In the quest for reliable, economical energy sources, biofuels have long been praised as a potential tool in the fight against carbon emissions. However, a study published in February 2022 suggested that America’s reliance on corn-based ethanol fuel might be doing more harm than good.
This is according to Reuters News Service’s Lewin Day. The article is “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 mindset 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, involved to varying degrees with almost half of all global biofuel production. The U.S. consumes the greatest amount of the planet’s biofuels. RFS required that 36 billion gallons of renewable fuel 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.
Let’s envision America’s shell corn industry as a pie graph. The biggest wedge, at 38.7%, would be livestock feed; next would be corn-based ethanol at 34%; exports leaving the country would weigh in at 17.5%; sweeteners would be 5.3%; and the other smaller sub-categories would tally 4.5% (beverages, seeds, cereal and starch). Without this proof, few people would believe that one-third of America’s corn crop gets made into ethanol.
There are at least two main benefits of biofuels – firstly, using Earth’s surface plant material to make fuel makes this energy source renewable, as opposed to relying on prehistoric hydrocarbon reserves buried hundreds of feet underground. Secondly, the idea is that emissions from vehicles burning biofuels are offset by the fact that the crops becoming biofuels capture carbon out of the air during their growth.
Initially, biofuels look great – until we consider how American corn-based ethanol is produced. Then the clear picture gets really cloudy. Analysis done by Day and his coworkers 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 nationally. This led to an uptick in fertilizer use from 3% to 8%. The biggest increase in emissions was caused by widespread changes in land use. Day’s crew noted that land that would have otherwise been fallowed was instead growing corn for ethanol.
Their study’s result was unflattering, shown by the quote from these scientists: “The carbon intensity of corn ethanol produced under the RFS is no less than gasoline and likely at least 24% higher.” This study directly condemned a program originally intended to benefit the environment. It also contradicted long-established thinking relative to biofuels.
Notably, a study from USDA in 2019 claimed that U.S. ethanol production from corn had outperformed expected targets, suggesting the biofuel had a greenhouse gas (GHG) emission profile between 39% and 43% lower than gasoline. However, as these scientists grasped the bigger picture, questions surfaced relative to the impact of land use changes supporting corn-based ethanol. Corn ethanol enthusiasts didn’t like such questions.
Geoff Cooper, president and CEO of the Renewable Fuels Association, told Reuters journalists that the study was “completely fictitious and erroneous,” criticizing the authors for making “worst-case assumptions” and using “cherry-picked data.” Regardless, the study suggested 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 its seeds or fruit. It can be produced from grasses, wood, algae or other plants, usually destined to become biofuel. The carbon dioxide that growing plants absorb offsets some of the CO2 emitted when their ethanol is burned, so cellulosic ethanol fuel has the potential for a lower carbon footprint than ethanol made from corn or sugarcane.
Since these two plants are primarily food products, diverting them for ethanol production can cause food price increases. Cellulose-based sources, on the other hand, do not compete with food – their fibrous parts are mostly inedible to humans.
Another potential advantage is the high diversity and abundance of cellulose sources. Grasses, trees and algae are found almost universally on our planet. Even municipal solid waste components like paper could be made into ethanol. Presently, the main disadvantage of cellulosic ethanol is its high cost of production, which is more complex and requires more steps than corn- or sugarcane-based ethanol.
However, switchgrass is one source of cellulosic ethanol now drawing favorable reviews from the sustainable science community, because it’s a perennial crop. This fact alone absolves it from the guilt of GHG creation associated with intensive tillage so prevalent with annuals.
Cellulosic ethanol received significant attention in the first decade of the millennium. Many new companies specializing in cellulosic ethanol 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. Fortunately, the favorable environmental score card claimed by switchgrass may make corn-based ethanol look even worse by comparison.
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 – the same as they have little to do with waste vegetable oil (WVO)-based biodiesel. Since I have personally manufactured a good-to-excellent quality WVO-based biodiesel, I feel that this alternative fuel oil deserves very few of the barbs hurled at ethanol. WVO not made into fuel ends up in a landfill – and where does that leave us?
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