Researchers examine solar-powered system for inexpensive desalination

Two-thirds of the world population is estimated to face shortage of water, and several areas in the developing world face shortage of dependable electricity. This has led to widespread research efforts that are focused on ways to desalinate brackish water or seawater using only solar heat.

A number of such efforts could not bear results with fouling of equipment caused by salt accumulation, which often adds to the complexity and cost.

A team of researchers at MIT and a research team in China have come up with a solution to address the challenge of salt accumulation. In this process, the researchers have developed a desalination system that is more efficient as well as less expensive that previously used solar desalination methods.

In addition, the process could also be used to treat impure wastewater, or to produce steam for sterilizing medical instruments, which does not require any power source except sunlight.

The findings are published in Nature Communications in a paper from a graduate at MIT, and four others.

In fact, there has been lot of concerns regarding salt rejection and solar-based evaporation designs of various really high-performing devices. Salt fouling has been the challenge for these devices that has not really been addressed.

While the performance numbers of desalination methods appear attractive, but they have been limited because of longevity.

Meanwhile, a number of attempts for solar desalination systems depend on some kind of wick to draw salty water through the device. These wicks, however, are subject to salt accumulation and are relatively difficult to clean. This aroused the interest of the team to develop wick-free system instead.

The effort led to the development of a layered system for desalination of water.  The system has dark material at the top to absorb the heat of the sun, followed by a narrow layer of water above a a layer of material with perforations that sits on the top of a deep reservoir of salty water such as a pond or tank.