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Tapping the Ocean to Quench California’s Thirst
Tapping the Ocean to Quench California’s Thirst
CreditDamon Winter/The New York Times
CARLSBAD, Calif. — Every time drought strikes California, the people of this state cannot help noticing the substantial reservoir of untapped water lapping at their shores — 187 quintillion gallons of it, more or less, shimmering so invitingly in the sun.
Now, for the first time, a major California metropolis is on the verge of turning the Pacific Ocean into an everyday source of drinking water. A $ 1 billion desalination plant to supply booming San Diego County is under construction here and due to open as early as November, providing a major test of whether California cities will be able to resort to the ocean to solve their water woes.
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Across the Sun Belt, a technology once dismissed as too expensive and harmful to the environment is getting a second look. Texas, facing persistent dry conditions and a population influx, may build several ocean desalination plants. Florida has one operating already and may be forced to build others as a rising sea invades the state’s freshwater supplies.
In California, small ocean desalination plants are up and running in a handful of towns. Plans are far along for a large plant in Huntington Beach that would supply water to populous Orange County. A mothballed plant in Santa Barbara may soon be reactivated. And more than a dozen communities along the California coast are studying the issue.
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The facility being built here will be the largest ocean desalination plant in the Western Hemisphere, producing about 50 million gallons of drinking water a day. So it is under scrutiny for whether it can operate without major problems.
“It was not an easy decision to build this plant,†said Mark Weston, chairman of the agency that supplies water to towns in San Diego County. “But it is turning out to be a spectacular choice. What we thought was on the expensive side 10 years ago is now affordable.â€
Still, the plant illustrates many of the hard choices that states and communities face as they consider whether to tap the ocean for drinking water.
In San Diego County, which depends on imported freshwater supplies from the Colorado River and from Northern California, water bills already average about $ 75 a month. The new plant will drive them up by $ 5 or so to secure a new supply equal to about 7 or 8 percent of the county’s water consumption.
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The plant will use a huge amount of electricity, increasing the carbon dioxide emissions that cause global warming, which further strains water supplies. And local environmental groups, which fought the plant, fear a substantial impact on sea life.
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The Pacific Ocean will feed a desalination plant in Carlsbad, Calif. The intake of seawater and the disposal of salt into the ocean can harm sea life, environmentalists say. Credit Damon Winter/The New York Times
The company developing the plant here,
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The technological approach being employed here, and in most recent plants, is called reverse osmosis. It involves forcing seawater through a membrane with holes so tiny that the water molecules can pass through but larger salt molecules cannot.
A huge amount of energy is required to create enough pressure to shove the water through the membranes. But clever engineering has cut energy use of the plants in half in 20 years, as well as improving their reliability.
Future desalination plants also have the potential to blend well with the rising percentage of renewable power on the electric grids in California and Texas. Since treated water can be stored, the plants could be dialed up at times when electricity from wind or
San Diego County, which includes the coastal neighborhood of La Jolla, could receive as much as 50 million gallons of drinking water a day from the desalination plant. Credit Damon Winter/The New York Times
It is in the late stages of construction, by an artificial bay opening to the sea in Carlsbad. On a recent day, the faint smell of glue wafted through the air as workers sealed joints on huge pipes. When it goes into operation, the plant will pump water through 16,040 cylinders containing the membranes that trap salt.
Peter MacLaggan, a vice president of Poseidon Water who is overseeing the project, said the plant was in some ways a response to longstanding public interest in desalination.
“Every time California has a drought, we get letters to the editor pointing out that there’s a lot of water in the Pacific Ocean,†he said as waves broke on the shoreline in the distance. “They say, ‘Hey, guys, what are we waiting for?’â€
Santa Barbara, a chic tourist destination on the coast, could face severe water shortages within a year if the drought continues. The city is on the verge of spending $ 40 million to reactivate the long-mothballed desalination plant there.
That step would drive water bills up sharply, acknowledged the mayor, Helene Schneider. But, she added, “no water is a worse option than very expensive water.â€
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For Drinking Water in Drought, California Looks Warily to Sea - New York Times
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