U.S. tops global energy output list

Workers change pipes at Consol Energy Horizontal Gas Drilling Rig exploring the Marcellus Shale outside the town of Waynesburg, PA on April 13, 2012.
Workers change pipes at Consol Energy Horizontal Gas Drilling Rig exploring the Marcellus Shale outside the town of Waynesburg, PA on April 13, 2012.

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    U.S. tops global energy output list

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