implications of low natural gas prices on life cycle greenhouse
Post on 03-Feb-2022
2 Views
Preview:
TRANSCRIPT
Carnegie Mellon University
IMPLICATIONS OF LOW NATURAL GAS PRICES ON LIFE CYCLE GREENHOUSE
GAS EMISSIONS IN THE U.S. POWER GENERATION SECTOR
Presented by Paulina Jaramillo Co-authors: Aranya Venkatesh, Mike Griffin, Scott
Matthews
USAEE, November 2012
Carnegie Mellon University
Motivation • With the increases in natural gas production
there has been increased interests in understanding the reductions in GHG emissions from power generation.
• Life Cycle Analysis assumes that 1 MWh of
natural gas-based power replaces 1 MWh of coal-based power.
• No consideration is given to the economics or the operations of the power system.
2
Carnegie Mellon University 3
Life cycle GHGs – US Natural gas
Life cycle GHG emissions (g CO2e/MJ)"
Den
sity"
Source: Venkatesh et al, 2011
Mean Life Cycle GHG Emissions of Domestic Natural Gas = 66 g CO2e/MJ 90% CI = 62-72 g CO2e/MJ
Carnegie Mellon University
Different studies have resulted in different values
4
Conventional
Unconventional
Howarth et al. 2011 Stephenson et al. 2011
Life cycle GHG emissions (g CO2e/MJ)"
Den
sity"
Carnegie Mellon University
80 90 100 110 120 130 140 1500
0.02
0.04
0.06
0.08
0.1
Den
sity
5
Life cycle GHGs – US Coal
Life cycle GHG emissions (g CO2e/MJ)"
Den
sity"
Mean Life Cycle GHG Emissions of Coal = 96 g CO2e/MJ 90% CI = 89-106 g CO2e/MJ
Source: Venkatesh, et al. 2012
Carnegie Mellon University
Life cycle GHG emissions of electricity
6 Source: Jiang et.al, 2011
Carnegie Mellon University
• We know, however, that the electricity grid is a complex system that has to be operated to instantaneously match supply and demand. Producing one additional MWh of natural gas will not necessarily replace one MWh of coal.
7
Carnegie Mellon University
Research Question
• Given the recent development on Shale gas and low natural gas prices, what will be the implications for life cycle GHG emissions associated with the fuels used for power generation?
8
Carnegie Mellon University
Method
Supply curve [eGRID & EPA
IPM data]
2010 hourly load
[ISO data] Annual
combustion emissions from
ISO
Upstream natural gas and coal
emissions factors
Total annual GHG
emissions from ISO
Ranking Algorithm
Fuels Used
9
Carnegie Mellon University
Supply Curve Inputs
10
*Ranges represent regional fuel prices 15 Newcomer et al (2008). Env. Science and Technology
Plant type Unit Price Nuclear ($/MWh) 16.515 Wind ($/MWh) 2015 Hydro ($/MWh) 1015 Biomass ($/MWh) 5015 Coal* ($/MMBtu) 1.88 - 2.6924 Natural gas* ($/MMBtu) 4.26 – 5.1324 Oil* ($/MMBtu) 19.99 - 22.3124
!
Carnegie Mellon University
Ranking Algorithm
• Some constraints – Added availability factors for thermal
units. Average capacity factors were used for hydro and wind.
– Added minimum operating limits • 30% for coal plants • 25% for NG plants larger than 800 MW • Must run nuclear
11
Carnegie Mellon University
Base Case Supply Curve (PJM)
12
0 20 40 60 80 100 120 140 160 180 2000
50
100
150
200
250
300
350
400
450
500PJM
Cumulative capacity (GW)
Short−ru
n marg
inal c
osts
($/MW
h)
HYDRONUCLEARWINDCOALNATURAL GASBIOMASSOIL
Natural gas price: $4.5/MMBtu
Carnegie Mellon University
Model Validation
• We confirmed that the supply model resulted in appropriate percentage generation by fuel type
13
Carnegie Mellon University
Modified NG prices
• Varied U.S. Average Delivered Natural Gas Prices between $1.5 and $7.5 per MMBtu – Delivered prices in the different regions are
not the same. The U.S. average was used as a basis to determine region specific delivered prices for PJM, MISO, and ERCOT through simple regressions
14
Carnegie Mellon University
Sample Modified Supply Curve for PJM (NG Price = $2.5/MMBtu)
15
0 20 40 60 80 100 120 140 160 180 2000
50
100
150
200
250
300
350
400
450
500PJM
Cumulative capacity (GW)
Short−r
un m
argina
l cos
ts ($/
MWh)
HYDRONUCLEARWINDCOALNATURAL GASBIOMASSOIL
0 20 40 60 80 100 120 140 160 180 2000
50
100
150
200
250
300
350
400
450
500PJM
Cumulative capacity (GW)
Shor
t−run
mar
ginal
costs
($/M
Wh)
HYDRONUCLEARWINDCOALNATURAL GASBIOMASSOIL
Original Supply curve (NG = $4.5/MMBtu
Modified Supply Curve
Carnegie Mellon University
Results of modified natural gas prices
16
Minimum coal generation limit = 30%
ERCOT MISO PJM
Per
cent
age
Ele
ctric
ity G
ener
atio
n
0
10
20
30
50
60
70
80
100
40
90
20
0
10
50
60
70
80
100
40
90
30
0
10
20
30
50
60
70
80
100
40
90
Base Case
4.5 5.5 1.5+ Must-run Nucl.
2.5
U.S. Average Electricity Sector Delivered NG Price ($/MMBtu)
3.5 Base Case
4.5 5.5 1.5+ Must-run Nucl.
2.5
U.S. Average Electricity Sector Delivered NG Price ($/MMBtu)
3.5 Base Case
4.5 5.5 1.5+ Must-run Nucl.
2.5
U.S. Average Electricity Sector Delivered NG Price ($/MMBtu)
3.5
Carnegie Mellon University 17
GHG Emission Reductions S
yste
m w
ide
GH
G E
mis
sion
Red
uctio
n (%
)
Carnegie Mellon University
Conclusions • LCA studies suggest a 50% reduction in GHG
emissions associated with displacing coal with natural gas. These studies do not consider grid operations
• Our numbers suggest that the maximum emission reduction that could be observed with the current power plant fleets are less than 25%. At a realistic natural gas price, they are less than 5%.
• Reductions of GHG emissions from the power system may not be a sufficient motivation for supporting increased production of unconventional gas resources; unless there is a complete transformation of the power plant fleet.
18
Carnegie Mellon University 19
Carnegie Mellon University
Acknowledgements • Funding for the authors was provided by the Energy
Foundation and the RenewElec Project, which was funded by the Doris Duke Charitable Foundation, the RK Mellon Foundation, the Heinz Endowment, the Electric Power Research Institute, the National Energy Technology Lab, and the Carnegie Mellon Electricity Industry Center
– Any opinions, findings, and conclusions expressed in this
material are those of the authors and do not necessarily reflect the views of these organizations.
20
Carnegie Mellon University
References • Jaramillo, P.; Griffin, W.; Matthews, H. Comparative life-cycle air emissions of coal,
domestic natural gas, LNG, and SNG for electricity generation Environmental Science and Technology. 2007, 41, 6290–6296.
• Newcomer, A.; Blumsack, S.; Apt, J.; Lave, L.; Morgan, M. Short run effects of a price on carbon dioxide emissions from US electric generators. Environmental Science Technology. 2008, 42, 3139–3144.
• Venkatesh, A.; Jaramillo, P.; Griffin, W. M.; Matthews, H. S. Uncertainty in Life Cycle Greenhouse Gas Emissions from United States Natural Gas End-Uses and its Effects on Policy. Environmental Science and Technology 2011, 45, 8182–8189.
• Jiang, M.; Michael Griffin, W.; Hendrickson, C.; Jaramillo, P.; VanBriesen, J.; Venkatesh, A. Life cycle greenhouse gas emissions of Marcellus shale gas. Environmental Research Letters 2011, 6, 034014.
• Howarth, R. W.; Santoro, R.; Ingraffea, A. Methane and the greenhouse-gas footprint of natural gas from shale formations. Climatic Change. 2011, 106, 679–690.
21
Carnegie Mellon University
References • Stephenson, T.; Valle, J. Modeling the Relative GHG Emissions of Conventional
and Shale Gas Production. Environmental Science & Technology. 2011, 45, 10757-10764
• Weber, C.; Clavin, C. Life Cycle Carbon Footprint of Shale Gas: Review of Evidence and Implications. Environmental Science & Technology. 2012, 46 (11): 5688–5695
• Venkatesh, A.; Jaramillo, P.; Griffin, W. M.; Matthews, H. S. Implications of changing natural gas prices in the United States electricity sector for sulfur and nitrogen oxides, and life cycle greenhouse gas emissions. Environmental Research Letters. 2012, 7: 034018
• Venkatesh, A.; Jaramillo, P.; Griffin, W. M.; Matthews, H. S. Uncertainty in life cycle greenhouse gas emissions from U.S. coal. Energy and Fuels. 2012, 26 (8): 4917–4923
22
Carnegie Mellon University
Thank you for your attention
You can contact me at paulina@cmu.edu
www.RenewElec.org
23
Carnegie Mellon University
Region specific delivered natural gas prices
24
2
4
6
8
10
12
a)ERCOT: y=0.94x, R2=0.97
0
2
4
6
8
10
12
14
Regi
onal
Ele
ctric
ity s
ecto
r del
ivere
d na
tura
l gas
pric
e ($
/MM
Btu)
b)MISO: y=0.96x, R2=0.91
2 4 6 8 10 12 140
5
10
15
U.S. Average Electricity sector delivered natural gas price($/MMBtu)
c)PJM: y=1.14x, R2=0.95
top related