ETHANOL - AN ALTERNATIVE FUEL
Present design internal combustion (IC) engines run on liquid fuels.
Ethanol requires few if any engine modifications to extract the maximum
power from this fuel. Ethanol is reported to lower tailpipe emissions.
Ethanol is more difficult to ignite than gasoline, especially in cold
temperatures. Thus, for an engine to operate on 100 percent ethanol, the
ignition and fuel systems may need modifications. Ethanol is energyintensive to produce and therefore could affect the total energy-cost
cycle. Ethanol may be produced from agriculture crops and is considered a
renewable energy resource. However, environmental considerations such as
increased use of fertilizers and the associated problems with ground
water runoff and limited supplies of ethanol when made from corn or other
grain crops, hinders its widespread usage. When ethanol is used as a
gasoline additive, antiknock compound and fuel extender, it becomes more
economical with very positive results, especially from the emissions
standpoint. It contains zero sulfur, thereby reducing tailpipe acids
significantly. Of the alternative fuels presently available, ethanol has
the lowest Btu/lb. net energy yield.
Several manufacturers have begun developing "multi-fuel" engines, that
is, engines that operate on many different fuels and in varying ratios. A
key component in these multi- fueled vehicles is the computer. Special
sensors detect the type of fuel(s) present. The fuel injection, ignition
and emissions control systems are recalibrated to accommodate the present
fuel(s). Limited production of 100 percent ethanol vehicles is being
offered in some Canadian and South American markets. For several years
Illinois, Iowa, Nebraska, and Michigan have mandated a 10 percent ethanol
to 90 percent gasoline mix for fuels used in state-owned vehicles. These
blends extend gasoline fuel stocks, reduce air pollution, and support the
agricultural community. Federal subsidies have brought production costs
of this antiknock additive into close competition to the cost of
producing other antiknock additives.
Initial changeover from gasoline to ethanol could present some problems
in the distribution system. Ethanol is a detergent and has the ability to
absorb water. Accumulated sediment and water sludge in storage tanks,
pipelines, and in the vehicle fuel tanks could clog filters and create
other operational problems. These systems must be scrubbed clean and
prepared prior to the introduction of ethanol fuels. Ethanol, in a highly
concentrated state, can be corrosive to some automotive metals, rubber,
and plastic components. Since the mid 1980's, most manufacturers have
redesigned their fuel systems to accommodate ethanol in a dilute mixture.
Owner's manuals describe acceptable ethanol concentration levels.
Ethanol is a very misunderstood alternative fuel. Many technicians and
pseudo automotive buffs equate ethanol with methanol. They also relate
"horror stories" of how alcohol based fuels have ruined automotive fuel
systems. In truth, ethanol, in low concentrations, will not harm late
model vehicles. The only possible harm could come if a highly
concentrated mixture was induced into the system. Methanol, however, is
highly corrosive even in moderate concentrations. Another possible side
effect of changing over to ethanol blended fuels is the possible
detergent action on an older vehicle's fuel tank and lines. A system
contaminated with fuel sludge and/or water will be cleaned by the
ethanol. In an extreme case, fuel filters could repeatedly clog until the
system would be entirely cleansed of these contaminants.
REFERENCES:
New Transportation Fuels, American Petroleum Institute, Washington, D.C.1991. Special Issue Department, Public Affairs Group, _______.
The Automobile. Earth Day, 1990, Fact Sheet, Stanford, CA. 1990.
Gordon, Deborah, Steering A New Course: Transportation, Energy, and the
Environment. A Report by the Union of Concerned Scientists, Cambridge, MA
1991.
Motor - Vehicle Fuel Efficiency and Global Warming. Union of Concerned
Scientists Briefing Paper: Cambridge, MA. 1991