The US Environmental Protection Agency (EPA) has issued the Mercury and Air Toxics Standards (MATS), the first national standards for power plant emissions of mercury and toxic air pollutants (also known as hazardous air pollutants, HAPs) such as arsenic, acid gas, nickel, selenium, and cyanide.
EPA also signed revisions to the new source performance standards (NSPS) for fossil-fuel-fired power plants. This NSPS revises the standards that new coal- and oil-fired power plants must meet for particulate matter (PM), sulfur dioxide (SO2), and nitrogen oxides (NOx).
Power plants are the largest remaining source of several toxic air pollutants, including mercury, arsenic, cyanide, and a range of other dangerous pollutants, and are responsible for half of the mercury and more than 75% of the acid gas emissions in the United States, according to EPA. Today, more than half of all coal-fired power plants already deploy pollution control technologies that will help them meet these standards. Once final, these standards will level the playing field by ensuring the remaining plants—about 40% of all coal fired power plants—take similar steps to decrease dangerous pollutants.
MATS requirements include:
For all existing and new coal-fired EGUs (electric generating units, i.e., power plants), the rule establishes numerical emission limits for mercury, PM (a surrogate for toxic non-mercury metals), and HCl (a surrogate for all toxic acid gases).
For existing and new oil-fired EGUs, the standards establish numerical emission limits for PM (a surrogate for all toxic metals), HCl, and HF. EGUs may also show compliance with the HCl and HF limits by limiting the moisture content of their oil.
The rule establishes alternative numeric emission standards, including SO2 (as an alternate to HCl), individual non-mercury metal air toxics (as an alternate to PM), and total non-mercury metal air toxics (as an alternate to PM) for certain subcategories of power plants.
The standards set work practices, instead of numerical limits, to limit emissions of organic air toxics, including dioxin/furan, from existing and new coal- and oil-fired power plants. Because dioxins and furans form as a result of inefficient combustion, the work practice standards require an annual performance test program for each unit that includes inspection, adjustment, and/or maintenance and repairs to ensure optimal combustion.
The standards also set work practices for limited-use oil-fired EGUs in the continental US.
A range of widely available and economically feasible technologies, practices and compliance strategies are available to power plants to meet the emission limits, including wet and dry scrubbers, dry sorbent injection systems, activated carbon injection systems, and fabric filters.
The revisions to the NSPS for fossil-fuel-fired EGUs include revised numerical emission limits for PM, SO2, and NOx.
More than 20 years ago, a bipartisan Congress passed the 1990 Clean Air Act Amendments and mandated that EPA require control of toxic air pollutants including mercury. To meet this requirement, EPA worked extensively with stakeholders, including industry, to minimize cost and maximize flexibilities in these final standards. There were more than 900,000 public comments that helped inform the newly announced final standards.
As part of the commitment to maximize flexibilities under the law, the standards are accompanied by a Presidential Memorandum that directs EPA to use tools provided in the Clean Air Act to implement the Mercury and Air Toxics Standards in a cost-effective manner that ensures electric reliability. For example, under these standards, EPA is not only providing the standard three years for compliance, but also encouraging permitting authorities to make a fourth year broadly available for technology installations, and if still more time is needed, providing a well-defined pathway to address any localized reliability problems should they arise.
EPA estimates that the new safeguards will prevent as many as 11,000 premature deaths and 4,700 heart attacks a year. The standards will prevent 130,000 cases of childhood asthma symptoms and about 6,300 fewer cases of acute bronchitis among children each year.
Mercury has been shown to harm the nervous systems of children exposed in the womb, impairing thinking, learning and early development, and other pollutants that will be reduced by these standards can cause cancer, premature death, heart disease, and asthma.
The Mercury and Air Toxics Standards, which are being issued in response to a court deadline, are in keeping with President Obama’s Executive Order on regulatory reform. They are based on the latest data and provide industry significant flexibility in implementation through a phased-in approach and use of already existing technologies.
EPA estimates that for every dollar spent to reduce pollution from power plants, the American public will see up to $9 in health benefits. The total health and economic benefits of this standard are estimated to be as much as $90 billion annually.
EPA says that The Mercury and Air Toxics Standards and the final Cross-State Air Pollution Rule, which was issued earlier this year (earlier post), are the most significant steps to clean up pollution from power plant smokestacks since the Acid Rain Program of the 1990s.
Combined, the two rules are estimated to prevent up to 46,000 premature deaths, 540,000 asthma attacks among children, 24,500 emergency room visits and hospital admissions.