“Our project aims to address the clean water problem, which is really a global problem,” Qiaoqiang Gan, associate professor of electrical engineering, told Digital Trends. “Ninety-nine percent of the water on this planet is in the sea, but that water can’t be drunk. Because of different types of environmental pollution, the stress on clean water is more and more significant. People are on the lookout for new technologies that can help.”
There is a good reason why Gan and his colleagues stuck with the basis of a solar-powered water purifier concept that’s been around for years: if it ain’t broke, don’t fix it. Solar stills are portable and cheap, and best of all don’t require any electricity to run.
These are all positive traits, but Gan and his colleagues thought they could improve efficiency in terms of the amount of heat loss that takes place during the process. “Our question was how could we enhance the energy efficiency and accelerate the vapor generation speed?” he said.
The “solar vapor generator” the team has developed cleans or desalinates water through evaporation, before it is collected in a separate container free of any salt or contaminants. Rather than using an optical concentrator like a mirror or lens to concentrate the sunlight, however, the team used insulating polystyrene foam for the device’s body, and porous paper coated in carbon black. The paper absorbs the water, and the carbon black absorbs the sunlight and then turns the solar energy into heat.
“Conventional solar heating for solar stills have an efficiency of only 30 to 40 percent,” Gan said. “Only that percentage of the solar energy is converted. In our solution, on the other hand, it is 88 percent — and we’re getting closer to a solution which will give 100 percent efficiency.”
Based on test results, the researchers think the new solar still could produce 3 to 10 liters of water every day, which compares favorably to the 1 to 5 liters produced by the majority of commercial solar stills. And at $1.60 per square meter, water would also be significantly cheaper to produce than it is using systems that require optical concentrators, which come in at $200 per meter.
At present, Gan said that the team is looking to attract investors to commercialize the device. He estimated that prototypes could be manufactured and brought to market within about a year.
“This could be very useful in disaster areas where people don’t have easy access to clean water,” he said. “This could also work very well in the hiking market, where people want an emergency device to produce clean water in a resource-limited area, as well as in the military.”
