How Does Ethanol Fuel Work? (2024)

In today's quickly-changing world, the need for sustainable and efficient transportation fuels is more important than ever!

Ethanol fuel, an alcohol-based biofuel derived from plant material, has emerged as a potential contender in this race for a greener solution to gasoline. But how exactly does ethanol fuel work? And how do plants become fuel, anyways?
Here’s all you need to know about ethanol fuel, how it’s made and what makes it a good (and bad) option!

What is ethanol fuel?

How ethanol fuel is made

Though the process to convert a kernel of corn into a drop of fuel is a super scientific and complex one, the process can be broadly divided into five steps.

Harvesting the base ingredients

The journey of ethanol fuel begins with our collected biomass. Corn, sugarcane and other crops rich in carbohydrates are the most common sources, though wood chips, algae and even animal waste can also be used! These biomass sources hold the key ingredient – sugars – which are essential for ethanol production.

The first step involves breaking down the complex carbohydrates present in the biomass into simpler sugars, which is done through a natural process called saccharification. In corn-based production processes, the starches in the corn kernels are broken down into simple sugars like glucose using enzymes that are added to the mixture.

It helps to think of the vodka-making process when picturing this complex system, as it follows similar steps. Take a starch, add water, blend it up and allow the starches to break down into sugars in a big, liquidy mush!

Fermentation

With the sugars ready, the transformative powers of fermentation come into play. Yeast is introduced to the sugary solution and, in the oxygen-limited environment, it starts to consume the sugars. As the yeast feeds on the sugars and ferments them, it releases carbon dioxide and ethanol as a byproduct. The more sugars that the yeast can feed on, the more ethanol can be produced, so it’s up to the scientists and chemical engineers to make sure that all the conditions are just right for maximizing ethanol production.

Distillation

The fermented broth, often referred to as "beer" (but not the kind you can drink, obviously), contains high levels of ethanol along with water, yeast and other impurities. In order to both remove the solids and isolate the ethanol, the beer has to undergo distillation.

The fermented liquid is moved to large distillation stills and heated to about 173.1°F causing the ethanol, which has a lower boiling point than water, to vaporize first. The ethanol vapor is then condensed back into a liquid form and collected in a separate still, resulting in a clean, pure and more concentrated ethanol solution. Multiple rounds of distillation may be necessary to achieve the desired purity for fuel-grade ethanol.

Dehydration

Though the distilled ethanol is around 95–96% pure ethanol, some water molecules inevitably find their way into the mix and, depending on the type of ethanol fuel being created, may have to be removed.

For certain applications, particularly E85 fuel blends containing 85% ethanol, further dehydration is usually called for. This process typically involves passing the fuel through molecular sieves, which are materials with tiny pores that allow ethanol molecules to pass through but trap water molecules.

Storage and distribution

Once produced, ethanol needs to reach its point of use where it can then be mixed with other forms of fuel for its various applications. At the destination, ethanol is stored in tanks before being blended with gasoline at specific ratios (such as E10 or E15) for use in vehicles or transported to industrial facilities for other uses.

And there you have it! That’s the very basic process of how we can turn a bushel of corn into approximately 2.8 gallons of ethanol (and, alternatively, how we can make beer, wine and liquor).

Benefits & drawbacks to ethanol fuel

The potential benefits of ethanol fuel are plenty. As a biofuel it’s derived from renewable plant matter, unlike gasoline which is a finite resource made from fossil fuels. This renewable nature can also contribute to higher energy security and a potentially lower dependence on foreign oil, which can build economic stability and strengthen job markets.

Additionally, ethanol burns cleaner than gasoline, resulting in reduced emissions of harmful pollutants like carbon monoxide and particulate matter — leading to improved air quality and fewer greenhouse gasses, particularly in urban areas!

However, the use of ethanol fuel also comes with drawbacks.

One key concern is its impact on fuel economy. Ethanol has a lower energy density compared to gasoline, which means that a vehicle running on pure ethanol will travel fewer miles on a gallon of fuel compared to gasoline. However, the exact impact on fuel economy depends on various factors like the specific ethanol blend and vehicle efficiency.

The production of ethanol from corn and other food crops also raises concerns about the "food vs. fuel" debate, in which large-scale production of ethanol crops can potentially lead to increased food prices and competition for land resources.

And, like with any type of resource we take from the planet, the environmental impact of ethanol fuel is a complex issue in its own right. While it can reduce emissions from vehicles once it’s being used, the land-use changes associated with large-scale ethanol production can have its own fair share of hidden costs. Water, land, energy and manpower goes into the production process, and all of those have an impact on our natural resources, too. The lifecycle analysis of ethanol production (which considers the total energy used in cultivation, processing and transportation) needs to be factored in to determine its true greenhouse gas reduction potential.

All in all

Ethanol fuel offers a promising alternative to traditional fossil fuels, thanks to a production process that utilizes renewable resources and a fuel that boasts a fair amount of environmental benefits. However, challenges like a lower fuel economy, economic considerations and the impact on land use are big pieces of the puzzle, too.

As research and development efforts continue to improve ethanol production efficiency and explore alternative feedstocks, biofuels like ethanol have the potential to play a significant role in a sustainable future. It’s not going to be perfect, but it’s certainly a step in the right direction when it comes to exploring options that keep us and our planet safer, cleaner and healthier than before!