US Greenhouse Gas Emission
Scenarios to 2050
Ron Sands
Joint Global Change Research InstituteBattelle – PNNL – University of Maryland

Global Challenges Toward a Low-Carbon Economy:
Country-Specific Scenario Analysis
Montreal, Canada
3 December 2005

Introduction¾ Results for the United States from Energy Modeling Forumstudy (EMF-21)¾ Goalszz

Provide policy-relevant analysis (not policy prescriptive)
Economic comparison of major classes of greenhouse gas (GHG)
mitigation options¾ Classes of Mitigation Optionszzzzz

Energy efficiency improvements
Fuel switching
Carbon dioxide capture and storage (CCS)
Non-CO2 GHGs
Terrestrial options (biofuels, carbon in soils, carbon in trees)¾ Main Conclusionszz

No single model can represent all relevant processes
Each type of mitigation option contributes significant fraction of total

2Models¾ Energy System and Geologic Storagezz

CO2 emissions from energy combustion, carbon dioxide captureand storage from electricity generation
Battelle Second Generation Model¾ Non-CO2 Greenhouse Gases
zz

Methane, Nitrous Oxide, F-gases
Energy Modeling Forum (EMF-21) baselines and marginalabatement cost curves¾ Agricultural Offsets
zz

Soil sequestration, Afforestation, Biofuel Offsets
Agricultural Sector Model (McCarl, B.A. and Schneider, U.A. 2001.
“Greenhouse Gas Mitigation in U.S. Agriculture and Forestry.”
Science 294, 2481-2482.)3

U.S. Carbon Equivalent Emissions (baseline)
4,000

million tons carbon equivalent

3,500
3,000
2,500
F-gases
nitrous oxidemethaneenergy system + CCS

2,000
1,500
1,000
500
0
1990

2000

2010

2020

2030

2040

2050
4

U.S. Carbon Equivalent Emissions ($100 constant)
4,000

million tons carbon equivalent

3,5003,000
2,500
F-gases
nitrous oxidemethaneenergy system + CCS

2,000
1,500
1,000
50001990

2000

2010

2020

2030

2040

2050
5

U.S. Carbon Equivalent Emissions ($200 constant)
4,000

million tons carbon equivalent

3,500
3,000
2,500
F-gases
nitrous oxidemethaneenergy system + CCS

2,000
1,500
1,000
5000
1990

2000

2010

2020

2030

2040

2050
6

Carbon Dioxide Capture and Storage (CCS)¾ Carbon Dioxide Capture from Electric Power GenerationzTechnologies with and without CCS
Coal integrated gasification combined cycle (IGCC) Natural gas combined cycle (NGCC)
zEngineering cost model for capture process from David and Herzog,
2000, “The Cost of Carbon Capture,” Proceedings of the Fifth
International Conference on Greenhouse Gas Control Technologies¾ Geologic Storagezz

Cost of storage assumed constant ($40 per tC)
Ongoing work at Battelle to construct storage supply curves for theUS and other countries

7U.S. Electricity Baseline Scenario
9,000
8,000
7,000

billion kWh

6,000
5,000
coal (IGCC)

4,000
coal (PC)3,000
gas (NGCC)

2,000

gas (single cycle)
oilhydronuclear

1,000
01990

2000

2010

2020

2030

2040

2050

8Constant-Carbon-Price Scenario
Carbon price of $200 per tC starting in 2015
9,000
8,000
7,000
6,000
billion kWh

IGCC+CCS

5,000
PC+CCS

4,000

IGCC

3,000

PC

2,000

NGCCgas (single cycle)
oilhydronuclear

1,00001990

NGCC+CCS

2000

2010

2020

2030

2040

2050

9

Economic Comparison of Mitigation Options¾ View 1: Components of US emission reductions relative tobaseline over timezz

Constant carbon price of $200 per t C-eq
Components
Energy system CO2
 Carbon dioxide capture and storage Non-CO2 GHGs (methane, nitrous oxide, F-gases) Terrestrial options (soil carbon, afforestation, biofuels)
¾ View 2: Cumulative emission reductions over a range of carbon
priceszzzz

Results derived from a set of constant-carbon-price experiments
Carbon prices up to $300 per t C-eq
Expressed as cumulative marginal abatement cost curves
Cumulative emissions reductions over 40 years
101,8001,600

Components of U.S.
Emissions Reductionsat $200 per t CE

afforestation
biofuelmillion metric tons carbon equivalent

1,400
afforestationsoil seq.

1,200

biofuelafforestation

1,000

soil seq.
F-gas
N2O

biofuel

800

CH4afforestationsoil seq.
biofuel

600

F-gas
N2O
CH4F-gas
N2O
CH4F-gas
N2O
CH4400CO2afforestationsoil sequestration
biofuel offset
CCS
F-gases
nitrous oxidemethaneenergy system CO2

CO2
CO2200CO2CO20
1990

2000

2010

2020

2030

2040

2050
11

U.S. Cumulative Emissions Reductions(40 years with constant carbon price)
$350

$300

$250

energyenergy+CCS
all GHGs
all GHGs + Ag/For$200
carbonprice
$150

$100

$50

$0
0

10,00020,00030,00040,00050,00060,00070,000

million metric tons carbon equivalent (2013-2052)
12

Conclusions¾ No single model can represent all relevant processeszBottom-up: specialized analysis or models by sector
Agriculture / Forestry
 Buildings
 Industry
 Transportation
 Electricity generationz

Top-down: combine results across sectors¾ Each type of mitigation option contributes significant fraction oftotalzzzzz

Energy efficiency improvements
Fuel switching
CO2 capture and storage
Non-CO2 greenhouse gases
Terrestrial storage and biofuels¾ Potential of each mitigation option varies across countries
13