Just How Environmentally Friendly is Corn-Based Ethanol?

Biofuels have long been touted as a potential tool in the fight against carbon emissions. However, a study published last February suggests that America’s reliance on corn-based ethanol fuel could actually be doing more harm than good, reported Reuters News Service. On Feb. 14, Reuters published an article by Lewin Day titled “Ethanol Made from Corn Could Be Worse for the Environment than Petrol, Study Claims.”

Also published in the Proceedings of the National Academy of Sciences, the study’s findings strongly take issue with established thought on the value of biofuels. The study aimed to assess the environmental outcomes of the U.S. Renewable Fuel Standard (RFS). It’s an important government program, which is involved to one degree or another with almost half of all biofuel production worldwide, as the U.S. is the world’s largest consumer of biofuels. The RFS requires that 36 billion gallons of renewable fuel must be blended into transportation fuels in 2022, and that all renewable fuels in the program emit less greenhouse gas than their traditional fossil fuel counterparts.

The main benefits of biofuels in general, as well as making ethanol from corn, are two-fold. Firstly, using plant matter to make fuel makes the fuel source renewable versus relying on prehistoric reserves of hydrocarbons buried deep underfoot. Secondly, the idea is that emissions from vehicles burning biofuels are offset by the fact that the crops grown to produce biofuel capture carbon out of the air as they grow. On a simplistic level, then, biofuels look great. However, when it comes to the way that corn-based ethanol has been pursued in the U.S., the bigger picture stops being so rosy. Analysis done by the study’s authors shows that the RFS led to a 30% increase in corn prices and drove an increase in land use for corn production by a full 8.7%. Follow-on effects led to a 20% increase in prices for other crops and a further 2.4% price increase in total cropland countrywide. This led to an uptick in fertilizer use from 3% to 8% and increased emissions overall resulting from the widespread changes in land use. In particular, the study noted that land that would have otherwise been used for conservation purposes was instead put to farming use.

The result is a net negative, as per the study, which states that “the carbon intensity of corn ethanol produced under the RFS is no less than gasoline and likely at least 24% higher.” This study pulls no punches in condemning a program that was intended to benefit the environment rather than hurt it. It’s also a major contradiction to established thinking when it comes to biofuels. Notably, a study from the USDA in 2019 claimed that U.S. ethanol production from corn had outperformed expected targets, suggesting the biofuel had a GHG emissions profile between 39% and 43% lower than gasoline. However, questions have been raised by the study’s authors around the manner in which emissions from land use changes were considered.

Not surprisingly, response from within the ethanol industry has been negative. Geoff Cooper, president and CEO of the Renewable Fuels Association, had some strong words regarding the study when speaking to Reuters. Cooper called the study “completely fictitious and erroneous,” criticizing the authors for making “worst-case assumptions” and using “cherry-picked data.” Consensus is difficult to reach when considering such issues. Adding in government departments and industry lobbyists with money on the line muddies public debate further. Regardless, the study suggests that the real impact of corn-based ethanol production may not be as clean as was once thought.

On the other hand, cellulosic ethanol is ethyl alcohol produced from cellulose (the stringy fibers of a plant) rather than from the plant’s seeds or fruit. It can be produced from grasses, wood, algae or other plants, usually destined to become biofuel. The carbon dioxide that plants absorb as they grow offsets some of the CO2 emitted when ethanol made from them is burned, so cellulosic ethanol fuel has the potential to have a lower carbon footprint than fossil fuels.

Interest in cellulosic ethanol is driven by its potential to replace ethanol made from corn or sugarcane. Since these latter plants are also used for food products, diverting them for ethanol production can cause food prices to rise; cellulose-based sources, on the other hand, generally do not compete with food, since the fibrous parts of plants are mostly inedible to humans. Another potential advantage is the high diversity and abundance of cellulose sources; grasses, trees and algae are found in almost every environment on our planet. Even municipal solid waste components like paper could conceivably be made into ethanol. The main current disadvantage of cellulosic ethanol is its high cost of production, which is more complex and requires more steps than corn- or sugarcane-based ethanol.

Cellulosic ethanol received significant attention in the first decade of the millennium. The U.S. government in particular funded research into its commercialization and set targets for the proportion of cellulosic ethanol added to vehicle fuel. A large number of new companies specializing in cellulosic ethanol, in addition to many existing companies, invested in pilot-scale production plants. However, the much cheaper manufacturing of grain-based ethanol, along with the low price of oil (prior to the pandemic) meant that cellulosic ethanol was not competitive with these well-established fuels. As a result, most of the new cellulosic refineries were closed eight to 10 years ago, and many of the newly founded companies went belly up. A few still exist but are mainly used for demonstration or research purposes; as of 2021 none produces cellulosic ethanol on an economical scale.

My opinion on these negative “chickens” that are coming home to roost on corn-based ethanol is that they have little to do with cellulosic ethanol. Since I have personally manufactured a good-to-excellent quality waste veg oil-based biodiesel, I feel that this alternative fuel oil deserves very few of the barbs hurled at ethanol.

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