What’s the Fracking Problem?
One image in the HBO movie Gasland changed our perception of shale gas: a Pennsylvania resident held a lit matchstick up to a running kitchen faucet and turned it into a blowtorch. An army of hydrogeologists cannot expunge that image from our consciousness: tap water caught fire.
The United States is the Saudi Arabia of natural gas. According to the Energy Information Administration, the U.S. has more than 2,552 trillion cubic feet of technically recoverable natural gas – enough to fuel the United States for 110 years. Unconventional sources, such as shale gas found in the Marcellus Shale Formation beneath Pennsylvania and parts of New York and the Barnett Formation under Texas account for 60% of our reserves. Unlike conventional gas fields where natural gas can be extracted simply by venting underground pockets, extracting natural gas from shale formations is hard work. The extraction technique, known as “hydraulic fracturing” or “fracking,” works as follows. First, drill a mile down into the earth, then take a right turn and drill laterally into a shale rock formation. Next, fracture the shale rock by blasting it with millions of gallons of water, sand and a small amount of chemicals. Finally, withdraw that water/sand/chemical mixture, along with natural gas released from the interstices of the fractured rock.
Shale gas offers many advantages if it can be safely extracted. It could lessen our dependency on foreign oil and thereby enhance national security. Moreover, combustion of natural gas releases less carbon dioxide per Btu than combustion of either coal or gasoline. Thus, natural gas has the potential of being the transitional fuel of choice until renewable energy becomes both more cost-effective and sufficiently developed to meet our energy needs. From the moment that kitchen faucet became a blowtorch, however, shale gas has been subjected to intense scrutiny. Congressional committees have called for disclosure of the chemicals used in fracking fluids. Environmental groups have demanded that federal and state regulators develop strict rules for fracking to prevent groundwater contamination. The picture that is emerging from this scrutiny is not yet complete, but here is what we know.
Chemicals Used in Fracking. As noted above, fracking fluids consist of water, sand and a small amount of chemicals. Water and sand can make up more than 99.5 % of the fluid. Water acts as the primary carrier fluid in hydraulic fracturing, and sand props open the fractures so that gas may escape. The 0.5% chemical component of fracking fluids has garnered a disproportionate share of the attention. This is partly because fracking fluid providers have been reluctant to disclose the identity of the chemicals, which they contend are trade secrets. The function of these chemical additives, however, is not secret. Some chemical additives improve the flow of the fluid (making it “slippery”); others kill bacteria that can reduce fracturing performance. According to a House Committee that investigated the chemicals used in fracking, over 750 different chemicals have been used. Most of the chemicals used are innocuous (e.g., sodium chloride (salt), gelatin and even instant coffee). A few pose significant human health hazards (e.g., methanol, isopropanol and 2-butoxyethanol).
Groundwater Contamination. Conceptually, fracking fluid that is pumped 6,000 feet below the surface through a steel pipe should not come into contact with groundwater, which is at most 1000 feet deep (and usually much shallower). The potential for groundwater contamination is much greater, however, when fracking fluids are brought back to the surface. These returning fracking fluids (referred to as “flowback”) can carry back many naturally occurring substances that pose hazards, including heavy metals (e.g., barium) and radioactive matter. Some operators hold returned flowback in rudimentary lagoons or pits – little more than excavated holes in the ground. Flowback can leach out of the bottom of these pits and contaminate underlying groundwater. To prevent such contamination, operators are beginning to utilize closed loop systems, which store and transport flowback within a series of pipes and aboveground tanks.
Leaking well casings are another potential pathway for groundwater contamination. Observers believe that the flammable tap water depicted in Gasland was caused by methane gas that escaped through well casing cracks and fissures, and contaminate groundwater. As a precautionary measure, some operators have begun encasing well borings with multiple layers of steel.
At some point, flowback becomes too dirty to be reused, and must be discarded. Proper disposal of flowback is critically important to the protection of both surface water and groundwater. The vast majority of flowback is disposed of in underground injection wells, regulated by EPA’s “Underground Injection Control” program. Although disposal of flowback in permitted injection wells is currently the most effective means of safely isolating these fluids from the near-surface environment, the required specific geological conditions that are required for such wells do not exist in all areas. Depending on the location, there may be other methods of handling flowback such as treatment and discharge. Treatment of flowback can be conducted on-site or in centralized treatment facilities. If discharge is allowed under state or federal law, it must be done under strict controls which would typically require the issuance of a National Pollutant Discharge Elimination System (“NPDES”) permit from EPA or a state environmental agency.
Advances in flowback treatment technology offer the promise of using flowback for other purposes, rather than simply disposing of it. The use of filtration, reverse osmosis, decomposition in constructed wetlands, ion exchange and other technologies may eventually result in the widespread practice of using flowback for such things as managed irrigation and land application. One practice in use today is the recycling of flowback for reuse in other hydraulic fracturing jobs, which saves water. This technology is being used by companies like Devon Energy in the Barnett Shale Formation around Ft. Worth, Texas. Several companies also use this technology in the Marcellus Shale Formation in Pennsylvania.
The explosive growth of hydraulic fracking has exposed some of the environmental risks associated with shale gas, particularly in the Northeast where gas is often located closer to population centers. The dramatic image of tap water catching fire may look frightening, but it pales by comparison to the images from the Deepwater Horizon blowout in the Gulf of Mexico, as well as the Fukushima Daiichi nuclear disaster. Every source of power has its pros and cons. We must exercise patience with shale gas as we develop improved methods of extraction. Shale gas offers enormous promise for this country’s energy needs, and the risks are manageable.
Peter L. Gray is a partner with McKenna Long & Aldridge LLP, where he chairs the Environment, Energy and Product Regulation Department.
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