Floating solar farms could cool down lakes

Floating solar farm

Solar power is now the cheapest source of electricity in history, according to a 2020 report by the International Energy Agency. But there is something holding this clean energy powerhouse back: space. Unlike fossil fuel power stations, solar farms need a lot of room to generate enough electricity to keep up with demand. Most solar farms are composed of ground-mounted panels that take up land that could be used to grow food or provide habitat for wildlife.

Although electricity and water do not usually mix, a growing number of floating solar farms are being deployed worldwide. Floating solar panels on a lake or reservoir might sound like an accident waiting to happen, but recent studies have shown the technology generates more electricity compared with rooftop or ground-mounted solar installations. This is thanks to the cooling effect of the water beneath the panels, which can boost how efficiently these systems generate electricity by as much as 12.5%.

That said, lakes and reservoirs are already important for people and the planet. While these freshwater bodies cover less than 1% of Earth’s surface, they nurture almost 6% of its biodiversity and provide drinking water and crop irrigation that’s vital to billions of people. Worryingly, climate change has raised the surface temperatures of lakes globally by an average of 0.34°C per decade since 1985, encouraging toxic algal blooms, lowering water levels and preventing water mixing between the distinct layers which naturally form in larger and deeper lakes, starving the depths of oxygen.


In the rush to decarbonise energy to slow global warming, might turning to floating solar farms simply add to the strain on the world’s precious freshwater reserves? Remarkably, in new research, we found that carefully designed floating solar farms could reduce the threats posed by climate change to lakes and reservoirs.

A buffer against warming

Along with colleagues, I used a computer model to simulate how floating solar farms are likely to affect lake water temperatures. Our simulations are based on Windermere, the largest lake in England and one of the most well-studied lakes in the world.

Floating solar farms reduce how much wind and sunlight reaches the lake’s surface, changing many of the processes that occur within. As each floating solar farm has a different design, we ran simulations to see how lake temperatures changed with over 10,000 unique combinations of wind speed and solar radiation.

Our results suggest that the changes to water temperatures caused by floating solar farms could be as big as climate change itself, only in the opposite direction.
A floating solar farm that reduces wind speed and solar radiation by 10% across the entire lake could offset a decade of warming from climate change. Designs that shaded the lake more than sheltered it, by reducing sunlight more than wind, had the greatest cooling effect. Evaporation fell and the lake was mixed more frequently, which helps oxygenate the deeper water.The full article is for subscribed members only. To view the full article please subscribe. It’s FREE!Log In Register

Author

  • Associate Lecturer of Energy and Environment, Lancaster University

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