Mercury Falling

Many Power Plants Already Have Equipment to Slash Mercury, Toxic Contamination

Many power plants can reduce their mercury and other toxics emissions without significant hardship, write Daniel J. Weiss, Valeri Vasquez, and Stewart Boss.

Trucks carry out loads of coal at the Pine Creek Coal Company in Spring Glen, Pennsylvania. A new EPA standard aims to limit carbon pollution from new power plants, including coal-fired plants.
Trucks carry out loads of coal at the Pine Creek Coal Company in Spring Glen, Pennsylvania. A new EPA standard aims to limit carbon pollution from new power plants, including coal-fired plants.

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Coal-fired power plants shoot 772 million pounds of airborne toxic chemicals into the sky every year—more than 2.5 pounds for every American man, woman, and child. In March the Environmental Protection Agency proposed to dramatically reduce the mercury, lead, acid gases, and other toxics from more than 400 plants in 46 states.

Some of the nation’s largest utilities—including the Southern Company and DTE (formerly Detroit Edison)—have publicly and privately lobbied to delay, weaken, or block these safeguards. They claim, as such polluters usually do, that cutting emissions of mercury, arsenic, lead, acid gases, and other cancer-causing pollutants from coal-fired power plants will cause economic hardship. History has taught us such claims about pending public health protection measures are nearly always wrong.

Analyses from CAP and others have found that many power plants have already installed or have under construction the pollution-control technologies that can significantly reduce mercury as well as other pollutants. Plants in 17 states are already required to address their mercury pollution, regardless of federal requirements. These measures vary in stringency, with some of them imposing more protective mercury-emissions limits on coal-fired power plants than the EPA has proposed.

Mercury chart 1

Many of the power plants in these states have already installed the equipment necessary to reduce mercury pollution, although most state safeguards have yet to take effect. A CAP analysis of the coal-fired power plants in these 17 states found that more than half of their total electricity-generation capacity has pollution controls that can reduce mercury.

Mercury chart 2

Pollution-control technologies

A variety of technologies can capture point-source or smoke-stack mercury emissions from coal-fired power plants. Scrubbers, which are most often installed to control sulfur oxide, or SOx, and acid gas emissions, can also capture mercury. “Wet” scrubbers capture oxidized mercury (mercury that has chemically bound with oxygen) while “dry” scrubbers enable a simple fabric filter to trap mercury. The EPA estimates that scrubbers can capture 36 percent to 90 percent of the mercury produced by burning bituminous coal, and 15 percent to 66 percent of mercury from sub-bituminous coal.[1] A CAP analysis found that scrubbers are installed for 54 percent of the electricity-generation capacity of the 353 coal-fired units in states with their own mercury-pollution measures.

Activated Carbon Injection, or ACI, is the primary control technology for mercury reduction. Activated carbon—which is highly processed, extremely porous carbon—absorbs mercury in its gaseous form and converts it to a particulate that can then be captured. As an added benefit, “an ACI system is relatively simple and inexpensive,” according to a report prepared for the Northeast States for Coordinated Air Use Management, or NESCAUM. Units with low SOx emissions could meet all their reduction obligations using ACI, eliminating the need for more expensive scrubbers. There are ACI systems in one-sixth of the electricity-generation capacity in states with mercury programs.

According to the Brattle Group, an independent consulting firm, the capital costs for scrubbers and activated carbon injection technology are up to $120 million and $30 million, respectively, to install on a 300-megawatt power plant. EPA has larger projected costs for scrubbers but lower costs for ACI. Plants that have already installed either or both of these control technologies may be able to comply with EPA’s proposed standards without undertaking any further capital expenditures, which means a significantly lower impact on electricity rates.

NESCAUM case studies: ACI controls

In response to a 2006 Minnesota state mercury law, Xcel Energy agreed to install an ACI system on the 900 MW Unit 3 at its Sherburne County plant (Sherco 3). The unit, which burns low-sulfur western coal from Montana and Wyoming, already had a dry scrubber operating to reduce SO2 emissions. Once tuned to the unit’s operational specifications, the ACI system should reduce the plant’s mercury emissions by about 90 percent. The system was completed in December 2009 for a total capital cost of $3.1 million, or $3.46/kW.

Wisconsin Power and Light installed ACI controls at its Edgewater Generating Station. The system was operational in the first quarter of 2008. Edgewater Unit 5 is a 380 MW plant that fires sub-bituminous western coal and employs an “electrostatic precipitator” to capture fine particles. The total installed costs of the Edgewater Unit 5 ACI system were approximately $8/kW, or approximately $3.04 million.

Both of these power plants installed these controls to comply with the Minnesota and Wisconsin mercury-reduction laws. These plants should find it relatively inexpensive to meet the pending federal standards.

Embracing pollution controls

The large number of plants that have already installed pollution controls explains the recent finding that many coal-fired power plants are already meeting the proposed mercury reduction standard. The Clean Energy Group—an electric company coalition that has nearly 100,000 megawatts of the United States’ total fossil-fuel electricity-generation capacity—conducted an analysis that found that:

Nearly 60 percent of all coal fired boilers that submitted stack test data to EPA are currently achieving the Utility Toxics Rule’s proposed mercury emissions standard. This translates to more than 100 boilers (out of a total of 178). These power plants are meeting the proposed standard with a wide variety of pollution control systems and configurations (e.g., wet scrubbers, dry scrubbers, bag houses, and carbon injection systems).

This level of mercury reduction from plants that already have the appropriate pollution controls reinforces that EPA’s proposed safeguards are cost-effective, technology-achievable standards that many utilities have already met.

Some utilities began compliance efforts several years ago. Edison International’s President and CEO Theodore Craver told investors during a call on 2011 first-quarter earnings that the company “installed the necessary equipment back in 2009 and [is] already achieving these [mercury] limits.”

Gale Klappa, chairman, president, and CEO of Wisconsin Energy, says his company anticipates “very little impact on customer electric rates or our capital plan between now and 2015 as a result of all the new EPA regulations that have been proposed.” And by the fourth quarter of 2010, the head of PPL Generation, William Spence, had already equipped “96 percent of [the utility’s] competitive coal generation” with scrubbers.

Old, inefficient units already scheduled to close

Despite the fact that many coal-fired plants across the nation have installed the pollution-control equipment to reduce their mercury pollution, some utilities are still digging their heels in the fight to block or delay the proposed EPA rules.

Many plants without this pollution-control equipment will soon be retired due to their age and inefficiency. A CAP review found that utilities plan to shut down at least 80 of these aging units—closures announced before the EPA proposed the air toxics reduction rules. These plants are 52 years old on average, with the oldest unit built during World War II. Many of these units have little or no pollution controls, are relatively small, and utilized infrequently.

In the ongoing debate over the proposed mercury rules, some utilities have cited the pending mercury-reduction rules as the reason to shut down some of these old power plants, even though their retirements were previously made public, some as part of Clean Air Act enforcement agreements. A New York Times editorial noted that “Blaming the rules [for plant closures] is a transparent scare tactic designed to weaken the administration’s resolve while playing to industry supporters on Capitol Hill.” (See attached list of plants scheduled for retirement.)

Another tactic some recalcitrant utilities are pursuing is advocating the delay of the air toxics protections. MidAmerican Energy, owned by Warren Buffett’s Berkshire Hathaway Inc., testified to the Senate last week in favor of delaying the air toxics rule:

MidAmerican, like many utilities, is concerned about the costs and timetables for the implementation of these EPA rules.

If the timetable of the rules remains unchanged, compliance costs will be shouldered by our customers in the form of higher rates. … these increases will dramatically increase production costs for industrial plants and could result in job losses.

NESCAUM found that pollution-control technology can be added within the proposal’s timeframe:

EPA estimates that the total time needed to complete the design, installation, and testing of a wet FGD [scrubber] system at a typical 500 MW power plant with one FGD unit is 27 months, and longer if multiple boilers or multiple absorbers are necessary. Actual installation times will vary based upon the specifics of the plant, the need to schedule outages with FGD hook up, and other factors.

Plants with scrubbers can install ACI in a year if there is already a bag house. These installation times suggest that utilities will have ample time to install pollution controls. Those that do not can seek an extension from EPA.

Delaying implementation of the air toxics reduction measures would actually disrupt compliance with the standards by injecting more uncertainty into the final requirements and deadlines. This would upset the efforts by many utilities to comply with the standards. On June 15 the Clean Energy Group wrote EPA Administrator Lisa Jackson to urge her to:

… proceed with finalizing the rule. Companies have begun to prepare for a 2015 compliance deadline, and the electric power markets are factoring in the capital expenditures that will be required to comply with the rule. Any delay would threaten to undermine those decisions.

MidAmerican also claimed in its June 15 testimony that the 2015 compliance deadline could lead to shortages of equipment and labor to install the necessary pollution-control technologies. This claim, however, was debunked last year. On November 3, 2010, the Institute of Clean Air Companies—the trade association of pollution-control suppliers—wrote Sen. Tom Carper (D-DE) that:

We are extremely confident in the ability of the industry to deliver and satisfy, as we have so successfully in the past, the labor, materials and resources needed to meet the demand. … EPA’s efforts to move forward expeditiously with the proposed interstate Transport Rule and the upcoming utility MACT [air toxics] rules will be helpful in this regard.

Delays in issuing the air toxics rule would harm, not help, companies reduce their mercury, lead, and other toxic air pollution.

The benefits of reducing air toxics

Efforts by Southern Company, DTE, MidAmerican, and other big utilities to block or delay the air toxics reduction rules for coal-fired power plants ignore the overwhelming benefits of pollution reductions to Americans. Coal-fired power plants are the “largest human-caused source of mercury emissions in the United States,” according to Senate testimony by Dr. Jerome Paulson of the American Academy of Pediatrics. Power plants spew 40 percent of mercury emissions in the United States. Mercury causes severe developmental disabilities, deafness, and blindness in cases of prenatal and infant exposure. The chemical can lower fertility rates and raise chances of heart disease in adults.

These new rules would also slash significant amounts of the three-quarters of a billion pounds of airborne toxic chemicals shot into the skies annually. These contaminates include lead, which causes learning disabilities in children as well as organ failure. Arsenic—used for rat poison—would also be reduced. And the proposed standards would reduce the millions of pounds of “acid gases” that trigger “irritation to skin, eye, nose throat, [and] breathing passages,” according to the American Lung Association. Three-quarters of these gases come from power plants.

The EPA projects that once the air toxics safeguards are implemented in 2016, the pollution reductions will have annual benefits that include:

… [up to] 17,000 fewer premature mortalities, 4,300 fewer cases of chronic bronchitis, 10,000 fewer non-fatal heart attacks, 12,000 fewer hospitalizations (for respiratory and cardiovascular disease combined), 4.9 million fewer days of restricted activity due to respiratory illness and approximately 830,000 fewer lost work days.

We also estimate substantial health improvements for children in the form of 110,000 fewer asthma attacks, 6,700 fewer hospital admissions due to asthma, 10,000 fewer cases of acute bronchitis, and approximately 210,000 fewer cases of upper and lower respiratory illness.[2]

In addition to alleviating this pain and suffering, the total net economic benefit of the air toxics rule is $48 billion to $130 billion in 2016 alone.[3]


The Clean Air Act of 1990 included measures to reduce emissions of airborne mercury and other toxic chemicals to protect public health. Twenty-one years later, we are on the cusp of final adoption of essential cleanup standards that protect children, seniors, and other Americans from cancer-causing and smog-forming pollution from coal-fired power plants. CAP’s analysis of electricity producers in states with their own mercury rules found that a majority of their coal-fired generation capacity already has the pollution-control equipment necessary to reduce mercury. Congress must ignore the arm twisting and campaign contributions from the big utilities that want to continue to spew these poisons into the skies—and our lungs, waters, fields, and wildlife. Instead, senators and representatives should urge the Obama administration to promptly issue and enforce these long-delayed safeguards.

Daniel J. Weiss is a Senior Fellow and the Director of Climate Strategy, Valeri Vasquez is a Special Assistant, and Stewart Boss is an intern with the Energy team at American Progress.

Very special thanks to Amlan Saha, operations research analyst, M.J. Bradley & Associates, for his cheerful assistance with this analysis.

Thanks to Arpita Bhattacharyya, Special Assistant, Center for American Progress, and to CAP interns Ciera Crawley and Kylie Donnelly.


[1]. The mercury capture rates depend on the type of scrubber, and whether there are controls for NOx and particulate matter, or soot.

[2]. P. 25090.

[3]. P. 24979.

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Daniel J. Weiss

Senior Fellow