Drilling rigs in the midst of cow pastures are hardly a novelty for Texans. But on a warm May day at a site about 30 miles south of San Antonio, a rig was not trying to reach oil or fresh water, but rather something unconventional: a salty aquifer. After a plant is built and begins operating in 2016, the site will become one of the state’s largest water desalination facilities.
They’re going to need lots and lots of really cheap power.
“This is another step in what we’re trying to do to diversify our water supply,” said Anne Hayden, a spokeswoman for the San Antonio Water System.
More projects like San Antonio’s could lace the Texas countryside as planners look to convert water from massive saline aquifers beneath the state’s surface, as well as seawater from the Gulf of Mexico, into potable water. The continuing drought has made desalination a buzzword in water discussions around the state, amid the scramble for new water supplies to accommodate the rapid population and industry growth anticipated in Texas. But the technology remains energy-intensive and is already causing an increase in water rates in some communities.
“If you look around Texas and you look at the climate situation and the fact that the reservoirs are being drawn down, there just isn’t much of an alternative,” said Tom Pankratz, the Houston-based editor of the Water Desalination Report, who also does consulting for the industry.
Across the state, 44 desalination plants — none using seawater — have been built for public water supplies, according to the Texas Water Development Board. Ten more, including San Antonio’s, have been approved for construction by the Texas Commission on Environmental Quality.
Most projects are small, capable of providing less than three million gallons per day, often for rural areas. The state’s largest is in El Paso, where the $91 million Kay Bailey Hutchison Desalination Plant, completed in 2007, can supply up to 27.5 million gallons of water a day, though it rarely operates at full capacity because of the high energy costs associated with forcing water through a membrane resembling parchment to take out the salts. (Production of desalinated water costs 2.1 times more than fresh groundwater and 70 percent more than surface water, according to El Paso Water Utilities.) Last year, the plant supplied 4 percent of El Paso’s water.
Interest in desalination surged more than a decade ago, when the technology became more efficient and cost-competitive, according to Jorge Arroyo, a desalination specialist with the Texas Water Development Board. But the severe drought of the past two years has triggered extra calls to his office. Texas holds 2.7 billion acre-feet of brackish groundwater — which translates to roughly 150 times the amount of water the state uses annually — in addition to some brackish surface water.