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Natural Gas: Fracking: What Is It and Why Does It Matter?

by Bob Shively, Enerdynamics President and Lead Instructor

Those who follow environmental issues and/or are involved in the energy industry have no doubt heard about the fracking debate. One headline announces that fracking is a huge advancement that has given us a huge new supply of domestic natural gas supply (see for instance this summary of a talk by U.S. Department of Energy Secretary Steven Chu). The next headline reads that fracking is one of the biggest current threats to the environment and human health (see Greenpeace’s take on the issue). This article examines what fracking is and the potential environmental issues at the heart of the fracking debate. 

What Is Fracking?

Hydraulic fracturing, commonly called “fracking,” is a method of stimulating gas flow in underground formations.  Under so-called conventional natural gas production, the underground formations that hold natural gas are permeable rock meaning that small holes and fissures in the rock allow gas to flow within the formation. The gas is normally trapped by a layer of non-permeable rock that forms a cap. To produce natural gas, a well is drilled into the rock holding the gas and the gas flows from the higher pressure underground to the lower pressure wellhead. 

The need for fracking arises when the rock holding the gas does not have sufficient permeability to flow adequate volumes to make a well economic. Producers have learned that by increasing permeability of the rock, more gas can be recovered. This is the purpose of fracking, which is a technique that fractures the underground rock as a means of increasing the flow.

The process of fracturing begins with drilling a well. First the well is drilled vertically, but once the desired depth is reached, the well is then drilled horizontally. After pipe has been inserted in the well and the pipe has been cemented in, perforations are made in the pipe and cement in sections where gas flow is desired. This is done using a device called a perf gun. Next, a mixture of fluids including water and chemical additives are pumped into the well at high pressure. The fluids flow through the pipe and out the perforations and, given the high pressure, cause fractures in the rock. When the fluids are then pumped back out of the well, gas flows through the newly created fractures, into the pipe via the perforations, and then to the wellhead. (For a good video of the process see the American Petroleum Institute’s website.)

   source: http://www.propublica.org/special/hydraulic-fracturing-national


What Fracking Technology Has Done for Gas Reserves

The technique of fracking has resulted in a huge boost to U.S. gas reserves. It allows more gas to flow from some conventional wells, but more importantly, it allows use of gas in formations where the rock is not permeable enough to allow economic gas production. The key unconventional resource is shale gas, which in 2009 made up 14% of U.S. gas supply but is projected to increase to 45% by 2035 according the U.S. Energy Information Administration.

Production of these unconventional reserves is not possible without fracking. So using these techniques means we have access to a large domestic energy resource that is the cleanest of the fossil fuels and is useful for heating our homes, running our power plants, and fueling large industry such as chemical production. And gas power plants function well with renewable energy production since gas units have the flexibility to ramp up and down in response to variability of wind and solar supply. 

What’s the Concern with Fracking?

Considering the above benefits, fracking sounds great. It gives access to a clean domestic energy source that works well in conjunction with renewables. But there is a catch. As fracking has been used more, it is apparent that there are potential environmental impacts. These include:

  • Disposal of fracking fluids: Anywhere from 15 to 80% of the fracking fluids are returned to the surface and must be disposed of.  The fluids include chemical additives that are used to improve the fracking process and may also include additional substances absorbed from the underground formation. Until recently, the production industry has been reluctant to reveal what chemicals are in the fracking fluids, which must be disposed of in a safe manner. In a few limited cases, humans appear to have had severe reactions after coming in contact with fracking fluids.

  • Migration of fracking fluids and/or natural gas into water supplies: While the production industry claims that fracking fluids and produced natural gas cannot leak into water supplies because fracking is performed at much lower depths than the water tables, anecdotal evidence seems to indicate that, either through improper drilling techniques or through other causes, cases of ground water pollution have occurred in limited incidents.

  • Leaks of greenhouse gases: At least one study has suggested that the fracking process can result in significant release of methane during the development process. Methane is a significant greenhouse gas.

Can these Issues be Resolved?

So, can these issues be resolved and safe production occur? It’s the million dollar question. Most within the gas industry believe the answer is yes, but the industry must convince the public and regulators. The U.S. Environmental Protection Agency (EPA) is currently performing a comprehensive study with results expected by 2012 (see http://water.epa.gov/type/groundwater/uic/class2/hydraulicfracturing/index.cfm). France has banned fracking until studies are complete. On a domestic front, New Jersey has halted all fracking until more research is done, and many other U.S. states are grappling with the question of how to regulate fracking. And it is possible that the EPA study may lead to federal regulations on fracking.

Worst-case scenario? The public and policy makers decide that fracking is unsafe and suddenly natural gas supplies are very tight, which will result in major gas price increases. A best-case scenario is that the production industry works closely with scientists, regulators and the public to develop and implement safe techniques that allow for exploitation of huge gas resources. It remains to be seen whether the outcome is worst-case, best-case or somewhere in between. 

Meanwhile, the U.S. Department of Energy (DOE) is also looking into safety issues related to developing shale gas. Chu said he sees evidence that "bad things have happened," including water pollution where fracking fluids and natural gas have appeared in drinking water supply.

"The question is, what is the cause of that, and how can they be prevented and mitigated," Chu said. "Science will give us better ways of monitoring what is going on."

A sub-panel of scientists set up by the DOE to come up with recommendations released a report on August 11 (http://media.npr.org/documents/2011/august/Shale_Gas_Production_90_Day_Report.pdf). It suggests that impacts of fracking are manageable, but it also presented a number of recommendations on how fracking could be made safer.

"The question is, what is the cause of that, and how can they be prevented and mitigated," Chu said. "Science will give us better ways of monitoring what is going on."

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