E85

For the road, see European route E85

Logo used in the United States for E85 fuel

E85 is an alcohol fuel mixture of 85% ethanol (ethyl alcohol) and 15% gasoline (petrol) that can be used in flexible-fuel vehicles.

Availability

The fuel is widely used in Sweden and is becoming increasingly common in the United States, mainly in the Midwest where corn is a major crop and is the primary source material for ethanol fuel production. Minnesota has the largest number of E85 fuel pumps of any U.S. state, with almost 150 of the 300+ pumps in the country. As of July 2005, Illinois has the second-greatest number of E85 pumps (about 60); most other states have fewer than two dozen. Even in Minnesota, the ethanol pumps represent a tiny fraction of the fuel outlets—there are about 4,000 gas stations in the state, each with several individual pumps (however, all stations there are required to carry E10, a 10% mixture of ethanol and gasoline). However, concerns about rising gasoline prices and energy dependence has led to a resurgence of interest in E85 fuel; for example, Nebraska mandated the use of E85 in state vehicles whenever possible in May 2005.

Cost

As of mid-2005, E85 is frequently sold for a 0 to 35% lower cost than gasoline. Much of this discount can be attributed to various government subsidies, and, at least in the United States, the elimination of state taxes that typically apply to gasoline and can amount to 47 cents, or more, per gallon of fuel. In the aftermath of Hurricane Katrina, the price of E85 has risen to nearly on par with the cost of 87 octane gasoline in many states in the United States, and is often the only fuel available when gasoline is sold out.

Unfortunately, because ethanol contains less energy per gallon of fuel than gasoline does, fuel economy is normally negatively impacted for most FFVs (flexible fuel vehicles) that are currently on the road by about 30% when operated on pure E85. (Newer vehicles can sometime lessen this impact to only 5-15% through using higher compression ratio engines.) Still, for all FFVs, more E85 is needed to do the same work as can be achieved with the same volume of gasoline. This difference is partially or totally offset by the lower cost of the E85 fuel, depending on E85's current price discount relative to the current cost of gasoline.

For example, an existing FFV vehicle that normally achieves, say, 30 MPG on pure gasoline will typically achieve about 20 MPG, or slightly better, on E85. To achieve any short-term operational fuel cost savings, the price of E85 should therefore be 30% or more below the price of gasoline to equalize short term fuel costs for most existing FFVs. Life-cycle costs over the life of the FFV engine are theoretically lower for E85, as ethanol is a cooler and cleaner burning fuel than gasoline. Provided that one takes a longterm life-cycle operating cost view, a continuous price discount of only 20% to 25% below the cost of gasoline is probably about the break-even point in terms of vehicle life-cycle operating costs for operating an FFV on E85 continuously.

Fuel economy in fuel-injected non-FFVs operating on a mix of E85 and gasoline varies greatly depending on the mix. For a 60:40 blend of gasoline to E85, a typical fuel economy reduction of only around 6.5% often results, relative to the fuel economy achieved on pure gasoline. For a 50:50 blend of gasoline to E85, a typical fuel economy reduction of around 25% results. Operation of non-FFVs on less than a 50% blend of gasoline to E85 is not recommended, as this will generally cause the check engine light to illuminate, due to the presence of more oxygen in E85 than in gasoline and this will, in turn, cause the ECU not to be able to completely compensate for the differences in fuel of E85 relative to gasoline.

All fuel-injected automobiles sold in the United States since approximately 1988 can usually safely be run on up to a 50:50 blend of gasoline to E85, as all the components are already designed to accomodate gasohol (E10, i.e., 10% ethanol and 90% gasoline), and there is no appreciable difference in the corrosive properties between E10 and a 50:50 blend of gasoline and E85. Operation with more than 50% E85, however, is not recommended on fuel-injected non-FFVs. Besides, most of the operational cost savings is most likely to occur while keeping to a 60:40 blend, or higher, of gasoline to E85 in a fuel-injected non-FFV, provided that the cost of E85 to gasoline is at least 6.5% below the cost of gasoline. To do this practically, buy 10 gallons of gasoline, and then buy no more than 4 gallons of E85 the next time you buy fuel. Then, the next time, buy at least 10 gallons of gasoline and repeat the cycle.

Flexible-fuel engines

E85 is best used in engines modified to accept higher concentrations of ethanol. Such flexible-fuel engines are designed to run on any mixture of gasoline or ethanol.

So far, most flexible-fuel vehicles that built in the United States have been sport-utility vehicles and other members of the "light truck" vehicle class, with smaller numbers of sedans, station wagons, and the like.

Swedish automobile maker Saab developed a turbocharged flexible-fuel engine called the BioPower which takes advantage of the high-octane fuel. The engine allows the vehicle to accelerate faster and attain higher speeds when running on E85 than when running on straight gasoline.

General Motors subsidiary GM do Brazil adopted GM's Family II and Family 1 straight-4 engines with FlexPower technology that enables the use of ethanol, gasoline, or their mixture. The vehicles with FlexPower include the Chevrolet Corsa and the Chevrolet Astra.

Standard engines

E85 has a considerably higher octane rating—about 110—which means that it doesn't burn as efficiently in traditionally-manufactured internal-combustion engines.

Modern (most cars built after 1988) fuel-injection engines with oxygen sensors will attempt to adjust for the extra oxygenation of E85 by running a very lean mixture, with variable effects on performance. Prolonged exposure to high concentrations of ethanol may corrode metal and rubber parts in older engines (pre-1988) designed primarily for gasoline.

After-market conversion kits, for converting standard engines to operate on E85, are generally illegal to manufacture in the United States. Still, there is one Brazilian after-market kit available that will nonetheless permit the conversion of 4, 6, or 8 cylinder engines to operate from pure gasoline upto pure ethanol, including E85.

External links

References

Matthew Phenix. Liquor Does It Quicker. Popular Science, June 2005.