Drought and the Water–energy Nexus in Texas

Environmental Research Letters (2013, v8, 045033; doi:10.1088/1748-9326/8/4/045033) / by Bridget R Scanlon, et al.
http://iopscience.iop.org/1748-9326/8/4/045033/

[Abstract] Texas experienced the most extreme drought on record in 2011 with up to 100 days of triple digit temperatures resulting in record electricity demand and historically low reservoir levels. We quantified water and electricity demand and supply for each power plant during the drought relative to 2010 (baseline). Drought raised electricity demands/generation by 6%, increasing water demands/consumption for electricity by 9%. Reductions in monitored reservoir storage <50% of capacity in 2011 would suggest drought vulnerability, but data show that the power plants were flexible enough at the plant level to adapt by switching to less water-intensive technologies. Natural gas, now ~50% of power generation in Texas, enhances drought resilience by increasing the flexibility of power plant generators, including gas combustion turbines to complement increasing wind generation and combined cycle generators with ~30% of cooling water requirements of traditional steam turbine plants. These reductions in water use are projected to continue to 2030 with increased use of natural gas and renewables. Although water use for gas production is controversial, these data show that water saved by using natural gas combined cycle plants relative to coal steam turbine plants is 25–50 times greater than the amount of water used in hydraulic fracturing to extract the gas.

[Time] … a new study argues that fracking for natural gas actually seems to save water in the aggregate, by making it easier for utilities to switch from thirsty coal plants to more efficient natural gas power. Researchers from the University of Texas at Austin collected water use data from all 423 of the state’s power plants. They estimate that the water saved by switching from coal to natural gas is 25 to 50 times greater than the amount of water used in fracking to extract the shale gas in the first place. In 2011, the researchers estimate that Texas would have consumed an extra 32 billion gallons of water if all its natural gas-fired power plants were instead burning coal. “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 of Texas’s Bureau of Economic Geology and the lead author on the study.

The study is a reminder that for all the focus on the water consumed in fracking or by farms through irrigation, one of the single biggest users of water is the power industry itself. Thermoelectric generation—that would be technologies like coal, natural gas and nuclear, which use heat to generate steam—account for approximately 40% of the freshwater withdrawals in the U.S. In arid regions and during droughts—like the historic 2012 drought, which at its height covered up to 65% of the U.S.—water can become so scare that power plants may need to reduce operations or shut down altogether. With population increasing—especially in fecund and popular Texas—and demand rising, the so-called “water-energy nexus” will be a growing challenge for decades to come.

But the huge amount of water used by power plants tends not to get the kind of attention that fracking does—probably because fracking, especially on a large scale, is relatively new, while coal and natural gas plants have been around for decades. (The Texas State Water Board estimates that hydrofracking accounts for less than 1% of total water use, while providing more than 10% of the state’s total economic output.) Fracking for oil and gas is also much more distributed than a centralized power plant is; if you live in Texas, chances are much better that you live closer to a fracked well than you do a power plant. Power plants—and the mining of the coal used in many of them—are out of sight, and thus they’re out of mind.

Still, the fact remains that Texas was a water-stressed state well before the first gas well was fracked, and the concentration of fracking in certain areas of the state can strain local water supplies. Water use for fracking in Texas is also growing rapidly, from 36,000 acre-feet in 2008 to 81,500 acre-feet in 2011. That’s why oil and gas drillers will need to start recycling frac water, or find substitutes that don’t need water at all, like the liquid petroleum gel made by the Canadian company GasFrac. Water is scarce now in Texas and its likely to be even scarcer in a hotter and more crowded future. Every industry—including oil and gas—will need to figure out a way to use our most precious resource more efficiently.

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