U.S. Navy Has the Solution to Rising Sea Levels: Drink It

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In its search for more fuel efficient‌ ways to provide drinking water for long sea voyages and remote bases, the U.S. Navy has developed a second-generation desalination unit that use 65% less energy than conventional technology.  It’s only in the prototype stage but the Navy is already looking beyond seagoing use, and has deployed an earlier version of the technology to provide emergency water supply to disaster areas.

Called the EUWP (Expeditionary Unit Water Purification Program) Gen 2, the new unit also offers a significant secondary benefit that applies to land operations.  By providing an on-site source for potable water, it eliminates the need to run convoys of tanker trucks.  The generators that power the EUWP units still use conventional fuel, but that could change.  If they could be adapted to run cost-effectively on solar power and other sustainable energy, the door is open to desalination on a mass scale.

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The U.S. Navy and Desalination

The U.S. Navy has long relied on reverse osmosis systems to provide drinkable water for its ships.  That equipment chews through precious supplies of shipboard fuel because it runs off the same generators that power the ship’s other systems.  Finding a more fuel efficient way to deliver water became an official Navy research priority in 2004.  On top of that, Navy strategists foresaw the need for improved technology that could effectively desalinate littoral (delta/marshland) and coastal waters, which contain more sediments and other contaminants than the open ocean.  In short order the EUWP Gen 1 was developed, and by 2005 it was deployed to the Gulf Coast after hurricane Katrina.  Each day it supplied 100,000 gallons of water daily to a Biloxi hospital, keeping 18 tanker trucks off the road.

The U.S. Navy EUWP Gen 2 Desalinator

The EUWP Gen 2 uses a high efficiency pump and an energy recovery system to achieve much of its fuel savings.  Using an experimental reverse osmosis system, it can produce about twice as much usable water as conventional systems, while not requiring any more space; the unit is about 40% smaller and lighter compared to conventional naval desalination systems, an extremely important factor on cramped ships.  It was also designed with crew efficiency in mind.  One operator can start it up in less than five minutes and it runs automatically after that, and the low maintenance microfiltration step involves no need to replace filters.  The Office of Naval Research estimates that the entire unit requires 75% less maintenance than a conventional unit.

More Desalination on the Horizon

The Navy may not have too much time to rest on its laurels.  Yale ‌researchers are developing a desalination system that uses 90% less energy, a U.K. company called Seawater Greenhouse has invented a low energy distillation-based system that provides fresh water for greenhouse crops, and the discovery of stretchable salt could leader to the development of new, highly effective nanofilter systems.

Image: BK59 on flickr.com.

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