Will 'floatovoltaics' become the next big thing?

Floatovoltaic system in Thailand
This floatovoltaic system resides on a lake in Thailand.

Energy and water keep showing up together in many articles and conversations. We now have the energy-water nexus,  a term that highlights the interdependencies of the two. Getting water, moving it around and purifying it requires a great deal of energy.

At the same time, you need water to make energy, especially if you use hydropower or any type of thermal plants, which accounts for most of the electricity being produced today. You also need lots of water for fracking. New energy production methods such as tidal power or ocean thermal energy conversion also link the two.

But another combination that recently has caught my attention could become significant. We know that fully two-thirds of the Earth’s surface is covered with water. We also know that enough sunshine hits the surface of the Earth every hour to provide energy for all of humanity, at today’s conversion rates. So if you put these two things together, it makes sense to put solar collectors out on the water, to make the most of these two things.

As it turns out, a number of people have been doing that — several of them, in fact, claiming to have the largest project around. Let’s take a look.

Wine country wastewater power

First, there is Sonoma County, California. Because land is so valuable there (and they haven’t yet figured out how to turn water into wine), the folks at Sonoma Clean Power decided to float a bunch of solar panels on top of several wastewater ponds. Said CEO Geof Syphers, “The advantage to us is we’re in a community that values open space and farmland. We have solar on land, but this helps deploy more renewable energy and cut emissions without using farmland for our systems.”

The ponds for the 12.5 MW installation, enough to power 3,000 homes, are leased by developer Pristine Sun, whose CEO, Troy Helming, refers to these projects as “floatovoltaics.” The water helps to keep the panels cool, which keeps their efficiency up. The project is the largest of its kind in the U.S.

Evaporation avoidance

Not to be outdone, India’s largest hydroelectric company, National Hydro Power Corporation, is planning a 50MW project in the southern state of Kerala. According to the developers, “The ecology of the water body is not likely to be affected much and it will also reduce evaporation, thus helping preserve water levels during extreme summer. Solar panels installed on land face reduction of yield as the ground heats up. When such panels are installed on a floating platform, the heating problem is solved to a great extent.”

That project will be overtaken by another project in Japan.  A new project near Kato City is being developed by Kyocera Corporation in collaboration with Century Tokyo Leasing LLC (video). It uses a modular approach, combining thousands of modules floating on ponds. Together they eventually will provide a combined 70MW. According to Liat Clark at Wired UK, keeping the panels cool improves efficiency by 11 percent.

If you think that sounds big, listen to this: Brazil’s National Electric Energy Agency (ANEEL) has announced plans for a 350MW floating solar plant at the Balbina hydroelectric plant in the Amazon. Given the severe drought that Brazil has been experiencing, if this large array will reduce evaporation, that will be a major fringe benefit.

Last but not least is the 465 MW Sunflower Solar Power Plant in South Korea. The modules were provided by SolarPark Korea. The system uses active tracking which keep[s the floating panels aimed at the sun, which, combined with the cooling effect of the water, increases the efficiency by 22 percent over land-based systems. In addition to benefits already noted, these floating arrays help to suppress algae growth and also can be combined with fish hatcheries.

This idea, which has managed to float under the radar, so to speak, could, considering its many advantages, become a relatively big deal.

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