Turning UAE’s sunlight into steam

MITThe floating receiver acts like a sponge, constantly soaking up water and evaporating it, producing a continuous stream of steam. (Image source: Masdar)The UAE’s Masdar Institute of Science and Technology and Massachusetts Institute of Technology (MIT) have developed a low-cost solar device that can convert sunlight to steam

The solar conversion system can help make technologies that rely on steam, like seawater desalination, wastewater treatment, residential water heating, medical tool sterilisation and power generation, more efficient and affordable in the UAE.

The new device floats on water, converting 20 per cent of incoming solar energy into steam at 100ºC without expensive optical concentration devices and is made of cheap, commercially available materials, including bubble wrap and a polystyrene (plastic) foam. 

“This project is an excellent demonstration of how international collaboration and use-inspired research can yield cutting-edge scientific findings that have direct application to the sectors that are at the core of the UAE’s continued evolution toward an innovation and knowledge-based economy,” said Steve Griffiths, vice-president for Research and Associate Provost, Masdar Institute.

“The system we have developed enables us to generate steam with solar energy without having to rely on direct sunlight,” added Dr TieJun Zhang of Masdar Institute Assistant Professor of Mechanical and Materials Engineering. “The technology is particularly suited for the UAE’s dusty climate, as it fully uses the entire spectrum of sunlight for thermal applications rather than just the direct portion, which can be hindered by the aerosols,” he noted. 

The receiver’s design is relatively simple: A floating, sponge-like device made of a spectrally-selective absorber allows visible light energy from the sun in, while restricting the amount of heat that radiates back out into the atmosphere. This heat-trapping effect significantly improves the device’s sunlight-to-steam efficiency. 

The absorber is sandwiched between a top bubble-wrap layer, which allows for sunlight absorption while reducing the amount of heat lost to the air through convection, and a bottom insulating foam layer, which floats the entire structure on a body of water and reduces the thermal loss of the generated heat to the water below. 

The floating receiver acts like a sponge, constantly soaking up water and evaporating it, producing a continuous stream of steam. The solar receiver was validated at MIT and the research is part of the MI-MIT active flagship programme.

Dr Zhang, MIT’s mechanical engineering department head Dr Gang Chen, PhD student Hongxia Li and post doctorate Weilin Yang at Masdar Institute, published a paper on their new floating solar receiver last week in the journal Nature Energy, along with George Ni, an MIT graduate student and the paper’s leading author, and two other researchers at MIT.

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