Hydraulic Fracturing, or Fracking, is a process for extracting natural gas trapped within shale thousands of feet below the Earth's surface. Millions of gallons of water are pumped into wells, along with sand and toxic chemicals, to draw out the gas. This water has contaminated drinking supplies while being stored in open pits above ground, awaiting removal and treatment. This water is also more difficult to treat in water treatment facilities, due to the high levels of toxic chemicals.
Read below for more information about fracking.
Volume 13, No. 1
What are the risks of extracting natural gas by means of hydraulic fracturing ("fracking")?
Ninety percent of new natural gas wells utilize fracking, in which high-pressure water and sand are used to free up gas trapped in impermeable rock (such as shale and coal beds) deep underground. These operations can have a significant negative impact on local water systems.
For example, fracking just one well typically requires 2 million to 4 million gallons of water, as well as a variety of chemicals—some of them toxic—to reduce friction, prevent corrosion, and kill bacteria in the well.
Though most shale gas deposits are far deeper than freshwater aquifers, reducing the potential for groundwater contamination from fracking chemicals, there have been incidents of aboveground chemical spills and gas leaks into well water, which can make people sick and increase the risk of fires and explosions.
Once a well has been tapped, the fracking chemicals are pumped out along with any naturally occurring water. This “flow-back” water is often temporarily stored in open-air pits that, while lined, can leak or overflow during heavy rains. Because of its large volume, high salinity, and the presence of fracking chemicals, flow-back water is difficult to process in municipal wastewater treatment plants.
We therefore need strong policies to support renewable energy and energy efficiency, which can reduce natural gas demand, and regulations to minimize the environmental damage caused by fracking and other methods of fuel extraction. To learn more, visit the UCS website at www.ucsusa.org/naturalgas.
Natural gas in the United States has traditionally been extracted from deep vertical wells that require relatively small amounts of water for drilling but that produce more than 200 billion gallons of water per year that surfaces with the gas on extraction. This produced water is often trapped in these underground formations alongside natural gas. The main methods of disposing of produced water involve pumping it back into oil- or gas-producing wells to bolster production, or injecting it deep into other formations below usable groundwater resources.
|Hydrofracking Diagram. Graphic Source: ProPublica
In the last few years, major new U.S. sources of natural gas have begun to be tapped from shale gas deposits. These new sources are less readily accessible than conventional deposits, and extracting the gas requires a process called hydraulic fracturing or “hydro-fracking.” The process involves drilling vertically down to where the gas is trapped and then turning to follow the deposit horizontally. A mixture of water and chemicals is then sent through the drill hole at high pressures, creating fractures in the rock and allowing the trapped natural gas to escape to the surface. According to oil and gas industry estimates, 90 percent of currently operating wells have used hydraulic fracturing, and the technique is responsible for 30 percent of total domestic oil and natural gas.
Hydro-fracking has become controversial because of concerns about groundwater being contaminated with natural gas and the chemicals used in the process. A single hydro-fracking treatment can yield 15,000 gallons of chemical waste from the fracking fluids. Due to the failure of the industry to disclose the mix of chemicals used in the process and to its successful lobbying to exempt the process from the Federal Clean Water and Safe Drinking Water Acts, concerns have emerged about the ability of local wastewater facilities to properly treat the produced fracking water. Recognizing the potential health and environmental impacts on local water sources, the EPA is studying water impacts of hydro-fracking on gas shale production.
In addition to concerns about water quality, water quantity is also an issue. A single hydro-fracked well can require several million gallons per treatment--dozens of times what is used in conventional vertical drilling. Withdrawing this amount of water over a short period of time can strain local water sources.
Science, Democracy, and Community Decisions on Fracking
A Lewis M. Branscomb Forum
Hydraulic fracturing ("fracking") involves drilling a well into shale formations deep underground and injecting millions of gallons of water, chemicals, and sand under high pressure to break open fissures in the rocks and release oil and natural gas. Recent advances in horizontal drilling and fracking techniques have dramatically changed the American energy landscape. Fracking makes it easier to reach previously inaccessible oil and natural gas reserves, leading to a rapid expansion in domestic oil and gas production.
As public attention to fracking has increased significantly over the past few years, policy decisions and public discussions throughout the country have become impassioned and polarized. Opinions, rhetoric, and approaches to decision making on fracking at both the local and national level are extremely diverse. While some states and towns are restricting fracking as they determine how to proceed, others are allowing development at an exponential pace. In many cases, fracking projects are moving forward without sufficient consideration or availability of robust and independent scientific information and data. Many people believe that better information and stronger regulations are needed to understand and reduce the potential environmental and public health risks of fracking.
In policy debates, we hear much discussion about the immense potential for cheaper energy production. Some also perceive the growth in natural gas production as positive news for mitigating climate change, since burning natural gas produces fewer global warming emissions than coal and oil. However, the drilling and extraction of natural gas from wells, and its transportation in pipelines, results in the leakage of methane—a far more potent heat-trapping gas than carbon dioxide. Methane losses must be kept below 2-3 percent for natural gas power plants to have lower lifecycle emissions than coal and below one percent and 1.6 percent if burning natural gas in a vehicle is to deliver even marginal benefits compared to diesel fuel and gasoline.
Fracking is also being used to extract oil from unconventional sources such as shale formations, which requires a higher number of drilling wells per barrel of crude oil as compared to conventional oil extraction, leading to potentially higher lifecycle emissions for shale oil extraction. Moreover, indirect impacts of fracking operations, including the largely unknown composition of fracking fluid, the fate and disposal of waste fluid, high levels of fresh water use, industrialization of rural landscapes, increased traffic and air pollution, and the impacts of mining the sand needed for fracking, have raised public health, environmental, and economic questions.
A stronger role for independent science to inform public dialogue and decision making on fracking is essential for communities to responsibly approach this complex issue.