Solar Stills to be available for commercial use

Ahmedabad: Solar Stills, a low-tech way to distill sea water, powered by heat of sun with improvised water output efficiency, will soon be made available to industry for commercial utilisation, a top CSMCRI official said.

"Through innovation we have doubled water output of stills, which earlier used to be 3-4 ltr a day. They shall be entering trial phase and soon be available for commercial production," Director of Central Salt Marine & Chemical Research Institute (CSMCRI) Dr Pushpito Ghosh told PTI.

Solar Stills technique is ideal for installation in households falling in remote areas of saline water regions to meet their drinking water requirements. "Making a prototype of the still costs around Rs 10,000 per unit, but once it goes for commercial production its cost is expected to be much lower as economy of scale comes into play," Ghosh said.

The novel units having easy clean option for the black base at the bottom, for better efficiency, have been developed by the CSMCRI Chemical Engineering wing. "During summers one can draw up to 7 ltrs of drinking water per day from these Still units. In initial trials, even in months like December we got 5 ltrs per day output of water from it," Chemical Engineer at CSMCRI Subarna Maiti said.

The trials of these units are to be conducted in remote areas of Rajasthan, Madhya Pradesh, Gujarat, Southern (Rameshwaram), Eastern (Sunderbans) and Northern regions of India, where availability of safe drinking water in households under saline water regions is an issue, Ghosh said.

Bhavnagar-based CSMCRI, a laboratory of the Council of Scientific and Industrial Research (CSIR), has filed for a provisional Indian patent for this new device.

Among other such solar products, CSMCRI has developed an automatic solar dryer finding application in cooking, baking and drying proposes, besides a parabolic trough concentrator for extraction of essential oils. "Our multifarious solar dryer can be used for drying, cooking and baking purposes. Its automatic feature helps it track the sun, eliminating the need to rotate it in direction of sun as required in conventional solar dryers," Maiti said.

The appliance also can efficiently remove last stage vapours (with help of solenoid bulbs inside to recirculate air), which in traditional solar dryers was not a possibility, she said.

The institute during trial phase had successfully converted grapes into raisins in a day`s time using this dryer, which otherwise through manual processing takes atleast 2-3 days, Maiti said.

CSMCRI has got approval under Patent Cooperation Treaty (PCT) for its solar dryer and shall soon be filing international patents for this new device.

The institute has also developed a small solar energy driven household device handy in extracting essential oils from rose, clove, orange amongst others. "As the proof of concept we have successfully derived 2.16 per cent of the weight of fresh peel of orange, which is highest extraction in percentage terms," Ghosh said. "The effort is to scale up the technology to a cottage industry level," he added.