We encourage you to republish this article online and in print, it’s free under our creative commons attribution license, but please follow some simple guidelines:
  1. You have to credit our authors.
  2. You have to credit SciDev.Net — where possible include our logo with a link back to the original article.
  3. You can simply run the first few lines of the article and then add: “Read the full article on SciDev.Net” containing a link back to the original article.
  4. If you want to also take images published in this story you will need to confirm with the original source if you're licensed to use them.
  5. The easiest way to get the article on your site is to embed the code below.
For more information view our media page and republishing guidelines.

The full article is available here as HTML.

Press Ctrl-C to copy

The people of the southwest Indian island of Karavatti are using the ocean's own thermal gradients to desalinate seawater and make bad drinking water a thing of the past, reports Yudhijit Bhattacharjee in this Science article.

Most desalination plants remove the salt from seawater either by boiling it and condensing the steam, or by pumping it across a salt-retaining membrane, but these methods are expensive.

The Karavatti plant, built by India's National Institute of Ocean Technology, uses a process akin to rain formation. Warm surface water is pumped into an onshore vacuum chamber, where some of the water vaporises.

Cold water drawn from 350 metres below the sea's surface then condenses the vapour in an adjoining chamber.

Using this process, called low-temperature thermal desalination, the plant produces 100,000 litres of fresh water a day. Although the process consumes 30 per cent more energy than its rival technologies, installing more chambers should make it more efficient and — at US$1 per 1,000 litres — cheaper.

Plans are afoot to build ten more plants on neighbouring islands. But on the mainland, where cold deep water is farther offshore, the method may be harder to implement.

Link to full article in Science

Related topics