Fracking is often criticized for the amount of water it consumes, with a common figure given of 2-3 million gallons per well. One way to look at this is to ask what amount of rainfall would be needed to replace this.
Let's take an actual example. A drilling unit near me covers 351 acres, with two drilling pads. There is no actual work started but both pads have been issued permits. One pad has 1 horizontal bore, the other has 3. Let's assume that the greatest amount of water will be used--3 million gallons for each of the 4 legs. To produce the required 12 million gallons would require rainfall of 1.26 inches on 351 acres. Even in the driest month, October, with an average monthly rainfall in Pittsburgh of 2.25 inches, this means that the water required for fracking all legs would be replaced in just 17 days of rain on just this unit.
Of course, the drillers are not going to use rainfall as a water source. They'll probably take water from the creek. I couldn't find the flow rate of our creek but for one of similar size I found 80 cubic feet/second. The total 12 million gallons could be taken from the creek in less than 6 hours, if it were taken all at once. In other words, every day the creek carries 4 times as much water as needed to frack all 4 legs.
To me this doesn't seem like a large amount of water. But it would still be of concern, if the groundwater were a valuable resource. But it's not, at least not in Pennsylvania, at least for most of the year. Right now, my soil is saturated. All across the hillside below our house, there are springs every 100-200 feet, pouring out water that eventually finds its way to the Ohio river. I know that there are cities and industries that use this water, but they use only a small amount. Look, if anyone thinks the water is valuable, they are welcome to take it. But no-one is taking it. Remember, all the river dams in this part of the country are to control flooding and for navigation and some hydroelectric power. None were built to save water.
I just can't see water consumption by tracking as a problem.
If the water used was all returned to the water cycle, as water from a golf course or swimming pool might be, I doubt anyone in the eastern states would be concerned unless we hit a drought year. The concern is the contaminants in the water that make it unsafe to put back into any usable water source. It's not the water that goes in, but the water that comes out people worry about. And the water that never comes out. Is that water permanently lost to the water cycle? if so, will that eventually impact water flow in the area? The EPA is doing a major study of water life cycle -which should be done by the end of 2012. http://www.epa.gov/hfstudy/
And what happens if Ohio decides it's no longer willing to accept PA wastewater? http://stateimpact.npr.org/pennsylvania/2012/02/02/ohio-officials-g...
There's an interesting comment on that State Impact site:
The solution for fracking pollution is waterless fracking; Gasfrac has
done over a 1000 fracks with gelled propane; you don’t need any water;
you don’t produce any waste fluids (no need for injection wells); no
need to flare (no CO2 emissions); truck traffic is cut to a trickle from
900+ trips per well for water fracking to 30 with propane fracs; and on
top of that the process increases oil and gas production; it is a win
for the industry, a win for the community and a win for the environment.
I've never heard of waterless fracking - but if that was possible, it would be a gamechanger, wouldn't it?
Really....explain to me how ALL water (your words, not mine) is returned from a golf course or a swimming pool? So, your premise is that nothing used on a golf course or a swimming pool evaporates to the atmosphere? ALL of the water used on a golf course and in a swimming pool mysteriously finds its way back... that would be news to quite a few hydrologists. Can't wait to hear the details!
when I say it all returns to the water cycle -I'm including water that perks down through the ground, evaporates and returns as rain, etc. That's all part of the water cycle, right? Evaporation, condensation, etc. Water put deep into the ground doesn't perk back up - it's basically gone from the water cycle.
This is crazy. Carol, I have to say, you are either a very scared person, or a person who likes to yell fire in crowded room. I suppose next you'll be wanting us bad human's fitted with a recycling unit to our bladder's, because what's going in is not coming out in a re-usable state.
The more of your post's I read, the more convinced I am that no matter what the industry does, you would quickly find issues with it.
As Andy Dufresne might say, "Why are you being so obtuse?"
I'm not sure I'm the one being obtuse. Water used on the earth's surface - golf courses, drinking water, whatever, might come out in a different form, but it continues to be part of the water cycle - perks down to water tables, runs through streams, evaporates to clouds, rains down again. Ninth grade earth science - right?
But a large percent of water used in fracing wells doesn't come back up to the water table, or if it does, very very slowly. So - it's permanently removed from the cycle. Does that matter? Apparently -that's one of the questions the EPA is trying to understand.
Some studies have shown that anywhere from 20-85% of fracking fluids may remain underground. . . In 2010, the U.S. Environmental Protection Agency estimated that 70 to 140 billion gallons of water are used to fracture 35,000 well.... This is approximately the annual water consumption of 40 to 80 cities each with a population of 50,000. Fracture treatments in coalbed methane wells use from 50,000 to 350,000 gallons of water p..., while deeper horizontal shale wells can use anywhere from 2 to 10 million gallons of water to fracture a single well. The extraction of so much water for fracking has raised concerns about the ecological impacts to aquatic resources, as well as dewatering of drinking water aquifers.
I'm sure there's some reason that source is suspect - it's not funded by the industry, so, why believe it, right? - but the question remains, and it's at least worth thinking about.
And to go back to the original question: there are quite a few reservoirs in this region built to maintain water supply during dry years. And there have been years when the water level in those reservoirs is dangerously low. So impacting the water table, even in an area where drought isn't normally a problem, could be a problem in years with less rainfall.
Don't worry. Really, don't worry. The polar ice caps are melting, so there will be plenty of water.
You've mentioned previously that you're interested in open and fair discussion of the dangers involved in natural gas drilling in general and hydraulic fracturing in particular. To that end you weighed in here, questioning the consumption of surface water. It's a valid concern and I am happy that the on-site recycling of flowback water is coming online (Rettew has recently designed a system, among others). It will reduce traffic, damage to roads, water treatment facilities, and surface water supplies. All good things. And yes, your understanding of the water cycle is correct. :)
So you see this isn't an attack. I appreciate your position but think it would help your credibility if you acknowledged what PA roughneck pointed out that combustion creates a net gain in surface water. You asked a good question and got a good answer. If you're truly interested in honest discussion and expect people to see reason you should do so yourself and acknowledge that. Perhaps it would help some of the more excitable members here to keep calm when someone doesn't agree with them wholeheartedly. Just a suggestion. Have a good day.
Carol, what many forget to note is the water formed during the combustion process of gas.
When methane (CH4) is burned, the resulting products are CO2 and H2O.
For every 1000 cubic feet of methane burned, be it in a power plant, water heater, furnace, stove or even when the wells are flared, that 1000 cf will produce 12 GALLONS of water.
If we take a look at the most productive well in PA, the King 2H in Susquehanna Co. it produced 3.9 billion cubic feet of gas as of 12/31/11. According to Fracfocus.org, the King well required 10 million gallons of water to frac. When all this gas was burned, it returned some 46.8 million gallons of water to the hydrological cycle.
The operator of that well recently estimated it's ultimate production to be some 20 billion cubic feet. When this well is finally exhausted, the gas produced will have ADDED 240 million gallons of water to the atmosphere, that's 24 times the amount of water removed from the Susquehanna watershed used to extract the gas.
What these wells require in water to be fraced is a fraction of the amount of water that the combustion of the gas they produce will ultimately add to our water cycle.
I'm no math major but according to what I found your math is off a bit. Of course some of it depends on air pressure and temperature but it appears that one Mcf (thousand cubic feet) of gas gives off something closer to 2.5 gallons of water during combustion.
Jim, my figures may be off, it's been some time since HS Chemistry class :)
I arrived at my numbers via the following-
Combustion of methane-
CH4 +2 O2--> CO2 + 2 H20
Thus one mole of CH4 at STP occupies 22.4 liters (ideal gas law), producing 2 moles of H2O.
1000 cubic feet =28,316.8 liters/22.4= 1264 moles.
1264 moles x 2= 2528 moles of H2O
2528 moles of H20 @ 18g/mole=45,504g of H2O
45,504g/454 (g/lb)=100.22 lbs H20
100 lbs H20/ 8.36 (lb/gal)=11.96 gallons.
If you happen to see any errors in my math or the chemistry itself, feel free to point them out. Like I said, it's been a loooong time since chemistry class!
I'm impressed by all the math. And by the idea - which makes sense- that the water is recaptured when the gas is burned.
But that sets me wondering if it matters where the gas ends up - if it's piped to the coast and shipped to China, do they get our water?
Not sure that matters - there's more on that one that sets me wondering: like how it helps our energy independence if we ship our gas to china, and why it would be considered "public domain" to build the pipelines, if the profits go to the gas companies. But those are different questions. So thanks for the info about the water produced.
re: who gets 'our' water when the gas is burned? As you've noted it would depend upon where the gas was burned. Considering that water vapor is a byproduct of the combustion of ANY hydrocarbon, as well as the fact that weather, at least in the US, tends to move west to east, here in PA we are seeing the water produced via the burning of hydrocarbons in the states to our east. Water from the gas burned here will probably actually end up falling as rain over the Atlantic!
As far as exports go, I have my doubts regarding the financial viability of exporting Marcellus gas to China, or anywhere else for that matter. Certainly in the short term, more money can be made selling our gas on the world LNG market than can be realized selling it domestically.
The advent of shale drilling however, has basically turned the tables on energy production. Some countries, like China and India, that lacked conventional reserves have in fact VAST shale resources that may very well be worthwhile for themselves to exploit.
I'm thinking that the co's looking at spending enormous sums of capital on LNG export terminals, will see their investments sitting idle, much as their domestic LNG import terminals do now, thanks solely to the advent of the shales.
See what China is looking at here-http://www.ogj.com/articles/print/vol-110/issue-3/exploration-devel...
To get an idea of just what a 'game changer' the 'shale revolution' is, try this essay-http://www.cst.net/geoscience/oil-business/129-extrapolate-horizont...