Controlling Power Plant Emissions: Overview

While total mercury emissions in the U.S. have fallen substantially since 1990, power plants are the largest remaining human-caused source of mercury emissions. EPA is currently working to complete aggressive emission reduction requirements for the power industry. However, important progress on this issue began years ago. These pages cover this history; the proposed regulations to reduce mercury emissions in the power sector; the extensive comments received on these proposals; the process EPA is pursuing to best understand how to finalize these regulations, and information about existing and emerging technologies to reduce mercury emissions from power plants.

As published in the January 30, 2004 Federal Register, EPA proposed the Clean Air Mercury Rule for controlling mercury emissions from power plants. On March 16, 2004, EPA proposed a supplemental proposal addressing areas not covered in the January 30 Federal Register notice. In a separate but closely related action, EPA proposed the Clean Air Interstate Rule which focuses on states whose SO₂ and NOx emissions are significantly contributing to fine particle and ozone pollution problems in other downwind states. Together, the Clean Air Mercury Rule proposal and the Clean Air Interstate Rule proposal create a multi-pollutant strategy to improve air quality throughout the U.S.

President Bush directed EPA to pursue this multi-pollutant strategy through legislation. Clear Skies legislation would establish a mandatory program to reduce and cap emissions of mercury, as well as emissions of sulfur dioxide (SO2) and nitrogen oxides (NOx) from electric power generation to approximately 70% below 2000 emission levels. Clear Skies was submitted as proposed legislation in the US House of Representatives on July 26, 2002 and in the US Senate on July 28, 2002. The legislation was reintroduced in both Houses of Congress as the Clear Skies Act of 2003 on February 27, 2003. While EPA believes this legislative approach is the preferred option to achieve these important reductions, the Agency is pursuing a regulatory solution in the absence of Congressional action.

Chronology of Actions to Date
Since the Clean Air Act was amended in 1990, EPA has researched mercury, including how best to require reductions from power plants. This page provides a detailed chronology of events that lead up to the proposal in January 2004 and EPA's current work to finalize a rule by March 2005.

Guiding Principles
Reducing mercury from power plants must be done right. The Administrator is taking into account relevant information about emissions, control technologies, health effects, and the impacts on our electrical system and economic competiveness. Given the complexity surrounding all of these factors, the Administrator has identified five principles that provide a context for additional inquiry and focus as we enter the decision phase of the rulemaking. This page describes these principles and areas of additional inquiry.

Applying Technology
Approximately 75 tons of mercury are found in the coal delivered to power plants each year and about two thirds of this mercury is emitted to the air, resulting in about 50 tons being emitted annually. This 25-ton reduction is achieved in the power plant boilers and through existing pollution controls such as scrubbers (for SO2) and SCRs (for NOx). As more scrubbers and SCRs are installed to comply with the Clean Air Interstate Rule and other regulations, mercury emissions are expected to decrease. This multipollutant approach is central to the Agency's plan to reduce mercury from power plants.

In addition to relying on existing technologies, the Agency believes several mercury-specific technologies currently under development show promise. Currently none of these technologies are in commercial operation on power plants in the U.S. but extensive research is being done to develop and test these technologies for application to the power sector.

This page provides more information on technologies to reduce mercury from power plants.

Global Context
This page provides information about sources of mercury emissions throughout the world, the global distribution of emissions, and how U.S. mercury emissions fit into the global picture.

Public Comments
EPA has received a record number of comments on its proposed rule. This page provides a summary of the comment process and information for people interested in reviewing comments.

Where to find more information

Summary of the proposed Utility Mercury Reductions Rule - as well as a summary of the design of the program and the benefits it would provide.

Regulatory Actions - Links to proposed and final rules, fact sheets, and other rulemaking documents.

Technical Information - Technical support information and links to related information.