Ethanol is an alcohol, made from corn or grains, added to gasoline to oxygenate fuel at the gas pumps. Compared to conventional gasoline, E10 and E85 (ethanol blend fuels), will absorb much more water, very quickly.
Ethanol gasoline fuel is commonly called E10,
E85, corn fuel, alcohol fuel and reformulated, renewable fuel and gas.
10% ethanol gasoline can dissolve 50 times more water than conventional non-alcohol gasoline.
Over 10% ethanol content in gasoline will damage conventional engines.
Ethanol is hygroscopic (will absorb water), and is an excellent solvent (dissolves materials).
Ethanol is added to gasoline at the pumps (local terminal) because of risk of water contamination when traveling through the pipelines.
Unlike MTBE, water will actually dissolve in an ethanol blended fuel and phase separation occurs much sooner.
Phase separation happens in E10 gas, when only 0.5% water or 3.8 teaspoons water per gallon of fuel is absorbed.
Ethanol alcohol, an excellent solvent, can dissolve fuel system parts, rubbers, plastic, certain fiberglass, and even aluminum. The rubber that is used in fuel system parts, such as seals and hoses, may shrink, swell, or lose strength when exposed to ethanol reformulated gasoline.
Ethanol releases less energy and compared to non-alcohol fuels, it gets a lower mpg rating.
After E10 was introduced on a widespread basis (2006-onward) there have been increased reports of dangerously high levels of ethanol (over 10%) in fuel tested at the pumps. This has caused the "ethanol scare".
Not a single major engine manufacturer currently approves of use of gas that contains over 10% alcohol. This may change in the future as ethanol organizations push for increase to E15 and E20 (15 to 20% ethanol in conventional fuel. Note E85 (85% ethanol is only for use in flex fuel vehicles).
Fuel Testers recommends testing gasoline for alcohol at the pumps before buying. Alcohol Fuel Test Kits will assure gas contains 10% or less ethanol.
E10, Ethanol has dramatically changed fuel system management, precautions and gas shelf life...
Ethanol's Water Absorbing Qualities and High Risk for Gas Contamination:
At 70 degrees Fahrenheit, conventional (non-alcohol) gasoline can dissolve up to 150 parts per million (ppm) water.
The situation is different for gasoline oxygenated with 10 % volume ethanol...
The ethanol blend can dissolve much more water, up to 6000-7000 ppm.
When this blend is cooled, both the water and some of the ethanol become insoluble.
The process described above, results in "phase separation", where two layers of liquid are visible.
An upper ethanol-deficient gasoline layer and a lower ethanol-rich (up to 75% ethanol) water layer.
This process is called phase separation.
It occurs because ethanol is completely soluble in water but only marginally soluble in hydrocarbons...
After phase separation, the gasoline layer will have a lower octane number and may knock in an engine. The fuel also is less volatile.
Running an engine on the phase-separated fuel can cause serious engine difficulty and problems.
Ethanol fuel expires in 90 days.
At around 90-100 days, under ideal conditions (mid-temperature and low humidity), ethanol blend fuels will enter phase separation (contaminated gas).
After phase separation occurs, it is contaminated and distorted gas that must be discarded.
One effect of phase separated fuel is that the octane will drop as much as 3 points or more. If you bought 87 octane unleaded gas, after phase separation, you will be running on an 84 octane or lower. This is dangerous and will cause problems in most engines.
Using fuel sooner is recommended to decrease the risk of running your engine on bad contaminated gas, that's water-contaminated, phase-separated fuel.
Due to ethanol's affinity for water, nowadays engine manufacturers recommend refilling/replacing your fuel every 14 to 30 days.
The dangers of ethanol's amazing water absorbing qualities are most prevalent in the boating industry:
Boat engines live in a water environment. Boaters increase their risks even further because they tend to store fuel in their boat gas tanks much longer than in their automobiles. Fuel systems of cars also tend to have better seals, (EG. tightly closed gas caps).
Boat engines also are used during the most humid and moist (spring/summer) months.
One drawback of E10 and E85 fuel is it generates less energy than fuels without alcohol.
E85 generates only about 75 percent as much power as a gallon of gasoline. That means that ethanol would have to be roughly 25 percent cheaper per gallon to be a bargain for consumers, which it is not true today.
Chemical Structure of Ethanol Gasoline:
The chemical name of ETHANOL is C2H5OH. Chemically pure ethanol is a colorless liquid which looks like water but has a mild odor.
Gasoline is a refined product of petroleum crude oil, consisting of a mixture of hydrocarbons, additives, blending agents, dyes and more. Depending on the blend of gasoline, this mixture contains between 150 - 1000 different compounds. Ethanol is the compound added to oxygenate the fuel.