What is ethanol?
Ethanol is a clean-burning, high-octane fuel that is
produced from renewable sources.
At its most basic, ethanol is grain alcohol, produced
from crops such as corn.
Since pure 100% ethanol is not generally used as a
motor fuel, a percentage of ethanol is combined with
unleaded gasoline, to form E10 and E85
E10: 10% ethanol and 90% unleaded gasoline, is
approved for use in any US vehicle
E85: 85% ethanol and 15% unleaded gasoline, is an
alternative fuel for use in flexible fuel vehicles (FFVs).
How is it made?
Ethanol production is based on two major
(i) Chemical Synthesis
Catalytic hydrolysis of Ethylene derived from
CH2 = CH2 + H2O
Fermentation sources have four categories of feed
Sugar containing materials, Carbohydrates,
Lignocel-Lulosics and urban and industrial wastes.
The conversion of cellulose, starch and sugars to ethanol
(C2H5OH) is :
(C6H10O5)n + nH2O
2C2H5OH + 2CO2
The conventional batch process for production of Ethanol
from molasses was developed in days of inexpensive
The concept of continuous tower fermentation was
developed for the brewing industry in Britain in the 1960
Some factors limit the use of tower fomenters, like for
e.g. as the feed sugar concentration is increased (15-20
%) to raise the Ethanol concentration, it increases the
yeast floc washout in tower with an increase in the
Minimizing the cost of
preparation of ethanol
Significant improvements in ethanol production technology
are necessary in order to reduce production costs.
A balance must be struck among the three principal goals
of ethanol fermentation.
(i) High substrate utilization
(ii) High ethanol productivity
(iii) High ethanol concentration in product stream to the
In batch fermentations, complete sugar consumption
means long fermentation times and, hence low average
ethanol productivity by volume with continuous stirred tank
fermenters, it is common to have maximum ethanol
productivity at a dilution rate as near to maximum as
possible, leaving some residual sugar in fermenter effluent.
Although CO2 is released during ethanol production and combustion,
it is recaptured as a nutrient to the crops that are used in its
Unlike fossil fuel combustion, which unlocks carbon that has been
stored for millions of years, use of ethanol results in comparatively
lower increases to the carbon cycle.
Ethanol also degrades quickly in water and, therefore, poses a
smaller risk to the environment than an oil or gasoline spill.
Research studies from a variety of sources have found ethanol to
have a positive net energy balance. The most recent, by the U.S.
Department of Agriculture, shows that ethanol provides an average
net energy gain of at least 77%.
It takes less than 35,000 BTUs of energy to turn corn into ethanol,
while the ethanol offers at least 77,000 BTUs of energy. Thus
ethanol has a positive energy balance—meaning the ethanol yields
more energy than it takes to produce it.
Impact on air quality
Using ethanol-blended fuel has a positive impact on air
quality. By adding oxygen to the combustion process
which reduces exhaust emissions—resulting in a
cleaner fuel for cleaner air.
Ethanol reduces the emissions of carbon monoxide,
VOX, and toxic air emissions:
Since ethanol is an alcohol based product, it does not produce
hydrocarbons when being burned or during evaporation thus
decreasing the rate of ground level ozone formation.
Ethanol reduces pollution through the volumetric displacement
of gasoline. The use of ethanol results in reductions in every
pollutant regulated by the EPA, including ozone, air toxins,
carbon monoxide, particulate matter, and NOX.
Impact on energy
Since it is domestically produced, ethanol helps reduce
America's dependence upon foreign sources of energy.
U.S. ethanol production provides more than 4 billion
gallons of renewable fuel for our country.
Current U.S. ethanol production capacity can reduce
gasoline imports by more than one-third and effectively
extend gasoline supplies at a time when refining
capacity is at its maximum.
According to the Energy Information Administration, the
7.5 billion gallon ethanol production level in the
recently enacted Renewable Fuels Standard could
reduce oil consumption by 80,000 barrels per day.
Impact on economy
In a 1997 study The Economic Impact of the Demand for Ethanol,
Northwestern University’s Kellogg School of Management found that:
During ethanol plant construction, approximately 370 local jobs are
During ethanol plant operation, up to 4,000 local jobs are created.
Ethanol plant construction creates $60 million to $130 million in additional
Ethanol plant operation creates $47 million to $100 million in additional
American-made, renewable ethanol directly displaces crude oil we would
need to import, offering our country critically needed independence and
security from foreign sources of energy.
The U.S. Department of Agriculture has concluded that a 100 million
gallon ethanol facility could create 2,250 local jobs for a single
community. Ethanol production creates domestic markets for corn and
adds 4-6 cents a bushel for each 100 million bushels used. Better
prices mean less reliance on government subsidy programs not to
mention higher income and greater independence for farmers.
Impact on auto industry
Ethanol could be the alternative fuel source that
catapults sales of American auto manufacturers.
GM and Ford are looking for environmental fixes that are
quicker and cheaper than the more costly hybrids and
futuristic fuel cells. Both companies started promoting
flexible-fuel vehicles (FFVs) aggressively this year.
General Motors tied their new campaign "Live Green, Go
Yellow.'' to not only Super Bowl Sunday but the opening
of the Winter Olympics as well.
Since only about 600 of the nation's 170,000 filling
stations sell E85, both companies
have begun programs to install
E85 pumps at more stations.
Problems with Ethanol
Odors as a public nuisance, ex: New Energy Ethanol
Plant here in South Bend
Green house gas emissions have sometimes shown
to be equivalent to those of gasoline (data is often
Environmental performance of ethanol varies greatly
depending on the production process
Costs involved with building new facilities for ethanol
New ways to maximize crop production are
Research is needed to refine the chemical processes
to separate, purify and transform biomass into usable
Problems with Ethanol
Soil erosion from increased agriculture
Conversion of forests into agricultural land—which
could lead to future environmental dilemmas…