How are We Reducing the Sulfur Oxides Emissions?
In 1967, the U.S. Congress passed legislation aimed at reducing pollution. Although the Air Quality Act of 1967 did not reach its goals, it established a framework for more effective legislation to follow. The two elements contributing to reduced emissions are active legislation and new technologies.

	Click the chart to view a larger image.
	SO2 Air Quality Chart Source: EPA - National Trends in Sulfur Dioxide Levels
	SO2 Emissions Chart Source: EPA's Latest Findings on National Air Quality - page 12 Note: One thousand “thousand short tons” equals one million tons; a graph value of “20,000” equals 20 mil. tons.

Active Legislation
The Clean Air Act of 1970 and formation of the Environmental Protection Agency established the Nation's first major effort to reduce air pollution. Since then, industry has developed new technologies to reduce pollution from new and existing coal-fired power plants.

• In 1971, the EPA established New Source Performance Standards (NSPS)— for the first time quantitatively limiting SO₂ and other emissions.
• In 1977, Congress amended the Clean Air Act to require States to set limits on existing sources in regions not meeting goals.
• In 1979, Congress enacted new regulations to further reduce SO₂ emissions from boilers.
• In 1990, Congress amended the Clean Air Act to include requiring a 10-million ton reduction in annual SO₂ emissions from 1980 levels, occurring in two phases. These amendments were particularly focused on acid rain.
• Finally, in 2005 the Bush Administration’s Clear Skies Initiative was passed, requiring reductions in SO₂ emissions from major power generating facilities from the year 2000 total of 11.2 million tons. This initiative requires a reduction to 4.5 million tons by 2010, and down to 3 million tons by 2018, or an overall reduction of 73 percent.

Nationwide, SO₂ emissions have been reduced by over one-third in the past 20 years. Between 1993 and 2002, SO₂ emissions fell by 31 percent. Much of the gain in reduced emissions has been accomplished by the power generation industry. This trend is expected to continue in the future, due to advances in technology and strict regulation. The following graphs show national trends in SO₂ reduction.

	The PFBC demonstration at the repowered 70-MWe unit at Ohio Power's Tidd Plant led to significant refinements and understanding of the technology.

Reduction Success Stories
The Department of Energy joins with industry to demonstrate new technologies that include new retrofits to existing power plants. An example is the Tidd Power Plant in Brilliant, Ohio. Tidd was the first large-scale operational demonstration of pressurized fluidized-bed combustion (PFBC) in the United States. The project represented a 13:1 scaleup from the pilot facility and was deemed a success. The plant accomplished greater than 90% SO₂ removal and a NOx emission level of 0.2 lb per million BTUs at full load.