RFA, NBB See CARB Progress

OAKHURST, N.J. (DTN) -- The Renewable Fuels Association on Monday, Sept. 15, submitted comments to the California Air Resources Board voicing support for the agency's proposal to transition to a new version of the Greenhouse Gases, Regulated Emissions and Energy Use in Transportation Model, but also recommending several additional improvements.

CARB uses the GREET model to estimate direct lifecycle carbon intensity for fuels regulated under California's Low Carbon Fuel Standard, which requires fuel producers and suppliers to annually reduce the CI of fuel the provide to the market, designed to cut the overall CI of the state's fuel pool by 10% by 2020. Transportation fuels, including gasoline, diesel fuel and their substitutes or blendstocks are assigned a CI score, measured in grams of carbon dioxide-equivalent/mega joule, based on CARB's estimate of the total lifecycle emissions associated with the production, distribution and marketing of the fuel. A lower score is better.

CARB has proposed to use Argonne National Laboratory's latest version of GREET as the basis of its update to the original California GREET model, which was introduced in early 2008 and has been in use for the past six years.

According to CARB documents, the CA-GREET 2.0 has more pathways and feedstocks built-in, while also updating emissions factors. The changes increase the CI for some fuels, while others register a decline.

Under the latest version of GREET, the tentative CI for the state's reformulated gasoline before blended with ethanol edges up 0.82 to 99.20 gCO2/MJ, while the state's ultra-low sulfur diesel fuel CI gains 4.54 to 102.55 gCO2/MJ.

The tentative CI value using corn ethanol under the updated model drops 8.46 to 59.86 gCO2/MJ but for grain sorghum ethanol the tentative value jumps 9.64 to 71.47 gC02/MJ.

For biodiesel, using soybean as a feedstock the CI tentatively rises to 23.90 gCO2/MJ versus 21.25 gCO2/MJ under the older GREET model, although the CI score for renewable diesel with soybean as a feedstock falls 0.58 to 19.58 gCO2/MJ.

Don Scott, National Biodiesel Board Director of Sustainability, said the NBB, which has been involved in the update process as a stakeholder submitted detailed comments to CARB on the GREET modeling.

"We pointed out a number of errors in the data that would improve the final carbon intensity scores for biodiesel when corrected. We are confident CARB will take these into consideration as the process continues to move forward."

RFA's Geoff Cooper wrote in comments to CARB, "We believe Argonne's GREET1_2013 model contains a number of important improvements and updated inputs that more accurately reflect the current CI performance of corn ethanol and many other fuel pathways ... it is encouraging to see the LCFS regulation finally catching up to the actual state of the industry."

RFA believes CARB's migration to the newer GREET version is s step in the right direction, but "several additional revisions to CA-GREET2.0 should be considered."

Cooper said CARB should integrate the Argonne GREET1_2013 default assumptions on ethanol co-product feed (i.e., distillers grains) displacement rates; and also revise the CA-GREET2.0 model's treatment of emissions from agricultural lime application based on new data from the U.S. Department of Agriculture.

"Adopting these recommendations would further reduce corn ethanol's direct CI score by 8-10%, and would slash CARB's current ILUC factor by 70%" according to Cooper. "Integrating RFA's suggested revisions, along with the proposed changes already planned by CARB, would better reflect the actual nature of ethanol's lifecycle carbon intensity and confirm ethanol's ability to significantly reduce GHG emissions relative to gasoline."

(BM/AG)

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