Technical Support Docum ent (TSD)
for the Transport Rule
Docket ID No. EPA-HQ-OAR-2009-0491



## Capacity Factors Anal ysis for New Units

U.S. Environmental Protection Agency

Office of Air and Radiation
July 2010

1Capacity Factors Analysis for New Units

This Technical Support Document (TSD) pr ovides information that supports the EPA’s determination of default capacity factors for new units in the Transport Rule proposal. Section V.D.4 in the Transport Rule preamble describes the proposed remedy including the use of default capacity factors for new units. This TSD describes how EPA determined the proposed default capacity fact ors. The TSD is organized as follows:
1. Introduction
2. Determination of de fault capacity factors

1. Introduction Section V.D.4 in the preamble of the Transport Rule describes EPA’s proposed remedy including the assurance provisions. As described in the preamble, if the assurance provisions in a stat e are triggered then EPA woul d apply additional criteria to
determine which source owners in the state would be subject to an allowance surrender requirement. In the case where the assurance provisions are triggere d in the year that a new unit first operates, in order to apply the additional cr iteria, EPA would determine a specific surrogate emissions number for the new unit. As discussed in the preamble, in calculating a new unit’s surrogate emissions number EPA would use a default capacity fact or specific to the unit type: a new unit’s surrogate emissions number would be calcu lated by multiplying the unit’s allowable emissions rate (in lbs/MWe) by the unit’s maximum hourly load (in MWe/hr) and the default capacity factor for the unit type. The proposed default capacity factors for new units – which are provided in preamble section V.D.4.b – are shown below in Table 1. This TSD describes how EPA determined these default capacity factors.

2Table 1. Default Capac ity Factors for New Units for Transport Rule Trading Programs (Percentage)

Unit Types Annual SO 2 & NO X Programs Ozone Season NO X Program Coal Steam 84 89 Simple cycle combustion turbine 15 22 Combined cycle combustion turbine 66 72

2. Determination of Default Capacity Factors EPA determined the default capacity f actors for new units in Table 1 based on analysis of capacity factors us ing data reported to EPA by so urce owners and operators as part of EPA’s emissions trading programs. These programs require industry sources to report hourly emissions data each quarter. Using the reported data, for coal boilers EPA calculated an annual capacity factor for each unit for each full year of operation between the years 2000 and 2009. For combustion turbines, EPA calculated an annual capacity factor for each unit for each full year of operation between 2004 and 2009. 1 For this analysis, we removed any partial years from the data sets. To determine annual capacity factors, EPA calculated the capacity factor for units reporting in electrical load units (MW) by dividing the gro ss electrical output (MWhr) by the maximum hourly load times 8,760 hours (the nu mber of hours in a year). For units reporting in steam units (KLBsteam), i.e., coal boilers only, we divi ded the total mass of steam produced by the maximum steam rate times 8,760 hours. The maximum hourly
load or maximum steam rate are reported to EPA. From these annual capacity factors that EPA calculated, we then determined the
50 th , 67 th , 75 th , 90 th , 95 th , 99 th , and 100 th percentile values of ca pacity factors for each unit type. Table 2, below, show s these percentile values.

1 The year 2009 was the most recent full year of data available at the time EPA conducted the analysis. We looked at more years of coal da ta (2000 through 2009) because there were fewe r new coal units to draw on compared to the number of recent combustion turb ines (CT). We looked at fewer years of CT data because there were more data points available in th e recent data and the more recent data was thought to better represent the present, given that CT operation is more variable.

3To determ ine ozone season capacity factors, EPA performed the same calculations except based on the possible cap acity that could be produced during the 3,672 hours of the ozone season contro l period. Table 3 shows the 50 th , 75 th , 90 th , 95 th

, and 100 th percentile values of ozone season capacity factors for each unit type. From the values in Table 2, the EPA c hose the 95th percen tile annual capacity factors for use as default capacity factors fo r new units in the Transport Rule annual SO 2 and NO X trading programs. Similarly, from the values in Table 3 we chose the 95th percentile ozone season capacity factors for us e as the default capacity factors for new units in the Transport Rule ozone season NO X trading program. EPA believes that this approach would cover a range of operating conditions for new units.

Table 2. Summary of Annual Capacity Factors
Percentile Coal Steam Boiler Simple Cycle Combustion Turbine Combined Cycle Combustion Turbine 50 th 0.76 0.02 0.26 67 th 0.79 0.03 0.37 75 th 0.80 0.05 0.43 90 th 0.83 0.09 0.57 95 th 0.84 0.15 0.66 99 th 0.86 0.42 0.73 100 th 0.87 0.63 0.78

Table 3. Summary of Ozone Season Capacity Factors
Percentile Coal Steam Boiler Simple Cycle Combustion Turbine Combined Cycle Combustion Turbine 50 th 0.77 0.03 0.35 75 th 0.82 0.08 0.51 90 th 0.87 0.15 0.65 95 th 0.89 0.22 0.72 100 th 0.92 0.93 0.92

4Figures 1, 2, and 3, below, show the dist ribution of annual capacity factors for
coal-fired u nits, simple cycle turbines, and combined cycle turbines, respectively, based on the annual data EPA analyzed (the data is summarized in Table 2). Figures 4, 5, and 6 show the distribution of ozone season capacity factors for coal-fired units, simple cycle turbines, and combined cycle turbines, respec tively, based on the ozone season data EPA analyzed (the data is summarized in Table 3).

Figure 1. Distribution of Annual Capaci ty Factors for Coal-Steam Boilers

Distribution of Annual Capacity Factors for Coal-Steam Boilers

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%
PercentileCapacity Factor

5Figure 2. Distribution of Annual Capaci ty Factors for Simple Cycle Turbines

Distribution of Annual Capacity Factors for Simple Cycle Turbines

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%
PercentileCapacity Factor

6Figure 3. Distribution of Annual Capacity Factors for Combined Cycle Turbines

Distribution of Annual Capacity Factors for Combined Cycle Turbines

0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100%
PercentileCapacity Factor

7Figure 4. Distribution of Oz one Season Ca pacity Factors for Coal-Steam Boilers

Distribution of Ozone Season Capacity Factors for Coal-Steam Boilers

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

1

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% PercentileCapacity Factors

8Figure 5. Distribution of Oz one Season Capacity Factors for Simple Cycle
Turbines

Distribution of Ozone Season Capacity Factors for Simple Cycle Turbines

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

1

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% PercentileCapacity Factors

9Figure 6. Distribution of Oz one Season Capacity Factors for Combined Cycle
Turbines

Distribution of Ozone Season Capacity Factors for Combined Cycle Turbines

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9

1

0% 10% 20% 30% 40% 50% 60% 70% 80% 90% 100% PercentileCapacity Factors

10