Is a floating solar boom about to begin?

Rob McCann investigates.

The world’s water cycle is speeding up (rb.gy/uy9rd). This is a big problem for the world’s water storage, on which we depend for our drinking water, recreation, agriculture and, not least, hydroelectricity.

Last year at China’s Three Gorges Dam, by far the world’s largest hydroelectric facility, drought and evaporation caused water shortages which put energy supply at grave risk. This happened too in Europe, where hydroelectric supply lost a whopping 75 TWh in about nine months (rb.gy/gjdli).

Similar patterns were seen globally, and during the 2019 drought here in Australia, towns which approached day zero, which is to say no more mains water supply, had to get water trucked in from elsewhere. We need to rapidly plan ahead and innovate as evaporation intensifies and our population grows. That is the first conundrum.

Here is the second. We need to increase the supply of energy for the world’s burgeoning populace while reducing our emissions. But there is only so much suitable land available, and there is a trade-off between reducing emissions by building solar farms, and those resulting from land use change by installing it at scale.

Is floating solar an option?
Enter floating solar, which may solve many of these problems all at once. Alas it’s not perfect; there are ecological and logistical challenges, like anchoring, reduction in light penetration, amenity impacts (you can’t water-ski over them) and visual impacts, although it seems that this can all be engineered out.

Solar PV is more efficient at lower temperatures, which means placing it over a body of water (which has cooler and more stable temperatures) is ideal. Dams are often located near existing electricity distribution infrastructure, meaning they may be connected easily without having to build kilometres of new transmission lines.

This means no terrestrial impacts, loss of farmland or habitat, and you get clean energy. But most importantly: they are really, really effective at slowing evaporation.

Wired magazine reckons that if the US covered just 30% of its reservoir area with solar panels, 5.5 trillion gallons (almost 21,000 GL) could be saved and 1900 terawatt-hours of energy could be produced (rb.gy/h421n). Extraordinary.

Floating solar could also spawn other flow-on innovations. I spoke with Soren Lunoe, inventor and chairman of floating solar solutions provider Hydrosun, an early mover in this space and winner of the prestigious Edison Award in 2021. He predicts that not only will this take off as water security concerns grow, but also as demand for cleanly- and affordably-produced hydrogen and ammonia grows, which is partly possible using floating solar. He sees huge waterbodies in the north of Australia as particularly promising sites for this.

Global adoption is growing
In India, people began to combat the challenges of land availability and evaporation several years ago by installing solar PV over irrigation channels, and last year switched on their largest floating solar plant at 100 MW in Ramagundam (rb.gy/gxqef).

In the same year, Huaneng Power International switched on a staggering 320 MW in Shandong Province, China (rb.gy/eshsr). The Seychelles have just announced that they will build the world’s largest saltwater floating solar plant (rb.gy/fn0jb).

Here in Australia, Wannon Water just installed Australia’s first in the Brierly basin, Warrnambool, which they expect will eliminate about 600 tonnes of CO2 emissions per year. Australian water authorities are keenly looking into this technology and reaching out to the market as we speak. I expect large scale projects here are inevitable, and for good reason.

The future is floating solar
The potential of this technology cannot be overstated. According to the World Bank, floating solar has a global estimated potential of 400 gigawatts, and under conservative assumptions, floating solar could double the current global capacity of solar PV (rb.gy/loa8c).

We have an opportunity to be drought-resilient, produce clean energy locally and send our emissions downward. This can be done at a farm-scale or at a utility-scale, producing megawatts of clean energy for towns, cities and industry.

“We are now in the era of floating solar,” says Roxy Diephuis, Energy Lead at Smart Infrastructure Consulting who works in energy transition and infrastructure. When asked about how Australia is positioned to get in on the action, she said “Innovating in Australia and being a first mover here can be challenging. We should look to projects overseas and reach out to these companies. They are all very collaborative and willing to help. We shouldn’t be so risk averse.”

She is right. In 2019, the first offshore floating solar was built in the Dutch North Sea, a capricious body of water prone to huge swells. This was built by Oceans of Energy, a Dutch engineering company which claims to be the first and only company in the world with a proven offshore solar system.

It has been building these for about three years, and has many more megawatt-scale projects in the pipeline. The future is floating solar. Watch this space.