Thirsty State Looks to Sea for Water
Drought, population growth combine to make costly use of seawater a more viable alternative. CALIFORNIA: DESALINATION
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Ted Kuepper, an environmental engineer for the Naval Civil Engineering Laboratory in Port Hueneme, Calif., says: ``If the drought continues, we'll be seeing these plants all along the coast.''Skip to next paragraph
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So far, no other states have seawater desalination, although reverse osmosis is commonly used in Florida to purify brackish water for drinking. Desalination is energy-intensive, experts note, and perhaps best suited to the oil-rich kingdoms of the Middle East. Half the desalting plants in use worldwide are in that region.
The cost of desalted water, high everywhere, differs from project to project. In general, the cost of a year's supply for two average families of four - about 292,000 gallons or one acre-foot (the amount of water it takes to cover an acre of land with a foot of water) - would be as much as $2,000. The same amount of normal ground water would cost about $150, according to Mark Silbernagel, project engineer on the San Nicolas operation.
Although the Marin plant would be comparable in size to Santa Barbara's - producing 5,000 acre-feet annually - it would cost nearly twice as much. The water it would produce would be cleaner than Santa Barbara's and more expensive at up to $2,400 per acre-foot. (Costs of Santa Barbara's desalinated water is projected to be $1,866 per acre-foot.) The Marin facility would be built as a permanent fixture, while the other facility will be housed in trailers.
There are several ways of removing the salt that makes up 3.5 percent of salt water: distillation, freezing, electrodialysis, and reverse osmosis, the process used on San Nicolas and in most commercial plants, including the Marin and Santa Barbara projects. Reverse-osmosis systems squeeze seawater against a thin plastic membrane that allows pure water - but not dissolved salts - to pass through.
Less energy required
Although reverse-osmosis pumps consume high quantities of electricity, the systems usually require far less energy than desalination plants that must boil seawater so fresh water can be extracted from steam.
``With oil prices going where they are going, that becomes significant,'' says Arthur Whipple, president of Campbell-based Aqua Design Inc., which has built 100 reverse-osmosis desalination plants, mostly in the Caribbean.
Marin Water District spokesmen contend that desalination plants may be less expensive than the two most likely alternatives: shipping spring runoff water from the Russian River in Sonoma County to Marin's system, or buying water from the Yuba River, nearly 100 miles away. Mr. Castle puts the price of a Russian River water project at $120 million and estimates it would cost $180 million for water from the Yuba River.
Building pipelines to distant areas is becoming politically more difficult because of the permitting process and other requirements, and because anyone with excess water is reluctant to let go of it, says Bill Katz, a spokesman for Ionics Inc. Environmental impact assessments are required for desalination projects. Both Marin's Castle and Santa Barbara's Mr. Ramsdell claim current public reports show that environmental impact is negligible.