Appendix A to Part 72 - Methodology for Annualization of Emissions Limits
40:18.0.1.1.1.11.1.1.1 : Appendix A
Appendix A to Part 72 - Methodology for Annualization of Emissions
Limits
For the purposes of the Acid Rain Program, 1985 emissions limits
must be expressed in pounds of SO2 per million British Thermal Unit
of heat input (lb/mmBtu) and expressed on an annual basis.
Annualization factors are used to develop annual equivalent SO2
limits as required by section 402(18) of the CAA. Many emission
limits are enforced on a shorter term basis (or averaging period)
than annually. Because of the variability of sulfur in coal and, in
some cases, scrubber performance, meeting a particular limit with
an averaging period of less than a year and at a specified
statutory emissions level would require a lower annual average SO2
emission rate (or annual equivalent SO2 limit) than would the
shorter term statutory limit. EPA has selected a compliance level
of one exceedance per 10 years. For example, an SO2 emission limit
of 1.2 lbs/MMBtu, enforced for a scrubbed unit over a 7-day
averaging period, would result in an annualized SO2 emission limit
of 1.16 lbs/MMBtu. In general, the shorter the averaging period,
the lower the annual equivalent would be. Thus, the annualization
of limits is established by multiplying each federally enforceable
limit by an annualization factor that is determined by the
averaging period and whether or not it's a scrubbed unit.
Table A-1 - SO2Emission Averaging Periods
and Annualization Factors
| Definition |
Annualization
factor |
| Scrubbed
Unscrubbed |
| Unit |
Unit |
| Oil/gas unit |
1.00 |
1.00 |
| ≤1 day |
0.93 |
0.89 |
| 1 week |
0.97 |
0.92 |
| 30 days |
1.00 |
0.96 |
| 90 days |
1.00 |
1.00 |
| 1 year |
1.00 |
1.00 |
| Not specified |
0.93 |
0.89 |
| At all times |
0.93 |
0.89 |
| Coal unit: No
Federal limit or limit unknown |
1.00 |
1.00 |