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Water Board to Fund Pilot Desalination Plant

Posted on: Thursday, 1 June 2006, 12:00 CDT

By Melissa Mcever, Valley Morning Star, Harlingen, Texas

May 22--As the Valley's population swells, the demand for drinking water grows. Officials have long worried about how the region's primary water source, the Rio Grande, will hold up against the increased demand, and have called for the Valley's cities and irrigators to look at diversifying water resources.

After years of discussion, the region soon will be able to tap into the most abundant and dependable water source of all -- seawater.

The Texas Water Development Board is funding the creation of a pilot desalination plant at the Port of Brownsville, which likely will begin operation in late summer. The pilot plant will help engineers and officials determine the feasibility of building a large-scale seawater desalination plant in the region, said John Bruciak, director of the Brownsville Public Utilities Board.

"We feel that if there's a plant to be built in the state, it should be here in Brownsville," he said. "We feel the area truly has a need."

The state agreed, awarding a $1.3 million grant for the project as part of the governor's call to explore alternative water sources. The Brownsville pilot plant will be the first in Texas.

The Laguna Madre Water District also is planning to build a smaller desalination plant on South Padre Island. Officials still are considering options for funding.

Investing in seawater desalination projects like these helps ensure that the Valley will have a healthy water supply in future decades, said Bill Norris of the Harlingen-based NRS Consulting Engineers. The firm is conducting studies on the two seawater-desalination projects.

"We're proving that it's feasible, and that you can guarantee the water," Norris said.

The Valley could face a serious water shortage in the next two decades if it doesn't better manage the water supply. According to a water-management plan recently submitted to the state by the Region M water planning group, irrigation demand already exceeds supply in the Rio Grande region, and municipal demand will exceed supply by 2020. The group represents interests in Maverick, Webb, Zapata, Jim Hogg, Starr, Hidalgo, Willacy and Cameron counties.

Several local water authorities already have warmed up to the idea of using desalinated water as a way to increase water reserves. Plants to treat brackish groundwater are springing up in Cameron, Hidalgo and Willacy counties. Seawater desalination, however, is a more expensive venture, and thus a harder sell. The proposed full-scale plant in Brownsville, which would produce 25 million gallons of drinking water per day, would carry a price tag of about $151 million. The Valley's largest brackish-groundwater plant, which produces 6 million gallons per day, cost $30 million to build.

The process of treating seawater is more complex and requires more energy than treating brackish groundwater. In the most widely used technique -- reverse osmosis -- seawater is first pumped through filters before reaching membranes that separate the salt to form freshwater. Because seawater is highly saline, the water must be pushed through the membranes at very high pressure, using up considerable power, engineers said.

"It's two to four times the cost of brackish groundwater," Norris said of energy costs.

To provide lower-cost power to the proposed plant, the Brownsville PUB might build a power-generation plant next door, Bruciak said. The PUB already had considered building a new power plant at the Port of Brownsville in the next 10 years.

The pilot plant will help officials answer questions about cost, environmental impact and other issues. The pilot plant will serve as a "miniature" of the large-scale plant, treating about 100,000 gallons per day.

"After the pilot study, we'll seek funding to build a larger facility," Bruciak said.

That request likely will include funds to offset increased costs to consumers. Without an external subsidy, the water's cost could approach $2.50 per 1,000 gallons, compared to about $1.70 per 1,000 gallons currently provided by the PUB.

Bruciak said, however, that the cost of surface water from the Rio Grande is increasing, while seawater cost will continue decreasing. So eventually, seawater desalination might be a more cost-effective choice, he said.

The Texas Water Development Board will help identify financing options for the desalination project, said Jorge Arroyo, TWDB director of special projects.

Arroyo said that the financial risks will be worth it.

"Increasing the reliability of water supply for a region ... it justifies investing ahead of when (the water) might be critically needed," he said.

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Copyright (c) 2006, Valley Morning Star, Harlingen, Texas

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Source: Valley Morning Star (Harlingen, Texas)

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