But past assumptions have been challenged by new technologies — and new uses of old technology. Years of pioneering work on drilling techniques by an independent oilman, George Mitchell, paid off. Despite concerns about water pollution risks linked to hydraulic fracturing of shale, drilling and production have soared.
The United States is rife with these shale plays, some rich in natural gas and others rich in oil. The United States is still producing less oil than in 1971, and prices are high. But the country is producing more oil than in any year since 1994, and production is rising.
Meanwhile, natural gas production has jumped to record levels. In 2000, shale gas was 2 percent of the U.S. natural gas supply; by 2012, it was 37 percent.
Natural gas supplies suddenly look bountiful enough to last a century at current consumption rates, the National Petroleum Council said in a report last year. Some advocates of natural gas have called it a “bridge” to a clean-energy future because its greenhouse gas emissions are half those of coal and because gas plants can start up quickly and pair with wind and solar to provide a reliable alternative to coal.
Others call it a detour, since it is still a fossil fuel and it is undercutting nuclear, wind and solar energy as well as coal. “Bridge to clean future or U-turn to dirty past?” said a headline on the blog of the environmental group Earthjustice. The United States has drilled more oil and gas wells than any other country, and the new wave of supplies has brought a new wave of rigs dotting the countryside and new crisscrossing pipelines.
For environmentalists, the abundance of shale gas poses a political and environmental dilemma. As new gas supplies fuel more and more industrial plants, new constituencies will have stakes in gas production, making it politically harder to impose new regulations. The Environmental Protection Agency is weighing whether to issue additional federal guidelines on various disruptive aspects of shale gas drilling, including the disposal of toxic water used to fracture formations and air pollution from drilling operations. The EPA might also issue rules requiring drilling techniques that would make contamination of water aquifers less likely.
But one thing is clear: Tumbling natural gas prices have changed every calculation and assumption about the energy business.
Perhaps no one benefits more from low natural gas prices than the petrochemical industry, which relies on natural gas as a feedstock and as a source of power. Natural gas, in turn, produces the building blocks for other products, including paints, solvents, plastics, packaging, inks, dyes and lubricants.