Environmental Engineering Reference
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The material then goes through fermentation to produce
alcohol. This is basically the same process that has been
used for thousands of years to make the alcohol in wine,
beer, or whiskey [
].
I will
look
rst at today
'
s major biofuels programs
which I will call Phase-
programs, focusing on those of
the United States and Brazil. The US program now is
based on corn as the source material; the Brazilian
program is based on sugarcane. The US program is of
marginal utility while the Brazilian program is highly
effective.
A more effective system for producing biofuels is under
study. This Phase-
program is aimed at making practical
a system called cellulosic ethanol where the entire plant is
used, not just the starches and sugars. There will still be
problems with competition with food crops and land and
water use, though these are claimed to be less severe.
Phase-
is still a research and development program;
there is no commercially viable process yet that scales up
what can be done in the laboratory to what has to be done
commercially. I will also mention the possibility of a
Phase-
where the inputs are different and the outputs
can be fuels that are different from alcohol.
.
Phase-
: Ethanol from Starch
and Sugar
The effectiveness of biofuels relative to gasoline (or diesel
fuel) can be measured in three ways. One way compares
greenhouse gas emissions taking all the emissions from
the energy used in biofuel production into account.
On this basis only sugarcane-based biofuels
reduce
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