Ethanol: Energy Panacea or False Promise?
By
Charles
Q. Choi
Special to LiveScience
Now that experts know how to convert prairie
grass and leftover lumber into ethanol,
six biorefineries scheduled for completion
within five years could help the United
States produce 130 million additional
gallons of the fuel per year.
Ethanol,
more commonly known as drinking alcohol,
is touted by some as a viable alternative
fuel for vehicles. Although
its energy content is roughly two-thirds
that of gasoline by volume, ethanol is
increasingly flowing into gas tanks, with
some one out of every eight gallons of
gas sold in the United States containing
8 to 10 percent ethanol.
Yet there is heated debate among scientists
as to whether or not ethanol really is
good for the environment.
Studies
hint, for instance, that ethanol might
guzzle more energy during its manufacture
than it provides, and that it might strain
valuable water
resources. Recent findings
also suggest fuels high in ethanol may
pose an equal or greater risk to public
health than regular gasoline.
Corn
ethanol and E85
Unlike gasoline, ethanol is made renewably,
from plants, which naturally soak up the
greenhouse
gas carbon dioxide. Ethanol
production and consumption might therefore
release less carbon dioxide into the atmosphere
than gasoline use does.
In
the United States, ethanol is most often
made from corn. Some 13 percent of the
U.S. corn crop was devoted to making ethanol
in 2004. "There are certainly benefits
with ethanol if you're a farmer in terms
of subsidies," said Stanford atmospheric
scientist Mark Jacobson.
E85,
a fuel blend of 85 percent ethanol and
15 percent gasoline, could power millions
of flexible-fuel
vehicles already on the roads and is available
at more than 1,000 service stations.
However,
the U.S. supply of ethanol is small when
compared with gasoline. The United States
currently uses roughly 140 billion gallons
of gasoline a year, more than any other
country. In contrast, the country produced
roughly 4 billion gallons of ethanol in
2004. Most stations carrying E85 are in
the Midwest, and the fuel is rare and
expensive in the rest of country.
Although
the six biorefineries scheduled for completion
by 2011 won't by themselves add great
volumes to existing U.S. ethanol production,
they are part of a strategy to demonstrate
that ethanol can be generated more cost-effectively
from the hundreds of millions of tons
of cellulose in plant scrap that would
otherwise go to waste.
"Those
could show that you can really bring the
cost of ethanol down," chemical engineer
Bruce Dale at Michigan State University
told LiveScience. "I believe we'll
demonstrate in less than five years that
we can make ethanol from cellulose for
in the neighborhood of $1.20 a gallon.
Given that gas is now about $3 a gallon
lots of places, I think people will fall
all over themselves trying to put together
supply chains to make cellulosic ethanol."
Energy
for making it
Critical points of contention over ethanol
regard whether or not creating it requires
more energy than consuming it gives off.
Although a great deal of energy that goes
into ethanol comes from the sun, much
human effort is also required when it
comes to processing raw plant material
to make ethanol. And there are the efforts
that go along with farming and pesticide
and fertilizer use.
Research
from applied economist Jason Hill at the
University of Minnesota and his colleagues
found you do get more energy from ethanol
than you put in it, some 25 percent more.
"So there is the benefit of energy
gain there," Hill said in a telephone
interview.
However,
research by chemical engineer Tad Patzek
at the University of California, Berkeley
and others finds you get less energy from
ethanol than you put in it, returning
just 26 percent of the energy invested
into making the fuel.
"Ethanol
has this false promise of satisfying our
transportation fuel needs," Patzek
said.
Also, ethanol may not cut down on carbon
dioxide emissions as much as hoped. Energy
expert Alexander Farrell at the University
of California, Berkeley and his colleagues
found that replacing gasoline with corn
ethanol would reduce a car's total greenhouse
gas emissions by only about 13 percent,
since creating ethanol in itself produces
a lot of pollution.
Dale
contended that cellulosic ethanol could
even cut total greenhouse gas emissions
by 90 percent. However, Patzek suggested
ethanol manufacture and consumption could
release more greenhouse gases into the
air than gasoline usage does.
"A
problem I see is the 'nirvana fuel syndrome,'
where there's some fuel with no problems,"
Dale said. "I would say instead,
'What problems does this fuel have compared
with others?' I would say that ethanol
as a replacement for gasoline is in almost
every measurement far superior to gasoline,
in terms of climate effects and getting
away from the screw
situation you have geopolitically
with oil."
Patzek
remained unconvinced. "Not only can
ethanol not supply all of the nation's
fuel demand, it can't even supply a small
fraction of it," he said. "That's
the bottom line."
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