One of the least understood impacts of natural gas development is its impact on the water cycle. We often hear about how much water is required to hydraulically fracture a well (as much as five million gallons) and how much of the water (as much 80%) stays underground. Many think this water is irretrievably lost, that is to say forever removed from the water cycle, because we are leaving it a mile or more underground. This is true, up to a point, but it’s far from the full story, because the combustion of natural gas yields water vapor that goes into the atmosphere, and a lots of it. It yields enough water, in fact, to more than replace what is lost in just a matter of months. It’s all a matter of chemistry – the kind we learned in high school. If you weren’t paying attention in class, you might find the whole idea rather fantastic, as some of our anti-gas friends do, but it’s about as basic as it gets and, yes, fire can produce water!
We hear a lot of tall tales and speculation about how water use for natural gas development and hydraulic fracturing, in particular, is threatening us all with potential water shortages. Here are just a few examples:
“The first problem is the massive quantities of water needed …”
Source: Marcellus-Shale.us website
“… the process … destroys and pollutes massive amounts of water, which is necessary for life.”
Source: ShalesShock Media website
The report is “Fracking: The New Global Water Crisis.” Written by Food and Water Watch, it documents the many ways in which the technology called hydraulic fracturing threatens the world’s vital water resources. That’s because fracking — when combined with horizontal drilling — uses prodigious amounts of water as a high-pressure hose to blow apart bedrock. The goal is to liberate the wisps of oil or bubbles of gas trapped inside. Source: Dr. Sandra Steingraber
“the fresh water used … is lost FOREVER, entombed underground, polluted and irradiated. There is a HUGE difference between recreational, manufacturing and power plant usage and the once-and-gone (hydraulic fracturing) usage. It might account for 1% of total usage today, but once 50,000 wells are in place (and fractured multiple times) and as water levels are permanently drawn down by drillers’ withdrawals, it takes a bigger and bigger percentage of available fresh water.”
Source: Comment on PennLive forum
None of this is true. We already know the amounts of water used are anything but massive, for example. The Susquehanna River Basin Commission (SRBC) indicates Marcellus Shale water use in total “represents a little more than half of the amount currently used consumptively by the recreation sector (golf courses, water parks, ski resorts, etc.).” The SRBC chart below illustrates. The most serious of the false assumptions adopted by our anti-gas friends, though, is that the water is lost forever and our overall supply of fresh is somehow depleted. It is not, and it’s all a function of basic chemistry, the kind you learned when you got that first chemistry set for Christmas, as so many of us did over the years. It was always an eye-opener to see how things reacted and combined and that’s what it is all about – the way natural gas reacts with oxygen.
The most serious of the false assumptions adopted by our anti-gas friends, though, is that the water is lost forever and our overall supply of fresh is somehow depleted. It is not, and it’s all a function of basic chemistry, the kind you learned when you got that first chemistry set for Christmas, as so many of us did over the years. It was always an eye-opener to see how things reacted and combined and that’s what it is all about – the way natural gas reacts with oxygen.
A simple combustion reaction is given for methane. The combustion of methane means that it is possible to burn it. Chemically, this combustion process consists of a reaction between methane and oxygen in the air. When this reaction takes place, the result is carbon dioxide (CO2), water (H2O), and a great deal of energy. The following reaction represents the combustion of methane:
CH4[g] + 2 O2[g] -> CO2[g] + 2 H2O[g] + energy
One molecule of methane, (the [g] referred to above means it is gaseous form), combined with two oxygen molecules, react to form a carbon dioxide molecule, and two water molecules are usually given off as steam or water vapor during the reaction, energy is developed as well.
Natural gas is the cleanest burning fossil fuel. Coal and oil, the other fossil fuels, are more chemically complicated than natural gas, and when combusted, release a variety of potentially harmful air pollutants. Burning methane releases only carbon dioxide and water. Since natural gas is mostly methane, the combustion of natural gas releases fewer byproducts than other fossil fuels.
Because this is a chemical reaction, it is also possible to quantify the amount of water produced when methane is burned. The U.S. Department of Energy describes the process as follows:
When one molecule of methane is burned, it produces two molecules of water vapor. When moles are converted to pound/mole, we find that every pound of methane fuel combusted produces 2.25 lb. of water vapor, which is about 12% of the total exhaust by weight.
How much water is produced from combustion of natural gas compared to the water required to develop it? That’s fairly easy to calculate, given what we know about the chemistry involved. A typical natural gas well, as noted above, will require five million gallons of water to develop. If we assume 80% of that stays underground, there is a total of four million gallons removed from the water cycle. That same well can be expected to produce as much as two billion cubic feet of gas over 10 years, as the following Penn State chart illustrates (bearing in mind the curves are improving over time with better technology):
The math connected with the chemistry tells us roughly 11 million gallons of water is added to the atmosphere from burning one billion cubic feet natural gas. Here’s the calculation:
1.5 litres (0.053 cubic feet) of methane = approximately one gram (0.0022 pounds)
One cubic foot of methane = approximately 0.0416 pounds
One billion cubic feet of methane = approximately 41,620,000 pounds
One pound of methane, when combined with oxygen, yields 2.25 pounds of water
One billion cubic feet of methane, when combined with oxygen, yields 93,644,000 pounds of water
One billion cubic feet of methane, when combined with oxygen, yields 11,242,000 gallons of water
Two billion cubic feet of methane, when combined with oxygen, yields 22,484,000 gallons of water
Therefore, our typical gas well will yield about 22 million gallons of water over 10 years as compared to the four million gallons sent permanently below the earth. The four million gallons temporarily removed from the water cycle is replenished within less than six months of production when combusted. If, to be conservative, we assume the well only yields one billion cubic feet of natural gas, combustion of that gas still produces about 11 million gallons of water that is added to the water cycle, which is more than twice that used or retained in fracture stimulation. This would require the combustion of perhaps 12 to 18 months of natural gas production. So much for the wild accusations about how natural gas development is using up our water supply!
Some of our friends on the other side will, undoubtedly, regard all of this as some form of heresy to be ridiculed, but the joke’s on them. Natural gas, when burned, produces water. It’s an undeniable fact. That won’t, of course, change the minds of our friends. They’ll simply pivot and argue the water (and carbon dioxide) added to the atmosphere increases the risk of global warming, but that’s an argument for another day. Moreover, we know natural gas is also a winner in that category. What we can say for now is simply this – natural gas doesn’t consume water but, rather, it generates it.