the border of Kern and Los Angeles counties. DWR in California Climate change and water scarcity are at the forefront and in the center of the western United States. Western countries follow many strategies to adapt to these stresses and prepare for the future. These include measures to promote the development of energy from renewable sources, water saving and more sustainable management of natural and working lands. As engineers working on climate-intelligent solutions, we found an easy, profitable combination of both water and climate in California with what we call a “solar channel solution.”
; About 4,000 miles of canals transport water to about 35 million Californians and 5.7 million acres of farmland nationwide. Covering these canals with solar panels would reduce the evaporation of valuable water – one of California’s most important resources – and help achieve the state’s renewable energy goals while saving money. Water and Drought Protection California is prone to drought and water is a constant concern. Now the changing climate brings hotter and drier weather. Severe droughts in the last 10 to 30 years have dried up wells, forced workers to impose water restrictions and ignited massive forest fires. By mid-April 2021, the entire country was officially experiencing drought conditions. At the same time, California has ambitious conservation goals. The state has a mandate to reduce groundwater pumping while maintaining reliable supplies to farms, cities, wildlife and ecosystems. As part of a broader climate change initiative, in October 2020, Gov. Gavin Newsum directed the California Natural Resources Agency to lead efforts to protect 30% of the land and coastal waters by 2030. Most rain and snow in California falls on north of Sacramento in the winter, while 80% of water consumption occurs in Southern California, mostly in the summer. That is why the snake channels in the country – this is the largest such system in the world. We estimate that about 1% -2% of the water they carry is lost to evaporation under the hot California sun. In a recent study, we found that covering all 4,000 miles of California’s canals with solar panels would save more than 65 billion gallons of water a year by reducing evaporation. That’s enough to irrigate 50,000 acres of farmland or meet the housing water needs of more than 2 million people. By concentrating solar installations on land that is already in use, rather than building them on undeveloped land, this approach will help California achieve its goals of sustainable water and land management. Climate Energy Shading California’s canals with solar panels would generate significant amounts of electricity. Our estimates show that it can provide about 13 gigawatts of renewable energy capacity, which is about half of the new sources the state must add to meet its clean electricity targets: 60% of carbon-free sources by 2030, and 100% renewable by 2045. Installing solar panels above the ducts makes both systems more efficient. Solar panels would reduce canal fumes, especially during the hot summer in California. And because the water heats up more slowly than land, the water in the channel flowing under the panels can cool them by 10 F, increasing electricity production by up to 3%. These panels can also generate electricity locally in many parts of California, reducing both transmission losses and costs to consumers. Combining solar energy with a rechargeable battery can help build microgrids in rural and underserved communities, making the energy system more efficient and sustainable. This would mitigate the risk of energy losses due to extreme weather conditions, human error and forest fires. We believe that the cost of covering ducts with solar panels is higher than building terrestrial systems. But when we added some of the side benefits, such as avoiding land costs, saving water, reducing weeds and improving PV efficiency, we found that solar ducts are a better investment and provide electricity that costs less throughout life of solar energy installations. Solar panels mounted above the ducts increase the efficiency of both systems. Brandi McKuin, CC BY-ND The benefits of land Solar channels are much more than just generating renewable energy and saving water. The construction of these long, thin solar massifs could hinder the conversion of more than 80,000 acres of agricultural land or natural habitat for solar farms. California grows food for a growing world population and produces more than 50% of the fruits, nuts and vegetables consumed by American consumers. However, up to 50% of the new renewable energy capacity to achieve the decarbonisation targets may be located in agricultural areas, including large areas of primary agricultural land. Solar installations will also protect wildlife, ecosystems and culturally significant lands. Large-scale solar development can lead to habitat loss, degradation and fragmentation, which can harm endangered species such as the tortoise in the Mojave Desert. They can also harm desert shrubs, including plants that are culturally important to local tribes. As an example, the construction of the Genesis Solar Energy Center in the Sonoran and Mojave Deserts in 2012-2014 destroyed paths and burial sites and damaged important cultural artifacts, causing a protracted legal conflict. [Get the best of The Conversation, every weekend. Sign up for our weekly newsletter.] Cleaning the air By generating clean electricity, solar ducts can improve air quality – a serious problem in central California, which has some of the dirtiest air in the United States. Solar power can help retire diesel engines, spewing particles that pump water through California’s agricultural valleys. It can also help charge the growing number of electric cars and trucks that move people and goods around the country. Another benefit would be to limit the water weeds that suffocate the canals. In India, where developers have been building solar ducts since 2014, shade from panels restricts the growth of weeds, which block drainage and restrict water flow. Controlling these weeds with herbicides and mechanical equipment is expensive, and herbicides threaten human health and the environment. For large, 100-foot-wide canals in California, we estimate that shady canals would save about $ 40,000 a mile. Across the country, savings could reach $ 69 million a year. An artist’s depiction of a system of solar channels for California. Solar Aquagrid LLC, CC BY-ND Translating Solar Channels in California While India has built solar grids over canals and the United States is developing floating solar projects, California lacks prototypes to study locally. There are discussions about both large and small demonstration projects in the Central Valley and Southern California. Prototyping would help operators, developers and regulators to improve projects, assess environmental impact, measure project costs and benefits, and assess how these systems work. With more data, planners can identify strategies to expand solar channels across the country and potentially across the West. It will take a dozen or more partners to plan, fund and implement a California solar canal project. Public-private partnerships are likely to include federal, state, and local government agencies, project developers, and university researchers. California’s aging energy infrastructure has contributed to catastrophic forest fires and long interruptions. Building smart solar developments on canals and other disturbed lands can make energy and water infrastructure more sustainable, while saving water, reducing costs and helping to combat climate change. We believe that this is a model that should be considered throughout the country – and on the planet. This article was republished by The Conversation, a non-profit news site dedicated to sharing ideas from academic experts. Written by: Roger Bales, University of California, Merced and Brandi McQueen, University of California, Santa Cruz. Read more: Young farmers in California find new ways to raise livestock and improve the land The US electricity sector is halfway to zero carbon There is nothing to reveal. Roger Bales does not work, consult, own shares or receive funding from any company or organization that would benefit from this article and has not disclosed any relevant links outside of their academic assignment.