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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
3
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
4
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?
6
Approach
+
+
+
1
2
n
=
Firm PowerVariable PowerCompensating Power
Time
Power
Gas
Wind
7
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
8
Objective Function for Baseload Plant
9
Calculating Pollutant Mass Emissions of Baseload Plant
10
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
11
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
12
GE LM6000 – Rated 40-45MW
Source: www.sealegacy.com Oct. 4th, 2007
13
CO2 Emissions vs Power for LM6000
(idle)
14
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)
15
Region 4
Region 2
Region 1
Region 3
Idle Power
16
Siemens-Westinghouse Combined-Cycle Turbine – Rated 200 MW
www.summitvineyardllc.com
17
Operating Limit Constraint
Operating Limit Constraint
18
CO2 Emissions vs Power for SW 501FD
19
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
21
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
22
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
23
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
24
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
25
Generating Smaller Wind Data Sets
1000 min
(16.6 hrs)
+1 min
26
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
27
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