Environmental Engineering Reference
In-Depth Information
manufacturers make
cars that can run on any
mix of ethanol and gasoline; sensors determine the blend
of fuel in the tank and feed this information to the engine-
control computer which makes the adjustment required to
use whatever blend it is. Most of the cars produced in
Brazil now are these
“
flex-fuel
”
flex-fuel vehicles. Ethanol makes up
about
% of total fuel used
for all vehicles including heavy trucks.
The ratio of energy contained in sugarcane-based etha-
nol to the energy required to produce it is roughly
% of automobile fuel and
,
far more favorable than US corn ethanol. Ethanol yield
per acre is about
-to-
times the
yield per acre of US corn ethanol. Greenhouse gas emis-
sions are only about
gallons, approximately
.
% of those of gasoline.
% of its arable land for cane growing,
almost all of it far from the rain forest. This is an import-
ant point for greenhouse gas emissions. Forests sequester
carbon dioxide and store a lot of it underground as well as
in the trees themselves. Conversion of forest land to use
for any annual crop releases large amounts of greenhouse
gases which continue over a long time. Changes in land
use already account for
Brazil uses
% of all world greenhouse gas
emissions, but this does not seem to be a problem yet for
ethanol in Brazil.
The bottom line is that Brazilian ethanol is sustainable
and not subsidized at the current level of blends with
gasoline. US corn ethanol is not sustainable and heavily
subsidized (
cents per gallon for a subsidy, plus the
% tariff to keep out imported ethanol). The mandated
amount of alcohol required for blending for gasoline by
US law in the year
.
is not doable without some new
source which might even come from Brazilian sugarcane.
