Regulations & Markets
On December 21, 2011 the U.S. Environmental Protection Agency (EPA) issued its Mercury and Air Toxics Standards (MATS) for power plants. The new rule is intended to reduce air emissions of heavy metals, including mercury (Hg), from all major U.S. power plants, which are the leading source of non-natural mercury emissions in the U.S. Existing power plants will have up to four years to comply with the new emission limits.
The new MATS rule applies to Electric Generating Units (EGUs) that are larger than 25 megawatts (MW) that burn coal or oil for the purpose of generating electricity for sale and distribution through the national electric grid to the public. They include investor-owned units, as well as units owned by the Federal government, municipalities, and cooperatives that provide electricity for commercial, industrial, and residential uses. The EPA estimates that there are approximately 1,400 units affected by this new rule, approximately 1,100 existing coal-fired units and 300 oil-fired units at about 600 power stations.
The final MATS identifies two subcategories of coal-fired EGUs, four subcategories of oil-fired EGUs and a subcategory for units that combust gasified coal or solid oil (integrated gasification combine cycle [IGCC] units) based on the design, utilization, and/or location of the various types of boilers at different power stations. The rule includes emission standards and/or other requirements for each subcategory. The rule sets nationwide emission limits and is estimated to reduce mercury emissions in coal-fired plants by about 90% overall.
The US EPA estimates the total national annual cost of this rule will be $9.6 billion.
While the ultimate costs for compliance in the U.S. may indeed be in the $9.6 billion per year range, that will not likely be the case until EGUs must comply starting early 2015. These on-going annual operating costs increases also do not include the capital costs to install the equipment and have it ready to operate when the emission limits are required.
In the near term, ME2C believes that utilities will explore and conduct numerous demonstrations of various technologies to determine which will work best to achieve the required reductions to bring each individual unit under the maximum allowed emissions rate. There are several choices of pollution control technologies that might be employed to reduce mercury emissions, but they do not all work well for every plant designs or for all of the various types of coal. It is important to note that very few units in the U.S. today consistently limit mercury emissions to below the new maximum allowed rates. In addition, the EPA estimates that 40% of the coal units in the U.S. affected by the new MATS have no advanced pollution controls in operation.
The most common technology employed to reduce mercury emissions is the injection of powdered activated carbon (PAC) or brominated PAC (BAC) into the flue-gas of an EGU after the boiler itself, but in front of the Electro-Static Precipitation (ESP). Such injections have proven effective with many coals, especially at reduction levels of 70% or less. At required mercury reduction levels above 80%, these injection systems required substantial injection rates which often has severe operational issues including over-loading the ESP and rendering the fly ash unfit for sale to concrete companies, and at times even causing combustion concerns with the fly ash itself.
The U.S. EPA publicly released its final rule (MATS) on December 21, 2011. Existing power plants will generally have up to 4 years if they need to comply with these standards (includes the 3 years provided by the Clean Air Act plus one extra year for extraordinary hardships), giving a final compliance date for most units of not later than early 2016.
Canada’s CWS for mercury emissions is under review, with most recent being October 11, 2006.
U.S. State Regulations
As of February 2011, there were over a dozen states (Colorado, Connecticut, Delaware, Illinois, Maine, Maryland, Massachusetts, Michigan, Minnesota, Montana, New Jersey, New York, North Carolina, Washington and Wisconsin) that have established more stringent emission limits, which were slated to take effect before the EPA’s limits.