Hold the Salt : Pilot Desalination Plant in Huntington May Eventually Help Quench Area’s Thirst

By mimicking nature’s way of producing fresh water from the sea, the Metropolitan Water District of Southern California is firing up a pilot desalination plant here that might use the ocean to quench the region’s growing thirst in the next century.

While desalination has been widely used for nearly 50 years in the Middle East, the same technology has been rejected as far too expensive in Southern California, which historically has had access to cheaper water from the Colorado River and the aqueduct system that imports fresh water from Northern California.

But MWD officials said Tuesday that they expect their new and improved technology to cut the cost of desalination in half. At the same time, they said, the area’s population growth of 250,000 people per year requires the district to tap alternative water sources.

It was California’s severe drought from 1988 to 1994 that kindled the district’s interest in adopting and fine-tuning a distillation process that had been researched two decades ago by the federal government’s Office of Saline Water.

“In the long range, as you look into the next century, [desalinated] water will play a growing role in the water resource mix,” said John T. Morris, a member of the MWD’s board and chairman of its special committee on desalination.

“We recognize droughts will come and go throughout the future, and development of new supplies will be difficult no matter where they come from,” Morris said. But the ocean, he said offers “an unlimited supply of potential water” if the brine is removed to make it potable.

The MWD’s distillation process for removing salt from ocean water resembles nature’s method of using the sun’s heat to evaporate seawater to form clouds that condense as rain.

Distillation, Morris said, is expected to be more cost-effective than the membrane filtering systems used at desalination plants in Santa Barbara and on Catalina Island. Those systems are so expensive to operate on large scale, he said, that they are currently shut down and will be used only in droughts and other situations when the water supply is low.

On Tuesday, Morris and other MWD officials conducted a media tour of the $2.5-million pilot plant, located on the grounds of Southern California Edison’s Huntington Beach power plant on Pacific Coast Highway at Newland Avenue.

The side-by-side desalination and power plants form “a perfect marriage,” Morris said, since steam and ocean water used in the production of electricity can also be used in the desalination process.

Water drawn from the ocean is pumped into two 30-foot-tall evaporators where it is heated until it releases steam. The steam is then condensed into fresh water, while the brine in the seawater collects at the bottom of the evaporator and is discharged back into the ocean.

The pilot plant is being geared up to full production by mid-August, when it will begin to produce 2,000 gallons of fresh water a day during a year of testing, MWD officials said. “It will prove whether the aluminum tubing can perform as we predict it will in withstanding very high temperatures of seawater without scaling or corroding,” said Gary Snyder, MWD’s chief engineer.

Synder said the aluminum in the pilot plant is far less costly than the copper nickel alloy used in the evaporator tubes that are commonly used in the Middle East and makes the process there so expensive.

Synder said fresh water produced by desalination in the Middle East costs an estimated $1,500 to $2,000 per acre foot, while MWD is hopeful that its technology will produce fresh water for less than $850 per acre foot.

If the pilot plant works, he said, “the next step would be to design a 5-million-gallon-per-day unit with the same technology. We are scheduled to have such a plant operating in 1999.”

After that, he said, if the costs are competitive with other new sources of water, similar desalination plants producing up to 75 million gallons per day could be placed at 12 power plant sites from Ventura County to the Mexican border.

“We are delivering about 1.6 million acre feet a year of water to our 16 million customers, which means desalination plants would supply about 5% of our current needs. It could be a very significant part of our water supply by the year 2025,” Snyder said.

He acknowledged that the MWD will also have to consider potential public concerns about how the desalination plants will look on the coast and learn how to mitigate any adverse affects that the concentrated briny discharge may have on marine life.

“So far we are very optimistic,” Snyder said. “All our conceptual work is proving out. . . . No one else in the world is developing a better, more cost-effective distillation technology.”