TVA began its fossil-plant construction program in the late 1940s, and today it has 48 active operating units at 11 coal-fired-plant sites in the Tennessee Valley.
TVA has 98 combustion-turbine units at four of its existing coal-fired sites (Allen, Colbert, Gallatin, and Johnsonville) and eight freestanding sites. The turbines burn natural gas or fuel oil. While they cost more to operate than TVAs other power sources, they are necessary for peak operating periods when the demand for power is high.
In fiscal year 2011, TVAs coal-fired and combustion-turbine units produced about 81.4 billion kilowatt-hours of electricity, accounting for about 57 percent of TVAs power supply from TVA-operated facilities.
TVA has long been committed to taking actions at its facilities to protect the environment and the area’s natural resources. TVA installed scrubbers and electrostatic precipitators at many of its coal-fired plants when these technologies were still in the early stages of development.
From 1977 to 2011, TVA invested about $5.4 billion to reduce emissions from its power plants. Of this, $264 million was spent from 2009 to 2011. To maintain compliance with future Clean Air Act requirements, TVA may need to invest an additional $3.4 billion through 2018.
To reduce sulfur-dioxide emissions, TVA has installed scrubbers on 17 of its coal-fired units and switched to lower-sulfur coals at 41 units. These measures have helped reduce TVA's sulfur dioxide emissions by at least 90 percent below their peak in 1977. The TVA board of directors has approved adding scrubbers to three units at Allen Fossil Plant and four units at Gallatin Fossil Plant.
To reduce nitrogen oxide emissions, TVA has installed selective catalytic reduction systems on 21 coal-fired units. TVA also has installed a variety of other emission control technologies on selected units. These include selective non-catalytic reduction systems, High Energy Reagent Technology, low-NOx burners and combustion systems, and combustion optimization measures. These measures have helped reduce TVA's nitrogen oxide emissions by at least 86 percent below peak 1995 levels.
To reduce particulate emissions, TVA has equipped all its coal-fired units with scrubbers, mechanical collectors, electrostatic precipitators or baghouses.
In support of recent environmental agreements and its vision of being one of the nation’s leading providers of low-cost and cleaner energy by 2020, TVA will idle or retire 2,700 megawatts of older, less-economical coal-fired capacity by the end of 2017.