Solar-paneling canals would not only produce renewable energy for use across the state, it would run the water system itself. “By covering canals with solar panels, we can reduce evaporation and avoid disturbing natural and working lands, while providing renewable energy and other co-benefits,” says environmental engineer Brandi McKuin of the University of California, Merced, and the University of California, Santa Cruz, lead author on the paper.Ironically enough, the performance of solar panels falls as temperatures rise. In a solar cell, photons from the sun knock electrons out of atoms, producing an electric current. When a panel gets too hot, that puts electrons into an already excited state, so they don’t create as much energy when dislodged by photons. Spanning panels over canals would, in a sense, make them water-cooled, boosting their efficiency. “And additionally,” McKuin adds, “shade from the panels mitigates aquatic weed growth, which is a major canal maintenance issue.”
The WIRED Guide to Climate Change
The world is getting warmer, the weather is getting worse. Here's everything you need to know about what humans can do to stop wrecking the planet.The engineering wouldn’t be all that complicated, either. You could throw a steel truss over a canal and cover it with panels. India has actually been experimenting with solar canals like this, and it has commissioned one 25-mile-long stretch for an estimated cost of $14 million.To be clear, this new paper is not a full-throated pitch to state officials to immediately cover all canals with solar panels. “Our paper is not a detailed engineering design or conceptual design—it's a feasibility study, a proof of concept for taking 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 statewide and locally.”
Bales and McKuin calculated all of this by incorporating a variety of models. Evaporation rates, for instance, came from hydrological models. They folded in climate models, too, to predict how the state will warm over the coming years. They got so granular that they also calculated how the cooling effect of the canal water would improve the panels’ generating efficiency.
Here's everything you need to know about what humans can do to stop wrecking the planet.“This is really significant, because it sends a clear signal about where California is going in terms of its vehicle fleet,” says Ethan Elkind, who directs the climate program at the Center for Law, Energy & the Environment at UC Berkeley.
Ultimately, they landed on a potential annual savings 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 pump their water with diesel generators. If solar panels provided that energy instead, that could cut local emissions, thus improving air quality. “You can look at the economic costs, but you can also look at the social benefit,” says Bales.