Technology Moving Toward Cheap, Efficient Water Desalination

While the world is focused on shortages of energy, another resource is becoming more and more scarce, especially in the third world. Due to rising populations and the occurrences of droughts, supplies of fresh water may become at a premium in the future. This is a problem that is potentially far more serious than shortages of energy. Without fresh water to drink, death can happen within days.

Fortunately, the surface of the world in comprised mainly of water. Unfortunately much of that water is brackish or salt water as exists in the oceans and seas of the world and is therefore undrinkable. Desalination technology has been around for decades. The technology is used take sea water and convert it to drinkable fresh water, mainly around arid locations such as the Middle East. Unfortunately these kind of desalination plants are inefficient and wastes energy.

An organization called Affordable Desalination Collaboration, which consists of a number of private companies, American state governments, the US federal government, and various local water districts is working on technology that promises to make desalination affordable and efficient. The technology is called Sea Water Desalination by Reverse Osmosis.

A demonstration plant is now being tested at the US Navy Seawater Desalination test Facility at Pt. Hueneme, California. It combines certain advances to make the desalination process cheaper and more efficient. These include a pressure exchanger developed by Energy Recovery Inc that reduces power to run it by 60 percent, a pump that processes thirty five million gallons a day, and a reverse osmosis seawater membrane that reduces feed pressure and thus saves energy.

So far the tests at Pt. Heuneme have had promising results. ADC has managed to generate good, drinkable fresh water, albeit at slightly higher than desired energy cost. Nevertheless, drinkable water has been produced at roughly thirty five percent reduced cost than experts had projected. This cost reduction has been enough for authorities to plan desalination plants in Carlsbad and Huntington Beach, California and to actually begin building a plant in Perth, Australia using the pressure exchange technology. Feasibility studies are being conducted in other communities in California, a state known for water distribution problems.

Tests at Pt. Heuneme seem to indicate that the desalination process is environmentally friendly as well. The dumping of brine into the ocean after it has been extracted from the water does not seem to have affected ocean life in any way.

The new technology seems to have already achieved lower to equal costs of obtaining water than traditional methods of distributing water in California. Seawater can be processed into fresh water at an energy cost of about 6 to 8 kilowatt hours per thousand gallons. This compares to a cost of 8 kilowatt hours per thousand gallons cost for a typical state water project and a 6 kilowatt hours per thousand gallons for the Colorado River Aqueduct.

Commercial plants, such as now being planned, will use off the shelf technology, such as the pressure exchanger, pumps, and membranes already mentioned. Also a standard design for a desalination plant is desired, to further reduce capital costs. It is hoped that water shortage problems can be addressed by accessing the resources of the world’s oceans in an efficient, cost effective, and environmentally friendly method.

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