You are here: ARB Home Low Carbon Fuel Standard CA-GREET 2.0 Model


This page last reviewed August 29, 2018

The California Air Resources Board (Board) is currently considering amendments to the Low Carbon Fuel Standard (LCFS) for adoption in 2019.  The proposed amendments would include an update to the CA-GREET model, based on the release of the GREET1 2016 by Argonne National Lab.  The current proposal includes three distinct fuel pathway classification types: Lookup Table, Tier 1, and Tier 2.  The carbon intensities (CI) for fuel pathways would primarily be calculated using the CA-GREET3.0 model as described below.

CA-GREET3.0 Model and Simplified CI Calculators (proposed under 2018 amendments)

The Board is currently considering the adoption of CA-GREET3.0 for LCFS fuel life cycle analysis.  Emission factors from the CA-GREET3.0 model would be used to generate the CIs of all fuel pathways, including Lookup Table pathways and applicant-specific Tier 1 and Tier 2 pathways.

To further streamline the fuel pathway application, evaluation, and verification process, staff is proposing to use fuel-specific Simplified CI Calculators to model Tier 1 pathways.  Similar to the current Tier 1 Calculator, the Simplified CI Calculators provide automated calculations using factors from CA-GREET3.0, but increase the simplicity and transparency of these calculations.  These Simplified Calculators ensure that most first-generation fuels could be certified under the Tier 1 classification, while also facilitating third-party verification by providing a transparent and pre-defined set of operational inputs subject to verification.  The CA-GREET3.0 model would still be used to model Tier 2 pathways.

August 13, 2018 release of CA-GREET3.0 model and Tier 1 Simplified CI Calculators

CA-GREET 2.0 - Currently In Use

In 2009, the Board approved the original LCFS regulation order. That order designated CA-GREET, version 1.8b xlsx as the model to be used for estimating direct life cycle emissions from the production, transport, and use of transportation fuels. CA-GREET 1.8b has remained in use since this original Board approval.

The regulation order the Board adopted at its September 2015 hearing replaces CA-GREET 1.8b with CA-GREET 2.0. Both CA-GREET versions are based on versions of the national GREET model developed at Argonne National Laboratory. The version currently in use was developed from Argonne’s GREET 1.8b, and the CA-GREET 2.0 model was developed from GREET1 2013. Argonne’s currently supported GREET versions are available on its website.

The changes staff made in converting GREET1 2013 into CA-GREET 2.0 are documented in the Supplemental Document pdf. First- and next-generation fuels are referred to as “Tier 1” and “Tier 2” fuels, respectively, in the current regulation. The difference between first-generation and innovative/next-generation fuels is easily ascertained from the model: fuels not included in the Tier 1 model are in the Tier 2 category.

September 29, 2015 Release
  • CA-GREET 2.0 Tier 1 xlsm for 23 common conventionally produced first-generation fuels (starch- and sugar-based ethanol, biodiesel, renewable diesel, CNG, LNG).
  • CA-GREET 2.0 Tier 2 xlsm for next-generation fuels (cellulosic alcohols, hydrogen, drop-in fuels, etc.) or first-generation fuels produced using innovative production processes.
  • CA-GREET 2.0 Supplemental Document pdf

CaRFG Calculation

The carbon intensities (CIs) of the LCFS baseline fuels—California reformulated blendstock for oxygenate blending (CARBOB), California reformulated gasoline (CaRFG), and California ultra-low sulfur diesel (ULSD)—are also determined using CA-GREET 2.0 (in conjunction with the Oil Production Greenhouse Gas Emissions Estimator, or OPGEE. The CIs of CARBOB and ULSD are have already been using CA-GREET 2.0 (which contains the necessary crude recovery and transport emissions data from the OPGEE model). Calculating the CI of CaRFG, however, is more complicated. The CIs of the ethanol blendstock (itself a blend of ethanol with various CIs), the CARBOB, and the denaturant in the ethanol must all be properly accounted for. The spreadsheet staff uses to calculate the CI of CaRFG is called the California Reformulated Gasoline and Ethanol Denaturant Calculator excel

Previous CA-GREET Models

Contact Us

If you have general questions regarding the information posted to this site, please contact Mr. Anil Prabhu, Manager, Fuel Evaluations Section; for more technical, CA-GREET-specific questions, please contact Mr. Chan Pham, Air Resources Engineer.

Join Email List

ARB List Server for Low Carbon Fuel Standard:
If you would like to receive e-mail when changes are made to this website, please sign up here.