The overall goal of the Acid Rain Program is to achieve significant environmental and public health benefits
through reductions in emissions of sulfur dioxide (SO2) and nitrogen oxides (NOx), the
primary causes of acid rain. To achieve this goal at the lowest cost to society, the program employs both
traditional and innovative, market-based approaches for controlling air pollution.
Title IV of the Clean Air Act sets as it primary goal the reduction of annual SO2 emissions by 10
million tons below 1980 levels nationwide. To achieve these reductions, the law requires a two-phase
tightening of the restrictions placed on fossil fuel-fired power plants.
Phase I began in 1995 and affected 14 boilers at 6 power plants in West Virginia. Phase II began in 2000 and
tightened the annual emissions imposed on the large, higher emitting plants covered under Phase I and also
set restrictions on smaller, cleaner plants fired by coal, oil and gas, encompassing 34 boilers at 14 power
plants in West Virginia. The program affects existing utility plants serving generators with an output
capacity of greater than 25 megawatts and all new utility units.
The Clean Air Act Amendments of 1980 set a goal of reducing NOx by 2 million tons below 1980
levels nationwide. The Acid Rain Program focuses on one set of sources that emit NOx, coal-fired
electric utility boilers. As with the SO2 emission reduction requirements, the NOX program is
implemented in two phases, beginning in 1996 and 2000.
NOx emission limitations for the affected boilers provide flexibility for utilities by focusing
on the emission rate to be achieved (expressed in pounds of NOX per million Btu of heat input). Three
options for compliance with the emission limitations are provided:
Compliance with an individual rate for a boiler.
Averaging of emission rates over two or more units to meet an overall emission rate limitation (note,
these units must have the same owner/operator).
An alternative emission limit (AEL) that corresponds to the level that the utility demonstrates is
achievable, if the utility properly installs and maintains the appropriate control equipment designed to
meet the emission limit established in the regulation, but is still unable to meet the limitation.
These options give utilities flexibility to meet the emission limitations in the most cost-effective way and
allow for further development of technologies to reduce the cost of compliance.
For more information on the Acid Rain Program, please visit the EPA.