CARB to review ethanol carbon intensity amendments

By Kris Bevill | January 19, 2011

The California Air Resources Board will hold a public hearing Feb. 24 to consider 25 amendments proposed by various ethanol producers, representing 1.6 billion gallons of annual domestic production, to reduce the carbon intensity of their fuel. Fuel pathways are used to determine a fuel’s carbon intensity (CI). The CI of the fuel is then recorded in the state’s CI look-up tables, the reference point used by providers of transportation fuels to demonstrate compliance with California’s Low Carbon Fuel Standard. 

CARB refers to the CI of transportation fuels as “the currency of the LCFS” and measures it in grams of CO2 equivalent per megajoule (g CO2e/MJ) of fuel energy. The final rule issued in 2009 included the controversial decision to consider indirect land use change calculations in its full lifecycle measurement of ethanol, which also encompasses the production, transport, storage and use of the fuel. As a result, the CI of Midwest ethanol is rated nearly three points higher than the baseline CI of gasoline, effectively discouraging regulated parties from utilizing it in their fuel mix.

To provide room for improvement of CIs, the LCFS regulation allows parties to develop and submit new pathways for fuel production. Fuel providers may propose new pathways that consist of modified versions of existing pathways or pathways for entirely new fuels or production processes. The majority of the amendments that will be considered at the Feb. 24 hearing have been proposed by Poet LLC, Archer Daniels Midland Co. and Green Plains Renewable Energy Inc.

In its application, ADM said it employs advanced process technology and biomass co-generation at its newly constructed plants in Columbus, Neb., and Cedar Rapids, Iowa, which provide the basis for eight new pathway requests. There is currently no pathway for an ethanol dry mill that uses coal and/or co-generation, ADM said. The company’s proposed pathway includes co-firing up to 15 percent biomass at its coal-powered facilities, reducing the CI of ethanol produced at those plants to approximately 10 points less than the baseline CI for gasoline.

Poet has proposed 11 modified pathways for its no-cook, raw starch hydrolysis production method, some of which also utilize alternative energy sources including landfill gas, combined heat and power using waste heat from electricity generation, and biogas fuel. Poet’s most aggressive proposal uses an 80/20 combination of natural gas and biomass to produce ethanol and wet distillers grains at a Midwest dry mill, resulting in a total CI rating of 86.8 g CO2e/MJ, compared to gasoline’s baseline rating of 95.85 g CO23/MJ.

GPRE’s modification applications are based on operations at its Lakota, and Central City, Iowa, plants. The Lakota application includes updated corn yield data which shows the average corn yield for 2009 was 26 percent more than CARB’s initial pathway average, therefore requiring fewer acres to supply feedstock to the facility. Additionally, GPRE said it uses less natural gas and electricity than the initial pathway at both plants, therefore ethanol produced at those facilities should have a reduced CI rating.

Comments are currently being accepted on all applications to be considered at the Feb. 24 hearing. A regulatory advisory issued by CARB in December allows pathway applicants to begin using the draft CI values as soon as they are posted to CARB’s web site, rather than requiring them to wait until the agency’s executive officer officially approves the amendments. Additionally, if the amendments are not approved by the executive officer during the formal hearing, applicants are still allowed to use the proposed CI values for six months after the hearing.

Amended and new pathways are not facility-specific, meaning that any producer who shows they utilize the same production method as an amended or new pathway can begin rating their fuel’s CI at the approved reduced rate. On Jan. 6, CARB said it’s staff is currently evaluating 16 additional pathways for corn ethanol, five pathways for ethanol produced from feedstock combinations including corn or sorghum, corn and sorghum and a mix of corn, sorghum and wheat slurry, one application for a beverage waste-to-ethanol pathway and one application for a pathway using molasses from the Indonesian sugar industry as feedstock. CARB staff is also internally developing two pathways for Midwest ethanol produced using sorghum.

Comments on the proposed amendments must be received by CARB no later than Feb. 23. To view the staff report or to submit comments, visit