Concerns fracking hits water supplies are unfounded says a study showing shifting power generation from coal to gas offsets any loss.
The investigation has found that in Texas, the US state that generates the most electricity annually, the transition from coal to natural gas for electricity generation is saving water and making the state less vulnerable to drought.
Though exploration for shale gas through hydraulic fracturing requires significant water consumption in Texas, researchers from the University of Texas estimate that water saved by shifting a power plant from coal to natural gas is 25 to 50 times as great as the amount of water used to extract the gas.
In addition the move to gas also enhances drought resilience by providing so-called peaking plants to complement increasing wind generation, which consumes no water.
"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 at the university's Bureau of Economic Geology, who led the study.
Environmentalists have raised concerns about the amount of water that is consumed in fracking for gas, especially in Texas where water supplies are dwindling as the third year of a devastating drought grinds on.
But in results published in the journal Environmental Research Letters the researchers estimate that in 2011 alone, Texas would have consumed an additional 32 billion gallons of water if all its natural gas-fired power plants were instead coal-fired plants, even after factoring in the additional consumption of water for hydraulic fracturing to extract the natural gas.
The study focused exclusively on Texas, but the authors believe the results should be applicable to other regions of the U.S., where water consumption rates for the key technologies evaluated – hydraulic fracturing, natural gas combined cycle (NGCC) plants with cooling towers and traditional coal steam turbine plants – are generally the same.
The Electric Reliability Council of Texas, manager of the state's electricity grid, projects that if current market conditions continue through 2029, 65 per cent of new power generation in the state will come from NGCC plants and 35 per cent from natural gas combustion turbine plants, which use no water for cooling, but are less energy efficient than NGCC plants.
"Statewide, we're on track to continue reducing our water intensity of electricity generation," said Scanlon.
Fracking accounts for less than 1 per cent of the water consumed in Texas, but in some areas where its use is heavily concentrated, it strains local water supplies, as documented in a 2011 study by Jean-Philippe Nicot of the Bureau of Economic Geology.
The authors concede that because natural gas is often used far from where it is originally produced, water savings from shifting to natural gas for electricity generation might not benefit the areas that use more water for fracking.