Title IV (Acid Rain)

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 (NO_x), 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 NO_x by 2 million tons below 1980 levels nationwide. The Acid Rain Program focuses on one set of sources that emit NO_x, 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.

NO_x 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.

• EPA Clean Air Markets