Date: December 16, 2011 

Subject: Conversion of EGU MACT Emissions Data for Two Integrated Gasification 

Combined Cycle (IGCC) Units to the Same Basis 

From: Stephen Boone (RTI International) 

To: Bill Maxwell 

 OAQPS/SPPD/ESG (D243-01) 

 U.S. Environmental Protection Agency 

 Research Triangle Park, NC 27711 

Public comments on the EGU MACT proposal noted that the two IGCC units that 

provided emissions data under the Information Collection Request (ICR), reported emission rates 

using different basis, and claimed that these data were not comparable. RTI conducted an 

analysis that confirmed the concerns of the commenters and developed a methodology for 

conversion of the emissions data to the same basis. The emissions data from Tampa Electric 

Company’s (TECO’s) Polk IGCC facility was based on an estimate of the heat content in the 

solid fuels being fed into the reaction vessel that produces the syngas, while the emissions data 

for Duke Energy’s Wabash IGCC facility was reported based on the heat content in the syngas 

exiting the reaction vessel. Since the affected source under the MACT standard is the 

combustion unit (i.e., the combustion turbine for an IGCC facility), the heat input from the 

syngas to the combustion turbine was used as the common basis for both sources. Available 

CEMS data from TECO’s Polk IGCC facility were converted from a solid fuel heat input basis 

(to the reactor) to a syngas heat input basis (to the combustion turbine). Since the Wabash data 

was submitted on a basis consistent with the rule, no conversion of the Wabash data was 

necessary. 

The available CEMS data included 30 days of operating data submitted from the Wabash 

facility that indicated the heat rate varied from 10.7 MMBtu per gross MW at 90 percent to 10.1 

MMBtu/MWg at 100 percent of capacity. Similarly, the 30 days of operating data submitted by 

TECO for the Polk facility indicated that it has a slightly better heat rate than Wabash (i.e., 10.3 

MMBtu/MWg at 90 percent of capacity and 9.9 MMBtu/MWg at 100 percent of capacity). 

The attached file includes a spreadsheet showing the heat rate derivations for conversion 

of the lb/MMBtu emission factors to a lb/MWg basis. There is also a spreadsheet with 

calculations that convert the lb/MMBtu emission rates reported under the ICR for TECO based 

on an oxygen-based F-factor of 9780 for bituminous coal to a CO2 based calculation using the Ffactor for syngas used in the TECO data acquisition and handling system. 

The top section of the filterable particulate (fPM) calculations spreadsheet shows the 

revised calculations (based on Equation 19-6 of Method 19) necessary to apply the CO2 based F 

factor to the stack testers sampling data. The bottom of the spreadsheet includes a QA measure, 

where the data reported by the stack tester (based on the oxygen based F-factor for bituminous 

coal) were re-entered into Equation 19-1 to confirm the units of measure and the wet or dry basis 

of the submitted stack testing data. Upon verification of the units of measure by obtaining the 
same results as the stack tester, these same parameters were utilized in Equation 19-6 to 

complete the carbon-based F-factor calculations for syngas combustion. 

In the preceding manner both the heat input based emission data and the output based 

emissions data for TECO’s Polk IGCC unit were converted to the same basis as that submitted 

for Wabash. The results from this analysis indicated that the reported lb/MMBtu emission rates 

on an O2 basis for bituminous coal for TECO’s Polk facility needed to be increased by a factor of 

1.16 to be consistent with the reported values for Wabash (i.e., both sources emissions on a 

lb/MMBtu basis reflecting the heat input to the combustion turbine.)