IISc researchers develop energy efficient solar desalination system for areas which do not have continuous supply of electricity

The most common method for desalination is thermal desalination. The researchers explained, “Under this process, saline water is converted into vapour. This vapour is free of the salt and minerals which were present in saline water. The vapour, when condensed, forms freshwater.”

The IISc, in a statement issued on Tuesday said that thermal desalination consumes a lot of energy. “Thermal desalination systems work by heating saltwater and then condensing the resulting vapour to obtain freshwater. But the energy required for evaporation is usually obtained from either electricity or combustion of fossil fuels. An environment-friendly alternative is using solar stills in which solar energy is employed to evaporate saltwater in large reservoirs and the vapour that condenses on a transparent roof is collected.”

Susmita Dash, Assistant Professor in the Department of Mechanical Engineering and corresponding author of the study said, “As an alternative to solar stills, the IISc team has developed a novel design for a solar-powered desalination unit that is more energy-efficient, cost-effective and portable, making it convenient to set up in areas with limited access to continuous electricity. It comprises a reservoir of saline water, an evaporator, and a condenser enclosed within an insulating chamber to avoid heat losses to the ambient air.”

The setup is designed by Dash and her PhD student Nabajit Deka. Apart from seawater, the system can also work with groundwater containing dissolved salts as well as brackish water. It can be adjusted to align with the shifting positions of the sun during the day, researchers from the IISc said.

The researchers are currently working on scaling up the system and improving its durability and increasing the volume of drinking water produced, so that it can be deployed for domestic and commercial uses.