How Ethanol Affects Fuel Efficiency: What You Need to Know

U.S. corn ethanol producers are increasing production in expectation of support of American energy independence from the Trump administration and anticipation of growing foreign demand. Producers are planning refineries in Iowa and South Dakota that would add 500 million gallons a year in production capacity by 2018, according to the Renewable Fuels Association. U.S. ethanol production capacity now stands above federal mandates, with the excess being exported to countries such as Canada and Brazil.

Meanwhile, the ethanol lobby is pushing for legislation that would boost domestic demand by lifting the federal ban on summer sales of fuels with more than 10 percent ethanol. Consumers may soon have the option of buying E15 during summer months.

Being faced with this new option naturally confronts consumers with the question, is ethanol a better buy than gasoline? The answer to that question pivots around ethanol’s fuel efficiency and whether its lower cost per gallon translates into lower cost per mile. Here’s a look at how ethanol affects fuel efficiency and how that affects you at the pump.

Fuel Factors

One of ethanol’s advantages over gasoline is its high octane properties, making it more resistant to engine knock. In the United States, ethanol has an octane rating of 109. This is significantly higher than gasoline. Regular unleaded gas has an octane rating of 87, while midgrade has an octane rating of 88 to 90, and premium has an octane rating of 91 to 94.

It should be noted that the octane advantage of pure ethanol is significantly higher than that of ethanol-gasoline blends. For instance, a blend containing 10 percent ethanol does not have an octane advantage over pure gasoline.

Further offsetting ethanol’s octane advantage is its lower energy content, which translates into lower fuel efficiency. A gallon of ethanol provides a third less energy than a gallon of gasoline, says Bell Performance. A blend of 85 percent ethanol with 15 percent gasoline would be 30 percent less powerful than pure gasoline. As a result, using E85 lowers gas mileage per gallon by 30 percent compared to pure gasoline.

Engine Issues

Fuel efficiency also depends on engine design. Ethanol is a strong solvent, making it tougher on engines than gasoline. Recent car models can accommodate low levels of ethanol due to computer-adjusted fuel injection and the use of chemical-resistant and heat-resistant materials such as fluorocarbon. But older car models and other vehicles such as motorcycles and tractors are susceptible to ethanol damage, and even car models predating 2012 can be damaged by ethanol levels of 15 percent or higher, says USA Today. Car manufacturers have warned that using E15 can void vehicle warranties due to corrosive damage to engine parts.

Price at the Pump

Ethanol is cheaper per gallon than gas. In April 2017, the national average price of E85 was $2.11 per gallon, compared to $2.38 a gallon for gasoline, according to information compiled by the U.S. Department of Energy.

However, when it comes to mileage, gasoline is cheaper per mile than ethanol. Using E10 instead of gas lowers gas mileage by 3 percent, says the Environmental Protection Agency. For a 2014 Ford Focus to achieve cost savings by running on E85, the price of E85 would need to be 30 percent lower than the price of gas, Kiplinger estimates. Unless a technology breakthrough lowers the price of ethanol production, gasoline will continue to be more cost-efficient when it comes to cost per mile.



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Jimmy Rustling

Born at an early age, Jimmy Rustling has found solace and comfort knowing that his humble actions have made this multiverse a better place for every man, woman and child ever known to exist. Dr. Jimmy Rustling has won many awards for excellence in writing including fourteen Peabody awards and a handful of Pulitzer Prizes. When Jimmies are not being Rustled the kind Dr. enjoys being an amazing husband to his beautiful, soulmate; Anastasia, a Russian mail order bride of almost 2 months. Dr. Rustling also spends 12-15 hours each day teaching their adopted 8-year-old Syrian refugee daughter how to read and write.