In 2012, the Obama Administration set groundbreaking standards to increase fuel economy to the equivalent of 54.5 MPG for cars and light-duty trucks by model year 2025.
Although the auto industry has made many design innovations during the years, it will take a better fuel to meet this lofty goal. That better fuel contains ethanol.
Engine efficiency is how much of the energy in the fuel is converted to “useful work.” In a vehicle “useful work” is measured as MPG (miles per gallon). Gasoline engines in vehicles are typically 25-30% efficient, which means that only 25% of the energy contained in the fuel is used to move the car down the road. Diesel engines are 40-50% efficient, much higher than gasoline engines.
The main reason for the increased efficiency is that diesel engines run on a much higher compression ratio or a higher pressure. Higher compression means greater engine efficiency. Gasoline engines cannot be operated at higher compression, because the fuel prematurely combusts under high engine pressure causing “engine knock,” which greatly decreases engine efficiency and can be harmful to the engine.
Reducing engine knock is all about octane – and what’s added to our fuel to get it. But what’s octane?
Octane is a measure of the ignition quality of gasoline. The higher the octane number the less susceptible the fuel is to knocking. Knocking occurs when the fuel prematurely burns in the engine’s combustion chamber due to compression, instead of being ignited by the spark as the engine is designed. The higher the octane number, the more compression the fuel can withstand before igniting.
These numbers at the fuel pump represent the octane number. You can see that E85 (85% ethanol) has an octane of 105. Traditionally, denatured ethanol from an ethanol plant usually has a 113 octane number.
A recent report by the National Renewable Energy Laboratory noted high-octane ethanol blends containing 20-40% ethanol are being “extensively studied” as fuels that would enable the design of engines that get better performance and fuel economy and produce fewer emissions.
Ethanol is a non-toxic, cleaner-burning octane booster that combusts more completely in the engine. Higher blends of ethanol dilute the level of toxic additives in our fuel, which helps reduce pollution.
It’s important that flex fuel infrastructure is available now to supply higher blends of ethanol for flex fuel vehicle drivers and new high-compression engine vehicles hitting the market.
Ethanol is truly the fuel of the future.
This post was submitted by the Nebraska Ethanol Board. The Nebraska Corn Board and Nebraska Ethanol Board continue to work together to establish procedures and processes necessary to the manufacturing and marketing of ethanol fuel.