National Policy National Policy Issues i. Acid Rain Program ii. NOx SIP Call iii. Clean Air Interstate Rule iv. Clean Air Mercury Rule v. Retrofit Technology vi. Industrial Boiler MACT

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National Legislation and Regulations

The Acid Rain Program

The Clean Air Act (CAA) of 1970, and subsequent amendments have been the primary drivers requiring reductions in emissions of SO₂ and NOx from sources such as EGUs, as well as numerous other air quality programs.  A key component of the CAA is the Acid Rain Program (ARP), which was a significant part of the CAA Amendments of 1990.

The ARP sought to cap SO₂ emissions from fossil-fuel-fired EGUs at half of 1980 emissions, ultimately reaching a cap of 8.95 million tons by 2010.  NOx emissions specifically from coal-fired EGUs were also reduced as part of the ARP, to reach 6.1 million tons by 2002, 2 million tons below forecasted 2000 levels without the program.  SO₂ emissions were reduced in two phases, the first in 1995 and the second in 2000.  NOx emissions were also reduced in two phases, 1996 and 2000, respectively. 

The SO₂ program established a cap and trade market-based program to reduce emissions in a cost-effective and efficient manner.  The cap and trade program required that units have enough allowances to cover total emissions, where one allowance is equal to one ton of emissions.  Units must control emissions at or below the cap and can then bank excess allowances for future use or sell remaining allowances to units that exceed their allowance allocation.  The NOx program did not permit a cap and trade approach but instead established emission rate limits according to boiler types for coal-fired units. 

As of 2003, the most recent year for which EPA has data, SO₂ emissions from fossil-fuel-fired EGUs were 10.6 million tons, a 38% reduction from 1980 levels and NOx emissions from coal-fired EGUs were 4.2 million tons, nearly 4 million tons less than the emissions forecasted for 2000 and 37% below 1990 levels.  In 2003, approximately 3,500 fossil fuel-fired units were subject to the SO₂ program and approximately 1,000 coal-fired units were subject to the NOx program.  SO₂ and NOx emissions will decline further from ARP levels as a result of implementation of the Clean Air Interstate Rule (CAIR) (discussed below).

For more information:

EPA Acid Rain Program website: http://www.epa.gov/airmarkets/arp/home.html

EPA Acid Rain website: http://www.epa.gov/airmarkets/acidrain/