In 2021, Campbell published another paper based on the same principles: If California spanned 4,000 miles of canal system with panels, it would save 63 billion gallons of evaporated water per year and provide half of the new clean energy capacity the state needs to achieve. decarbonization target.
Because the U.S. has so many reservoirs—approximately 26,000 of various sizes, totaling 25,000 square miles of water—it would especially benefit from large-scale floating photovoltaics, the new study finds. If 30 percent of the country’s reservoir area were covered with floating slabs, it could generate 1,900 terawatt-hours of energy—roughly one-fifth of the global potential total—while saving 5.5 trillion gallons of water annually.
China can manage 1,100 TWh per year, followed by Brazil and India with 865 and 766 respectively. Egypt could deploy 100 square miles of floating photovoltaics and generate 66 TWh of electricity while saving more than 200 billion gallons of water annually.
The study further found that floating PV capacity in 40 developing economies, including Zimbabwe, Myanmar and Sudan, exceeds current energy demand. (Though as they develop, energy demands rise.)
Another benefit of floating PV is that many reservoirs are equipped with hydroelectric dams, so they already have the electrical infrastructure to deliver solar energy to cities. The two power sources complement each other well, says Zhenzhong Zeng of Southern University of Science and Technology in China, a co-author of the new paper. “The intermittent nature of solar power is one of the main obstacles to its development. Hydropower is often controlled to make up for when solar power doesn’t work at night,” Zeng said. “Also, it can be combined with wind power, which is often complementary to solar power.”
Conserving water will become even more important as climate change exacerbates droughts like the historic drought that gripped Western states. But even if reservoir levels drop severely and hydropower production begins to decline, floating PV can still generate electricity. (However, more remote reservoirs without hydroelectric systems would require the solar panels to be connected to a larger grid, adding to the cost.)
Sika Gadzanku, an energy technology and policy researcher at the National Renewable Energy Laboratory, said floating photovoltaics could also work well with microgrids. They are off the larger grid and use solar energy to charge batteries, which can, for example, power buildings at night. “If you might have a giant pond in a remote location, deploying floating photovoltaics might look similar to applying solar-plus-battery projects in other remote locations,” said Gadzanku, who was not involved in the new paper but peer-reviewed it.
It could also benefit small communities in other ways, Gadzanku said: Installing floating systems in local ponds saves water and may be cheaper than trying to connect remote areas to a larger grid. “Extending the grid is very expensive,” she said.
Placing the panels on canals or reservoirs could take advantage of spaces that have already been modified by humans, and would not require clearing additional land for huge solar farms. (Floating photovoltaics could also be deployed on polluted bodies of water, such as industrial ponds.) “Solar energy requires 70 times more land than a natural gas plant for the same capacity,” says Brandi McKuin, an environmental engineer at the University of California, California. , Merced, who co-authored the canal paper with Campbell but was not involved in this new work. “If we’re going to meet these ambitious climate goals while protecting biodiversity, we really need to look at these solutions that use the built environment.”
In recent years, floating PV technology has grown from smaller-scale projects to gigantic solar farms, such as at Singapore’s Tengeh Reservoir, where panels occupy an area equivalent to 45 football fields. As the system scales up, “we really need to look further into some of the potential impacts, considering these aquatic ecosystems,” Gadzanku said. For example, shade trees may hinder the growth of aquatic plants, or panels may cause problems for local waterfowl and migratory birds that rely on the reservoir as a docking station. For example, it may be useful to determine whether the optimal spacing of panels allows species to move freely in the water.
While these projects alone won’t be able to power an entire metropolis, they will help diversify generation, making the grid more resilient as the renewable energy revolution accelerates. “Energy is such a big problem that we’re not going to have a silver bullet,” Campbell said. “We need floating photovoltaics and about a hundred other things to meet our energy needs.”
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