Global demand for American natural gas and coal is booming, but recent clashes on both U.S. coasts underscore that getting American supplies to eager foreign buyers will be anything but easy.

Last week, the Sierra Club announced that it would use a unique 1970s environmental agreement to halt the construction of a natural gas liquefaction and export plant at Cove Point in Maryland. Energy giant Dominion, which hopes to build the first such plant on the East Coast, plans to move forward and could end up fighting environmentalists in court.