Water Utilities Are Using Solar Panels to Cut Evaporation Losses
(Bloomberg) -- Every year, about 1,400 gigaliters of water evaporates from dams and reservoirs across arid Australia, enough to fill Sydney Harbour three times, according to researchers at Deakin University.
To reduce this loss, Australian utilities are turning to floating solar installations on lakes and reservoirs. Covering and cooling a large part of the surface of bodies of water with panels reduces evaporation, while also generating electricity. In a country where climate change is making conditions even hotter and drier, and where fresh water is scarce, solutions like this are becoming more attractive.
“Evaporation is the single largest cause of water loss from Australian dams,” said Saman Gorji, a senior lecturer in electrical and renewable energy engineering at Deakin University. That’s more than what’s lost through leakage, seepage or infrastructure inefficiencies, he said.
Canopy Power, a Singapore-based firm that’s backed by TotalEnergies SE and the Gaia Impact Fund, is among companies bringing the technology to Australia. It secured exclusive rights last December to distribute a system developed by Norway’s Ocean Sun AS, a leading developer of floating solar arrays, in the country.
Each floating ring, made from modified polypropylene, in Ocean Sun’s system is roughly 70 meters in diameter and generates around 670 kilowatts of solar power. The rings are also equipped with integrated pumps that harvest rainwater.
Canopy Power is currently in talks with five water utilities in Victoria and expects to launch its first project in the state in the coming months, according to Mahasti Motazedi, managing director for Australia.
By covering around 70% of a reservoir’s surface, evaporation can be reduced by 55%, she said. Unlike full-cover solutions that could trigger algal blooms by blocking sunlight and oxygen, the floating rings help keep the water clean while limiting evaporation, and some of the excess power from bigger projects can be sold to the grid, Motazedi said.
Floating solar to cut evaporation is also being explored in other freshwater-scarce places, including the Maldives, where it could serve as an alternative energy source to fossil fuels and offset the high cost of water. Ocean Sun first deployed the technology off the Norwegian coast and at aquaculture sites.
“Starting out we focused a lot on the near shore, but then we realized that the biggest market is actually in the reservoirs and lakes,” said Ocean Sun Chief Executive Officer Kristian Tørvold.
The technology is also being looked at in other parts of Australia. The state government of Western Australia has invested A$2.8 million ($1.8 million) for a pilot known as the Great Southern Evaporation Trial. The 19-month program tests the use of hundreds of thousands of interlocking hexagonal discs — developed by Danish company Hexa-Cover ApS — in dams in the state.
As the climate gets hotter, the potential payoff for implementing these systems becomes more attractive.
“Evaporation has increased by 5% to 15% in some parts of Australia due to the higher temperature and lower humidity since the early 2000s,” said Mustafa Abed, a lecturer in civil engineering at the Engineering Institute of Technology in Melbourne. As the climate gets hotter rates of evaporation could go up by as much as 30% to 40%, he said.
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