The virtually limitless expanse of ocean off North County's coastline may soon be more than just a tourist magnet. It looks increasingly like a long-term answer to the decades-old problem of serving this metropolis set in a desert.

Declining costs and an increasing uncertainty about supply from traditional sources have taken desalination from a dream to the mainstream. And North County companies active in the desalination field worldwide are eager to show their prowess locally.

A desalination plant that would produce 50 million to 100 million gallons of drinkable water a day is being considered at Carlsbad's Encina Power Plant. The San Diego County Water Authority, which imports 90 percent of the water used in the county, plans to use desalination for 8 percent to 15 percent of the county's total water supply by 2020, said Bernie Rhinerson, chairman of the authority and of the U.S. Desalination Coalition.

Desalination has piqued the interest of the county's biotechnology companies ---- many located in Carlsbad ---- which place a reliable water supply near the top of their needs.

On Sept. 30, local biotech officials are scheduled to join a tour of a pilot desalination plant in operation at the Encina site. The tour is being jointly presented by the Carlsbad Chamber of Commerce, the San Diego North Economic Development Council, and Biocom, a San Diego-based biomedical industry trade group.

Desalination powerhouse

The proposed Encina plant is expected to produce hundreds of jobs locally, according to Poseidon Resources Corp., the company negotiating with the Water Authority and the city of Carlsbad to build the plant. That's because North County, and San Diego County in general, is a major hub of the desalination industry and make much of the needed supplies.

La Jolla-based General Atomics pioneered breakthroughs in desalination technology decades ago, said Randy Truby, vice president of operations for Hydranautics, an Oceanside-based desalination company. Spinoff companies further developed the technology, creating a desalination industry native to San Diego County.

The pilot desalination plant, which can produce 40,000 gallons of desalinated water a day, shows the potential local economic impact. It uses salt-removing membranes made by Hydranautics and containers made by Bekaert Progressive Composite Technologies Corp. of Vista. These cylindrical vessels are sturdy enough to contain water pressurized to 900 pounds per square inch.

Other North County desalination companies include:

Sepro, an Oceanside maker of membranes for reverse osmosis and other applications;
Professional Water Technologies, an Oceanside-based seller of chemicals used in reverse osmosis;
Lakota Engineering Systems, LLC, a Poway-based maker of industrial equipment and control systems.
In total, about 1,500 people throughout the county work in companies that make reverse osmosis products, Truby said, with about 380 at Hydranautics alone.

Hydranautics' membranes are used in desalination facilities on all seven continents, including Antarctica. They're used for desalination in Iraq, Kuwait and Afghanistan to provide water for the U.S. military, and for civilian plants in Carbaneros, Spain, and Larnaca, Cyprus.

"San Diego is to desalination what Silicon Valley is to wafer chips," said Peter MacLaggan, senior vice president of Poseidon Resources.

MacLaggan said San Diego County-based companies will probably supply 65 percent of the goods and services used to construct the $270 million desalination plant. About 2,100 jobs will be created for the construction.

"That's about $170 million of economic activity during the construction phase," MacLaggan said.

Once the plant is operational, about 400 permanent jobs will be created directly and indirectly in the county, at the plant and at local companies that supply it, MacLaggan said. Local spending will total about $37 million, he estimated.

At the pilot plant, seawater is filtered through sand to remove solid particles, then filtered again to remove microscopic particles. Then the seawater is passed through Hydranautics' membranes. These membranes contain tiny pores that block dissolved salts but allow highly pressurized seawater to pass through. This process, known as reverse osmosis, is the most common method of desalination.

The filtered seawater is pushed through the outside edge of the membrane sheets, which are wound in spirals like rolls of paper towels, but much more tightly. Desalinated water emerges from the hollow core.

The leftover brine, twice as salty as seawater, is pumped back into the ocean, using the power plant's outflow pipes. This method of piggybacking off the power plant's intake and outflow is the same method that the operational plant will use in order to minimize its environmental impact.

Desalinated water is now about 30 percent more expensive than the San Diego County Water Authority's current supply. The cost has gone down considerably in recent years, Truby said, mainly due to advances in membrane technology, and some further incremental cost reductions are likely.

Biotechnology's thirst for reliability

The need for water is what first pulled San Diego County's biotechnology companies together to lobby for their interests in 1990, when a previous drought prompted warnings that water supply might be reduced or interrupted to businesses.

Back then, nearly all biotechs were situated in the city of San Diego. Today, it's estimated from various sources that from 30 to 80 biotech companies are in the city of Carlsbad alone, with many more throughout other parts of North County. Biogen Idec, based in Cambridge, Mass. is building a major manufacturing plant in Oceanside.

Joe Panetta, Biocom's president and chief executive, said he and Biocom have looked at various water supply alternatives for years, such as reclaimed water, and toured the Carlsbad pilot desalination plant last year.

Panetta said biotech companies would like to get water as cheaply as possible, but reliability is more important. That makes desalination more attractive as costs come down and the region's growing population puts greater demands on the existing supply.

"We recognize the fact that if water is in short supply, cost is not going to be as great a concern as reliability," Panetta said.

Panetta likened the situation to the concern a few years ago over electricity supply. While costs during shortages rose from 2 or 3 cents per kilowatt hour to 18 or 19 cents per kilowatt hour, biotechs were most concerned about blackouts.

At the same time, Panetta said. biotechs want "some stability in the price so you can plan or budget. You don't want to have dramatic changes in the price throughout the year."

Contact staff writer Bradley J. Fikes at bfikes@nctimes.com or (760) 739-6641.