50

None

a Short tons VOCs per year for ozone; short tons CO per year for carbon monoxide.

a Short tons VOCs per year for ozone; short tons CO per year for carbon monoxide.

25 short tons per year are required to burn clean fuels or install advanced control technologies.

The 1990 CAAAs also established similar programs for areas that do not meet federal health standards for carbon monoxide and PM10. Areas exceeding the standards for these pollutants are divided into moderate and serious classifications. The classifications for nonattainment areas for carbon monoxide are shown in Table 4-3.

Areas not attaining required levels of PM10 at the time the 1990 CAAAs were passed were designated as moderate areas and given an attainment deadline of December 31, 1994 [4]. Nonattainment areas subsequent to passage of the 1990 CAAAs are designated moderate and are given 6 years to achieve compliance. Major sources in moderate areas are those that emit 100 short tons or more of particulate matter per year. Moderate areas require the adoption of reasonably available control measures (RACM).

Moderate areas that fail to reach attainment are redesignated as serious areas and have 10 years from the date of designation as nonattainment to achieve attainment. For serious areas, major sources include those that emit 70 short tons or more of particulate matter per year. Serious areas must also adopt best available control measures (BACMs).

Title III: Air Toxics

Hazardous air pollutants, also known as toxic air pollutants or air toxics, are those pollutants that cause or may cause cancer or other serious health effects, such as reproductive effects or birth defects, or adverse environmental and ecological effects but are not specifically covered under another portion of the Clean Air Act. Most air toxics originate from humanmade sources, including mobile sources (e.g., cars, trucks, buses), stationary sources (e.g., factories, refineries, power plants), and indoor sources (e.g., building materials and activities such as cleaning) [16]. The Clean

Air Act Amendments of 1977 failed to result in substantial reductions of the emissions of these very threatening substances. Over the history of the air toxics program, only seven pollutants had been regulated. Title III established a list of 189 (later modified to 188) HAPs associated with approximately 300 major source categories. The list of HAPs is provided in Appendix B [17]. Under Title III, a major source is defined as any new or existing source with the potential to emit, after controls, 10 short tons or more per year of any of the 188 HAPs or 25 short tons or more per year of any combination of those pollutants. These sources may release air toxics from equipment leaks, when materials are transferred from one location to another, or during discharge through emissions stacks or vents.

The EPA must then issue maximum achievable control technology (MACT) standards for each listed source category according to a prescribed schedule. These standards are based on the best demonstrated control technology or practices within the regulated industry, and the prescribed schedule dictated that the EPA must issue the standards for 40 source categories within 2 years, 25% of the source categories within 5 years, 50% of the source categories within 7 years, and 100% of the source categories within 10 years of passage of the new law. Eight years after MACT is installed on a source, the EPA must examine the risk levels remaining at the regulated facilities and determine whether additional controls are necessary to reduce unacceptable residual risk [16].

The Bhopal, India, tragedy, where an accidental release of methyl iso-cyanate at a pesticide-manufacturing plant in 1984 killed approximately 4000 people and injured more than 200,000, inspired the 1990 CAAAs requirement that factories and other businesses develop plans to prevent accidental releases of highly toxic chemicals. In addition, the Act established the Chemical Safety Board to investigate and report on accidental releases of HAPs from industrial plants.

Title III did not directly regulate air toxics from power plants but did state that regulation of air toxics from utility power plants would be based on scientific and engineering studies. Mercury is one pollutant that was identified for study and will be discussed in more detail later in this chapter. At power plants, compounds in the vapor phase (e.g., polycyclic organic matter) and those combined with or attached to particulate matter (e.g., arsenic) are subject to the Title III provisions [18].

Title IV: Acid Deposition Control

The Acid Rain Program was established under Title IV of the 1990 CAAAs. The program required major reductions of sulfur dioxide (SO2) and nitrogen oxides (NOZ) emissions, the pollutants that cause acid rain. Using an innovative market-based or cap-and-trade approach to environmental protection, the program sets a permanent cap on the total amount of SO2 that may be emitted by electric power plants nationwide. The cap is set at about one-half the amount of SO2 emitted in 1980, and the trading component allows for flexibility for individual fossil-fuel-fired combustion units to select their own methods of compliance. The program also sets NOx emission limitations for certain coal-fired electric utility boilers, representing about a 27% reduction from 1990 levels [19].

Under the Acid Rain Program, each unit must continuously measure and record its emissions of SO2, NOx, and CO2, as well as volumetric flow and opacity [19]. In most cases, a continuous emissions monitoring (CEM) system must be used. Units report hourly emissions data to the EPA on a quarterly basis. These data are then recorded in the Emissions Tracking System, which serves as a repository of emission data for the utility industry. Emissions monitoring and reporting are critical to the program as they instill confidence in allowance transactions by certifying the existence and quantity of the commodity being traded and provide assurance that NOx averaging plans are working. Monitoring also ensures, through accurate accounting, that the SO2 and NO x emissions reduction goals are met.

The SO2 Program Title IV of the 1990 CAAAs called for a two-step program to reduce SO2 emissions by 10 million short tons from 1980 levels and, when fully implemented in 2000, placed a cap of approximately 8.9 million short tons per year on SO2 emissions, forcing all generators that burn fossil fuels after 2000 to possess an emissions allowance for each ton of SO2 they emit. By January 1, 1995, the deadline for Phase I, half of the total SO2 reductions were to have occurred by requiring 110 of the largest SO2-emitting power plants (with 263 boilers or units) located in 21 eastern and Midwestern states to cut their emissions to an annual average rate of 2.5 lb SO2 per million Btu. These stations, specifically identified in the 1990 CAAAs (see Appendix C), consisted of boilers with output greater than or equal to 100 MW and sulfur emissions of greater than 2.5 lb SO2 per million Btu. Plants deciding to reduce SO2 emissions by 90% were given until 1997 to meet the requirements. By the year 2000, the deadline for Phase II, virtually all power plants greater than 75 MW and discharging SO2 at a rate more than 1.2 lb/million Btu were required to reduce emissions to that level. In 2001, 2792 units were affected by the SO2 provision of the Acid Rain Program [19].

The Phase I reductions were accomplished by issuing the utilities that operated these units emission allowances equivalent to what their annual emission would have been at these plants in the years 1985 to 1987 based on burning coal with emissions of 2.5 lb SO2 per million Btu. One allowance is equivalent to the emission of one short ton of SO2 per year. Utilities were allowed the flexibility of determining which control strategies to be used on existing plants as long as the total emissions from all plants listed in Phase I and owned by the utility did not exceed the available allowances. The law was designed to let industry find the most cost-effective way to stay under the cap. This differs in approach from previous air quality regulations, such as the NSPSs and PSD, which are based on controlling emissions at their source and then monitoring to ensure compliance [20]. If a utility's emissions exceeded the available allowances, they were subject to fines assessed at $2000/short ton of excess emissions with a requirement to offset the emissions in future years. Any emission reductions achieved that were in excess of those required could be banked by the utility for use at a later date or traded or sold to another utility.

The SO2 component of the Acid Rain Program represents a dramatic departure from traditional regulatory approaches that establish source-specific emissions limitations; instead, the program uses an overall emissions cap for SO2 that ensures that emission reductions are achieved and maintained and provides for a trading system that facilitates lowest-cost emissions reductions. The program features tradable SO2 emissions allowances, where one allowance is a limited authorization to emit 1 short ton of SO2. A fixed number of allowances is issued by the government and they may be bought, sold, or banked for future use by utilities, brokers, or anyone else interested in holding them. Existing units are allocated allowances for each year; new units do not receive allowances and must buy them. New coal-fired boilers are subject to the NSPSs that remain in effect (i.e., 70-90+% reduction), with the provision that they must acquire emission allowances to emit the residual SO2 that is not controlled [4]. At the end of the year, all participants in the program are obliged to surrender to the EPA the number of allowances that correspond to their annual SO2 emissions [19].

The NOx Program Title IV also required the EPA to develop a NOz reduction program and set a goal of reducing NOz by 2 million short tons from 1980 levels. As with the SO2 emission reduction requirements, the NOZ program was implemented in two phases, beginning in 1996 and 2000 [21]. The NOx program embodies many of the same principles of the SO2 trading program in its design: a results orientation, flexibility in the method to achieve emission reductions, and program integrity achieved through measurement of the emissions. However, it does not cap NOZ emissions as the SO2 program does nor does it utilize an allowance trading system, although NOx trading programs have been implemented, as discussed later in this chapter.

Emission limitations for the NOZ boilers provide flexibility for utilities by focusing on the emission rate to be achieved, expressed in pounds of NOx per million Btu of heat input. Two options for compliance with the emission limitations are provided:

• Compliance with an individual emission rate for a boiler;

• Averaging of emission rates over two or more units, that have the same owner or operator to meet an overall emission rate limitation.

These options give utilities flexibility to meet the emission limitations in the most cost-effective way and allow for the further development of

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