On October 27, the Energy Information Administration (EIA) reported that the use of ten percent ethanol in the gasoline supply has lowered gasoline energy’s content by three percent in a 20 year period.  According to EIA, while the use of oxygenate additives, like ethanol have “reduced air pollution, they also resulted in lower heating value compared with conventional gasoline, translating to fewer miles per gallon, because they have lower energy density.” While it is true that ethanol has an ‘energy penalty’ as compared to gasoline, this tells only half the story. 

Neat ethanol needs to be about 25 to 30 percent cheaper than gasoline to make up for the energy penalty it incurs.  According to EIA, E85 (85 percent ethanol, 15 percent gasoline) was cost competitive with E10 gasoline for at least eight months out of a ten month period in 2012 to 2013.  Today, AAA reports that the average retail price for gasoline on October 31 is $3.00.  Despite retail gasoline being the lowest price it’s been in four years, E85 is still an average of 29 percent cheaper than gasoline without any ethanol (E0), and 20 percent cheaper than E10, as reported by the independent website E85prices.com.  In the Midwest, there are even gas stations where E85 is up to 40 percent cheaper than E10.  Additionally, driving conditions such as tire pressure, excess weight, the use of air conditioning, and vehicle maintenance have been found to have a much greater effect on fuel economy.

More importantly, engines can be optimized for ethanol use, considerably narrowing any ‘energy penalty’ gap between ethanol and gasoline.  FlexFuel Vehicles (FFVs), whose engines are specifically designed for using high ethanol blends, such as E85, are not actually optimized for these fuels, unfortunately.  Rather, the manufactures are optimizing these engines for gasoline (E10), and even filling them with E10 at the factory!  Despite this, ethanol still makes sense from an efficiency standard, particularly in newer, more efficient engines. According to William Woebkenberg of Mercedes-Benz, E30 would provide “ridiculous power and good fuel economy,” providing the best of both worlds – ethanol for octane and gasoline for energy density.  Another option would be to design an engine specifically for ethanol, which is being done by Ricardo, Inc., a British engineering and environmental consulting firm. Their Ethanol Boosted Direct Injection (EBDI) engine seeks to improve performance when run on ethanol fuels, and has reached efficiencies similar to diesel engines. 

Today though, there are at least 11 million FFVs on the road.  Unfortunately, due to limited fuel choice, only about 12 percent of FFV owners are filling up on E85. What is critical now is to invest in the infrastructure needed to support higher blends – in particular, blender pumps, which can blend ethanol and gasoline on-site. While the use of E10 may have dropped fuel efficiency 3 percent, consumers have, however, seen an increase in savings due to ethanol’s more often than not recent price parity, as well as lower harmful emissions, such as toxic tailpipe emissions and greenhouse gases.  And while issues of engine optimization can easily be fixed, for now, a 3 percent energy penalty seems like a small price to pay for all the benefits ethanol provides.



For more information see: 

Increasing ethanol use has reduced the average energy content of retail motor gasoline, EIA 

How much ethanol is in gasoline and how does it affect fuel economy?, EIA 

Squeezing More From Ethanol, The New York Times

A More Efficient Ethanol Engine, Technology Review