Writing about different types of fuel is a daily practice on this blog. However, we haven’t answered every question yet. Therefore, we will use this blog to discuss the differences between E-85 and bio-diesel. Let’s start with a quick answer:
E85 is not diesel because it consists of 51 – 83% ethanol mixed with 17 – 49% regular or premium gasoline. Furthermore, the ethanol that’s used in E-85 is mainly made from corn, whereas the bio-products that are made for use in bio-diesel are mostly oils made from soybean, cottonseed, and canola.
However, that doesn’t answer the question wholly. Below, we’ll first explain how to check if your vehicle can take a mix of E-85 and unleaded gasoline without any problems. Furthermore, we’ll explain how to mix these types of gasoline safely and what happens if you do it carelessly. Read on!
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1. Gasoline Substitute Vs. Diesel Substitute
E-85 is a fuel that consists of ethanol and regular or premium unleaded gasoline. How much ethanol is in E-85 depends on the season and the climate you live in. In general, E-85 in the United States has 51 – 83% ethanol, whereas, in Australia, it has 85% (hence the term E-85).
E-85 is generally used as a substitute for gasoline in so-called Flex-Fuel vehicles. These are vehicles that have a special computer inside of them that adjusts the output of the engine and the way it works depending on the ethanol levels it detects.
On the other hand, there’s biodiesel. Biodiesel is an alternative to regular diesel, just like E-85 is an alternative to regular gasoline.
Just like ethanol (which will always be mixed in gasoline in one way or another in gasoline such as E-10 and E-15), biodiesel also has variants that can be used by most diesel cars without modifications. These types of biodiesel are called B5 and B20, which means they contain 5% and 20% biodiesel. Most diesel engines can run B20 without a problem.
On the other hand, there’s B100 which means it’s made out of biofuel. Luckily for most vehicle owners in the United States, B100 can also be used without having to change anything to your vehicle.
2. Corn vs. Oils
Furthermore, there’s a difference between how the two fuels are made. E-85 is a blend between ethanol and regular gasoline. Regular gasoline is produced the way we know, by pumping it out of the ground. However, this fuel mainly consists of ethanol. In the United States, ethanol is primarily made from corn.
Therefore, many ethanol plants in the United States are located in the mid-west since this is the region where the corn is made. Other sources for ethanol production include sugar cane and bio-waste, but these are far less common in North America.
On the other hand, biodiesel is made from various sources, mainly oils. These include soybean oil, cottonseed oil, canola oil, beef tallow, pork lard, and yellow grease. Just like the production of ethanol, the production of biodiesel mainly takes place in the mid-west (Iowa is a top producer of both) since most soy crops are made here too.
3. Octane / Cetane Rating
Another difference between the two fuel types is how their combustion is measured. E-85 is gasoline which means it’s estimated in octane. Regular and premium gasoline typically has an octane of 87 – 95. However, depending on the number of ethanol, E-85 typically has an octane of 100 – 105.
This means that ethanol is more stable and combusts at higher temperatures. The result of this is that it generates more horsepower but has a worse fuel mileage than regular gasoline.
On the other hand, there’s biodiesel, of which the combustion is measured in cetane. Regular diesel typically has a cetane level of 48, whereas biodiesel is around 55. Similarly to E-85, a higher cetane number means complete combustion, which results in more power output. However, the fall in gas mileage isn’t as significant with biodiesel vs. diesel as with E-85 compared to unleaded gasoline.
4. Fuel Mileage
What kind of fuel mileage you’re going to get depends on the vehicle you’re using. However, there are differences between the two fuel types we’re comparing today.
First, it’s important to note that E-85 typically has a 20 – 30% worse fuel economy than regular gasoline. The higher octane number results in more mechanical power, but you lose out on MPG.
On the other hand, the drop between B5 and B100 is much less severe. In most cases, a diesel vehicle owner isn’t aware of a difference in fuel mileage. Furthermore, studies have shown that the difference between B5 and B100 is in the 5 – 10% range, making it much more acceptable.
If we were to compare E-85 and B100 directly, we would see that B100 has the better fuel mileage. Regular diesel already has a 20 – 40% better fuel mileage than regular gasoline. The fact that E-85 is much less fuel-efficient and experiences a more significant drop in fuel mileage than B100, and you know the winner.
Another difference that’s not to be overlooked is the number of emissions that both fuels produce. In studies that have come out in recent years, it became clear that biodiesel is much more efficient and polluting than the production of ethanol is.
In PNAS, which is a scientific magazine, they noted the following aspects in this debate:
“Relative to the fossil fuels they displace, greenhouse gas emissions are reduced 12% by the production and combustion of ethanol and 41% by biodiesel.“
Furthermore, the production of biodiesel compared to ethanol is also much more energy efficient when we look at the complete lifecycle of both fuels:
“Ethanol yields 25% more energy than the energy invested in its production, whereas biodiesel yields 93% more.“
So, since biodiesel is more energy-efficient and produces less greenhouse gas emissions throughout its life cycle, it’s the superior choice.
Then, there’s always the aspect of price. If you’re a diesel car owner, in this case, you have the option between regular diesel and B100. Regular diesel costs $3,48 per gallon as of the writing of this article. However, biodiesel has a price of $3,80 per gallon. This means biodiesel is 9% more expensive.
That’s also immediately one of the reasons why biodiesel has struggled so hard in the past decades to gain popularity. Biodiesel hasn’t been subsidized. As a result, it has a slightly worse fuel economy but is 9% more expensive than regular gasoline. Even though it’s much better for the environment, people refuse to buy it because of the price.
On the other hand, there’s E-85. This fuel carries a price of $2,73 per gallon, whereas gasoline (E-10) carries a cost of $3,25 per gallon. This means E-85 is around 19% cheaper at the pump. However, let’s not forget that E-85 is also 20 – 30% less fuel-efficient.
However, these factors do kind of balance each other. Furthermore, because E-85 is cheaper at the pump, people are more inclined to buy it.
Finally, we want to discuss the availability and needs for both kinds of fuel. In total, the United States has around 21 million Flex-Fuel vehicles. This means these vehicles can use E-85 gasoline. On the other hand, there are only 7.4 million diesel vehicles in the United States (these are the only vehicles that can take biodiesel).
As a result, E85 is much more commonly sold, and biodiesel is much less widely available. Combine this with the higher price per gallon, and you realize that biodiesel doesn’t have as strong of a foothold in the American market as E85 has.
Hi! My name is Stefan; I’m the owner and lead writer at TheDriverAdviser.com.
I’m an active writer on this blog myself, as well as a novice car mechanic. For the really technical stuff, I find writers with experience as a mechanic or who have studied mechanical engineering.
Read more about our fantastic team on our about page!