Floating Solar

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Power cuts and the soaring cost of electricity have seen the revival of interest in domestic solar, as consumers struggle to keep the lights on and the bills down.

But so far, the progress has been slow in developing large scale solar facilities that can be hooked up to the grid. Some of this can be put down to difficulties in balancing intermittent solar power with demand.

Solar farms also take up a lot of space which is a problem in crowded Sri Lanka, with its high population density, agriculture needs, and declining forest cover.

But, according to the World Bank, there is plenty of potential for installing solar panels on water in Sri Lanka.

“Floating solar can potentially work well with hydro power generation. Any new power generation also requires new power infrastructure, but if you put solar near hydro, the same power infrastructure can be used. Sri Lanka has many water bodies that could potentially be used for floating solar,” said World Bank Senior Water Supply and Sanitation Specialist Kristoffer Welsien.

By identifying large water bodies for floating solar, Sri Lanka also can tap into the multiple benefits of lower evaporation, higher solar panel efficiency due to cooling effect, complementarity with hydro power generation and aid grid balancing through the efficient management of peak-hours demand.

Sri Lanka has already trialled a small floating solar project, but its capacity is just some tens of kW. The pilot project in Kilinochchi was a result of collaboration between the University of Jaffna and the Western Norway University of Applied Sciences. But, experts believe that to reap economics of scale and for floating solar to make a significant contribution to power generation, projects need to be scaled up to about 100MW-200MW.

“We think this technology can make a significant contribution to meeting the renewable energy targets of Sri Lanka. Over time, it can help lower the overall cost of electricity supply in the country and complement existing power generation capacities, in particular hydro,” said the World Bank energy sector lead for Sri Lanka, Senior Energy Specialist Jari Väyrynen.  

There have been various proposals for larger scale floating solar farms, including one on Diyawanna Lake to provide electricity for parliament.

Floating solar is a proven technology for producing electricity – and now scientists at Cambridge University have developed floating ‘artificial leaves’ that generate clean fuels from sunlight and water.

The ultra-thin, flexible devices take their inspiration from photosynthesis and are light enough to float on water. The researchers believe, they could be used to generate a sustainable alternative to petrol, without taking up space on land.

Outdoor tests of the lightweight leaves on the River Cam in Cambridge, showed that they can convert sunlight into fuels as efficiently as plant leaves.

This is the first time that clean fuel has been generated on water, and if scaled up, the artificial leaves could be used on polluted waterways, in ports or even at sea.

In 2019, the Cambridge researchers developed an artificial leaf, which makes syngas – a key intermediate in the production of many chemicals and pharmaceuticals – from sunlight, carbon dioxide and water.

The earlier prototype generated fuel by combining two light absorbers with suitable catalysts. However, it incorporated thick glass substrates and moisture protective coatings, which made the device bulky.

“Artificial leaves could substantially lower the cost of sustainable fuel production, but since they’re both heavy and fragile, they’re difficult to produce at scale and transport,” said Dr. Virgil Andrei, the paper’s co-lead author.

“We wanted to see how far we can trim down the materials these devices use, while not affecting their performance,” said Professor Erwin Reisner, who led the research. “If we can trim the materials down far enough that they’re light enough to float, then it opens up whole new ways that these artificial leaves could be used.”

Solar farms have become popular for electricity production; we envision similar farms for fuel synthesis,” said Andrei. “These could supply coastal settlements, remote islands, cover industrial ponds, or avoid water evaporation from irrigation canals.”

“Many renewable energy technologies, including solar fuel technologies, can take up large amounts of space on land, so moving production to open water would mean that ‘clean energy’ and ‘land use’ aren’t competing with one another,” said Reisner. “In theory, you could roll up these devices and put them almost anywhere, in almost any country, which would also help with energy security.”

By Michael Gregson