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Incorporating Wind into a Natural-gas Turbine Baseload Power System Increases NOx and CO2 Emissions from the Gas Turbines
CMU - FUTURE ENERGY SYSTEMS: EFFICIENCY, SECURITY, CONTROL
Warren Katzenstein and Dr. Jay Apt
[email protected]@cmu.edu
March 11th, 2008
22
Today I will discuss
• Background and Motivation• Research Question• Approach
– Actual wind data– Actual emissions data from two types of natural-gas turbines
• Model Construction– General Electric LM6000 turbine– Siemens-Westinghouse 501FD turbine
• Results• Implications
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Renewables Portfolio Standards
State Goal
☼ PA: 18%¹ by 2020☼ NJ: 22.5% by 2021
CT: 23% by 2020
MA: 4% by 2009 +1% annual increase
WI: requirement varies by utility; 10% by 2015 goal
IA: 105 MW
MN: 25% by 2025(Xcel: 30% by 2020)
TX: 5,880 MW by 2015
☼ AZ: 15% by 2025
CA: 20% by 2010
☼ *NV: 20% by 2015
ME: 30% by 200010% by 2017 - new RE
State RPS
☼ Minimum solar or customer-sited RE requirement* Increased credit for solar or customer-sited RE
¹PA: 8% Tier I / 10% Tier II (includes non-renewables)
HI: 20% by 2020
RI: 16% by 2020
☼ CO: 20% by 2020 (IOUs)*10% by 2020 (co-ops & large munis)
☼ DC: 11% by 2022
DSIRE: www.dsireusa.org September 2007
☼ NY: 24% by 2013
MT: 15% by 2015
IL: 25% by 2025
VT: RE meets load growth by 2012
Solar water heating eligible
*WA: 15% by 2020
☼ MD: 9.5% in 2022
☼ NH: 23.8% in 2025
OR: 25% by 2025 (large utilities)5% - 10% by 2025 (smaller utilities)
*VA: 12% by 2022
MO: 11% by 2020
☼ *DE: 20% by 2019
☼ NM: 20% by 2020 (IOUs)10% by 2020 (co-ops)
☼ NC: 12.5% by 2021 (IOUs)10% by 2018 (co-ops & munis)
ND: 10% by 2015
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Intermittent Power
Time
Power
1 Hour 2 Hour
5
Research Question
Does operating one or more gas turbines to fill in intermittent wind power result in increased NOx and CO2 emissions compared to full-power steady-state operation of natural-gas turbines?
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Approach
+
+
+
1
2
n
=
Firm PowerVariable PowerCompensating Power
Time
Power
Gas
Wind
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Approach
Wind Power Output
Calculate Power Leveland Ramp Rate Needed
GT’s Control and Regression Map
GT Emissions Model
+-
Error
Calculated Emissions
Ideal Fill Power
Realized Fill Power
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Objective Function for Baseload Plant
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Calculating Pollutant Mass Emissions of Baseload Plant
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0 0.5 1 1.5 2 2.50
10
20
30
40
50
60
70
80
90
Time (hours)
Pow
er (M
W)
Data Slice from Output of Two Wind Farms in Pennsylvania
Wind Data Obtained
• Wind Data– Output of 3 existing
wind farms• Eastern• Southern Great
Plains• Central Great
Plains– 1 to 10 seconds
resolution– 32 total days of data– From anonymous
source
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Gas Turbine Data Obtained• NOx emissions & heat
rate for 7 CTs & 1 NGCC– 1 minute resolution– Ranges from 38 days of
data to 135 days of data– CTs are LM6000s– Have
• Gas flow (HSCFH)• Load (MW)• NOx ppm and lbs• NOx ppm corrected to
15% O2• O2 %• Heat rate (mBtu/hr)
– From anonymous source
90 95 100 105 110 115 1200
5
10
15
20
25
30
35
40
45
50
Time (hours)
Pow
er (M
W)
Data Slice of Power Output of LM6000 Data Obtained
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GE LM6000 – Rated 40-45MW
Source: www.sealegacy.com Oct. 4th, 2007
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CO2 Emissions vs Power for LM6000
(idle)
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0 5 10 15 20 25 30 35 40 45 50-20
-15
-10
-5
0
5
10
15
20
Power (MW)
Ram
p R
ate
(MW
/Min
)
LM6000 NOx Emissions as a Function of Power Level and Ramp Rate
0
0.2
0.4
0.6
0.8
1
1.2
Model Construction - Regression AnalysisN
Ox
Em
itted (lbs/min)
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Region 4
Region 2
Region 1
Region 3
Idle Power
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Siemens-Westinghouse Combined-Cycle Turbine – Rated 200 MW
www.summitvineyardllc.com
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Operating Limit Constraint
Operating Limit Constraint
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CO2 Emissions vs Power for SW 501FD
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Siemens-Westinghouse - Regression Analysis
0 20 40 60 80 100 120 140 160 180 2000
0.5
1
1.5
2
2.5
3
3.5
Power (MW)
NO
x E
mitt
ed (l
b/m
in)
GE Document GER-3568G
Results
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0 0.5 1 1.5 2 2.50
10
20
30
40
Time (hours)
Pow
er L
evel
s (M
W)
Wind + CT Operating Parameters
Ideal Fill PowerWind PowerActual Fill Power
0 0.5 1 1.5 2 2.5-20
-10
0
10
20
Time (hours)
Ram
p R
ate
(MW
/min
)
Ramp Rates
Results (1) – LM6000
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Expected Emission Reductions Calculation
⎥⎥⎦
⎤
⎢⎢⎣
⎡
∗
−∗= +
nPenetratioWindMMM
NaturalGasTotal
GasNatuarlWindTotalral GasTotal,Natu
,
,100ReductionEmissionExpected
%1005.0)5.01(
100ReductionEmissionExpected,
=⎥⎥⎦
⎤
⎢⎢⎣
⎡
∗−
∗=NaturalGasTotal
ral GasTotal,Natu
MM
Example Calculations
If Wind Penetration is 0.5, then expect MTotal, Wind + NaturalGas = 0.5·MTotal,NaturalGas
If Wind Penetration is 0.3, then expect MTotal, Wind + NaturalGas = 0.7·MTotal,NaturalGas
%1003.0)7.01(
100ReductionEmissionExpected,
=⎥⎥⎦
⎤
⎢⎢⎣
⎡
∗−
∗=NaturalGasTotal
ral GasTotal,Natu
MM
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Expected Emissions ReductionEastern Wind Farm
6,400 lbs1,500 lbs-240%± 250%
NOx
6,968 tons732 tons76%± 1%
CO2
501FD (NGCC, DLN)
1,595 tons176 tons80%± 1%
CO2
8,300 lbs290 lbs29%± 4%
NOxLM6000 (CT)
Mass Emitted by Wind + NG
Emissions Reduced
Expected Emissions Reduction
Turbine
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Expected Emissions Reduction
-530% + 150% - 5%
-600% + 100% -75%
-240% ± 250%
NOx
78.9% ± 0.1%
76.8% ± .2%
76% ± 1%
CO2
501FD (NGCC, DLN)
77% ± 1%
77% ± 1%
80% ± 1%
CO2
31% ± 4%
21% ± 3%
29% ± 4%
NOxLM6000 (CT)
Central Great Plains
Southern Great Plains
EasternWind Farm
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Generating Smaller Wind Data Sets
1000 min
(16.6 hrs)
+1 min
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Implications• 1 MWh of wind energy does not eliminate 1 MWh of emissions• Impacts
– Clean Air Interstate Rule (CAIR)• Significant penetration of wind power will make it harder for
CAIR to achieve emission reduction goals– Emission displacement studies
• Overestimating the amount emissions are displaced by wind– Life Cycle Analyses
• Don’t account for wind’s effect of decreasing emission efficiencies of conventional generators
– Technology• Not all gas turbines are equally suitable for pairing with wind• R&D program to improve emissions of heavily cycled gas
turbines
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AcknowledgementsAllen Robinson, Cliff Davidson, Lester Lave, Mitchell Small
Anonymous resource for power plant emissions data,
Anonymous resource for wind data
Funding CEICNETL CIT Dean’s Fellowship
Warren [email protected]
Dr. Jay [email protected]
Questions?
Renewable Portfolio Standard which would require
electric utilities to obtain 15 percent of their electricity
from wind, solar, or biomass energy by 2020
– NYTimes June 15th, 2007
RPS dsireusa.org C.A.I.R epa.gov
LA Smog Apt
