CHICAGO, Oct 21 (Reuters) - When the Obama administration unveiled new emission regulations for coal-fired power plants earlier this year, the National Association of Manufacturers (NAM) blasted the proposed rules, saying they would hurt its members "twice" - as energy users and as polluters "next in line" for such rules.

Last Tuesday, a NAM-supported effort to challenge the rules cleared an important hurdle when the U.S. Supreme Court agreed to hear arguments in the case. The regulations, which critics call a "war on coal," will cost industry "tens of billions of dollars per year," according to the petition to the high court.

But the proposed carbon caps, which come as the United States is on the brink of a potential power plant construction boom, could be a billion-dollar bonanza for the manufacturers that supply utilities and others with the pumps, boilers and turbines used to generate power.