S.117 establishes a market-based cap and trade program for the reduction of emissions of sulfur dioxide (SO2), nitrogen oxides (NOX), and carbon dioxide (CO2) and limits on emissions of mercury (Hg) for the electric generating sector.

The bill proposes to cut sulfur dioxide emissions by 82 percent, nitrogen oxides emissions by 68 percent, and mercury emissions at each power plant by 90 percent, all by 2015. S.1177 also proposes to implement a cap-and-trade program to reduce CO2 emissions.

The bill would require the EPA Administrator to review the annual tonnage limitations and mercury emission requirements every ten years. For calendar year 2030 and thereafter, Section 702(d)(2) would require that the Administrator take into consideration the practicability of increasing the reduction in emissions of CO2 to at least a 3 percent annual reduction.