Power plants are currently the dominant emitters of mercury, sulfur dioxide, acid gases and arsenic in the United States, and they are major sources of nitrogen dioxide emissions. In addition, about one third of the nation’s greenhouse gas emissions come from power plants.
A number of EPA regulations limit air pollutant emissions from power plants. The Mercury and Air Toxics Standards (MATS) set limits for hazardous air pollutants emitted by coal- and oil-fired power plants. EPA has established New Source Performance Standards for emissions of criteria pollutants from this sector and recently proposed greenhouse gas emissions standards for new fossil fuel-fired power plants. EPA’s Regional Haze Rule requires electric generating units to adopt Best Available Retrofit Technology in order to limit emissions that impair visibility. Electric generating units in the Eastern portion of the United States are required to reduce their emissions of sulfur dioxide and nitrogen oxide in order to address cross-boundary air pollution.
State and local air agencies also implement programs to reduce air pollutant emissions from power plants. Before a new large plant can start construction, or an existing large plant can implement a major modification, it must apply for a permit. Pursuant to these permits, the plants must meet air pollutant emissions limits according to the rules of the jurisdiction in which they are located. Power plants are generally subject to more stringent emissions control requirements if they are located in areas with air quality that violates the health-based National Ambient Air Quality Standards.
There are a number of pollution control technologies available to limit air pollution emissions from power plants. These include low-NOx burners, overfire air, selective catalytic reduction, flue gas desulfurization, fabric filters, activated carbon injection, dry sorbent injection and electrostatic precipitators. The most cost-effective way to reduce emissions, however, is to use energy more efficiently, and thus most states fund energy efficiency programs or have adopted energy efficiency resource standards. Renewable energy – such as wind and solar power – also can serve as a source of non-polluting electricity.