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Creating Fresh, Drinkable Water Powered Only by Ocean Waves

A North Carolina startup thinks its desalination device can solve water crises in coastal communities, on islands, and after disasters.   

kongsky / Shutterstock.com

“Water, water everywhere / Nor any drop to drink”: Samuel Taylor Coleridge’s adage might prove literally true within our lifetimes. Currently, 150 million people live in cities with a perennial shortage of fresh water, and by 2050, this number will increase to nearly 1 billion. On top of that, climate change is expected to cause water shortages for an additional 100 million city-dwellers.

The predictions are dire, but two recent college graduates have invented a solution that could increase fresh-water availability, simply by harnessing the power—and the water—of the ocean.

Chris Matthews, 24, and Justin Sonnett, 25, are co-founders of SAROS Desalination, a startup that grew out of their senior design project at the University of North Carolina at Charlotte in 2014. Their Swell Actuated Reverse Osmosis System (SAROS) is a a system of high-pressure pumps, built atop a buoy, that powers itself solely with energy drawn from the vertical motion of waves.

The wave-powered system draws in sea water, pumps it at high pressure through a reverse-osmosis membrane, and emits clean, drinkable water, which it stores in a tank until it’s ready to be run back to shore. The team’s first prototype had a pendulum, but the latest, smaller model sits on a buoy and rides the swells of the ocean.

“What’s unique about this is that we don’t need any kind of electricity or fossil fuels that are normally associated with desalination, so it’s very environmentally friendly,” says Sonnett, SAROS’ director of research and development. “It’s also going to be a lot less expensive than traditional desalination plants, which take a whole lot of energy to build and run.”

While traditional desalination plants are doing a good thing, they are expensive to build, rely on a city’s established infrastructure, use a lot of energy, and can contaminate oceans with a heavily concentrated salt runoff. Matthews and Sonnett’s solution is small and portable—their buoy measures four feet in diameter and can fit in the bed of a pickup truck. It’s also relatively inexpensive.

They expect a SAROS unit to retail for around $23,000, with a lifespan of 10 years and the ability to produce 2,000 gallons of clean water per day.

Moreover, the unit’s small size and the fact that it’s self-contained make it ideal for use in developing cities and countries, on islands, in coastal communities, at eco-friendly resorts and military outposts, and for disaster relief—all of which SAROS is targeting as primary uses when the product officially launches within the next two years.

How the SAROS unit works (SAROS Desalination)

“We are still conducting initial conversations with contacts in Hawaii and a few other small-island developing states,” says Laura Smailes, SAROS’ director of operations. Once SAROS has a proven track record, “this will then allow us to partner with NGOs and enter developing coastal areas that are in desperate need of a water solution. These areas, such as the Philippines and Madagascar, could benefit from SAROS, a solution that provides a consistent source of water and price stability and is able to run off-grid.”

Wave energy is, well, the wave of the future. Sonnett says it’s where solar energy was 15 years ago, and several companies large and small are currently developing ways to harness the ocean’s power for various uses.

But while many companies are using wave energy to create electricity (which is then often used to power a nearby desalination plant, for instance), SAROS says it’s the only such company producing clean water directly—which makes the water cheaper and the system more efficient.

John H. Lienhard V, the director of the Center for Clean Water and Clean Energy at MIT, says that while such technology provides certain advantages—namely no carbon emissions and the potential to serve areas that lack grid electricity—there are limitations that mean a system like SAROS isn’t a universal solution.

“Some parts of the world’s oceans are better suited than others,” Lienhard says, noting that the system can only work where waves have the proper intensity to drive it. “A second consideration is the cost of this source of water relative to locally available alternatives, such as solar-energy-driven reverse osmosis or water hauled by truck.”

The SAROS team members admit they’ve thought about other hindrances, too, like barnacles, storms, and even theft. Still, Matthews and Sonnett are confident that their design will work in many areas, though the right wave conditions—windchop, two-to-three-foot waves, and rough water—are key.

After being one of 30 projects chosen from among 3,600 to compete at the Hello Tomorrow Conference in Paris this summer, SAROS is beginning to gain some recognition. The next steps for the team are securing funding, building a second prototype, and establishing partnerships for pilot programs. From there, they hope to bring the technology to market and partner with NGOs to bring clean water to cities that need it.

“It’s never going to be something that’s going to make tons of money, but we just want to see it make tons of water,” Sonnett says.

Top image: kongsky / Shutterstock.com

About the Author

  • Iza Wojciechowska is a writer based in Durham, N.C. She has written for The New York Times, The Millions, and other publications.