Startups Exploring Tech to Tap Seawater

Water agencies facing droughts and shortages of freshwater, such as in coastal California, have been turning increasingly to desalination this year.

oceansunsetPhotos8 However, current desalination methods can be expensive and energy inefficient. Watchdog groups prefer water conservation and efficiency efforts, and charge that tapping the oceans for potable water can pollute waterways and kill marine creatures.

Yet could desalination become more viable and efficient? The Global Cleantech 100 list anointed several companies with that aspiration as technology innovators earlier this month.

Among the varied approaches, NanoH2O of Los Angeles is working on a nanotech membrane to produce fresh water via reverse osmosis, a common water purification method. The company says its technology can cut costs in part by reducing bacterial buildup, fitting within existing desalination systems. NanoH2O projects that its methods could increase a plant’s water output by up to 70 percent while shrinking energy costs by 20 percent.

Danfoss AquaZ of Denmark says it can filter water with a membrane up to 10 times as efficient as with standard desalination technologies. Key to its process are aquaporins, proteins that function like a plumbing system for living cells and that require minimal energy. Danfoss AquaZ plans to integrate aquaporins within artificial nano membranes, filtering out only pure H2O. Aquaporins were discovered relatively recently, leading in part to the 2003 Nobel Prize in Chemistry.

Taking yet a different tack, Oasys Water of Cambridge, Mass., is exploring what it calls engineered osmosis. As Jonathan Fahey of Forbes explains:

Instead of dividing salt water and fresh water, Oasys divides salt water and saltier water. This saltier water is water mixed with a unique type of salt called thermolytic salt… This extremely salty solution draws fresh water from the industrial wastewater or seawater through the membrane, leaving brine behind. Then a small amount of heat is applied to the thermolytic mixture, boiling away the ammonia and carbon dioxide and leaving fresh water…

And Oasys claims its process only requires modest electricity and heat, so it would cost one-tenth of what’s required by reverse osmosis methods for producing drinking water.

Water shortages are expected to increase in the coming decades, becoming a greater burden to businesses and taking an ever higher human toll. More than 1 billion people currently lack access to clean drinking water, according to the World Health Organization. By most accounts, businesses are just beginning to address water woes.

If any of these startups have their way, could desalination become more attractive and less expensive on a grand scale? Which approaches look the most or least promising?

[photo credit: photos8, cipher]

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