MIT Invention Turns Salt Water Into Drinking Water Using Solar Power
Mary Beth Griggs
at 12:44 PM Apr 24 2015
Energy // 

From plants to people, every living thing on this planet needs water. But getting enough to survive, and survive comfortably, that can be a little tricky. Just look at the furor around California's new water restrictions. If a state as wealthy as California is having to get creative in order to start saving water, you can bet that governments and municipalities with less money and clout are having to turn to even more inventive methods to get clean water without breaking the bank.

Luckily, some of the brightest minds in the world are on the case. USAID recently announced the winners of the Desal Prize, part of a competition to see who could create an affordable desalination solution for developing countries. The idea was to create a system that could remove salt from water and meet three criteria: it had to be cost-effective, environmentally sustainable, and energy efficient.

The winners of the $140,000* first prize were a group from MIT and Jain Irrigation Systems. The group came up with a method that uses solar panels to charge a bank of batteries. The batteries then power a system that removes salt from the water through electrodialysis. On the most basic level, that means that dissolved salt particles, which have a slight electric charge, are drawn out of the water when a small electrical current is applied. In addition to getting rid of salt (which makes water unusable for crops and for drinking), the team also applied UV light to disinfect some of the water as it passed through the system.

Using the sun instead of fossil fuels to power a desalination plant isn't a totally new idea. Larger solar desalination plants are being seriously investigated in areas where water is becoming a scarce resource, including Chile and California. While proponents hope to eventually could provide water to large numbers of people, the technology is still expensive (though prices are dropping) and requires a lot of intricate technology.

In rural areas or developing countries, durability is key, and technology that requires constant upkeep won't last long. The MIT/Jain team and their competitors tested their projects at the Brackish Groundwater National Desalination Research Facility in New Mexico, where they had to run the system for 24 hours at a time, removing salt from 2,100 gallons of water each day. The next step is to test it in an even harsher environment, exposing it to everyday use with rural farmers in an area where USAID is active. If all goes well, the system could provide enough water to irrigate a small farm.

  • This article has been updated to reflect that the first prize amount was raised to $140,000, supplied by US Agency for International Development's Securing Water for Food initiative
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