The California Aqueduct, which carries water more than 400 miles south of the Sierra Nevada, splits as it enters southern California on the border of Kern and Los Angeles counties. California DWR
Climate change and water scarcity are at the fore in the western United States. The region’s climate is warming, a severe drought lasting several years is underway, and groundwater supplies are over-pumped in many places.
Western states are pursuing many strategies to adapt to these tensions and prepare for the future. These include measures to promote the development of renewable energies, to conserve water and to manage natural and exploitable land in a more sustainable manner.
As engineers working on smart climate solutions, we have found a win-win solution for water and climate in California with what we call the “solar channel solution”. About 4,000 miles of canals carry water to some 35 million Californians and 5.7 million acres of farmland across the state. Covering these canals with solar panels would reduce evaporation of precious water – one of California’s most critical resources – and help meet the state’s renewable energy goals, while saving energy. silver.
Preserve water and land
California is prone to drought and water is a constant concern. Now the changing climate brings hotter and drier weather.
Severe droughts over the past 10 to 30 years have dried up wells, forced authorities to put in place water restrictions and fueled massive forest fires. By mid-April 2021, the entire state was officially experiencing drought conditions.
At the same time, California has ambitious conservation goals. The state’s mandate is to reduce the pumping of groundwater while maintaining a reliable supply to farms, cities, wildlife and ecosystems. As part of a broad initiative on climate change, in October 2020, Governor Gavin Newsom asked the California Natural Resources Agency to lead efforts to conserve 30% of land and coastal waters by 2030.
Most of California’s rain and snow falls north of Sacramento during the winter, while 80% of its water use occurs in Southern California, mostly in the summer. This is why the canals meander through the state – it is the largest such system in the world. We estimate that about 1% to 2% of the water they carry is lost through evaporation in the hot California sun.
In a recent study, we showed that covering 4,000 miles of California canals with solar panels would save over 65 billion gallons of water per year by reducing evaporation. That’s enough to irrigate 50,000 acres of farmland or meet the residential water needs of over 2 million people. By focusing solar installations on land already in use, instead of building them on undeveloped land, this approach would help California meet its goals of sustainable management of water and land resources.
Shading California canals with solar panels would generate substantial amounts of electricity. Our estimates show that it could deliver around 13 gigawatts of renewable energy capacity, or about half of the new sources the state needs to add to meet its clean electricity targets: 60% from carbon-free sources. by 2030 and 100% renewable by 2045..
Installing solar panels on the canals makes both systems more efficient. Solar panels would reduce evaporation from the channels, especially during hot California summers. And since the water heats up more slowly than the earth, the canal water flowing under the panels could cool them by 10 F, increasing electricity production by up to 3%.
These panels could also generate electricity locally in many parts of California, reducing both transmission losses and costs to consumers. The combination of solar power and battery storage can help build microgrids in rural areas and underserved communities, making the power system more efficient and resilient. This would mitigate the risk of energy loss due to extreme weather conditions, human error and forest fires.
We estimate that the cost of crossing canals with solar panels is higher than building ground systems. But when we added some of the related benefits, such as avoided land costs, water savings, water weed mitigation, and improved PV efficiency, we found solar channels to be a better investment and provided electricity that was cheaper over the lifetime of solar power. facilities.
Benefits for the land
Solar channels are more than just the production of renewable energy and saving water. The construction of these long, thin solar panels could prevent the conversion of more than 80,000 acres of farmland or natural habitats to solar farms.
California grows food for an ever-growing global population and produces more than 50% of the fruits, nuts, and vegetables that American consumers consume. However, up to 50% of the new renewable energy capacity to meet decarbonization targets could be located in agricultural areas, including large tracts of prime agricultural land.
Solar canal installations will also protect culturally important wildlife, ecosystems and lands. Large-scale solar developments can lead to habitat loss, degradation and fragmentation, which can adversely affect endangered species such as the Mojave Desert Turtle.
They can also harm desert scrub plant communities, including plants that are culturally important to native tribes. For example, the construction of the Genesis Solar Power Center in the Sonoran and Mojave Deserts in 2012-2014 destroyed trails and burial sites and damaged important cultural artifacts, causing a protracted legal dispute.
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Purify the air
By producing clean electricity, solar channels can improve air quality – a serious problem in central California, which has some of the dirtiest air in the U.S. Solar electricity could help remove particulate-spitting diesel engines that pump water through California’s agricultural valleys. It could also help charge a growing number of light and heavy electric vehicles that carry people and goods around the state.
Another benefit would be to reduce the aquatic weeds that choke the canals. In India, where developers have been building solar canals since 2014, the shade of the panels restricts the growth of weeds that block drains and limit water flow.
Controlling these weeds with herbicides and mechanical equipment is expensive and herbicides threaten human health and the environment. For the large 100 foot wide canals in California, we estimate that canals shading would save about US $ 40,000 per mile. Statewide, savings could reach $ 69 million per year.
Bringing solar channels to California
While India has built solar panels on the canals and the United States is developing floating solar projects, California lacks prototypes for local study.
Discussions are underway for large and small demonstration projects in the Central Valley and Southern California. Building prototypes would help operators, developers and regulators refine designs, assess environmental impacts, measure project costs and benefits, and evaluate the performance of these systems. With more data, planners can strategize to expand solar channels across the state, and potentially across the West.
It will take at least a dozen partners to plan, finance and deliver a solar canal project in California. Public-private partnerships are likely to include federal, state, and local government agencies, project developers, and academic researchers.
California’s aging electrical infrastructure has contributed to catastrophic wildfires and multi-day outages. Building smart solar developments on canals and other disturbed land can make power and water infrastructure more resilient while saving water, lowering costs and helping fight climate change. We believe it is a model that should be considered across the country – and around the world.
This article is republished from The Conversation, a nonprofit news site dedicated to sharing ideas from academic experts. It was written by: Roger Bales, University of California, Merced and Brandi McKuin, University of California, Santa Cruz.
Nothing to disclose.
Roger Bales does not work, consult, own stock or receive funding from any company or organization that would benefit from this article, and has not disclosed any relevant affiliations beyond his academic appointment.