"But rising awareness of water scarcity issues has led researchers like Gan and his team in Buffalo to apply new techniques to make solar distillation more efficient. Their solar vapor generator and condenser uses porous paper covered with carbon black, a material that has a near-zero reflectivity and therefore absorbs a higher amount of solar heat. The carbon-covered paper is then placed over floating white polystyrene foam and a thermal insulator that helps concentrate the solar heat onto the carbon layer. The device is then placed on the surface of a dirty water source while the paper acts as a sponge and the carbon as an evaporator. The vapor then condenses on the angled wall of the vaporizer, seeping into a culvert that collects the potable water.Gan and his team have claimed that their prototype produces as much as three times more potable water as comparable solar stills, or about 4.2 cups an hour under sunny conditions. The average healthy adult needs about eight cups of water a day. Crucially, this is all done using cheap materials that can be scaled, meaning arrays of floating stills could be tapped in emergency situations to provide a considerable amount of fresh drinking water to a disaster-struck community, especially in the sunny parts of Africa, Asia and Latin America.
In November, the researchers registered a company called Sunny Clean Water and are hoping to have a production-ready version of their prototype by the end of the year. "
I believe clean water will be one of the most important problems in the near future, around the world. Any cheap method like this will be very welcome.