US Government Aims to Turn Corn into Sustainable Aviation Fuel - But is it Really a Climate Solution?

Sunday - May 5 2024, 14:14 UTC - 6 months ago

The US government recently announced a new program to provide tax credits for corn-based sustainable aviation fuels produced with certain sustainable agricultural practices. However, critics warn that this may not be an effective solution for reducing carbon emissions from commercial aviation and that the emissions benefits of corn-based ethanol have been debated for years. This new program could set a template for future programs as the US works towards producing billions of gallons of sustainable aviation fuels per year by 2030.

Eliminating carbon pollution from aviation is one of the most challenging parts of the climate puzzle, simply because large commercial airlines are too heavy and need too much power during takeoff for today’s batteries to do the job. But one way that companies and governments are striving to make some progress is through the use of various types of sustainable aviation fuels (SAFs), which are derived from non-petroleum sources and promise to be less polluting than standard jet fuel. This week, the US announced a push to help its biggest commercial crop, corn, become a major feedstock for SAFs. Federal guidelines announced on April 30 provide a pathway for ethanol producers to earn SAF tax credits within the Inflation Reduction Act, President Biden’s signature climate law, when the fuel is produced from corn or soy grown on farms that adopt certain sustainable agricultural practices. It’s a limited pilot program, since the subsidy itself expires at the end of this year. But it could set the template for programs in the future that may help ethanol producers generate more and more SAFs, as the nation strives to produce billions of gallons of those fuels per year by 2030.

Consequently, the so-called Climate Smart Agricultural program has already sounded alarm bells among some observers, who fear that the federal government is both overestimating the emissions benefits of ethanol and assigning too much credit to the agricultural practices in question. Those include cover crops, no-till techniques that minimize soil disturbances, and use of "enhanced-efficiency fertilizers," which are designed to increase uptake by plants and thus reduce runoff into the environment. The IRA offers a tax credit of $1.25 per gallon for SAFs that are 50% lower in emissions than standard jet fuel, and as much as 50 cents per gallon more for sustainable fuels that are cleaner still. The new program can help corn- or soy-based ethanol meet that threshold when the source crops are produced using some or all of those agricultural practices. Since the vast majority of US ethanol is produced from corn, let’s focus on the issues around that crop. To get technical, the program allows ethanol producers to subtract 10 grams of carbon dioxide per megajoule of energy, a measure of carbon intensity, from the life-cycle emissions of the fuel when it’s generated from corn produced with all three of the practices mentioned. That’s about an eighth to a tenth of the carbon intensity of gasoline.

Ethanol’s questionable climate footprint .

Today, US-generated ethanol is mainly mixed with gasoline. But ethanol producers are eager to develop new markets for the product as electric vehicles make up a larger share of the cars and trucks on the road. Not surprisingly, then, industry trade groups applauded the announcement this week. The first concern with the new program, however, is that the emissions benefits of corn-based ethanol have been hotly debated for decades. Corn, like any plant that uses photosynthesis to produce food, sucks up carbon dioxide from the air. But using corn for fuel rather than food also creates pressure to clear more land for farming. That, in turn, releases carbon stored in trees and other plants, ultimately into the atmosphere.