Sunday, April 4, 2010

Ethanol and Gasoline and Diesel - References

rev. 10-14-2010

There is little question; although the addition of ethanol to gasoline has caused no impact to the motoring public - other than a bite in the wallet at tax time and at the grocery store -  the boating community will be living with the down sides for years to come. A few articles containing pertinent facts, since there is certainly plenty of rumor in circulation. These seem to support my varied experiences with several boats. I have kept my opinions to myself.

Will ethanol find its way into the diesel supply? This has been discussed but is not yet in practice. There are links below regarding this potential as well.

I will add more articles as I find them.


Gasoline/Ethanol. E-10, possibly moving to E-15 and beyond.

E-15 Aproved by US EPA. Only for 2007 and newer cars, but broader aproval are expected.

An interesting report to Australia Environment. Some good technical information about E-10 to E-30 concentrations that I have not seen elsewhere. A different spin that most US documents. Enleanment is addressed on page 10, vapor pressure on page 15, and mileage on page 26. Read the whole piece.

EPA is likely to approve increase from E-10 to E-15 by mid- 2011. They are waiting on tests expected to be completed in June 2010. These are automotive tests and do not address marine or motorcycle engines.

The volume of biofuels will probably triple in the next 12 years. This will include ethanol and bio-diesel. The amount may be less if the fuel is not available, but the EPA clearly has authority to increase the geography and concentration of ethanol in gasoline.

EPA memo on E-10 and phase separation. It explains why temperature changes can cause dramatic fall-out. It explains that EPA based their absorption risk statement on a relative humidity of 70% and 70F temperature. Since many boats see humidity very close to 100% and are not used for 6 months at a time, as general reasoning it is reasoning is flawed.

White paper on ethanol fuels from Renewable Fuel Association. Includes simple home-test for ethanol content of gasoline (page 31) and information on vapor pressure (page 12-14). Higher vapor pressure equals increased tank breathing, a factor the EPA phase separation analysis disregarded.

Also from the RFA site (buried in the Technician's paper):
Enleanment: Oxygenates such as ethanol chemically enlean
the air/fuel (A/F) mixture. As an example, in engines set at an
A/F ratio of 14.7:1 on all hydrocarbon fuel, the introduction of
3.5% oxygen in the fuel would enlean the A/F ratio to about
15.2:1. Computerized vehicles can compensate for this shift
by sending a command to increase fuel flow. Most nonautomotive
equipment is not sophisticated enough to accomplish
this. However, this small change in air/fuel ratio is not of
concern in most equipment and usually no modifications are
required. Some manufacturers have expressed concern that
the enleanment resulting from fuel bound oxygen could create
problems in certain severe applications. In particular, there is
concern about continuous operation at wide open throttle
(WOT) such as in marine applications. Also of concern is
equipment that typically operates rich at specified settings.
An example here would be snowmobiles. The two primary
concerns are octane quality and excessive heat. Properly
blended ethanol blends should not present problems in the
area of octane quality because ethanol is actually an octane
enhancer. Ethanol is routinely used to improve the octane
quality of gasoline. The more predominant concern is the
potential for higher operating temperatures. The maximum
combustion temperature (and resulting engine temperature)
occurs at an air/fuel ratio of 14.7:1. Going rich or lean from this
point will result in lower temperatures. Therefore, equipment
with richer initial A/F ratio settings such as 13 or 14 to 1 may
experience increased operating temperatures when switched
to oxygenated fuels. This increase is not significant and most
manufacturers do not require any modifications, but some do.
For instance, Polaris recommends that their older carbureted
sleds "jet up" one size when operating on oxygenates. Further,
some of their fuel injected 2 cylinder models require a
"shim kit" to lower the compression ratio. Polaris fuel injected
3 cylinder models are computerized and the E-Prom is already
calibrated to compensate for changes in oxygen content.
Arctic Cat recommends that when using oxygenated
fuels in their older Tiger Shark Watercraft, the high speed
needle valve should be "opened" 1/8 of a turn from its setting.
In the case of their Arctic Cat sleds, they recommend "jetting
up" the carburetor jets one size. Only a handful of marine and
recreational manufacturers offer such recommendations but
consumers should be advised to consult their owner's manual
or servicing dealer to determine if any modifications are
Excerpted from (pages 33-36 discuss non-automotive engines):

 White paper from the National Marine Manufacturers Association regarding ethanol and aluminum tanks corrosion.
white paper

 Practical Sailor Testing. None of the tested additives were able to prevent phase separation in E-10 gasoline, including several well know brands that claimed they could. Typical puffery in an unregulated market.

Corrosion problems with E-85. Every state publishes similar information; this is from Florida. No, boats don't run E-85, but when the fuel separates, the water phase concentrations are this high and these are the problems we see.


Diesel/Ethanol. Only discussion at this point, since retail sales is not permitted at this time. Presumably, since boats are off-road, it would still be permissible to use #2 fuel oil, which could not be converted to ethanol blending because of the overwhelming danger of fires in home and apartment furnaces.

USEPA is researching the possibility of adding ethanol to diesel. Nothing has been decided at this time, although clearly the ethanol lobby is pressing hard.

 DOE is researching ethanol/diesel blends. However, this is only a combustion test in an engine, not research on the broader topic.

 This DOE study addresses safety and some practical problems. It discusses problems such as phase separation (ethanol does not stay in diesel as well as it stays in gasoline), flammability, and high cloud point (room temperature). They discuss all of this from a truck view point, not marine.

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