NGVAmerica Comments on Planned CA GREET Changes

On Monday, NGVAmerica commented on planned changes to the California GREET model. The GREET model is used to evaluate the potential greenhouse gas emissions resulting from using different fuels, focusing on the full fuel cycle — including production, transmission and end-use of these fuels. The GREET model was created and is maintained by staff with the Argonne National Laboratory. However, other users like the California Air Resources Board (CARB) can make changes to suit their particular circumstances. California uses GREET to shape decisions for its low-carbon fuel standard as well as other programs.

CARB currently is considering updates to its version of the model and in August presented information concerning possible changes. Based on information presented by CARB staff, it appears that some of the proposed changes will drastically alter the carbon intensity of some fuels. One of the comments that we (and many others commenting on the proceedings) made is that the information supporting these changes has not been made available and, therefore, there has not been a full vetting of the issues related to the changes. We also commented that the apparent increase in upstream natural gas emissions is not consistent with the most recent U.S. EPA report, Inventory of Greenhouse Gas Emissions and Sinks, which shows declining natural gas emissions. Like many other commenters, we urged CARB to release the data supporting the changes it is contemplating so that it may be properly evaluated. We also urged CARB to consider that many other studies are underway to provide a better estimate of the emissions associated with producing and transporting natural gas, and that it would be premature to make changes before the data from these studies is available.