Floating solar photovoltaic power plants, or ‘floatovoltaics’, are an emerging innovation where fixed-tilt solar panels are attached to floating structures moored to the bottom of lakes or reservoirs. Where land is at a premium, and might be needed for agricultural or other uses, floatovoltaics offer a viable alternative for renewable power generation. While they are more expensive to install than land-based solar power plants, the cost of solar is decreasing, which should help to encourage adoption in the future. They are also considered to be a better long-term investment because they are up to 16 per cent more efficient due to the cooling effect of the water reducing thermal losses and extending their lifespan.
A study by US-based market research and consulting company Grand View Research found that the global market for floating solar was estimated to be worth $13.8 million in 2015 and is expected to grow exponentially to $2.7 billion by 2025 thanks to soaring demand for renewable energy. The commercial energy sector is monitoring and reacting to this growing market. It’s almost 10 years since floating solar specialist developer, Ciel & Terre, switched focus away from land-and-roof-mounted solar arrays. The company anticipates that demand in areas like California in the US, where land is expensive, will increase with many ‘untapped surface areas’ still available.
Founded in 2011, the Sunseap Group is now Singapore’s largest clean energy provider. The company has announced plans to build one of the world's first and largest sea water floating solar plants, predicted to generate about 6,388 MWh of renewable energy annually. The company says this is equivalent to powering about 1,250 4-room flats, with a reduction in greenhouse gas emissions of around 2,600 tonnes per year.
Floating solar plants can be even more effective when combined with hydroelectric systems. In some instances, where energy production from hydroelectric dams is predictable, the electricity can be used to augment the intermittent production of solar energy. Conversely, solar energy can augment hydroelectric power when water levels are low. The reduction in sunlight caused by the array covering the reservoir surface also helps to prevent algae blooms, which are known to pollute water and raise treatment costs. The World Bank believes this type of innovation would be effective in Sub-Saharan Africa and in areas of developing Asia.
The world's first combined hydro and floating photovoltaic power plant was installed at the Alto Rabagao Dam in Portugal between 2016 and 2017. EDP, the utility that installed the panels, said in 2017: "There is still some way to go before the costs of this solution are in line with conventional on-land options. However, optimised solutions are already being studied and this cost difference should be reduced in the not too distant future."
The market for floating photovoltaics is growing, with the world’s largest array in the city of Huainan in China, developed above an artificial lake at a collapsed coal mine. Japan has the most installations with more than 60.
Whilst still a fairly nascent market, the potential for growth is significant and will undoubtedly contribute towards the achievement of the UN’s Sustainable Development Goal for affordable and clean energy for all.
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