Let’s Not Forget Carbon Just Yet

by Ron Alverson (Ethanol Producer Magazine/American Coalition for Ethanol) Life-cycle modeling for ethanol needs to be updated to reflect big improvements in corn's GHG emissions profile -- ... Fuels that help automakers achieve efficiency standards are going to be important.

California and the “left coast,” as well as numerous other states have or will be adopting low-carbon fuel standards. Countries importing our ethanol that require a low-carbon pedigree and the potential for a carbon tax all remain drivers to reduce our footprint.

This is good news for ethanol, despite the myths, misinformation and prejudices that have dogged corn ethanol for years.

For starters, the debits applied to corn ethanol for the use of fertilizer are based on numbers we left behind years ago. Similarly, dramatically higher corn yields and reductions in tillage over the past 30 years have reduced soil erosion and built soil carbon stocks in corn fields. These two revolutionary changes have made old carbon intensity calculations obsolete.

Recently, Dr. Paul Fixen, the immediate past president of the American Society of Agronomy, penned a piece called “Progress in Agronomy: A Story Worth Telling.” Since the early 1980s, he writes, corn yields have increased by 70 percent, yet nitrogen fertilizer use per acre has only increased by 5 percent; cropland under conservation tillage increased from 18 to 42 percent; soil erosion declined by more than 40 percent; and more than a quarter million soil tests from multiple labs have confirmed that the long decline of soil organic carbon (SOC) has been reversed in the western Corn Belt due to those higher yields and reduced tillage. On average, SOC has increased 25 percent.

The life-cycle greenhouse gas (GHG) emission models used to determine corn ethanol fuel’s carbon intensity do not consider a biofuel feedstock’s effect on SOC stocks. Small annual increases in SOC mean big reductions in corn carbon intensity that, when accounted for in GHG models, reduce corn ethanol fuel’s CI by 40 percent relative to the GREET 2016 model’s latest assessment. READ MORE