As a relatively clean-burning and domestically abundant fuel source, natural gas is widely seen as a part of the solution to the energy woes facing the U.S. Recent technological advances such as horizontal drilling and new methods of hydraulic fracturing, or fracking, have allowed companies to begin large-scale natural gas operations in many parts of the country, most notably Pennsylvania. But these methods can endanger local residents and the environment when methane—the main component of natural gas—enters drinking-water wells as the result of the extraction process. This connection was scientifically corroborated in a recent study in Pennsylvania and New York conducted by several Duke researchers. Avner Vengosh, professor of geochemistry and water quality, is one of the coauthors.
Why does everybody seem to be talking about fracking all of a sudden?
Many people see natural gas, coming from deep shale formations, as the future of energy in the U.S. And many people see that as changing the landscape of energy—stopping dependence on foreign oil and the idea that you have energy sources here and now.
The ability to penetrate into a deep shale formation through horizontal drilling was a pretty major technological breakthrough, which happened only in the last four or five years. You drill down like 7,000 feet or 6,000, depending on where you are, and then you start to drill horizontally through the layer.
The fracking process involves injecting fluids into the shale formation that release the gas, and nobody really knows exactly what is the chemistry of these fracking fluids, it’s kind of the secret of the oil and gas companies. The idea is that once the fluid is injected into the well, you’ve created tiny earthquakes in which the methane, the natural gas, which has been trapped within the shale gas, is released to the well and then pumped to the surface.
We’ve used natural gas for a long time in the U.S.
But this is different. This natural gas is harder to get to.
Until a few years ago, it was impossible to get shale gas. Currently, about 10 or 15 percent of the total natural gas that is produced in the U.S. —and in thirty years it is expected to rise to 50 percent —comes directly from shale gas.
That’s why there are so many interest groups—industry, different states, the governors—that want this to happen.
There is a lot of money at stake. People have known that there were some environmental issues before, but it hadn’t been systematically investigated. It was mostly anecdotal. There was Gasland, the movie, for instance. Our study was the first at trying to systematically address the potential environmental issues of hydraulic fracking.
And what you found is that methane gets into wells.
Yes, into shallow drinking-water wells of people who live less than a kilometer from an active shale-gas well.
What’s the risk of that?
The question is what is happening when you have methane in your well and the house. There were reports of some explosions of houses in Pennsylvania. We couldn’t find any literature about the direct health aspects of methane in drinking water because there have not been any studies of that.
I’m trying to understand how methane gets into the water supply.
In our study, we did several things. First, we documented the level of methane in the drinking-water wells. Second, we analyzed the isotopes in methane. The geochemical isotope is like a fingerprint in which you identify the source of the methane. And basically you can have two major sources of methane: one, thermogenic, is the methane exploited from deep shale gas and found in [drinking-water] wells. There is another type of methane that is called biogenic, which is formed in much more shallow depths.
Our study showed that the high methane in the shallow [drinking-water] wells located near gas wells has a deep thermogenic fingerprint. That means it has to be associated with fracking.
Now how this methane actually comes up into the [drinking-water] well, we don’t know. In our paper, we outline several possible mechanisms. We think the most likely mechanism is something wrong with the installation of the casing of those deep [gas] wells that is supposed to isolate the [gas] well from the environment.
You mentioned fracking fluid earlier. Most of what is shot into the rock is water, right, and then a small amount of chemicals?
“Small amount” is the way that the industry describes it. If you take the most concentrated brine on Earth, the Dead Sea, for example, it has a “small amount” of salt.
The idea is that [when] you frack the wells, about 50 percent, some people say 80 percent, of this injected fluid is lost in the geological formation. Some of it will come back to the surface, along with the water already trapped in the rock—formation brine, which contains a high level of salinity, radioactivity, and toxic metals like arsenic.
Which is naturally occurring?
Yes, which is naturally occurring. But, personally, I think that over a lifetime of a well, this water is more dangerous than the fracking fluid, although I should be careful as we do not know exactly what is the full composition of fracking water. The volume is much larger in the long term. Every time you produce gas from this well, you also produce water from the geological formation.
Some companies try to recycle this water. Other companies discharge it to the surface water with some sort of treatment, and it’s kind of in question how they do it and what’s happening to the environment. I’d say it’s one of the major environmental issues associated with fracking.
What do you think we should do about it?
First of all, acknowledge the problem.
There are other environmental issues. For example, there was a study in New York, which led to a moratorium of horizontal drilling and fracking, that only the movement of trucks and traffic—and we’re talking about drilling and fracking thousands of wells—is going to be a nightmare for people living there, even without any of the potential contamination we are talking about right now.
Things at stake here are huge: changing where we get energy, our dependence on foreign oil, getting away from coal. We are not taking it lightly. How you actually deal with the balance between protecting the environment and having energy—it’s a tough one.
But it’s better that we’re pursuing natural gas rather than oil?
Some say that natural gas is much cleaner in terms of CO2 emissions into the atmosphere than the combustion of coal and oil. However, there is a study that came out of Cornell just before our study —it was based on modeling, not on direct measurement—that argued that a lot of methane is escaping to the atmosphere during the fracking procedure. They argue that it’s worse than coal because once methane escapes into the atmosphere, its greenhouse-gas impact is about four times that of CO2. The fact is that we see this large amount of methane in the groundwater that we think is associated with the wells, and it’s going to escape to the atmosphere, eventually.
I see fracking as inevitable; I don’t see a way to stop it. The real breakthrough would be if industry were willing to work with the scientific community, which hasn’t been done so far. We were hoping to build those bridges, but it’s tough. We are really open to work with the industry, for example, by going into a site and trying to understand the mechanism for how this methane is escaping, and then to see how this can be prevented. By the end of the day, if there is escape of methane from the casing, the industry is losing a valuable product, so I think it’s in their interest as well. But the question is whether or when the industry will be ready to work with us.
This interview was conducted, condensed, and edited by Aaron Kirschenfeld.