Water Woes Spur Fresh Look at Desalination
The ocean long has been a source of frustration for Southern California. There's so much water so close, yet getting the salt out of it has been too expensive to ever be practical.
Santa Barbara tried it 10 years ago when the city, faced with a water crunch as its main reservoir ran nearly dry, scrambled to build a desalination plant. But costs were so astronomical that as soon as the reservoir filled up again, city officials ordered the plant torn down.
Now, desalination is back and it seems to be taken more seriously this time around. New technology has made the process of filtering salt out of the sea cheaper while other water sources have become more expensive.
Five proposals for desalination plants are being studied by the Metropolitan Water District of Southern California, the wholesaler serving 17 million residents and businesses in six counties. By next summer, the MWD expects to have signed contracts with water agencies that want to build plants. By the end of the decade several plants could be online from El Segundo to Carlsbad, producing enough desalted water to serve 1.3 million people for a year.
"The biggest benefit of desalinated sea water is that it's a firm supply that we have control over," said Paul Shoenberger, chief of engineering and operations for the Central and West Basin Municipal Water Districts, the water agency serving 17 South Bay cities and one of the agencies submitting proposals to the MWD. "Most of our water supply is beyond our control, leaving us at the mercy of the weather and environmental regulations in force hundreds of miles away."
There are several hurdles to overcome, including siting the plants, volatile operating costs, and disposing of millions of gallons of extremely salty water. But there's a widespread consensus that these problems can be overcome and that desalinated seawater will become a part of the local water mix in the next five to 10 years.
County sites considered
Four sites are being considered in L.A. County alone, three by the L.A. Department of Water & Power. The sites in El Segundo, Redondo Beach and near the L.A. and Long Beach harbors are all adjacent to existing power generating stations. That allows the desalination plants to piggyback on the power stations for water intake and power supply, thus reducing construction and operating costs.
"It's all about cost," said Steve Richardson, western region vice president for Eco Resources Inc., a unit of West Covina-based Southwest Water Co. "The cost curve for desalination is rapidly going down, while the costs for other sources of water are destined to go up, especially as our take from the Colorado River is reduced."
At that defunct Santa Barbara desalination plant, it cost roughly $2,000 per acre-foot to desalt seawater, while traditional water sources from the MWD ran about $350 per acre-foot.
Now, the cost to desalt seawater is pegged around $800 per acre-foot, while MWD water costs $431 per acre-foot. The drop in desalted prices is due largely to advances in the filtration process, in which membranes used to filter out the salt have become more efficient and less energy is required to pressurize the seawater.
In one closely watched project, the Tampa Bay Water agency is building a seawater desalination plant that when operational early next year will produce 25 million gallons of drinking water a day (enough for the needs of about 100,000 residents) and cost about $680 per acre-foot of water.
But the Tampa Bay project has run into a snag as the parent company of the main contractor, Covanta Energy, has filed for bankruptcy, apparently due to financial difficulties in other business units. Tampa Bay Water officials say that their project is still on track to be operational by March 1, 2003. And the cost to desalt water in Tampa Bay is likely to be less than in Southern California because of lower salinity levels and warmer water temperatures in that bay.
MWD officials say they intend to offer incentives of up to $250 per acre-foot to water agencies that build desalination plants. Such incentives could bring the cost down well under $800 per acre-foot for the participating water agencies and contractors.
"That's a very smart approach," said Jack Baylis, vice president and area manager for CH2M Hill, the Denver-based engineering and construction giant which has several water projects in L.A. County. "Rather than investing public agency money at full force, the MWD has come up with an approach that encourages the private marketplace to do the work."
MWD officials say that's the major purpose of the proposal process.
"We're trying to assess how much the costs have fallen with these proposals," said Andy Hui, civil engineer with the MWD. "We've heard assertions by business that they can actually deliver desalted seawater at costs well under $1,000 per acre-foot; now we're going to test that."
If those cost projections can be met, desalinated seawater can provide a good alternative for a region that will be increasingly strapped for water.
Currently, the MWD charges $431 per acre-foot of water it sells to member agencies. But that price is sure to head up over the next 20 years, as the agency is forced by federal mandate to decrease its intake from the Colorado River. The Colorado River water traditionally has been the cheapest in the MWD mix, so as the agency uses less of it, the overall cost of water will go up.
By the end of the decade, MWD officials hope that desalinated water will make up about 10 percent of the water supply. "Desalination gives us another tool to draw upon in the event of a drought or an earthquake that severs part of our aqueduct system," said Andy Seinkiewch, resources implementation manager for the MWD.
The impact on water rates is unclear. There are many variables, such as how much of a subsidy the MWD would contribute towards each desalination plant and how much costs for traditional water sources would rise in the meantime.
Since electric power is such an integral part of the desalination process, the cost of desalination depends in large part on volatile power costs. If power costs spike, those costs could be passed on to water ratepayers.
On the other hand, in a drought situation where other water supplies are hard to come by, desalinated seawater could actually lower water rates.
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