Could fracking actually save us water?

I am by no means a proponent of fracking and natural gas as the next savior in energy technology for this country, given the widespread signs of water contamination and pollution that have been reported.  But it’s important to keep an objective eye to make sure we take into account the benefits as well when making a decision about our country’s energy dependence.   A previous study has shown that natural gas emits half the CO2 emissions of coal [1], but does this alone outweigh the tangible and documented risks to public health?

A new study published last month in Environmental Research Letters by Scanlon et al may illustrate another benefit of fracking [2].  This study reports that the use of natural gas obtained from fracking in Texas has actually saved water in the state during 2011, a drought year.  The study goes on to project similar savings through 2030.

How could fracking save water when we know it uses so much?  Well, first I’ll say that fracking does use a significant amount of H2O, but not as much as you might think.  As described here, an annual estimate for water consumption from fracking is around 43,800 billion gallons per year.  This may seem like a lot, but this only accounts for 0.3% of the US total water consumption (behind golf courses, I might add, which use 0.5%).  So fracking does use water, but it’s not the main culprit (agriculture takes the cake on that one, I think).

Figure courtesy of Reference [2]
Figure courtesy of Reference [2]

But the main answer that Scanlon et al address is that we use a considerably larger amount of water for traditional electricity generation using thermoelectric power plants than fracking will ever use.  The figure above illustrates what they refer to as the water-energy nexus, which shows the interdependent relationship between energy we use and water withdrawn and consumed.  Energy is used to treat and transport water (righthand arrow) but water is also used for cooling purposes in thermoelectric plants, which account for 90% of electricity generation in the US.  In these types of plants, water is boiled to create steam that drives turbines, giving all of us electricity, but these turbines must be cooled with either air or water to prevent overheating.  Water ends up being more energetically efficient than air, but this results in a large consumption overall!

Figure courtesy of Ref [2]
Figure courtesy of Ref [2]

This fact became especially relevant to Texas in 2011, when major drought conditions impacted water supply while increasing demand.  As seen in the graph below, the total water reservoir capacity in the state per capita has been slowly decreasing over the years, leaving Texas more and more vulnerable to water shortages from drought conditions.  Thus, it is extremely important to determine the optimal methods to generate electricity with minimal water consumption.

Figure couresty of Ref [2]
Figure couresty of Ref [2]

The Scanlon et al paper set out to determine quantitatively how drought affects supply and demand, whether thermoelectric power plants are particularly vulnerable to drought, how power plants adapt during drought, and how using natural gas may help assist in alleviating energy stress during these times.  Using a variety of data sources from power plants across the state as well as federal and state agencies to quantify water use, the paper determined that the drought conditions increased electricity demand by 6%, which resulted in an increased water demand of 9%, due to the use of water in traditional electricity generation discussed above.

Most interestingly, the paper found that power plants are best able to deal with droughts due to increased dependence on natural gas production.  According to the report, about half of Texas’ energy comes from natural gas sources, allowing the state to rely more heavily on these sources when water availability is low.  The paper found that 25-50 times more water is used for steam turbines compared to fracking for the same amount of energy gained!  Although these data definitely need to be confirmed and replicated, it suggests that there is a benefit to natural gas sources that needs to be acknowledge.  That, and we may need to consider new methods of cooling traditional power plants as droughts become more common, especially in semi-arid regions in the southwest, and water becomes a scarcer commodity.

As a side note, the paper also mentioned that states in semiarid regions are not necessarily more drought vulnerable, mainly because these states have already invested in technology that reduces the amount of water required for cooling.  So these states may get less water, but they’re also using less for the same amount of generated electricity compared to eastern, more humid states.  Necessity is the mother of invention…

Finally, I think it’s always essential to examine the funding for research such as this that has become so politically charged.  According to the paper, the work has been funded by the State of Texas Comptroller office, run by Republican Susan Combs, as well as the University of Texas Jackson School of Geosciences.  Not sure how much we can take away from this, but important to remember.  Regardless, these findings raise important issues that should be further explored, especially shedding more light on the fact that we already use tremendous amounts of water for traditional electricity generation.  We can always deride fracking for using billions of gallons of water, but we rarely hear this discussed in terms of how much we use already.  This paper gives part of the answer.

References

[1] Laurenzi I J and Jersey G R (2013) Life cycle greenhouse gas emissions and freshwater consumption of Marcellus Shale gasEnviron. Sci. Technol. 47 4896–903.

[2] Scanlon BR, Duncan I, and Reedy RC (2013) Drought and the water–energy nexus in TexasEnvironmental Research Letters, 2013; 8 (4): 045033 DOI: 10.1088/1748-9326/8/4/045033

ResearchBlogging.org

Bridget R Scanlon, Ian Duncan and Robert C Reedy (2013). Drought and the water-energy nexus in Texas Environmental Research Letters DOI: 10.1088/1748-9326/8/4/045033

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