Now along comes natural gas, oil's quiet fossil fuel sibling. Like many energy sources, it holds both promise and peril. America does harbor large supplies of the fuel, which would help it break free of the vicissitudes of Arab sheikhdoms.
Yet extracting it from shale is causing new environmental concerns, and the historic volatility of domestic supplies evokes old issues of reliability.
Which leaves one fundamental question: How far can America really tilt toward a natural gas economy?
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No one disputes the prevalence of natural gas in America's basement. For evidence look no further than an Erector Set of pipes and docks and storage tanks in the marshes of Sabine Pass, La., on the edge of the Gulf Coast. There, Houston-based company Cheniere Energy Inc., which opened the facility four years ago to import natural gas amid an impending shortage, is now spending billions to transform it into an export site.
In fact, as recently as five years ago, oil and gas executives thought the nation's accessible natural gas reserves were almost played out. The industry was proposing building 47 import terminals to bring liquefied natural gas into the US. Five were actually constructed. Now most of them sit underutilized.
In March natural gas imports hit a 20-year low while domestic production hit a 20-year high. The US is now the largest producer of natural gas in the world.