2. EPA GRO FELLOWSHIP
The GRO Fellowship Program is administered by the National
Center for Environmental Research (NCER) in EPA’s Office of
Research & Development (ORD)
The Fellowship supports students during their junior and senior
years of undergraduate study and includes support for an
internship at an EPA facility during the summer of their junior year.
3. GOALS OF INTERNSHIP
Gain familiarity with the CAA Prevention of Significant
Deterioration permitting program for GHG emissions
Gain experience with a variety of EPA air pollution permit
technical programs and in how air pollution is generated and
controlled
Study the efficiency impacts for combustion turbine technology
related to GHG permitting to provide a comparative analysis of
EPAs BACT determinations and ISO conditions for electric
generation projects located in Texas
5. SIMPLE CYCLE RULES OF THUMB
Ambient Temperature: 0.4% reduction in power output per 1°F
increase in ambient temperature above 59°F, and a
proportionate increase in heat rate. The opposite holds true for
decreasing temperatures.
Site elevation: 3.3% reduction in power output per every 1,000-ft
increase in site elevation above sea level. Heat rate is
unaffected.
6. COMBINED CYCLE RULES OF THUMB
Ambient temperature: 2.5% reduction in power output per 10°F
increase in ambient temperature above 59°F, and a
corresponding increase with decreasing temperatures. 0.5%
impact on heat rate (up and down, respectively) per 10°F
change in air temperature from 59°F.
Site elevation: 3.3% reduction in power output per every 1,000-ft
increase in site elevation above sea level. Heat rate is
unaffected.
7. CO2 EMISSION CALCULATIONS
The equation for estimating CO2 emissions as specified in 40 CFR
75.10(3)(ii) is:
𝑊 𝐶𝑂2
=𝐹𝑐 ×𝑈𝑓 ×𝑀𝑊 𝐶𝑂2
Where:
WCO2
= CO2 emitted from combustion, tons/hour
MWCO2
= molecular weight of CO2, 44.0 lbs/mole
Fc = Carbon-based Fc-Factor, 1040 scf/MMBtu for natural gas or
site-specific Fc factor
Uf = 1/385 scf CO2/lb-mole
8. CO2 EMISSIONS CALCULATIONS (CONT)
𝐶𝑂2 TPY = [(CTHC*CTO) + (STHC*STO)] *𝑊𝐶𝑂2 )/2,000
Where:
WCO2
= CO2 emitted from combustion, tons/hour
CTHC = CT Heat Consumption, MMBtu/hr
CTO = CT Operation, hrs/yr
STHC = ST Heat Consumption, MMBtu/hr
STO = ST Operation, hrs/yr
10. DATA COLLECTION - Snapshot
Company Name City County Turbine Model
Temp Max
(F)
Temp Min
(F)
Temp Mean
(F)
Elevation
(m)
CT
hrs/yr
ST
hrs/yr
Duct
burning?
CT heat consump
MMBTU/KWH
ST heat consump
MMBTU/KWH
CT
Power Output
MW
ST
Power Output
MW
BACT Limit
lb CO2/MWH
Tenaska Roans Prairie Partners, LLC Shiro Grimes
GE 7FA.05, 7FA.04,
or S GT6-5000F(5) 79.8 54.4 67.1 107 2920 n/a No
Option 1 (Siem): 2441
Option 2 (GE(5)): 2378
Option 3 (GE(4)): 2198 n/a
Option 1 (Siem): 231
Option 2 (GE(5)): 212
Option 3 (GE(4)): 176 n/a
Option 1 (Siem): 1334
Option 2 (GE(5)):1310
Option 3 (GE(4)):1321
Southern Power Company Cushing Nacogdoches Siemens F(5) 76.9 54.1 65.5 125 2500 n/a No 2146 n/a 232 n/a pending
Indeck Wharton, LLC Danevang Wharton
GE 7FA.05
or Siemens SGT-5000F(5) 79.95 58.93 69.45 21 2500 n/a No 2054 n/a 216.6666667 n/a
Option 1 (GE): 1276
Option 2 (Siem): 1337
Invenergy Thermal Development LLC Goldsmith Ector GE 7FA.03 78.18 51.1 64.65 957 2500 n/a No 1611.48 n/a 165 n/a 1393
NRG Tx Pwr LLC (PH Robinson Sta) Bacliff Galveston GE 7E 76.8 62.46 69.73 5 1752 n/a No 921.67 n/a 65 n/a
pending/ ap withdrawn
proposed in ap: 1450
Golden Spread El. Coop. - Antelope Sta. Abernathy Hale GE 7FA.05 70.03 44 58 1024 4572 n/a No 1940.74 n/a 202 n/a 1304
Guadalupe Power Partners LP Marion Guadalupe GE 7FA.04 79.9 56.55 68.25 197 2500 n/a No 1788.82 n/a 165 n/a 1268
Lon C. Hill LP Corpus Christi Nueces
GE 7FA.04, or
Siemens SCC6-5000F 81.01 63.54 72.26 2 8760 8760 Yes 2412.8 670
Option 1 (GE): 183
Option 2 (Siem): 240 260 900
City of Austin - Sand Hill En. Ctr. Del Valle Travis GE 7FA.04 79.33 55.98 67.65 148 8760 8760 Yes 1911.6 681.5 173.9 189 930
Southern Power Company Trinidad Henderson Mitsubishi J model 75.9 53.8 64.9 92 8760 8760 Yes 3214 402 ? ?
pending
proposed in ap: 922
Victoria WLE LP Victoria Victoria GE 7FA.04 80.56 60 70.3 29 8760 4375 Yes 1816 483 182.684 92.5 940
NRG Texas Pwr LLC (Cedar Bayou) Baytown Chambers
GE 7FA-05 or Siemens F(5)
or M 501GAC 77.4 59 68.2 7 8760
Option 1 (GE): 3500
Option 2 (Siem): 3500
Option 3 (MHI): 3200 Yes
Option 1 (GE): 2101.2
Option 2 (Siem): 2337.6
Option 3 (MHI): 2586.1
Option 1 (GE): 523.1
Option 2 (Siem): 606.3
Option 3 (MHI): 632.5 264 ? pending
NRG Texas Pwr LLC SR Bertron La Porte Harris
GE 7FA-05 or Siemens F(5)
or M 501GAC 79.1 59.66 69.35 6 8760
Option 1 (GE): 3500
Option 2 (Siem): 3500
Option 3 (MHI): 3200 Yes
Option 1 (GE): 2101.2
Option 2 (Siem): 2337.6
Option 3 (MHI): 2586.1
Option 1 (GE): 523.1
Option 2 (Siem): 606.3
Option 3 (MHI): 632.5 264 ? pending
Tenaska Brownsville Partners LLC Brownsville Cameron MHI 501 GAC 82.9 65.4 74.185 10 5200 5200 Yes 2903 250 274 336 914
Pinecrest Energy Center LLC Lufkin Angelina
GE 7FA.05 or
S GT6-5000F(4)
S GT6-5000F(5) 77.25 54.2 65.7 95 8260 8260 Yes
Option 1 (GE): 2861
Option 2 (Siem(4)): 2764
Option 3 (Siem(5)): 3110 750
Option 1 (GE): 215
Option 2 (Siem(4)): 205
Option 3 (Siem(5)): 232 271
Option 1 (GE): 942
Option 2 (Siem(4)): 909.2
Option 3 (Siem(5)):912.7
La Paloma Energy Center Harlingen Cameron
GE 7FA.04
or SGT6-5000F(4)or (5) 82.9 65.4 74.185 12 8260 8260 Yes
Option 1 (GE): 1230.6
Option 2 (Siem(4)): 1626
Option 3 (Siem(5)): 1584.2 750
Option 1 (GE): 183
Option 2 (Siem(4)): 205
Option 3 (Siem(5)): 232 271
Option 1 (GE): 934.5
Option 2 (Siem(4)): 909.2
Option 3 (Siem(5)):912.7
Calpine/DeerPark Energy Center LLC Deer Park Harris Siemens 501F 79.1 59.66 69.35 8 8760 8760 Yes 1852.17 725 180 200 920
Calpine - Channel Energy Center Pasadena Harris Siemens 501F 79.1 59.66 69.35 9 8760 8760 Yes 1852.17 475 180 200 920
7 Simple Cycle
11 Combined Cycle
11. SIMPLE CYCLE
BACT limits in permits: 1268 – 1393
Average: 1317
BACT limits at ISO: 1099 – 1484
Average: 1222
Average % difference: 7.2%
0
200
400
600
800
1000
1200
1400
1600
TRPP LLC (1) TRPP LLC (2) TRPP LLC (3) Indeck (1) Indeck (2) Invenergy GSEC
lbsCO2/MWH
Simple Cycle
BACT Limit in Permit BACT Limit at ISO
12. SIMPLE CYCLE RULES OF THUMB
Biggest impact on efficiency: high temperatures
All turbines experience power output reduction and heat rate
increase in the 4.41 – 8.38% range, at an average of 7.35%
Elevation has little effect on power output, ranging from
reductions of 0.02 - 3.38%, averaging 1.15%
13. COMBINED CYCLE
BACT limits in permits: 900 – 942
Average: 915
BACT limits at ISO, 8760 hrs: 728 – 889
Average: 748
Average % difference: 10.7%
Combined cycle
calculations are much less
straightforward than simple
cycle calculations!
R6 issued permits contain a 10-
12% compliance margin
(design margin, performance
margin and degradation
margin) that results in a higher
BACT limit than ISO BACT limits.
0
100
200
300
400
500
600
700
800
900
1000
Lon C. Hill
LP (1)
Lon C. Hill
LP (2)
Austin
Energy
Victoria
WLE LP
Pinecrest
EC LLC
(1)
Pinecrest
EC LLC
(2)
Pinecrest
EC LLC
(3)
La
Paloma
EC (1)
La
Paloma
EC (2)
La
Paloma
EC (3)
Calpine
Deer
Park
Calpine
Channel
lbsCO2/MWH Combined Cycle
BACT Limit in Permit BACT Limit at ISO, 8760 Operating hrs/yr
14. COMBINED CYCLE ASSUMPTIONS
Combined cycle calculations have more variables than simple cycle
calculations, which make them more complex, and thus combined
cycle calculations should be made on a case by case basis.
Variables:
Duct burning
Different configurations
Hours of operation
Case by case example:
Austin Energy:
• Both the CT and ST operate at 8760 hrs/yr,
with duct burning
BACT Limit in permit: 930 lbs CO2/MWH
BACT Limit at ISO: 849.3 lbs CO2/MWH
% difference: 8.7%
15. COMBINED CYCLE RULES OF THUMB
Biggest impact on efficiency: high temperatures
All turbines experience power output reduction in the 4.23 – 5.98%
range, at an average of 5.13%
Elevation has little effect on power output, ranging from
reductions of 0.01 – 0.49%, averaging 0.13%
Temperature, high and low, has little effect on heat rate
The combined cycle is less affected by changes in ambient
temperature and pressure than the simple cycle across the
board.
16. RESULTS SUMMARY
Simple Cycle BACT limits are 7.2% different than estimated ISO
BACT limits.
Combined Cycle BACT limits are 10.7% higher than estimated ISO
BACT limits.
The Simple Cycle limit calculations are more accurate than the
Combined Cycle because less assumptions are required.
The largest impact on power output and heat rate for all turbines
in this data set was high ambient temperatures.
