162
Alternative Fuels for Transportation
tank are no longer a homogeneous blend of ethanol and gasoline, but in two
layers—gasoline on top and an ethanol layer at bottom. This phase separation causes problems in the fuel lines and in engine performance.
Gasoline distribution systems reach an equilibrium state where varnish,
gums, sludge, and water are deposited throughout the system. Ethanol
blending will disturb this equilibrium and can lead to severe handling and
performance problems. For this reason, it is essential that
• Gasoline should not be mixed with ethanol–gasoline blends in the
distribution network.
• The distribution system should be cleaned and dried before allowing ethanol–gasoline blends.
• Ethanol–gasoline and water contact must be avoided completely
(CONCAWE 1995).
5.8 Ethanol Opportunities and Challenges
Ethanol is produced from petroleum products as well as biomass sources.
Production of ethanol from renewable sources like sugar cane and next generation biomass sources like cellulosic materials reduces the exhaust emissions remarkably. Ethanol is nontoxic, less flammable than gasoline, and
less severe when spills or releases of vapor occur. It is safer than gasoline to
store, transport, and refuel. Because ethanol is water soluble and biodegradable, land and water spills are usually harmless, dispersing and decomposing quickly. Ethanol emits lower exhaust emissions in comparison to that of
gasoline except in unregulated emissions like unburned ethanol and aldehydes. Higher blends of ethanol with gasoline need some modification in the
engine fuel systems. In the fuel system noncorrosive materials are to be used
in order to avoid corrosion. Use of ethanol reduces the energy insecurity and
improves the environment also.
Unmodified ethanol cannot be used as the fuel for a conventional, unmodified CI engine because the ethanol will not ignite by compression. Either the
fuel or the engine must be modified and success has been demonstrated with
both approaches. Millions of conventional CI engines already exist. Also,
because petroleum diesel fuel is likely to be the predominant CCI engine fuel
for some years, engine manufacturers are unlikely to build many CI engines
optimized to run on ethanol. These considerations suggest that ethanol is
more likely to gain acceptance as a CI engine fuel by modifying the ethanol,
either by use of additives or by blending the ethanol with petroleum diesel
to achieve E-diesel.
There are technical barriers to the commercialization of E-diesel. More
detailed data are needed on the efficacy of the emulsifiers as a function of
Alternative Fuels for Transportation
tank are no longer a homogeneous blend of ethanol and gasoline, but in two
layers—gasoline on top and an ethanol layer at bottom. This phase separation causes problems in the fuel lines and in engine performance.
Gasoline distribution systems reach an equilibrium state where varnish,
gums, sludge, and water are deposited throughout the system. Ethanol
blending will disturb this equilibrium and can lead to severe handling and
performance problems. For this reason, it is essential that
• Gasoline should not be mixed with ethanol–gasoline blends in the
distribution network.
• The distribution system should be cleaned and dried before allowing ethanol–gasoline blends.
• Ethanol–gasoline and water contact must be avoided completely
(CONCAWE 1995).
5.8 Ethanol Opportunities and Challenges
Ethanol is produced from petroleum products as well as biomass sources.
Production of ethanol from renewable sources like sugar cane and next generation biomass sources like cellulosic materials reduces the exhaust emissions remarkably. Ethanol is nontoxic, less flammable than gasoline, and
less severe when spills or releases of vapor occur. It is safer than gasoline to
store, transport, and refuel. Because ethanol is water soluble and biodegradable, land and water spills are usually harmless, dispersing and decomposing quickly. Ethanol emits lower exhaust emissions in comparison to that of
gasoline except in unregulated emissions like unburned ethanol and aldehydes. Higher blends of ethanol with gasoline need some modification in the
engine fuel systems. In the fuel system noncorrosive materials are to be used
in order to avoid corrosion. Use of ethanol reduces the energy insecurity and
improves the environment also.
Unmodified ethanol cannot be used as the fuel for a conventional, unmodified CI engine because the ethanol will not ignite by compression. Either the
fuel or the engine must be modified and success has been demonstrated with
both approaches. Millions of conventional CI engines already exist. Also,
because petroleum diesel fuel is likely to be the predominant CCI engine fuel
for some years, engine manufacturers are unlikely to build many CI engines
optimized to run on ethanol. These considerations suggest that ethanol is
more likely to gain acceptance as a CI engine fuel by modifying the ethanol,
either by use of additives or by blending the ethanol with petroleum diesel
to achieve E-diesel.
There are technical barriers to the commercialization of E-diesel. More
detailed data are needed on the efficacy of the emulsifiers as a function of