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DC Insider: What happens when ethanol blended fuel mixes with water?

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A study involving several state environmental agencies and the U.S. Environmental Protection Agency wanted to find the answer to that question after a compliance inspector with the Petroleum Program in the Virginia Department of Environmental Quality noticed “odd corrosion reactions in some of the sumps” for the underground fuel tanks (Wilson, et al., 2011).

Virginia’s DEQ “speculated that acetic acid bacteria (Acetobacter) were producing acetic acid in the sumps. The EPA “speculated that ethanol vapor that originated from the motor fuel was finding its way into water in the sumps, which would provide a source of food for the acetic acid bacteria.” (Wilson, et al., 2011).

The study found that sump pumps containing water allowed the acetic acid bacteria to degrade the ethanol to acetic acid. The acetic acid would then cause corrosion of the copper tubing and valves of the pumps (See Figure 1) (Wilson, et al., 2011). Conversely, “If moisture was not available, there would be no opportunity for bacteria to degrade the ethanol to acetic acid” (Wilson, et al., 2011).

Figure 1 Corroded pump

Figure 1 Corroded pump

This troubling study raises even more concern about ethanol in fuel now that the EPA has publicly acknowledged that ethanol blends can damage internal combustion engines not designed for its use by increasing exhaust temperatures and indirectly causing component failures.

According to the EPA, "[e]thanol impacts motor vehicles in two primary ways. First ... ethanol enleans the [air/fuel] ratio (increases the proportion of oxygen relative to hydrocarbons) which can lead to increased exhaust gas temperatures and potentially increase incremental deterioration of emission control hardware and performance over time, possibly causing catalyst failure. Second, ethanol can cause materials compatibility issues, which may lead to other component failures.

"In motorcycles and nonroad products [using E15 and higher ethanol blends], EPA raised engine-failure concerns from overheating."

This study and EPA’s acknowledgement demonstrate that fuels containing high levels of ethanol can damage not only engines, but also fueling station infrastructure.

The American Motorcyclist Association opposes E15 fuel (15 percent ethanol by volume) because inadvertent misfueling can cause engine and fuel system failure to the estimated 22 million motorcycles and all-terrain vehicles currently in use and can void manufacturers' warranties.

The EPA needs to stick to its proposal rule to roll back the requirement for wider distribution and use of E15 under its Renewable Fuel Standard. However, even the EPA rollback is only a short-term fix. For a longer-term solution, we need Congress to address the RFS legislatively.

The AMA supports H.R. 1462. This bill would reduce the total RFS by 79 percent in 2014 and reduce the RFS by other significant percentages each year until 2022, when the total RFS is reduced by 42 percent. That is, the bill adjusts the mandate to 21 billion gallons in 2022, rather than 36 billion gallons.

Moreover, H.R. 1462 rescinds the EPA’s E15 waivers and caps the amount of ethanol content in gasoline at E10.

The AMA supports this common sense solution to make sure that motorcyclists have access to safe fuels.


Wilson, J. T., Adair, C., Paul, C., Wilkin, R., Skender, J., Keeley, A., . . . Hickey, J. (2011). Association between Ethanol in Fuel and Corrosion in STP Sumps.

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