New rules from the U.S. Environmental Protection Agency to reduce mercury and other toxic air emissions will affect dozens of antiquated power plants currently operating without pollution controls. These rules have stirred debate in some circles as to whether retrofitting or retiring outdated plants will cause shortfalls in electricity capacity. How will EPA mercury rules influence the electricity system? This fact sheet updates earlier assessments1 by taking a close look at recent studies on the reliability of the electricity grid to answer that question.
Electricity generation capacity adequacy and transmission and ancillary services reliability are difficult to quantify and forecast due to the inherently local scale of power flow modeling.2 However, the lack of reliability problems over decades of previous Clean Air Act3 regulation and the flexibility of the standards suggest that the U.S. can keep the lights on while costeffectively removing toxic pollutants from power plant emissions.
Power plants are the largest source of mercury emissions to the air. This mercury eventually makes its way into water, and can cause neurological problems for people who eat contaminated seafood.4 Because of the dangers of mercury emissions, especially to children and pregnant women, a court order mandated5 that the EPA issue a final set of Mercury and Air Toxics Standards (MATS) by December 16, 2011.
Recent modeling assessments have typically focused more broadly on the cumulative impacts of EPA regulations, including: the Cross-State Air Pollution Rule (CSAPR),6 the Coal Combustion Residuals rule,7 the 316 (b) Cooling Water Intake Structures rule,8 and the yet-to-be announced New Source Performance Standards for greenhouse gases.9 Recent studies (listed in box below) have varied largely based on assumptions regarding the stringency of pending regulations, the costs of compliance measures, and the legal flexibility of regulatory enforcement.
Rules Are Flexible, and States Are Prepared
While there are modeling and forecasting limits for assessing long-term electricity system reliability, recent studies indicate that MATS and other EPA rules can be effective and implemented in a timely way while allowing for a range of compliance outcomes. The feasibility of cost-effectively complying with new regulations while maintaining electricity system reliability is supported by four key points:
- Both state and federal regulators have a suite of flexible enforcement options, which they have been using for decades, to delay power plant closures when this is necessary to preserve grid reliability; for example, the Cooling Water rule requires states to first consider reliability in implementing new regulations;
- While states often have the authority to set more protective pollution control standards in the interest of public health and welfare, there is no evidence that they would do so at the risk of grid reliability. Many states have already exercised this authority without imperiling electricity reliability—as of 2011, 17 states have already imposed rules on mercury and other toxic emissions from power plants, including Montana;
- Adequate new plant capacity is in the pipeline to replace the majority of potentially affected power plants (see below); most American power companies are on record as already having prepared for expected environmental regulations;
- In terms of compliance, the MATS rule allows for temporal and technological flexibility. As this fact sheet goes to press, the final rule has not yet been published but is expected to allow three years for compliance, with an optional 4th year extension from the EPA or additional security-based extension from the President. A wide range of commerciallyviable, proven compliance technologies from Flue Gas Desulphurization (FGD) to Dry Sorbent Injection (DSI) and Activated Carbon Injection (ACI) are available to help reduce toxic air emissions and can be installed in 10 to 30 months, providing ample time for America’s skilled engineers, manufactures and technicians to conduct plant upgrades within the legally allotted time frame.