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CARLSBAD, California — Along the sun-dappled shores of the Pacific Ocean, the electronic signs up and down Interstate 5 flash constant reminders to save water during California’s worst drought in history.
It’s a cruel irony for residents of a state that borders water along more than 1,000 miles of coastline.
Desalination, the complicated, costly and environmentally sensitive process of drawing millions of gallons of seawater and taking the salt out to make it potable, has not been widely embraced in a state that is suffering a severe drought.
Until now. In Carlsbad, a giant desalination plant — the largest in the Western Hemisphere — is gearing up to start producing water for San Diego County residents by the end of this year.
The $1 billion project will deliver 50 million gallons of water a day, a sizable amount but still only about what 120,000 households, or 7 to 10 percent of county residents, use, said Scott Maloni, a vice president at Poseidon Water, the plant’s developer.
The company is lobbying hard to open another plant to the north, in Orange County’s Huntington Beach.
The county and its residents will be paying a high price for 30 years. Monthly bills are expected to go up by an average of $5 to $7 a month per household to help the San Diego County Water Authority meet annual payments of at least $110 million. The payments have to be made whether San Diego needs the water or not.
Despite the high cost, the severe drought has reignited interest in desalination, a process that has been widely adopted in Australia, Israel, Saudi Arabia and other Persian Gulf nations.
In California, the cost of desalinated water is at least $2,000 per acre foot (what a family of four might use in a year) compared with about $400 for groundwater and freshwater from reservoirs that collect from rivers and mountain runoff.
“There are 16 desalination plants anywhere between proposal and construction,” said Clare Waggoner, an environmental scientist and a desalination expert at the California State Water Resources Control Board. “It’s only being considered by communities where they really don’t have other water supply options.”
San Diego is an exception. The county relies on imported freshwater from the Colorado River and Northern California, and supplies haven’t dried up yet. But the county decided to make sure it has a backup plan if the drought continues.
Environmentalists, however, continue to fight desalination because they say that pumping ocean water and disposing of the concentrated brine harms sea life. Desalination plants also use a lot of energy.
In 2009 the State Water Resources Control Board ordered power plants to phase out the use of seawater intake pipes to cool their equipment because millions of fish and other marine life are killed in the process every year. But the Poseidon desalination plant and many of the proposed ones along the coast plan to use the same kind of pipes.
In San Diego County, Poseidon successfully fended off 14 legal challenges to the Carlsbad plant. But when a report by biologists concluded that the plant would destroy marine life, the company agreed to restore 66 acres of wetlands in the San Diego bay and spend $60 million to offset its carbon footprint.
“Ocean desalination is extremely energy intensive,” said Sara Aminzadeh, the executive director of the California Coastkeeper Alliance. “We should all be looking at Australia. They built six desalination plants during their drought, and four of them are now shut down. It’s not the best solution.”
The ‘ick’ factor
Environmentalists say better alternatives are more conservation and recycled water, which is being used in car washes and golf courses and for irrigation and industrial use but has yet to be a palatable alternative for drinking water. There is a huge “ick” factor when anyone mentions toilet-to-tap water.
“The primary obstacle is public perception,” Aminzadeh said. “There are safety concerns, and building public confidence has been a barrier. But water recycling is an excellent option and has a lot of promise in our state.”
In Texas two communities already get their tap water from recycling plants.
“The industry is ready, and the technology is really good,” Waggoner said. “The younger generation feels more comfortable with direct potable [recycled water direct to tap].”
Doug Eisberg, a director of the International Desalination Association, which will host its world congress in San Diego at the end of August, has no problem with recycling and points out that recycling also requires desalination.
“A lot of folks don’t understand that desalination in general is technology that’s applied to a lot of processes,” he said. “So much of the drinking water supply is desalinated and recycled. If you go to Disneyland, you’re drinking recycled water, and you don’t even know it.”
True. There were 26 desalination plants in California in 2010, according to the Department of Water Resources. Only three desalinate ocean water: one in Avalon on Catalina Island, a small one on Monterey Bay and another on the U.S. Naval Facility on San Nicolas Island.
The 23 others take the salt out of brackish water that is then put back into the groundwater and goes through water treatment plants.
But the amount of potable water that comes from seawater desalination is relatively minuscule. The three plants in the state produce only about 80,000 acre feet a year, 0.08 percent of the total municipal output of 9.5 million acre feet, Mills said.
The drought may change that.
More desalination plants
The 16 desalination plants proposed along the California coast, from Camp Pendleton and Redondo Beach to Monterey, would produce a total of up to 370 million gallons of water a day. Some would desalinate seawater, and others would take the salt out of brackish water in ground wells.
“People are starting to have a dialogue about the best use for [different sources of] water,” Waggoner said. “It doesn’t make sense to desalinate seawater and irrigate crops.”
Concerns over environmental and financial costs continue to block efforts to build seawater desalination plants. Santa Cruz rejected a proposed plant for those reasons.
In Carlsbad, Poseidon is using a dilution process to dispose of the brine. The desalinated water will be delivered to the county’s water authority through a 10-mile pipeline. The concentrated brine that remains will be mixed with enough ocean water to reach close to the natural salt level and will be flushed out back into the sea.
“It takes 2 gallons of seawater to make 1 gallon of drinking water,” Maloni said. “So our plant needs to withdraw 100 million gallons per day (MGD) in order to produce 50 MGD of drinking water.”
Actually, it's closer to 6 to 1, since the plant must dilute the concentrated brine that remains after desalination. Poseidon will draw an additional 204 million gallons of seawater to dilute it before it goes back out to the ocean. “So 304 MGD will be withdrawn, 50 MGD will become high-quality drinking water, and 254 MGD will be discharged back to the ocean,” Maloni said.
Poseidon uses reverse osmosis, a process that uses high pressure to push seawater through tight membranes that trap the salt and let the desalinated water flow. The process requires a lot of energy, but costs have dropped in the past two decades because of new engineering. The Carlsbad plant is using devices that recycle energy, the same way a hybrid car does, and Poseidon claims it has cut energy consumption by 46 percent.
California seems to be more open to alternative water sources. The governor recently released the California Water Action Plan, which streamlines the permitting process.
“It’s hard to be critical that they built that plant if you are responsible for water supply,” said Richard Mills, the chief of the water recycling and desalination center at the California Department of Water Resources. “You gamble with an expensive project just to make sure you survive … You shouldn’t be dependent on one thing or another or automatically rule out something because it’s too expensive.”
Santa Barbara built a desalination plant in the 1990s, in the thick of a drought. But then the rains returned, and plant operations stopped — the same reasons some of Australia’s plants stopped pumping. Now Santa Barbara is gearing up to spend $40 million to relaunch.
“In Santa Barbara, when they built that plant, they were very desperate,” Mills said. “If the rains did not come the next year, then everyone would’ve said they made a brilliant decision, but the rains did come, and it stopped operating.”
What the future holds
Mills said that new technology will reduce the cost of desalination — at least compared with other sources. As freshwater becomes scarcer, the cost of those traditional sources will climb because of the shortage. The result will be a smaller price differential.
One innovation is to turn the leftover brine into blocks of salt that can be sold to industries and to municipalities in snowy areas to use to melt snow on roads. That would eliminate concern over the disposal of brine back into the ocean.
But for now, even though there are 70 million people worldwide who rely on desalinated water, the number of Californians who do remains tiny.
“You’ll see many more desalination plants, but they’ll be smaller,” Eisberg predicted.
Seawater desalination and recycling are not magic bullets on their own, he said. “It’s a balanced combination. Conservation is important and needs to come first. Then recycling. Then seawater,” he said.
But he reminds Californians that seawater desalination is droughtproof. “That’s undeniable,” he said.