Test Desalination Plant May Be On-Line Next Year
A small test desalination plant could be operating in Huntington Beach next year, but a full-scale plant designed to provide water throughout Southern California is not expected to be on-line before the turn of the century, the Metropolitan Water District’s assistant chief engineer said Thursday.
Gary J. Hazel, speaking at a meeting of the Anaheim Utility Board, said that planning for the desalination project is “still in its infancy” and that many questions about costs, the environment and the practicality of the project need to be answered before it can proceed.
“Although the MWD has looked at desalinization projects in the past, they never went very far,” he said. “They have always been too costly. . . . That’s why you don’t see a lot of desalinization plants up and down the coast.”
The Huntington Beach test plant, which is planned for installation next to a Southern California Edison electric plant, would be small enough to fit in the back of a flatbed truck, Hazel said. It would produce only 100 gallons of water a day and cost $200,000 to $300,000.
A full-scale plant would produce 100 million gallons of water a day, sit on about 3 acres of land and cost more than $200 million to build, Hazel said. He added that the estimated cost of desalinated water would be more than $1,200 per acre-foot, the amount of water it takes to cover an acre of land under 1 foot of water. Anaheim residents currently pay about $350 per acre-foot.
The test plant would desalinate water through evaporation, Hazel said. Seawater would be pumped into an aluminum pipe leading into a chamber heated by excess steam from the electrical plant, he said. The seawater would then be heated to about 250 degrees and pumped into a low-pressure chamber.
Fresh water would evaporate and separate from the salt. The water would then be condensed and collected. The process would be repeated at gradually lower air pressures until most of the water is separated from the salt.
Such plants have been used elsewhere in the world, he said, but never using aluminum at such extreme temperatures. Because it takes less energy to heat aluminum, it would cost less to desalinate the water--provided the pipes can withstand the heat.
“Aluminum is usually used up to only 170 degrees, but we will try some different alloys and see if it will work,” he said.
A site for a full-scale plant has yet to be selected, but it would probably be next to one of 13 electric plants along the coast to use its excess steam and energy, Hazel said.