August 22, 2014

Low Carbon Fuel Standard

Reconsideration:

CA-GREET Model Update

California Environmental Protection Agency

Air Resources Board
Workshop Purpose

The LCFS reconsideration includes a proposed 

CA-GREET version update

• This update will change pathway CIs—many will 

rise

• In the interests of full transparency, we are 

presenting these changes to, and soliciting 

feedback from, the public

• The information presented in these slides is 

preliminary, since work on CA-GREET 2.0 is 

ongoing

August 22, 2014 2
GREET Update Approach

Direct GHG emissions have always been 

estimated using a model based on Argonne’s 

GREET

• GREET is still preferred:

– Considered to be authoritative for U.S. fuel pathways

– Freely available to the public

– Very flexible; readily modified (spreadsheet format)

• On the downside, GREET is:

– Very large and full of linked, sometimes recursive 

calculations

– Not easy to master

August 22, 2014 3
GREET Update Approach (Cont.)

Argonne is aware of these drawbacks

• Has released a non-spreadsheet version: 

GREET.net

• Standalone application

• Found it to be very promising

• Did not have time to make the transition during this 

rulemaking

• Will consider adopting GREET.net in a future 

rulemaking

August 22, 2014 4
CA-GREET 1.8b & 2.0 Compared

• CA-GREET 2.0 is based on Argonne’s GREET 1 

2013 (not CA-GREET 1.8b)

• CA-GREET 1.8b was based on Argonne’s GREET 

1.8b

• Updates from both ARB staff and Argonne are 

reflected in CA-GREET 2.0

• More pathways and feedstocks are built-in:

– Biomethane

– Used cooking oil to bio- and renewable diesel

– Corn oil biodiesel—wet DGS-associated

August 22, 2014 5
CA-GREET 1.8b & 2.0 Compared (Cont.)

• More pathways and feedstocks are built-in (Cont.)

– Animal waste biomethane pathway with methaneemissions-avoided credit

– Liquefied-compressed natural gas (L-CNG)

• Extensive life cycle inventory data updates

– Fertilizer production

– Farming and fuel production energy

• Emission factors are updated

– Updated California on-road mobile-source emission 

factors from ARB’s EMFAC 2011 inventory

– Updated CNG/LNG tailpipe emissions data

August 22, 2014 6
CA-GREET 1.8b & 2.0 Compared (Cont.)

• Emission factors are updated (Cont.)

– Updated natural gas leakage rates

– Crude production emissions data from ARB’s OPGEE 

model

– Soil N2O emissions

• Process efficiency factors are updated

• Electrical energy generation mixes are all based on 

latest USEPA eGRID database

• Tier 1 pathway calculator for expedited estimation 

of first-generation pathway CIs

• Some changes move CIs up; some move them 

down

August 22, 2014 7
Illustrative CI Examples

• Best way to summarize the differences is to look at 

actual direct (no ILUC) CIs

• The following comparisons are tentative

– Still in the verification stage

– All values presented are still subject to change

– Final CA-GREET 2.0 version will go public when the 

45-day comment period begins

• Tentative differences for baseline fuels

August 22, 2014

Model Version

Fuel 1.8b 2.0 Change

CARBOB 98.38 99.20 0.82

ULSD 98.01 102.55 4.54

CaRFG 98.95 99.78 0.83 8
Illustrative CI Examples (Cont.)

Tentative differences for natural gas

• Fossil and landfill gas

• Shows effects of updated methane leakage rates 

(additional efforts to quantify are ongoing)

August 22, 2014

Model Version

Fuel 1.8b 2.0 Change

N. American NG - CNG 68.01 78.37 10.36

N. American NG - LNG 83.13 96.92 13.79

Landfill Gas - CNG 11.26 33.52 22.26

Landfill Gas - LNG 26.31 54.50 28.19

9
Illustrative CI Examples (Cont.) 

Tentative direct CI differences for biodiesel

August 22, 2014

Model Version

Biodiesel Feedstock 1.8b 2.0 Change

Soybean 21.25 23.90 2.64

Tallow 39.08 46.31 7.23

UCO 18.73 23.69 4.96

Canola 31.98 41.72 9.73

Corn Oil, WDGS-Associated 29.27 34.35 5.08

10
Illustrative CI Examples (Cont.) 

Tentative direct CI differences for renewable 

diesel

August 22, 2014

Model Version

RD Feedstock 1.8b 2.0 Change

Soybean 20.16 19.58 -0.58

Tallow 39.33 44.56 5.23

UCO 17.22 19.26 2.04

Canola -- 36.85 --

Corn Oil, WDGS-Associated 29.72 -- --

11
Illustrative CI Examples (Cont.) 

Tentative direct CI differences for sugarcane 

ethanol

August 22, 2014

Model Version

Sugarcane Ethanol Pathway 1.8b 2.0 Change

No Harvest or Electricity Credit 27.40 34.55 7.15

Mechanized and Power Export 12.40 23.30 10.90

Mechanized Harvesting only -- 29.52 --

Power Export only 20.40 28.33 7.93

12
Illustrative CI Examples (Cont.) 

Tentative direct CI differences for corn and 

sorghum ethanol

August 22, 2014

Model Version

Pathway by Feedstock 1.8b 2.0 Change

Grain Sorghum 61.83 71.47 9.64

Corn Ethanol (100% NG) 68.32 59.86 -8.46

13
Current Work Priorities

Staff is focusing on these priorities as we 

finalize the model

• CARBOB and USLD refining efficiencies

• CNG and LNG truck tailpipe emission factors

• California NG leakage rate

• Used Cooking Oil rendering energy 

• Bio- renewable diesel production energy

August 22, 2014 14
Summary

The primary drivers of CI differences are:

• Corn, soybean, sorghum, and sugarcane CIs driven 

by changes in fertilizer use and soil N2O emissions

• Natural gas and biomethane pathways are higher 

due to 

– An approximate doubling of the leakage rate, and 

– An approximate 4x increase in pipeline energy 

requirements

• Tallow and UCO pathways now account for the 

transport of feedstocks 

August 22, 2014 15
Feedback and Contact Information

We welcome your feedback

• Please submit feedback by September 15th, 2014

– Katrina Sideco, Staff Lead, LCFS Re-Adoption Team

• katrina.sideco@arb.ca.gov

• (916) 323-1082

– Hafizur Chowdhury, Staff Lead, Fuel Pathways 

Reconsideration Team

• hafizur.chowdhury@arb.ca.gov

• (916) 322-2275

August 22, 2014 16
Contact Information (cont.)

– Wes Ingram, Manager, Fuels Evaluation Section

• wes.ingram@arb.ca.gov

• (916) 322-3984

– Chan Pham, CA-GREET Technical Team

• chan.pham@arb.ca.gov

• (916) 327-5600

– Todd Dooley, CA-GREET Technical Team

• todd.dooley@arb.ca.gov

• (916) 323-1069

August 22, 2014 17
Thank You