Why Aren’t We Doing More of This?

March 6, 2019

Whenever you can get a double benefit from something, it’s worth a closer look. Protecting water resources and generating renewable energy are both important—and increasingly publicized—goals. A relatively simple and already-existing technology can do both things at once. But are there drawbacks?

Several years ago, you might recall, Los Angeles deployed “shade balls” to cover various of its reservoirs. The idea was that the small black plastic balls would slow evaporation, prevent the formation of algae, keep at least some dust and debris from settling on the water, and deter birds and other wildlife from splashing about in it. (They’re also known as “bird balls,” and something similar has been used near airports to keep birds away from lakes close to the runways.) They were also supposed to prevent the chemical reaction in which chlorine in the water, when exposed to sunlight, produces bromate, a potential carcinogen.

Critics at the time noted that the water and energy needed to manufacture the balls might be greater than the amount of water they could possibly save. But open bodies of water that are used as a source of drinking water generally must be covered in some way. Los Angeles has since replaced the balls on most of its reservoirs with more traditional floating covers, although a few remain in place.

There’s a different kind of cover, however, that can serve the same general purpose and then some: floating solar panels. The panels are becoming less expensive and are now commonplace on roofs and on solar farms in many parts of the country. Scientists at the National Renewable Energy Laboratory say that if we put floating photovoltaic panels (inevitably dubbed “floatovoltaics”) on a quarter of the country’s reservoirs, we could generate 10% of our power. (For comparison, in 2017, solar power accounted for just under 2% of US needs.)

Although the technology has been in use for more than a decade—and although the first floating voltaic system was installed in the US—today just seven of the roughly 100 systems deployed worldwide are in this country. Japan has about 80%; the relative lack of open space for solar farms has been an incentive to adopt them.

Because the water helps keep the systems cool, floating solar panels are up to 22% more efficient than land-based ones. But the floating systems have some potential drawbacks as well. Accessing and maintaining them would be trickier than maintaining land-based photovoltaic panels. Some scientists have voiced reservations about how the systems would affect wildlife, although this would be more of a concern if they were placed on natural bodies of water rather than on drinking water reservoirs, which must have some sort of cover in any case. How to pay for them, how to connect them to existing transmission lines, and how to allocate the profits from the energy they produce are all questions to be worked out.

An engineer quoted in the article above says, “When you have fairly decent-sized companies that have installed two to three floatovoltaic systems, that will pull in other companies. I think it’ll only be a couple years before floatovolatics are commonplace.” Have you seen any of the current floating photovoltaic systems? (Most in the US are in California and New Jersey.) Do you think the technology will take off? Is it time to invest?

About the Author

Janice Kaspersen

Janice Kaspersen is the former editor of Erosion Control and Stormwater magazines. 

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