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The Second The Second Generation ModelGeneration Model
The Second The Second Generation ModelGeneration Model
US Environmental Protection Agency
Science Advisory Board
SAB-SGM Advisory Panel
Jae Edmonds, Ron Sands, Hugh Pitcher, Antoinette Brenkert
04 February 2005US Environmental Protection AgencyWashington, DC
2
OverviewOverviewOverviewOverview
Model Structure and Purpose
Hybrid Input-Output Table
International Trade
Production, Expectations and Market Clearing in the SGM
Access to the Model
3
SGM OriginsSGM OriginsSGM OriginsSGM Origins
The SGM is a computable general equilibrium model of an economy Original design began in 1988—at a time when there
were no CGE models in use to address climate change
Designed as a complement to the Edmonds-Reilly model—a long-term partial equilibrium model
Designed from the problem back to the model. Primary focus was on emissions of greenhouse
gases including CO2 from energy and land-use emissions and non-CO2 greenhouse gases
Time frame: 5-50 years into the future
4
MiniCAM-SGM RelationshipMiniCAM-SGM RelationshipMiniCAM-SGM RelationshipMiniCAM-SGM Relationship
MiniCAM Simpler, long-term, partial equilibrium model Test bed for new ideas
SGM Computable general equilibrium
Energy-economy and other interactions matter More detailed framework than MiniCAM
Medium term (5-year time steps, 50-year time horizon)
Tracks capital stocks by vintage
5
The SGMThe SGMThe SGMThe SGM
The SGM is a simple model at its base Implements an
Economics 101 circular flow diagram
Sectors chosen for emphasis reflect a concern for the climate issue in general and the emissions of GHG’s in particular
Final Goods and Services
Primary Factors of Production
Purchases of Final Goods and Services
Payments to Primary Factors of Production
Final Demand Sectors
Government
general government services
policy intervention
Households
demographic decisionslabor supply decisions
savings decisionsconsumer demand
ownership of landownership of capitalownership of mineral
resources
Energy Production & Transformation
crude oil productionnatural gas production
coal productionhydrogen productionelectricity production
oil refiningnatural gas distribution
Industrial Production & Inter-industry Transactions
Industry & Services
paper and pulpchemicals
primary metalsfood processingother industry &
constructionthe service sector
Transportation
passenger transportfreight transport
Agriculture-Land Use
grains and oil cropsanimal products
forestrybiomass productionother agriculturecarbon storage
Greenhouse Related
Emissions
Greenhouse Related
Emissions
6
Global Fossil Fuel Carbon Global Fossil Fuel Carbon Emissions 1999Emissions 1999
Global Fossil Fuel Carbon Global Fossil Fuel Carbon Emissions 1999Emissions 1999
1,251
2,723
2,229
0
1,000
2,000
3,000
4,000
5,000
6,000
7,000
Tg
C/y
GAS FLARINGCEMENTCOAL and other solidsOIL and other liquidsNATURAL GAS
total 6,457
Source: Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory.
Fossil fuel use (6.5 PgC/y in 1999) Natural gas 13.7 TgC/EJ Oil 20.2 TgC/EJ Coal 25.5 TgC/EJ
Industrial process emissions (e.g. cement) 0.2 Pgc/y
Land-use change emissions (1.7; 0.6-2.6 PgC/y) Deforestation Soil cultivation
7
SGM Production ActivitiesSGM Production Activities
Crude oil production Wood productsNatural gas production ChemicalsCoal production Non-metallic mineralsCoke and coal products Ferrous metalsElectricity generation Non-ferrous metals
oil-fired Other industrygas-fired Passenger transportcoal-fired Freight transportnuclear Grains and oil seedshydro Animal productsadvanced technologies Forestry
Oil refining Food processingGas distribution Other agriculture
Services (everything else)
8
Fossil Fuel Carbon EmissionsFossil Fuel Carbon Emissions19991999
Fossil Fuel Carbon EmissionsFossil Fuel Carbon Emissions19991999
SGM RegionsUSA,Western Europe, China, former Soviet Union, Japan, India, Canada, South Korea, Mexico, Eastern Europe, Australia/New Zealand, Brazil, Middle East, Rest of World
Source: Carbon Dioxide Information Analysis Center, Oak Ridge National Laboratory.
1,500
981
771
392
315294
1,021
0
1,000
2,000
3,000
4,000
5,000
6,000
7,000
Tg
C/y
196 OTHER COUNTRIES
INDONESIA
BRAZIL
ISLAMIC REPUBLIC OF IRAN
SOUTH AFRICA
AUSTRALIA
UKRAINE
MEXICO
REPUBLIC OF KOREA
CANADA
INDIA
JAPAN
RUSSIAN FEDERATION
CHINA (MAINLAND)
EUROPEAN UNION (25)
UNITED STATES OF AMERICA
total 6,122
50%
67%
75%
83%
9
Key IdeasKey IdeasKey IdeasKey Ideas
Emissions—energy, ag-land-use, otherProduction functions—why CES?Energy production Resources-reserves
Energy consumption Model sectors—chosen because they have emissions that
matter Households—energy services & transport Sector-subsector
Fuels matter Energy-emissions coefficients
Region choice—emissions today and tomorrowTime scale—5-50 years Complementarity with MiniCAM Need for vintaged capital stocks
10
Key FeaturesKey FeaturesKey FeaturesKey Features
14 regions of the world USA, Canada, Mexico, Western Europe, Eastern Europe, former
Soviet Union, China, India, Brazil, Japan, South Korea, Australia/New Zealand, Middle East, Rest of World
Can be operated in single region mode
Many regional models are developed in collaboration with in-country researchers
5-year time steps from 1990 to 2050
7 Greenhouse Gases CO2, CH4, N2O, HFCs, HFC-23, PFCs, SF6
11
Regional PartnershipsRegional PartnershipsRegional PartnershipsRegional Partnerships
SGM regions are developed with regional partnersRegional researchers have the best understanding of their regional data, institutions, market structure, and trendsRegional partnerships have helped shape the development of most SGM regions
12
Energy Supply in the SGMEnergy Supply in the SGMEnergy Supply in the SGMEnergy Supply in the SGM
Finite resources use a resource-reserve-production modelProduction occurs out of reservesEach period producers bring new reserves on
line from the resource base based on expected profitability
The resource base is gradedProduction can occur from more than one
grade of the resource simultaneously
13
Anthropogenic GHGsAnthropogenic GHGsAnthropogenic GHGsAnthropogenic GHGs
14
Mapping Emissions from Mapping Emissions from Production SectorsProduction Sectors
Mapping Emissions from Mapping Emissions from Production SectorsProduction Sectors
Gas Source # Emissions Source Associated Production Sector
1 Oil Combustion 2 - Crude oil production 2 Gas Combustion 3 - Natural gas production CO2 3 Coal Combustion 4 - Coal Production
4 Coal Production 4 - Coal Production 5 Enteric 21 - Other agriculture 6 Natural Gas Systems 10 - Distributed gas 7 Oil Systems 2 - Crude oil production 8 Landfills 1 - Everything else 9 Manure 21 - Other agriculture
10 Other Agricultural Methane 21 - Other agriculture 11 Other Non-Agricultural Methane 1 - Everything else
CH4
12 Wastewater 1 - Everything else
HFC-23 13 HFC-23 1 - Everything else
HFCs 14 Ozone Depleting Substances Substitutes 1 - Everything else
15 Industrial Processes 1 - Everything else 16 Manure 21 - Other agriculture 17 Mobile Source 1 - Everything else 18 Soil 21 - Other agriculture
N2O
19 Stationary Source 1 - Everything else
20 Aluminum 1 - Everything else PFCs
21 Semiconductor 1 - Everything else
22 Electricity Distribution 6 - Electricity generation SF6
23 Magnesium 1 - Everything else
15
Technology Matters to the Technology Matters to the AnswerAnswer
Technology Matters to the Technology Matters to the AnswerAnswerTotal Policy Cost
$0.0
$5.0
$10.0
$15.0
$20.0
$25.0
$30.0
Cos
t (T
rillion
$90
US)
Individual Technologies
Binary Technologies Cominations
Multiple Technology Cominations
MiniCAM Output: Limitation of GMST to 2oC
16
Technology Vintages in the Technology Vintages in the SGM (1)SGM (1)
Technology Vintages in the Technology Vintages in the SGM (1)SGM (1)
Technology is embodied in the SGM’s production functionsTechnology is tracked by vintageExisting technology vintages produce as long as they can cover their operating costs Each existing technology is associated with a level of
capital investment that constrains total production
17
Technology Vintages in the Technology Vintages in the SGM (2)SGM (2)
Technology Vintages in the Technology Vintages in the SGM (2)SGM (2)
New technologies are chosen from the ex ante technology possibility frontier Technologies are chosen based on expected
profitability Expectations are treated explicitly in the model (The
default is myopic foresight, but others have been tried)
The level of investment in the technology depends on expected profitability
Aggregate investment in the sector depends on expected demands for the sector
18
Technology Vintages in the Technology Vintages in the SGM (3)SGM (3)
Technology Vintages in the Technology Vintages in the SGM (3)SGM (3)
The capital market balances the demands and supplies for loanable funds Existing capital stocks are associated with a specific
production function (technology) and cannot move from sector to sector
Only new investments are perfectly malleable The interest rate clears the market
19
Production FunctionsProduction FunctionsProduction FunctionsProduction Functions
All goods are produced with either a non-nested Constant-Elasticity-of-Substitution (CES) production function New investment within the electricity sector (e.g.,
new coal, gas, oil, etc.) is allocated based on a logit sharing mechanism
or Leontief production function For production functions with elasticities of
substitution < 0.05 Oil refining Electricity generation from its various energy sources
20
Technological ChangeTechnological ChangeTechnological ChangeTechnological Change
Set of parameters that can be used to simulate technical change over time for production sectors Separate parameters are available for each input to
each production process (and each vintage)
Parameters that determine energy, land, labor, and capital productivity, i.e., non-neutral technical change Labor productivity parameters are the primary
determinant of economic growth Both energy efficiency and labor productivity
parameters can be altered to construct reference scenarios
21
The DetailsThe DetailsThe DetailsThe Details
Ron Sands Hybrid data structure Trade in SGM
Hugh Pitcher Production New technologies, vintage structure & expectations Solution mechanism
Lots of discussion
Hybrid Input-Output TableHybrid Input-Output TableHybrid Input-Output TableHybrid Input-Output Table
23
TerminologyTerminologyTerminologyTerminology
The term “hybrid” refers to model input data and not model structure No code changes needed Does not limit form of production function
The input-output table used to calibrate SGM base year uses hybrid units Joules for energy flows Base-year currency (e.g., 1990 US$) for all other goods
Reference: Miller, R. and P. Blair, Input-Output Analysis, Prentice-Hall, 1985, pp. 200-235. (Chapter 6, “Energy Input-Output Analysis”)
24
MotivationMotivationMotivationMotivation
Carbon dioxide emissions are tied closely to energy flows
Energy balance tables are the best source of data on energy flows Energy balance tables are actually energy input-output tables Can construct energy “use” and “make” tables
One price for each energy commodity ensures quantity balance during model operation Energy commodities are relatively homogeneous Strict energy accounting
25
Typical Energy Balance TableTypical Energy Balance TableTypical Energy Balance TableTypical Energy Balance Table
energy inputs (fuels)
productionimportsexports
electricity generationoil refiningcoking
agricultureindustrytransportresidential buildingscommercial buildings
sources
energy transformation
final consumption
26
Data SourcesData SourcesData SourcesData Sources
Base-year input-output table Locally produced and in local currency, if available Otherwise a composite in US dollars
Base-year energy balances Locally produced, if available International Energy Agency
Engineering parameters and costs for electric generating technologies
27
Composition of Hybrid Use Composition of Hybrid Use Table (United States)Table (United States)
Composition of Hybrid Use Composition of Hybrid Use Table (United States)Table (United States)
energy balances
technology parameters
economic input-output table
crude oilnatural gascoalcokeelectricityrefined petroleumdistributed gaswood productschemicalsnon-metallic mineralsferrous metalsnon-ferrous metalsother industrypassenger transportfreight transportgrains and oil seedsanimal productsforestryfood processingother agricultureservices (everything else)
landlaborcapital
electricity generation
factors
joules
dollars
joules
dollars dollars dollars
dollars dollars dollars
joules joules
oil p
rodu
ctio
n
gas
prod
uct
ion
coal
pro
duct
ion
coke
activities
petr
oleu
m r
efin
ing
gas
dist
ribu
tion
oil-f
ired
gas-
fired
coal
-fire
d
nucl
ear
hydr
o
woo
d pr
oduc
ts
chem
ical
s
non-
met
allic
min
eral
s
ferr
ous
met
als
non-
ferr
ous
me
tals
com
mo
ditie
s
othe
r in
dust
ry
pass
eng
er tr
ansp
ort
frei
ght t
rans
port
gra
ins
and
oil s
eeds
anim
al p
rodu
cts
fore
stry
food
pro
cess
ing
othe
r ag
ricul
ture
serv
ices
(E
TE
)
cons
umer
gove
rnm
ent
inve
stm
ent
expo
rts
impo
rts
finaldemand
International TradeInternational TradeInternational TradeInternational Trade
29
OverviewOverviewOverviewOverview
Current Configuration Single Region Global Operation
Design ConsiderationsStatus of Model Development Comprehensive revision of input data Theoretical considerations
30
Single-Region ConfigurationSingle-Region ConfigurationSingle-Region ConfigurationSingle-Region Configuration
Types of commodities Numeraire good (large services sector) is tradable Other tradables (crude oil, natural gas, emissions permits) Trade in remaining goods is fixed at base-year quantity
Prices Numeraire price set equal to 1.0 in each period Crude oil and gas price set exogenously (can vary by time period) Other prices solved endogenously each time period
Emissions Permits Can be traded in a regional market (endogenous price) Can be a traded in a global market (exogenous price)
Balance of payments constraint Specified as an exogenous capital flow (can vary by time period) Any increase in imports must be paid for with exports of another tradable
31
Global ConfigurationGlobal ConfigurationGlobal ConfigurationGlobal Configuration
Configuration for recent Energy Modeling Forum studies Emissions permits trade globally or in regional blocks, depending on policy
scenario Otherwise, each region operates in same way as its regional configuration
Numeraire, crude oil, natural gas are tradable Trade in other goods is fixed at base-year quantity Regional balance of payments constraint
Crude oil and natural gas prices set exogenously on a scenario basis
Many SGM regions modeled in local currency (USA, India, China, Canada, Mexico, Japan, S. Korea)Trade takes place between each region and a global market
Exogenous exchange rate converts world price of traded good to local price (set to base-year market exchange rate)
No attempt to track bilateral trade
32
Design ConsiderationsDesign ConsiderationsDesign ConsiderationsDesign Considerations
Full global trade in crude oil and natural gas Revisit fossil supply methodology (especially Middle East) Calculation of terms-of-trade component in the cost of a climate policy
Full global trade in agricultural products Draw from Battelle-PNNL experience with partial-equilibrium Agriculture
and Land Use (AgLU) model Commodity flows calibrated to base-year food balance tables from UN
Food and Agriculture Organization
Full global trade in energy-intensive goods Shift in production capacity across regions in response to a climate
policy Carbon leakage
33
Development ActivitiesDevelopment ActivitiesDevelopment ActivitiesDevelopment Activities
Comprehensive revision of input data Selective use of GTAP data
Greater coverage of input-output tables Consistent base-year trade data across regions
Automate data preparation process Methodology to move input-output table to a different base year Develop data templates applicable to all regions Organize data on national income accounts into a social accounting
matrix
Evaluate alternatives Fossil energy supply Trade in energy-intensive goods
Production, Expectations and Production, Expectations and Market Clearing in the SGMMarket Clearing in the SGM
Production, Expectations and Production, Expectations and Market Clearing in the SGMMarket Clearing in the SGM
35
Production, Expectations and Production, Expectations and Market Clearing in the SGMMarket Clearing in the SGM
Production, Expectations and Production, Expectations and Market Clearing in the SGMMarket Clearing in the SGM
Production technology representationCombining technologies (nesting)Expectations and InvestmentSolving the model
36
ProductionProductionProductionProduction
All technologies use either a flat CES or Leontief production function (no nested CES functions) 0 is constrained to be one All technical change occurs through changes in the i
Technologies produce at original capacity until they are retired either by reaching their physical or economic lifetime (they may operate at lower capacity if rate of return is low)
Nested energy bundles will not preserve energy balance
/1
10 )()(
N
iiiXαq x
37
Technology CharacteristicsTechnology CharacteristicsTechnology CharacteristicsTechnology Characteristics
Technologies have larger elasticities of substitution at the point of investment than in subsequent periods Putty-semi putty (or putty-clay) formulation Investment value chosen to be representative of
literature—operation value chosen to meet energy conversion constraints (0.1 or lower)
Fixed physical lifetime (typically twenty years with no life extension)A vintage has a fixed capacity until it is retiredNew technologies can be made available in future periods
38
Technology (2)Technology (2)Technology (2)Technology (2)
Technologies are represented as a series of vintages—each with its own capital stock which can be operated at full capacity, part capacity or prematurely retired depending on current period profit rateProfits in the SGM are defined as revenue minus variable costs
39
Parameterization Process for Parameterization Process for Existing TechnologiesExisting Technologies
Parameterization Process for Parameterization Process for Existing TechnologiesExisting Technologies
Exogenous value for elasticity of substitutionUse IO data and functional specification to derive remaining technology parametersNon-neutral technical change values can be used to tune energy technologies to match EIA forecastSector specific discount factor derived from historical sector level investments and the investment equation
40
New TechnologiesNew TechnologiesNew TechnologiesNew Technologies
Engineering cost studies are the primary source of data on new technologiesIssues: Optimism about costs Breaking out inputs into SGM sectors Consistency of discount rates and prices
Technologies have individual discount rate which reflects sub-sector specific factor plus cost of capital from capital market
Level playing field—Existing technologies reflect additional costs, such as transmission and distribution expenses, regulatory requirements, etc.
41
New Technology (2)New Technology (2)New Technology (2)New Technology (2)
Start up is an issue Single digit nameplate problem Penetration rates for new technologies
Assigning technology specific discount factorNesting or other sub-sectors that the technology competes with directly
42
Key Lessons Learned (1)Key Lessons Learned (1)Key Lessons Learned (1)Key Lessons Learned (1)
Neutral technical change in energy transformation technologies leads to violations of the conservation of energy principle For example, consider a petroleum refinery that
presently converts 80 percent of crude to refined product
Under a one percent per year neutral technical change assumption, after 25 years, the refinery will convert 103 percent of crude to refined product
Solution Only non-neutral technical change This allows capital and labor efficiency to increase but
maintains physical limits
43
Key Lessons Learned (2)Key Lessons Learned (2)Key Lessons Learned (2)Key Lessons Learned (2)
Elasticities of substitution in the range of the literature (say .3 to .5) in the presence of carbon prices can result in implied technologies that violate the second law of thermodynamics Existing coal fired electricity plant operating at 33%
efficiency Carbon price of $300 a ton
Elasticity of Substitution = .5 => Efficiency of 75% Elasticity of Substitution = .05 => Efficiency of 34.5%
Solution: Existing energy technologies have sharply limited elasticities of substitution or are Leontief once installed
44
Key SGM CharacteristicsKey SGM CharacteristicsKey SGM CharacteristicsKey SGM Characteristics
Technological change in the SGM under a greenhouse gas mitigation strategy is primarily a matter of shifting across technologiesThe model manages GHG emissions by introducing new technology, not by improving existing technology—essentially bottom upThis approach requires explicit new technologies and maintains physical consistency between energy inputs and outputs
45
Advantages of SGM approachAdvantages of SGM approachAdvantages of SGM approachAdvantages of SGM approach
The model can maintain a fully consistent energy balance table across time New technologies have to be explicitly identified and parameterizedThere is no vague implicit or explicit backstop technologyThe value of new technology can be assessedExplicit representations of technologies enable consideration of additional characteristics of a technology—e.g. safety or local air pollution
46
DisadvantagesDisadvantagesDisadvantagesDisadvantages
Non-standard production characterization makes it difficult to use existing literature on parameter values—i.e. estimates of technical change based are two-digit industries are of limited valueIt is difficult to foresee technology characteristics beyond the current set of potential new options (What comes after IGCC with capture and disposal?)
47
Nesting of TechnologiesNesting of TechnologiesNesting of TechnologiesNesting of Technologies
The specific nature of technologies requires a mechanism to shift across technologiesWe use a logit approach to share investment across technologies within a sectorA flat logit approach violates dominanceA logit approach based on expected profits prevents peak load technologies from entering into production—therefore we are using expected costs
48
Why Logit Sharing Rather than Why Logit Sharing Rather than Nested CES?Nested CES?
Why Logit Sharing Rather than Why Logit Sharing Rather than Nested CES?Nested CES?
Logit mechanism maintains mass balance if components are consistentIt is more flexible than a CES nest It does not require all inputs (subsectors) to be
positive
Logistic sharing does imply equal risk adjusted marginal returns within the industry
49
The Electricity Sector NestThe Electricity Sector NestThe Electricity Sector NestThe Electricity Sector Nest
Electricity Generation SGM-2004 nesting option
Hydro
Nuclear
Oil Gas
Coal
Solids (commercial biomass)
Wind-on shore
Solar
Geo
Wind-off-shore
Waste (municipal)
PCccsCoal IGCC
NGCC
Coal IGCCccs
NGCCccs
Coal IGCC Coal
Peak load Base load
Gas NGCC
50
ExpectationsExpectationsExpectationsExpectations
Expectations enter into production sector decision making through the investment processThe model computes either expected cash flow or levelized costs using current and future prices over the lifetime of the investmentAt present, future prices are projected to be the same as current prices (myopic expectations)Levelized costs (expected profits) are computed using a discount rate which is the sum of price of capital and a sector specific discount factor
51
Expectations and InvestmentExpectations and InvestmentExpectations and InvestmentExpectations and Investment
Current investment produces under the same price and output as used to make the investment decision (Expectations are realized in the first period)Current investment is driven by a scale factor representing either
(1) previous investment or (2) expected output
current period expected cash flow per dollar of investment
Investment in subsectors is allocated by a logistic process using subsector levelized costs (or expected profits) as arguments
52
Dynamic ExpectationsDynamic ExpectationsDynamic ExpectationsDynamic Expectations
A simple trend extrapolation experiment failed due to instabilityWe plan experiments using simulated values as the basis for price expectationsThe role of current investment in equating supply and demand may limit potential options
53
Solution MechanismSolution MechanismSolution MechanismSolution Mechanism
At solution, supply and demand for each market are equal to within the tolerance given to solution mechanism (typically .01%) Solution requires consistent model in order to solve—budget equations for all decision makers must holdFunctions rapidly and reliably as long as the problem posed to the model can be solved using available technology options => low to medium carbon price Single region run time 1-2 minutes Global run <10 minutes
54
Access to the SGMAccess to the SGMAccess to the SGMAccess to the SGM
1. http://www.globalchange.umd.edu/?models
2. http://www.globalchange.umd.edu/sgmrelease.php
3. http://www.globalchange.umd.edu/models/download/
SGM Users Guide I
\Exec
\SGM_US_A
\Inputs
\Outputs
\USInputs
\Paths
sgmctrl.csv
RunSGM_US.xlsDataViewer_US.xls
SGM.exe
CE policy files
US-specific input files
sgmgen2004_us.csv files
sgm_us.mbd
\screen.csv
datamover.exe
DONE.csvddao36.dll: required but Microsoft owned
Legal Notice.txt
SGM_output.xls files
56
RunSGM_US.xls Scenario Examples
USA baseline US CE$100 US CEstab2015
..\inputs\USinputs\usa_baseline_2004_A.csv
..\inputs\USinputs\usa_baseline_2004_A.csv
..\inputs\USinputs\usa_baseline_2004_A.csv
..\inputs\screen.csv ..\inputs\paths\us_CE_$100.csv
..\inputs\paths\us_CEstab2015.csv
..\inputs\USInputs\non-CO2_MACs_US.csv
..\inputs\USInputs\non-CO2_MACs_US.csv
..\inputs\screen.csv ..\inputs\screen.csv
57
Dataviewer_US.xlsExample of Single Query Output
Scenario Emission Comparison
0
500
1000
1500
2000
2500
3000
3500
1990 2000 2010 2020 2030 2040 2050
Time
Car
bo
nD
ioxi
de
Em
issi
on
s (M
MT
C) USA baseline
US CE$100
US CEstab2015
58
Carbon-Equivalent Emissions
0
500
1000
1500
2000
2500
3000
3500
4000
1990
1995
2000
2005
2010
2015
2020
2025
2030
2035
2040
2045
2050
Time
MM
TC
Mg ElecDist SemiconducAluminum StationarySoilN MobileN ManureN IndProcsN ODSSub HFC23 WastewaterOthNonAgMeOthAgMeth Manure Landfills OilSys NatGasSys Enteric CoalPr Coalcomb Gascomb Oilcomb
Example of SGMgen2004_US output