It would keep prices in the range of $10-$30 per ton.-- The legislation would aim to bring carbon emissions down by 17 percent by 2020, from 2005 levels.-- Firms with smokestack emissions below 25,000 tons would not face new pollution restrictions.-- Controls on smokestack emissions from factories, including steel, chemical, paper and cement, would be phased in beginning in 2016 under a cap and tr