HOUSTON — While criticized as a water-intensive technique for producing oil and natural gas, hydraulic fracturing ultimately cuts overall water use in Texas and makes the state less vulnerable to drought, according to a new study from the University of Texas at Austin.
Hydraulic fracturing, or fracking, has helped unleash a bounty of cheap natural gas in the United States by making it cheaper to access energy trapped in deep, dense shale rock. The technique flushes massive volumes of water mixed with sand and chemicals underground to break the rock and release the gas.
As the price of natural gas has dropped, some utilities have shifted away from using coal to produce electricity. The water saved by shifting a power plant from coal to natural gas is 25 to 50 times greater than the amount of water required to extract the natural gas through hydraulic fracturing, the study said.
“The bottom line is that hydraulic fracturing, by boosting natural gas production and moving the state from water-intensive coal technologies, makes our electric power system more drought resilient,” said Bridget Scanlon, senior research scientist for the University of Texas Bureau of Economic Geology.
Hydraulic fracturing can use up to five million gallons of water per well, leading critics to argue that it is overdependent on scarce environmental resources.
But UT researchers found that the consumption is offset by the greater water efficiency in generating power from natural gas versus coal.
In 2010, Texas generated about 40 percent of its electricity from coal and 38 percent from natural gas, according to the Electric Reliability Council of Texas, the state’s primary grid operator. This year, coal has dropped to a 37-percent share of the state’s power generation and natural gas had grown to 41 percent.
The water savings comes from the more efficient cooling towers used in natural gas combined-cycle plants, which have been the primary type of power plant built in Texas since the 1990s. Combined-cycle plants use about a third as much water as coal steam turbine plants.
The study notes that Texas would have consumed an additional 32 billion gallons of water in 2011 if all of its natural gas-fired power plants used coal instead, even after factoring in the additional water in hydraulic fracturing to extract the natural gas.
Hydraulic fracturing accounts for less than one percent of the water consumed statewide. But in some parts of the state that have been hit hard by drought conditions in the last three years, hydraulic fracturing may account for a larger percentage of water used, the report said. Those regions may not experience the statewide water savings, as the natural gas and generated electricity would not necessarily be consumed locally.
Texas grid planners have projected that under current natural gas prices, two-thirds of new power generation by 2030 will come from combined combustion natural gas plants.
Natural gas-fired plants, which can be started up quickly, are also a better complement to wind generation, which does not require water. The combination of wind and natural gas will further reduce the demand for water in electricity generation, the report said.
Researchers collected water use data for all 423 of the state’s power plants from the Energy Information Administration and from state agencies for the study.
Also on FuelFix: