MWD May Run Desalination Test at O.C. Plant

The Metropolitan Water District is talking with Southern California Edison about testing seawater-desalting technology at the company’s Huntington Beach power plant this year and perhaps building a $60-million demonstration plant there by 1993.

Until recently, California water suppliers have not seriously considered desalting seawater because it takes tremendous amounts of energy and is extremely expensive. The state’s five-year drought, however, is causing MWD to look toward the sea for help in supplementing its supplies.

MWD, which supplies imported water to Southern California, and Edison officials said Tuesday that a small test will probably begin this year, but building an experimental desalter, which would produce 5 million gallons of water daily, is in very early stages of discussion.

O.J. Ortega, Edison’s manager of engineering, said the company recently signed an agreement with MWD to cooperate with desalination projects but added that “a lot of things have to be worked out.”

“We’ve told them, ‘if we can help you out, we’ll be glad to do it,’ ” he said. “We agreed that we will cooperate in every way we can to help Southern California resolve its water problems.”

MWD plans to install a small test unit, costing about $200,000, at the Huntington Beach plant by the end of this year.

If that test succeeds, then MWD would start working out details of the demonstration desalter, which would be a 150-foot-tall concrete silo that would use steam created by the electric plant to heat seawater.

The Huntington Beach site is MWD’s first choice for the pilot plant, mainly because it is near a major water distribution line and the site has room for the facility. If that site doesn’t work out, however, 12 other oceanfront power plants from Oxnard to the Mexican border are under consideration.

“Right now it is the preferred site, but we are not 100% sure if (the desalter) can fit in the site properly and we can get the steam to it,” said Gary Snyder, MWD’s chief engineer. The district supplies imported water to six Southern California counties.

The 5 million gallons created daily would be a relatively small amount for Southern California--enough to serve about 10,000 households per day. Its real value would be in testing ways to cut the high cost of desalting seawater.

By 1996, MWD hopes to build a large, $400-million desalter at one of the 13 power plants in the Los Angeles basin. It would produce 100 million gallons daily.

Desalination has mostly been a technology used in water-poor, oil-rich nations such as Saudi Arabia, where high energy costs are not a deterrent.

At today’s estimates, each acre foot of desalinated water would cost $1,000--four times the cost of Southern California’s imported water and more than 10 times the cost of ground water. An acre-foot of water is enough to serve an average family of five for one year.

The proposed Huntington Beach plant would operate using a version of “flash distillation” similar to that used in Saudi Arabia. Steam generated by the power station would heat seawater, and the new steam that is created would then be captured, cooled and condensed.

Desalination is not new in California, but most of the plants clean up brackish ground water, not seawater. Several such plants are being constructed in Orange County using a technology called reverse osmosis, in which the salty water is passed through carbon filters instead of being exposed to steam.