Emissions Control Strategies for Power Plants

For more than the last quarter century, power plant operators in the United States have been installing new pollution-control technologies to meet ever-tightening regulatory standards for clean air. The Clean Air Act of 1970 (details of which can be found in Chapter 4, where the history of legislative action in the United States is discussed) established national standards to limit levels of air pollutants such as sulfur dioxide, nitrogen oxides, carbon monoxide, ozone, lead, and particulate matter. The act and its amendments in 1977 resulted in the development and installation of particulate matter and sulfur dioxide control technologies for coal-fired boilers. Particulate control devices, specifically electrostatic precipitators (ESPs) and fabric filter baghouses, began to be installed on power plants, and efforts to develop new control technology, including flue gas desulfurization units, commonly called scrubbers, to remove sulfur from flue gas led to the installation of such units on many power generation facilities. In addition, technologies to reduce nitrogen oxides began to be developed.

The 1990 Clean Air Act Amendments contained major revisions to the Clean Air Act and required further reductions in power plant emissions, especially sulfur- and nitrogen-containing pollutants that contribute to acid rain. Some of the resulting sulfur dioxide control strategies that were implemented include switching to low-sulfur fuels, installation of flue gas desulfurization units, and the development of a new market-based cap-and-trade system that requires power plants to either reduce their emissions or acquire allowances from other companies to achieve compliance. To meet the more stringent nitrogen oxide standards from the 1990 Clean Air Act Amendments, several technologies, specifically low-NOz burners, selective catalytic and noncatalytic reduction, cofiring, and reburning have been developed with varying levels of their implementation occurring. With impending legislation (e.g., Clear Skies Act, Multipollutant Control, fine particulate control) additional NOZ control is anticipated and is being planned for by the power generating industry.

This chapter begins by summarizing the progress that has been made over the last ~30 years in reducing emissions from coal-fired power plants. Commercial control strategies for pollutants that are currently regulated, such as sulfur dioxide, nitrogen oxides, and particulate matter, are discussed. Control technologies that are under development for reducing mercury emissions, where regulations will be promulgated in 2004 and full compliance expected by 2007, are also discussed. A summary of control options under development for carbon dioxide removal is provided. The chapter concludes with a discussion of multi-pollutant control technologies.

0 0

Post a comment