Sun-powered desalinator could quench thousands of Indian villages

(Shutterstock)
(Shutterstock)

A salt extractor powered by the sun could bring cleaner drinking water to thousands of villages in India and millions more across the world.

In a new report, MIT researchers describe a novel but practical system to purify salty groundwater for India’s villages off the electric grid, and argue that it’s a system that people can afford, and will choose to use.

“It’s a opportunity that affects half a billion people,” said Amos Winter, an assistant professor at MIT and a co-author on the study. An estimated 60 percent of villages in India depend on water sources that have a low-level salinity. But, he adds, “This is step one.”

The technology itself — using electricity to suck out salt from water across a membrane — is not a new one. “It’s just that it’s never been applied in this way,” Natasha Wright, a co-author on the report and a graduate student in Winter’s lab said.

The alternative, reverse osmosis, is the preferred system in use at other facilities across the world. It’s a reliable workhorse, and well understood, Wright explained. But it’s a power-hungry technology that isn’t suited for remote villages without reliable electricity.

Wright traveled to India to examine the challenges of implementing the desalination system.

Wright traveled to India to examine the challenges of implementing the desalination system.

Wright and Winter argue that for the low levels of salt in the groundwater in up to 60 percent of rural India, they can extract enough power from solar panels to run their electrodialysis setup. Wright visited India on five trips over two years and examined the various challenges to rolling out such a technique to make it cost-effective, and implementable.

It’s early days yet for the project, which has a long-term goal of having one of the systems supply a village of about 5,000 residents.

The group is currently building the first test system, which it will trial in January 2015.

Early field tests could bring the technology to single villages as early as next year, but a commercial solution could be years away, the team says. The big hurdle on the horizon is the capital cost of power, Winter says.

As their first test system is being planned, the team is chipping away at the design to try and scale the cost back further, by modifying the setup, or replacing parts with cheaper ones.

At MIT, Winter is the director of the Global Engineering and Research lab that creates new technology for developing countries with a keen eye on cost and usability.

“This marriage of technical and socio-economic problem-solving really defines what my group does,” Winter said. “Natasha’s work is such a good example of this.”

Image of water tap via Shutterstock

Nidhi Subbaraman writes about science and research. Email her at nidhi.subbaraman@globe.com.
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