There is a new front in the fight over whether Texas should build more coal-fired power plants — water.

The various water factions - farmers, environmentalists and growing, thirsty cities - have come together as allies against proposed coal plants across the state, with battles now raging from Abilene to Corpus Christi.

Their shared concern: The plants will use too much of an already stressed resource. So the unlikely allies are asking water suppliers to not sell the rights to billions of gallons to the plants, seizing on the notion that, perhaps more than ever, water still shapes destiny.

"Water is where they are most vulnerable," said Ryan Rittenhouse, who works on the watchdog group Public Citizen's anti-coal campaign in Texas. "If (water agencies) don't sell the water, we don't know where else they can get it."

The revival of the age-old debate about the best use of water represents the last, best chance to stop the state's coal boom - in keeping with an aphorism, often attributed to Mark Twain, that out West, whiskey is for drinking and water is for fighting, the anti-coal forces say.

Coal-fired power plants are commonly identified as the nation's biggest emissions villain. But that notoriety hasn't slowed the rush to build them in Texas, where there are nearly 30 coal plants either operating, permitted or proposed.

What has given many folks pause is the amount of water consumed by the plants.

Thermoelectric power plants - those that use heat to generate power, such as nuclear, coal and natural gas - are the single largest user of water in the United States. In Texas alone, they consume 157 billion gallons annually - enough water for more than 3 million people, each using 140 gallons per day, a recent University of Texas at Austin analysis found.

Burning coal produces heat that turns water into steam, which spins turbines that produce electricity. Even more water is used in the cooling process employed at some power plants in which steam is condensed back into water for reuse.

An alternative, known as dry cooling, uses fans and heat exchangers, much like a car's radiator, and consumes far less water. Even then, the proposed Tenaska Trailblazer Energy Center, which would be the first coal plant in Texas to use dry cooling, had asked nearby Abilene to sell it up to 2 million gallons of treated wastewater each day.

Mayor in opposition

Abilene's mayor said in June he couldn't support a sale, citing the need to save it for other uses, possibly as drinking water. The decision delighted the power plant's opponents, who had applied political pressure with yard signs and billboards that read: "Water Yes, Tenaska No."

In parched West Texas, "we felt we could influence people by talking more about water than pollution," said Jeff Haseltine, organizer of the group Abilenians Against Tenaska.

"This is a conservative area, and there are not a lot of people who believe in global warming or worry about air pollution," he said. "But they feel strongly about water."

Tenaska, meanwhile, is looking for other sources of water for the proposed plant, which would generate electricity for about 600,000 homes.

Options may include buying effluent water from various cities and towns around the Permian Basin or pumping groundwater.

The clash is the result of rising demand for both water and energy in Texas. With the state's population expected to double by 2060, there will be more neighborhoods, more businesses, more lights, more air conditioners. Meanwhile, the water supply is projected to decrease by 18 percent because of aquifer depletion and sediment accumulation in reservoirs, according to state forecasts.

The challenge is how to balance new energy demands with the need to preserve a limited resource, said Michael Webber, associate director of the Center for International Energy and Environmental Policy at UT-Austin.

In a report released last year, Webber recommended a framework for integrating water and energy planning in Texas, including requiring a clear demonstration of water availability in the siting of a power plant and providing incentives for cooling options that use less water.

The most water-efficient methods for producing power are not necessarily the most economical, especially at the start, but water shortages could give them a competitive edge, he said in an interview.

"Why would a state with such a scarcity of water even consider coal?" Webber said, adding that abundant natural gas requires far less water to generate power.

Critical habitat

It's a head-scratcher to many folks who rely on the Colorado River for water. They're rallying against the potential sale of as much as 7 billion gallons a year of water to the White Stallion Energy Center, a proposed coal-fired plant in Matagorda County, about 90 miles southwest of Houston.

Rice farmers are now the largest users in the basin. But their supply is interruptible during a period of drought, unlike the amount for cities and industry, and they are fearful that there won't be enough for them in dry times if the power plant is built.

Environmentalists also are concerned that there will not be enough water to protect the estuaries that lie at the river's mouth. The region provides critical habitat for wintering birds and nurseries for fish and shrimp.

The White Stallion plant would require about same amount of water as Cedar Park, an Austin suburb with a population of 65,000.

The river also could be tapped to supply water for the proposed Las Brisas power plant in Corpus Christi. The city has already purchased the water from Garwood Irrigation Co. for future use, but must decide whether to build a pipeline ahead of schedule to aid the plant.

'Just isn't enough'

At this time last year, the river authority informed rice farmers that there might not be enough water for them in 2010.

Then the rain came, breaking a year-and-half drought, the worst dry spell to strike Texas in 50 years.

"We're going to be in this battle every year," said Paul Sliva, a third-generation rice farmer in Matagorda County. "There just isn't enough fresh water. What saved us was the rain."

But Frank Rotondi, chief executive of Houston-based Sky Energy LLC, developers of the White Stallion plant, said the Colorado River has "more than enough water to support our use along with all other known uses," based on the Lower Colorado River Authority's long-range plans. Still, the firm is committed to develop more sources, he said.

The river authority has not set a date to consider the sale. But it is obligated to sell water if water is available and the use is beneficial.

Sliva, the rice farmer, said the river authority has other options: a surcharge on White Stallion's water to promote conservation or a moratorium on all new sales.

"It's water they just don't have," he said.

matthew.tresaugue@chron.com