On September 20, 2013, the United States Environmental Protection Agency (EPA) proposed new standards that would place limits on carbon dioxide (CO2) emissions from new power plants. Greenhouse gases, which include CO2, fall within the definition of an “air pollutant” under the federal Clean Air Act and are considered a major contributor to climate change. Power plants are the largest concentrated source of greenhouse gas emissions in the United States, and account for approximately one-third of all domestic greenhouse gas emissions. Some states have implemented or are implementing their own market-based programs to reduce carbon emissions. However, currently, there are no federal limits on the amount of carbon pollution new power plants can emit.

The proposed new standards would establish separate standards for fossil fuel-fired electric steam generating units (utility boilers and Integrated Gasification Combined Cycle (IGCC) units) and for natural-gas-fired stationary combustion turbines. New fossil fuel-fired utility boilers and IGCC units would have to meet a limit of 1,100 pounds of CO2 per megawatt-hour over a 12 month operating period, and would have the option of meeting a limit of between 1,000 and 1,050 pounds of CO2 per megawatt-hour if they choose to average emissions over an operating period of 84 months. New large natural gas-fired stationary combustion turbines would have to meet a limit of 1,000 pounds of CO2 per megawatt-hour over a 12 month operating period, while new small natural gas-fired turbines would need to meet a limit of 1,100 pounds of CO2 per megawatt-hour over a 12 month operating period.

The rule would not apply to existing sources, and would not apply to plants undergoing modifications or to reconstructed sources. EPA is expected to issue proposed standards for emissions from existing power plants by June 1, 2014.

The public comment period for EPA’s proposed standards will be open for 60 days following publication of the proposed rule in the Federal Register.

A rule proposed by EPA in April 2012 that would have applied one CO2 standard for all new power plants, whether fired by coal or natural gas, has been rescinded.