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Drinking water from the Gulf

Well, there is a lot of water there.

The wicked drought gripping Texas has made one thing clear to Bill West: There is not enough water to meet new urban demands and competing environmental needs.

So in his search for new sources of water, the general manager the Guadalupe-Blanco River Authority is looking in another direction. West plans to tap the Gulf of Mexico.

The river authority has launched a two-year, $2-million study into the economic viability of building a seawater desalination plant by the Texas coast, a technology being used in Australia, Singapore and the Middle East that has been slow to take hold in North America.

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The cost of desalting seawater is usually many times more than that of conventional water sources, such as rivers and reservoirs.

The Texas Water Development Board has estimated that water from a desalting plant will cost about $2,000 an acre-foot, roughly enough water to satisfy two or three families a year. The Guadalupe-Blanco River Authority, which supplies water for a fast-growing corridor between Austin and San Antonio, now sells water from the Canyon Lake reservoir for $125 an acre-foot.

Energy is the primary driver, accounting for as much as 70 percent of the operating costs of a seawater desalting plant, said Tom Pankratz, the Houston-based editor of the Water Desalination Report.

“In a number of places, desalination always has been too expensive,” he said. “But now the cost of developing conventional supplies is rising, making the cost of desalination more viable.”

The Guadalupe-Blanco River Authority would build the desalting facility with a power plant near Victoria, about 130 miles southwest of Houston. The power plant likely would be fueled by cheap and plentiful natural gas from the nearby Eagle Ford play, though the feasibility study also will look at renewable energy sources, such as solar and wind.

“The energy part of the equation has changed over the years,” said Les Shephard, director of the Texas Sustainable Energy Research Institute at the University of Texas at San Antonio, which will help the river authority on the project. “Now is a good time to look at natural gas.”

See here for previous blogging about desalinization. Most of what has been talked about so far has involved brackish water, of which there is plenty in Texas. It’s cheaper to process, since it’s not nearly as salty as seawater. I get the impression that things must be getting desperate if using water from the Gulf is looking like a viable option.

The Guadalupe-Blanco River Authority’s idea “seems awfully Herculean for what we need,” said Amy Hardberger, a water policy and law professor at St. Mary’s University in San Antonio. “It does not get to the heart of the matter.”

Hardberger said the river authority should look more closely at using water more efficiently before building a big desalting plant that could cost more than $1 billion. She is among those who are skeptical of the state’s projected needs, saying the estimate overstates demand by assuming each Texan will use the same amount per day in the future.

Others are bullish on a brackish desalination. The groundwater is much less salty than seawater, so purifying it is much less expensive. The San Antonio Water System, for one, is building a $145 million desalting plant above the Wilcox Aquifer, about 30 miles south of the city.

There are 46 brackish desalination plants across Texas, with nearly 40 more facilities included in the state’s long-range water plan. The state holds 2.7 billion acre-feet of brackish groundwater, which is 150 times the amount of water Texans use each year, according to the state water board.

But West said the Gulf is more attractive than a salty aquifer because he can avoid the often nasty permitting fights with the special districts that oversee groundwater. What’s more, the river authority’s project is an important piece in an “all-of-the-above” water portfolio, especially with climate models showing Texas getting less rainfall as global temperatures keep rising.

See here for more on what San Antonio has done, and here for all my previous blogging on desalinization. I’m curious about putting a desalting plant in Victoria – wouldn’t you also need to build a big pipeline to get the water there in the first place as well? Most of the previous stuff I’ve seen on desalinization had to do with brackish water, which is found all over Texas, but in browsing my archives I didn’t see any indication of how much it cost to desalinate brackish water, so I don’t have a basis for comparison. I do agree with Prof. Hardberger that conservation has to be the first priority, as that is always the cheapest option, but in the long term I suspect desalinization will be a part of the equation. I don’t know how much of that will be Gulf water, though.

One thing I’ve yet to see mentioned in any story about desalinization is what to do with all the excess salt – technically, the brine water that is left over, which can be 15 to 25 percent of the intake, from what I can tell. If you take salty water and extract all the fresh water you can, you’re going to have to do something with the extra super salty residual water, right? Fortunately, the Sierra Club of Texas has done the heavy lifting on that, and you can read all about it here. If we’re going to go down this road – and I believe we are – we need to make sure we have sufficient environmental controls in place so that we don’t create bigger problems than the ones we’re trying to solve.

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One Comment

  1. [...] Desalination is an expensive way to clean drinking water.  In the past, purifying fresh water, even heavily polluted fresh water, has been cheaper.  Those days might be past. [...]

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