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A low-cost system developed by U.S. and United Arab Emirates researchers could revolutionise steam-based technologies.
A team of researchers from the Masdar Institute of Science and Technology of Abu Dhabi and Massachusetts Institute of Technology (MIT) of Boston have developed a low-cost solar thermal energy conversion device that can easily generate steam from sunlight. The conversion system can help make technologies that rely on steam, like seawater desalination, wastewater treatment, residential water heating, medical tool sterilization and power generation, more efficient and affordable.
The new device floats on water, converting 20% of incoming solar energy into steam at 100°C without expensive optical concentration devices. The device is made of cheap, commercially available materials, such as bubble wrap and polystyrene foam.
Moreover, the system generates steam without having to rely on direct sunlight, as it fully uses the entire spectrum of sunlight. This makes it particularly suited for the dusty climate of Middle East countries too.
The absorbing device’s design is quite simple: it is a sort of floating sponge made up of a spectrally-selective absorber that allows visible light energy from the sun in, while restricting the amount of heat that radiates back out into the atmosphere. The absorber is sandwiched between a top bubble-wrap layer, which allows for sunlight absorption while reducing the amount of heat lost, and a bottom foam layer, which floats the entire structure on a body of water and works as an insulator. The floating receiver acts like a sponge, constantly soaking up water and evaporating it, producing a continuous stream of steam.
The system was tested at MIT, where it demonstrated the ability to rapidly reach 100°C and generate steam even when sunlight is not direct, such as during winter months and under heavy cloud cover.