Environmental Engineering Reference
In-Depth Information
Advanced biofuels come from sources other than corn-
starch, and they have to meet a goal of no less than a
%
reduction of greenhouse gas emissions (EPA can reduce
the requirement to
%). Cellulosic ethanol will be dis-
cussed later but it has to have a
% greenhouse gas
reduction (
% is its minimum). Cellulosic ethanol is
not now available at commercial scale. There are demon-
stration facilities struggling to come up with a commer-
cially viable production system.
Ethanol production in the United States gets a tax
credit of
cents per gallon. Foreign ethanol has an
import duty of
% levied on it, mostly to keep Brazilian
ethanol out of the United States. The Brazilian program
is discussed in more detail below, but it is much more
effective in greenhouse gas reduction and in reducing
energy use than the corn-based material required in the
United States today.
When all the energy inputs in making corn ethanol are
included, starting at the fertilizer factory and ending at
the ethanol factory
.
s loading dock, greenhouse gas emis-
sions range from a few percent worse than those of gas-
oline to about
'
% better on an equal-energy content
basis (remember it takes
.
gallons of ethanol to get you
as far as
gallon of gasoline will). Energy inputs in
making ethanol are typically about
% of the energy
content of the ethanol produced. The greenhouse gas
reduction depends on the energy sources used in the
fertilizer-through-factory chain. The numbers above are
based on the average mix of fossil, renewable, and nuclear
energy used in the United States today. In the Paci
c
Northwest, for example, the main source of electricity is
hydroelectric, and the greenhouse gas advantage would be
