As California's drought rumbles on, depleting groundwater and disrupting agriculture, there's been a renewed interest in desalination: a process which removes salt from water to provide a readily available supply of freshwater from oceans or other saline water bodies. There's only one problem: It takes an awful lot of energy and can leave a significant environmental footprint in its wake. 

That's why desalination powered by renewable energy is such a tantalizing prospect. We've already seen promises to run the desalination plants in Masdar on solar power and, as detailed in a recent New York Times piece, Poseidon Water, the company building new desalination plants in California, has promised to fund renewable energy to offset its emissions. But what about a desalination plant that is purposefully designed to run on a lot less energy, use solar power, and to travel to where it is needed most? 

That's what a team at MIT has created, at least in pilot form, winning the prestigious $140,000 Desal Prize for their efforts. Working with Jain Irrigation Systems, the group has created designs for a desalination system that uses electrodialysis, instead of the traditional reverse osmosis technology used in most industrial-scale desalination plants.

We shouldn't get too excited just yet about getting limitless freshwater from the sea. According to a piece over at MIT News, the system was designed primarily for treating salty groundwater in rural India. Despite the fact that salinity levels are relatively low compared to seawater, the unpleasant, salty taste often leads communities to choose dirtier water sources — putting lives and livelihoods in danger in the process. The MIT-designed system could, the team says, provide enough fresh drinking water for between 2,000 and 5,000 people while remaining financially viable, and if widely used it could also double the area of India in which groundwater becomes the preferable source over surface water, which is inherently less safe. (The team suggested that similar-scaled reverse osmosis systems would also be viable in areas where electricity was readily available.) 

Now whether or not such systems could address wider water shortages remains to be seen, but the MIT team did suggest that it could be deployed for disaster relief and/or remote military applications. 

This is by no means the only innovation going on with desalination these days. AzoNano has an interesting overview of how researchers across the world (including some folks at MIT, again) are exploring new materials for desalination membranes, potentially making freshwater from salt water in a much more energy efficient manner. Graphene (a material with numerous potentially groundbreaking applications) is perhaps one of the most promising. Here's MIT's David Cohen-Tanugi, a Ph.D. candidate at MIT, explaining how this might work.

Whether or not such innovative systems will scale up in the near future remains to be seen, but one thing seems certain. With climate change and human consumption continuing to put pressure on the world's freshwater supplies, interest in desalination is unlikely to dry up (sorry!) any time soon.

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Solar desalination makes freshwater from salt water
An award-winning MIT team has created a portable, solar-powered desalination system that could provide freshwater in remote locations.