An inexpensive device built and led by researchers at the University of Buffalo in New York aims to make dirty water drinkable with some help from sunlight. The researchers created a “solar vapor generator” that can clean or desalinate water by using heat generated by the sun. Such devices could help clean water in developing regions or those affected by crises.
"Using extremely low-cost materials, we have been able to create a system that makes near maximum use of the solar energy during evaporation. At the same time, we are minimizing the amount of heat loss during this process," explained lead researcher Qiaoqiang Gan, PhD, associate professor of electrical engineering at the university.
The researchers published their work in the journal Global Challenges. Their proposal is aimed at addressing global drinking water shortages, especially in developing areas and regions affected by disasters.
"The solar still we are developing would be ideal for small communities, allowing people to generate their own drinking water much like they generate their own power via solar panels on their house roof," said Zhejun Liu, a visiting scholar at UB, PhD candidate at Fudan University and one the study's co-authors.
The solar vapor generator is part of a larger solar still that the school says is about the size of mini-refrigerator. The device is made out of expanded polystyrene foam, which insulates the device and can also help it float, and porous paper coated in carbon black.
The paper absorbs or wicks water and the carbon black absorbs sunlight as heat to evaporate the water into a vapor, eliminating salt, bacteria and other elements in the process. The device operates at low temperatures, converting only surface water to vapor—as opposed to a mass of liquid. As the water vapor cools it’s collected in a separate container without salt or contaminants.
"People lacking adequate drinking water have employed solar stills for years, however, these devices are inefficient," contended Haomin Song, PhD candidate at UB and one of the study's leading co-authors. "For example, many devices lose valuable heat energy due to heating the bulk liquid during the evaporation process. Meanwhile, systems that require optical concentrators, such as mirrors and lenses, to concentrate the sunlight are costly."
The researchers said they believe the can produce three to 10 liters of water per day with materials that cost roughly $1.60 per square meter. They said that compares to a system with technical materials that can cost more than $200 per square meter.Tweet