New study looks at covering California’s canals with solar panels — High Country News – Know the West

Covering waterways would, among other things, save water and provide electricity.

An irrigation canal runs through the desert in California.

This story was originally published in WIRED and is reproduced here as part of Climate Desk Collaboration.

Peanut butter and jam. Hall & Oates. Now there is a duo that could literally and figuratively be even more powerful: solar panels and ducts. What if we didn’t leave the channels open and let the sun evaporate the water, but instead covered them with panels that would both shade the precious liquid and soak up solar energy? Maybe humanity can Do that.

Scientists in California just got the numbers on what would happen if their state slammed solar panels on 4,000 miles of its canals, including the great California aqueduct, and the results suggest a potentially beautiful partnership. Your feasibility Study published in the journal Nature sustainability, notes that if applied nationwide, the panels would keep 63 billion gallons of water from evaporating each year. At the same time, solar panels in California’s exposed canals would provide 13 gigawatts of renewable electricity annually, about half of the new capacity the state needs to meet its decarbonization goals by 2030.

California’s water extraction system is the largest in the world 35 million people and 5.7 million acres of farmland. 75% of the available water is in the northern third of the state, while the lower two thirds of the state account for 80% of urban and agricultural needs. To move all of the water, pumps are required to make it flow uphill. Accordingly, the water system is the largest single electricity consumer in the state.

“By covering channels with solar panels, we can reduce evaporation and avoid disrupting natural and work spaces, while at the same time offering renewable energy and other benefits.”

Solar collection channels would not only produce renewable energy for nationwide use, but would also operate the water system itself. “By covering channels with solar panels, we can reduce evaporation and avoid disrupting nature and work areas. At the same time, we can offer renewable energy and other benefits, ”says environmental engineer Brandi McKuin of the University of California, Merced and the University of California. Santa Cruz, lead author of the paper.

Ironically, the performance of solar panels decreases with increasing temperatures. In a solar cell, photons from the sun knock electrons out of atoms, Generating an electric current. If a panel gets too hot, this puts the electrons in an already excited state so they don’t generate as much energy when they are shifted by photons. Spanning panels over ducts would make them water-cooled, so to speak, and increase their efficiency. “Also,” adds McKuin, “the shade of the panels reduces the growth of aquatic weeds, which is a major problem in sewer maintenance.”

The engineering wouldn’t be too complicated either. You could throw a steel tie over a canal and cover it with panels. India has experimented with such solar channels and commissioned a 25-mile stretch for an estimated cost of $ 14 million.

To put it bluntly, this new paper is not a direct hit for state officials to immediately cover all channels with solar panels. “Our paper is not a detailed construction or concept design – it is a feasibility study, a proof-of-concept to take it to the next phase of investing in a demonstration project,” says engineer Roger Bales of the University of California, Merced. “But I think the amount of electricity could be significant both nationally and locally.”

Bales and McKuin calculated all of this using a variety of models. For example, the evaporation rates came from hydrological models. They also folded up climate models to predict how the state will warm in the coming years. They got so grainy that they also calculated how the cooling effect of the canal water would improve the panels’ generating efficiency.

Ultimately, they landed on a potential annual saving of 63 billion gallons of water across California. But they also took into account the human benefits of such a project, which are more nebulous. For example, many farmers use diesel generators to pump their water. If solar panels were to provide this energy instead, this could reduce local emissions and thus improve air quality. “You can look at the economic costs, but you can also look at the social benefits,” says Bales.

“You are taking something that has already been changed by human activity and doubling the benefits it offers.

An additional social advantage could be that by placing the panels over canals, the state would not have to convert any cultivation areas or disturb natural habitats in order to build extensive solar parks – a canal is already on a long-disturbed land. Think about how you would install a solar system in your own home. “I can put it on my roof instead of mowing the yard next to my house and putting panels up there,” says Michael Kiparsky, director of the Wheeler Water Institute at UC Berkeley School of Law. “You are taking something that has already been changed by human activity and doubling the benefits it offers. This is the profound piece. “

Cladding California’s canals in solar panels could also prepare the state for the widespread adoption of electric cars. The California aqueduct runs right along Interstate 5, the main artery between the northern and southern halves of the state. Where there are petrol stations now, there could be car charging stations in the future that draw electricity from the nearby aqueduct.

The plan could also help California prepare for future climate change. “Droughts are part of our history and our future,” says Kiparsky. “It’s just that with climate change they are likely to become both more common and more severe.” As the condition gets hotter, more and more water evaporates from its channels, which can be dampened by the panels.

While the researchers in this study focused on California, this type of modeling “could easily be applied to other locations,” McKuin says. “In water-stressed regions of the world with open channels, it makes a lot of sense to take this into account.” This could include California’s neighbors, like the increasingly melted southwestern states and Texas, which have only shown the need to do so Overhaul of his energy system whatever.

There are of course some challenges when you think about such a large infrastructure project. For example, these researchers failed to consider the potential impact on wildlife – covering channels could block access to waterfowl that depend on it for habitat, especially when you consider that California has more than lost 90% its wetlands. Placing solar panels and their trusses over water can cause rust on the devices and increase maintenance costs. And then there is the cost of solar collection channels on a large scale. (The study did not suggest an overall price. McKuin says it will be difficult to pre-evaluate without a demonstration project, and it would depend on variables such as which sites are selected for development.)

On the other hand, this is not an all-or-nothing idea: some channels here and there could be rebuilt while others remain open. While this might not save the full 63 billion gallons of water annually, it would still power water pumps and local car charging stations while reducing evaporation on a smaller scale. “With or without climate change, California’s water supply is tightening and the demand for water in California is increasing,” says Kiparsky. “And these two facts together mean that any water saving is indeed a good and welcome one.”

Matt Simon is a science writer at WIRED, where he works on biology, robotics, cannabis and the environment. He is also the author of Plight of the Living Dead: What Real Zombies Reveal About Our World – And About Us And The Wasp That Brainwashed The Caterpillar That Was Honored With An Alex Award. E-mail Highland news at the [email protected] or send a letter to the editor.

Continue reading

More from solar energy

Comments are closed.