Buzzword: Shale Gas

What it means. Shale is a fine-grained, sedimentary rock formed from compacted clay. Shale gas is the natural gas contained within the flakes and fragments of that rock. Geologists have long known that this country has abundant supplies of shale gas, as seen in the map (right), which shows shale-gas basins in this country. The map is from "Modern Shale Gas Development in the United States: A Primer," a paper prepared for the U.S. Department of Energy's Office of Fossil Energy and National Energy Technology Laboratory.

Why the buzz? What's generating interest in shale gas is a drilling technique that enables producers to extract the previously unreachable natural gas from deep beneath the earth's crust. The two-fold approach combines horizontal drilling with water fracturing, or hydraulic fracturing or hydrofracking. After penetrating a mile or so into the shale, the drill turns sideways to establish maximum contact with the gas-bearing shale formation. A water-based liquid, called fracking fluid, is then pumped into the formation under high pressure, fracturing the rock and releasing the gas up through the well.

Thanks to the drilling innovations, today's natural-gas reserves are considered 35 percent higher than they were just two years ago. On National Public Radio, Tom Gjelten has reported this week on the Marcellus Basin, a 400-million-year-old formation that stretches from New York to West Virginia and is said to contain 500 trillion cubic feet of natural gas, or the equivalent of 80 billion barrels of oil. Overall, this country sits atop more than 2,200 trillion cubic feet of natural gas, according to a separate industry study, enough to meet current projected natural-gas demands for many decades to come.

Those vast reserves could lead to lower natural-gas prices for you. Read about the Long Island Power Authority's move to give its customers $144 million in credits, which are directly linked to the price drop for natural gas.

Natural gas burns more cleanly than coal and produces less carbon dioxide. That has some environmental groups, including the Sierra Club, calling natural gas a "bridge fuel" that would allow the U.S. to burn less coal and oil while production ramps up on solar, wind, and other renewable-energy sources.

But not all environmentalists are gung-ho for shale gas. The National Resources Defense Council, Damascus Citizens for Sustainability, Riverkeeper, and others have come out against hydraulic fracturing, contending that the chemicals involved contaminate drinking water. A U.S. Senate bill, the Fracturing Responsibility and Awareness of Chemicals Act, would overturn a 2005 law that essentially exempted fracturing fluids from the Safe Drinking Water Act and also require natural-gas companies to disclose the chemicals used in hydrofracking operations.

Read more about the issue in the Department of Energy's "DOE-Funded Primer Underscores Technology Advances, Challenges of Shale Gas Development."—Daniel DiClerico | e-mail | Twitter | Forums | Facebook

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