Ethanol Biofuel: Methods, Pros & Cons
- Sylvia Rose
- Apr 8
- 4 min read
Updated: Apr 15
Ethanol, also known as ethyl alcohol, is a clear, flammable liquid with a wine-like odor. It's produced by microbial fermentation of sugars, soluble or reduced from polysaccharides like starches.
Ethanol (C2H5OH) is widely used as a fuel additive and as a foundational ingredient in chemical processes. It can be made from biomass materials including corn, sugarcane and agricultural waste.
Ethanol is the alcohol in beer, wine and other alcoholic beverages. It's created by yeast, who dine on sugars and excrete booze.
Yeast also produce CO2, which in beer forms the fizz. In bioethanol production some bacteria are used to ferment as well.
Bio-ethanol is denatured to make it undrinkable. Toxic or foul-tasting substances like methanol, benzene, pyridine, castor oil, gasoline, isopropyl alcohol or acetone are added to denature it.
How Ethanol Biofuel is Made
Feedstock Selection: The most common feedstocks are corn in the United States and sugarcane in Brazil. Other feedstocks are wheat, barley, sugar beets, sorghum, and cellulosic materials like agricultural residues and wood.
Pre-treatment: Cellulosic materials require pre-treatment to break down complex carbohydrates into simpler sugars which the yeast can ferment. Grains may be sprouted, as sugar content is highest then.
Fermentation: The chosen feedstock is processed to extract sugars or starches. They're then fermented to convert them into ethanol and carbon dioxide.
The most commonly used yeast is Saccharomyces cerevisiae. While yeast are famed for fermentation, certain bacteria can also ferment. They include Zymomonas mobilis and engineered bacteria like E. coli.
Distillation: The fermented mixture, known as "beer" in grain fermentation, has a fairly low concentration of ethanol (5-20% depending on yeast strain and conditions).
It is then distilled to separate the ethanol from the water and byproducts. Distillation separates ethanol from water and other compounds, increasing its purity and concentration for fuel use.
Dehydration: The distilled ethanol contains a small amount of water. Dehydration removes remaining water to produce anhydrous ethanol, which can be blended with gasoline.
Ethanol-blended fuels include E10 (10% ethanol), E15 (15% ethanol), or E85 (85% ethanol).
Producers & Consumers
United States: The US uses corn as its feedstock and is the world's leading producer and consumer of ethanol biofuel. A significant portion of its gasoline has ethanol blends. It's also the world's largest producer of gas.
Brazil: Brazil uses sugarcane as its feedstock and is the second-largest producer and consumer. It has a long history of ethanol production including a well-established infrastructure for its use, such as flex-fuel vehicles able to run on gasoline, ethanol, or any blend of the two.
Indonesia is the third-largest ethanol producer. As consumers, the EU and China are third and fourth respectively. The bioethanol market is valued at over USD 95 billion.
Pros & Cons of Ethanol Biofuel
Pros
Renewable Resource: Ethanol is derived from reasonably renewable sources, such as corn and sugarcane.
Reduced Greenhouse Gas Emissions: When burned, ethanol produces fewer greenhouse gas emissions compared to gasoline, although lifecycle emissions may be higher.
Higher Octane Rating: Ethanol has a higher octane rating than gasoline. A fuel with higher octane ratings resists knocking or premature ignition in engines.
Job Creation: Ethanol production supports agricultural industries and boasts of job creation. Balance of job creation and loss is a hidden factor to be considered.
Reduced Dependence on Fossil Fuels: Using ethanol helps reduce a country's reliance on foreign oil imports. The trend these days is deglobalization and national self-reliance.
Cons
Food vs. Fuel Debate: Using food crops like corn for ethanol production raises concerns about rising food prices and potential food shortages, especially in developing countries. Ethanol production drives up the price of food corn and restricts growing space for feed corn.
Land Use Impact: Expanding biofuel production requires clearing land for agriculture, leading to deforestation and habitat loss.
Hidden Costs: According to data from the Energy and Mineral Resources Ministry, the average market ceiling price for molasses rises 60% between 2018 and 2024, pushing bioethanol prices up by 40% while the gasoline price increase was only 30 percent.
Water Usage: Ethanol production can be water-intensive, straining water resources in many regions.
Lifecycle Greenhouse Gas Emissions: The overall lifecycle greenhouse gas reduction potential of ethanol has to be considered. Factors like fertilizer use, transportation and land use changes can influence the final effect.
Los Angeles is the smoggiest city in the United States largely due to vehicle emissions. The ethanol consumption of California is second only to Texas, which also has toxic air pollution levels.
Energy Balance: The energy required to grow, harvest, and process corn can be close to or even exceed the energy produced by the ethanol itself. Fertilizer runoff from mass agriculture is also a known pollutant.
Infrastructure Limitations: Not every vehicle and fueling station can accommodate high ethanol blends. However, for every fueling station shut down, owner and employees can work in the ethanol refinery. That's job creation.
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