Prime Minister Narendra Modi’s suggestion to a Danish wind energy company to explore the possibility of extracting water and oxygen from air by using wind turbines were ideas that were not just scientifically sound but are already under implementation at various places, scientists have said.
Extraction of water from air is already being done in several places, including in India, using different technologies, although not windmills.
But Sandeep Verma, Secretary, Science and Engineering Research Board, said wind turbines have the right design set-up for harvesting water from moisture-laden air, and even this idea was being tried out at several places. The challenge, he said, is to convert the ideas into implementation.
“Parameters such as design innovation, performance optimization, and right temperature gradients, can help extract water from air through a passive, energy-efficient process,” he said in a series tweets.
Ashutosh Sharma, Secretary, Department of Science and Technology, said separating oxygen from air is also a standard industrial process, and several companies engaged in separation of gases routinely do this. “Some membranes are used for separation. Some molecules would go through, others would not. That’s how you can separate oxygen as well,” he said.
In this process, wind turbines could be used mainly as a source of clean energy, Sharma said.
“But in the extraction of water, wind turbines can have an additional role,” he said. “The downstream of a wind turbine is throwing a lot of air, so it works like a compressor, or a pump. And for extracting water, the kind of systems that are used, it is again basically a network of membranes that air has to pass through, it condenses, and the water is collected by drip.
“The air needs to pass at a high rate, and the wind turbine can aid that process…. These things are already being tried. We have to make the processes more efficient,” he said.
In fact, the Hyderabad-based Indian Institute of Chemical Technology (IICT) has developed a technology with private-sector company called Maithri Aquatech for ‘atmospheric water generation’ that has been deployed at several places. This technology does not involve wind turbines.
“Wind turbines are just another technology alternative that can be explored, is already being explored. But otherwise, there is no scientific implausibility in trying to extract water or oxygen from air,” IICT director Dr S Chandrasekhar said. “At a very simple level, where do you get rain from? The technology we have developed provides extremely clean water from air. It is almost completely distilled water. It doesn’t have any salt or minerals, so it doesn’t have the taste we are used to. It requires a little bit of processing. But it is being done.
“And not just in India, but in many other parts of the world.”
“Of course,” he said, “water we generate from air is likely to be a little more expensive than water that is available normally. I do not have the exact estimates, but it is not exorbitant.”
Sharma said even the higher costs would be acceptable in locations where water is not readily available. “There are water-scarce places where these technologies are relevant even now. The higher costs are much more acceptable at certain places compared to other locations,” he said.
Shekhar Mande, director general, CSIR, said current technologies obviously need improvement, and that effort needs to be focused. “Technologies need to be improved so that they are more energy-efficient and less costly. These are not mature technologies, and that is where the challenge lies,” he said.
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