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Time Accounting Sub-Group Update
• Sub-group members: James Duffy, Keith Kline, Jesper Hedal Kløverpris, Jeremy Martin, Steffen Mueller, Michael O’Hare
• Outside Expert: Elizabeth Marshall, USDA ERS
• Agenda
15 min - Review of Fuel Warming Potential – Jeremy
15 min - Baseline Time Accounting – Jesper and Steffen
10 min - Simplified “time-shift” accounting – Michael
5 min – Forest transition approach – Keith
10 min - Social Cost of Carbon applied to biofuels – Liz Marshal
10 min - WRI Time Accounting Workshop Summary - Liz Marshall
30 min - Discussion
2
Fuel Warming Potential
• Biophysical approach to time accounting analogous to Global Warming Potential
O’Hare, Plevin, Martin, Jones, Kenall, Hopson
Considered by EPA and CARB during rule development for RFS and LCFS in 2008/2009
Published in Environmental Research Letters in 2009
Reviewed by EPA Peer Review panel in 2009
Discussed in EPA and CARB rulemaking documents
but just in case you forgot…..
3
Emissions trajectories over time are complex
• Figure above represents one set of assumptions
• 30 years production, GTAP+WH for ILUC, 60 g/MJ w/o ILUC
• Use BTIME to evaluate your own parameter choices
-100
0
100
200
300
400
500
600
2000 2010 2020 2030 2040 2050 2060 2070 2080 2090 2100
Ext
ra C
O2e
(g
per
MJ
ann
ual
pro
du
ctio
n)
Corn ethanol emissions
Gasoline emissions
4
BTIME: Choose your own parametersChoose scenario GTAP-WH
Discount rate 2.5% % Applied to cumulative CO 2
Gasoline baseline GWI 94 g CO2e/MJ Standard baseline gasolineEstimated EtOH GWI 60 g CO2e/MJ Approximate NG-fired dry-mill EtOH GWI, w/o indirect effects.Initial soil C loss period 5 y Years it takes to lose "soil C initially lost"Later soil C loss period 20 y Years it takes to lose the rest of lost soil CSoil C initially lost 80% % As a percentage of the lost soil C, not of the total soil C stockRecovery years 30 y The number of years over which land recovery occursPercent recovery 0% % The fraction of originally lost above- and below-ground C recoveredProduction period 30 y The period over which biofuels are assumed to be produced on the land triggering LUC emissions.
CO2 emitted/MJ increase 776 g CO2e/MJ/y NB: Excluding foregone sequestration
Emission breakdownAnnual foregone seq. 4 g CO2e/MJ/y Above Below ForegoneForest fraction 64% % 426 349 4Grassland fraction 36% %Forest above-ground 387 g CO2e/MJ 78%Forest below-ground 112 g CO2e/MJ 22%Pasture above-ground 40 g CO2e/MJ 14%Pasture below-ground 237 g CO2e/MJ 86%Total foregone seq. 123 g CO2e/MJ
Total iLUC emissions 898 g CO2e/MJ
Parameter Units FAPRI-WH GTAP-WH What-ifFuel capacity increment L 5.7E+10 5.0E+10 5.0E+10Initial Areal Fuel Yield L/ha 4375 3292 3292Average Areal Fuel Yield L/ha 4375 3350 3350Net Displacement Factor % 72% 28% 28%CO2 Flux: forest Mg CO2/ha 456 658 700CO2 Flux: grassland Mg CO2/ha 122 61 60CO2 Flux: wetland Mg CO2/ha 0 1200 1200Forest area fraction % 52% 26% 30%Grassland area fraction % 48% 74% 68%Wetland area fraction % 0% 0% 2%
Stream breakdown g CO2e/MJ
5
Extra CO2 in the Atmosphere
• CO2 has a long residence time in the atmosphere
• Annual additions are greater than annual decay
-200
0
200
400
600
800
1000
1200
1400
1600
1800
2000
2000 2010 2020 2030 2040 2050 2060 2070 2080 2090 2100
Ext
ra C
O2e
(g p
er M
J an
nu
al p
rod
uct
ion
)
Gasoline
Corn ethanol
Corn ethanol emissions
Gasoline emissions
Based on GTAP analysis
6
What do we really care about?
• Ultimately, human suffering and ecosystem damage from climate change, especially irreversible damage caused by global warming
• Quantitatively compare the extent of warming caused by scenarios with different temporal emissions profiles
• Analogous to the comparison of different global warming gasses using the Global Warming Potential
7
Global Warming Potential
GWP is the ratio of Cumulative Radiative Forcing (CRF)
dttCOa
dttCHa
dttRF
dttRF
CRF
CRFGWP
a
a
a
a
t
CO
t
CH
t
CO
t
CH
CO
CHCH
0 2
0 4
0
0
)(
)(
)(
)(
2
4
2
4
2
4
4
25100
4CHGWP7220
4CHGWP
8
Cummulative Radiative Forcing
Based on GTAP analysis
Cum
ula
tive R
ad
iati
ve F
orc
ing a
nd N
PV
(arb
itra
ry u
nit
s)
0.0E+00
2.0E+04
4.0E+04
6.0E+04
8.0E+04
1.0E+05
1.2E+05
2000 2010 2020 2030 2040 2050 2060 2070 2080 2090 2100
Cu
mm
ula
ive
Rad
iati
ve F
orc
ing
& N
PV
(A
rbit
ary
Un
its)
CRF Corn Ethanol
CRF Gasoline
9
By analogy, Fuel Warming Potential
)(tBtGatRF ij
ijji
at
o
iaii dttRFtCRFCRF )(
FWPp CRFbCRFg
Radiative Forcing
Cumulative Radiative Forcing
Ratio of biofuels policy case (b) to reference gasoline case (g)
10
Fuel Warming Potential
0.6
0.7
0.8
0.9
1.0
1.1
1.2
1.3
1.4
1.5
1.6
0 10 20 30 40 50 60 70 80 90 100
Analytic Horizon (years)
Fu
el W
arm
ing
Po
ten
tial
Ethanol (Flows only)
Ethanol FWIp
Corn Ethanol Direct
Carbon Intensity relative to gasoline
Based on GTAP analysis
11
By extension, Economic Fuel Warming Potential
FWPp CRFbCRFg
Physical Fuel Warming Potential
FWPe NPVbNPVg
NPV d RF t 1 r t0
ta dt
D t d RF t
Economic Fuel Warming Potential
Making the very rough assumption that economic damage is proportional to radiative forcing with constant ratio over time
12
FWIp and FWIe
Based on GTAP analysis
0.6
0.7
0.8
0.9
1.0
1.1
1.2
1.3
1.4
1.5
1.6
0 10 20 30 40 50 60 70 80 90 100
Analytic Horizon (years)
Fu
el W
arm
ing
Po
ten
tial
Ethanol (Flows only)
Ethanol FWIp
Ethanol FWIe (3%)
Ethanol FWIe (7%)
Corn Ethanol Direct
Carbon Intensity relative to gasoline
13
Social Cost of CarbonAPPENDIX 15A. SOCIAL COST OF CARBON FOR
REGULATORY IMPACT ANALYSIS UNDER EXECUTIVE ORDER 12866
Key assumptions are embedded in integrated assessment models (including damage functions) and
discount rates decisions
$5-$65/ton in 2010 rising to $16-$135 in 2050
The purpose of the “social cost of carbon” (SCC) estimates […] is to […] incorporate the social benefits of reducing carbon dioxide (CO2) emissions into cost-benefit analyses of regulatory actions that have small, or “marginal,” impacts on cumulative global emissions.
The SCC is an estimate of the monetized damages associated with an incremental increase in carbon emissions in a given year. It is intended to include (but is not limited to) changes in net agricultural productivity, human health, property damages from increased flood risk, and the value of ecosystem services due to climate change.
14
Summary
• Fuel Warming Potential aggregates emissions over time into a relative carbon intensity metric based on a biophysical analysis of their impact on global warming
Analogous to Global Warming Potential for different GHGs
Early emissions are weighed more heavily because of persistence of GHGs in the atmosphere
• Economic discounting should be applied to damages rather than emissions
Discounting damages increases the weight of near term emissions relative to longer term benefits
15
Additional References
O’Hare, Plevin, Martin, Jones, Kenall, Hopson, ERL 2009
BTIME – get the paper, play with the speadsheet at http://rael.berkeley.edu/sites/default/files/BTIME/
EPA, 2009.
Peer Review Report: Methods and Approaches to Account for Lifecycle Greenhouse Gas Emissions from Biofuels Production Over Time
Anderson-Teixeira & DeLucia. 2010. Global Change Biology.
The Greenhouse Gas Value of Ecosystems
Vasseur, Lesage, Emargni, Deschenes, Samson, EST 2010
Considering Time In LCA: Dynamic LCA And Its Application To Global Warming Impact Assessments