|
Analysis: Ethanol's Potential: Looking Beyond Corn
Environment News Service, USA
http://www.ens-newswire.com
July 1, 2005
By Danielle Murray
WASHINGTON, DC, July 1, 2005 (ENS) - At the fuel pumps in São Paulo,
customers have a choice: gas or alcohol? Since the mid-1970s, Brazil has
worked to replace imported gasoline with ethanol, an alcohol distilled
from locally grown sugarcane. Today ethanol accounts for 40 percent of
the fuel sold in Brazil.
Ethanol can be produced from a wide variety of plant-based feedstocks,
most commonly grain or sugar crops. It is then blended with gasoline as
an oxygenate or fuel extender for use in gasoline vehicles, or it can
be used alone in "flexible-fuel vehicles" that run on any blend
of ethanol and gasoline.
Brazil led world ethanol production in 2004, distilling four billion
gallons (15 billion liters). The United States is rapidly catching up,
however, producing 3.5 billion gallons last year, almost exclusively from
corn. China's wheat and corn rich provinces produced nearly one billion
gallons of ethanol, and India turned out 500 million gallons made from
sugarcane. France, the front-runner in the European Union’s attempt
to boost ethanol use, produced over 200 million gallons from sugar beets
and wheat.
In all, the world produced enough ethanol to displace roughly two percent
of total gasoline consumption.
Efforts to substitute alternative fuels for petroleum are gaining attention
in a world threatened by climate change, rural economic decline, and instability
in major oil-producing countries. Biofuel crops take in carbon dioxide
from the atmosphere while they are growing, offsetting the greenhouse
gases released when the fuel is subsequently burned. Replacing petroleum
with biofuel can reduce air pollution, including emissions of fine particulates
and carbon monoxide.
Biofuel production also can improve rural economies by creating new jobs
and raising farm incomes. As a locally produced, renewable fuel, ethanol
has the potential to diversify energy portfolios, lower dependence on
foreign oil, and improve trade balances in oil-importing nations.
Although ethanol’s popularity is growing, today’s inefficient
production methods and conversion technologies mean that this fuel will
only produce modest environmental and economic benefits and could impinge
on international food security.
The largest obstacle to biofuel production is land availability. Expanding
cropland for energy production will likely worsen the already intense
competition for land between agriculture, forests, and urban sprawl. With
temperatures rising and water tables falling worldwide, global food supply
and demand are precariously balanced.
World grain reserves are near all-time lows, and there is little idle
cropland to be brought back into cultivation. Shifting food crops to fuel
production could further tighten food supplies and raise prices, pitting
affluent automobile owners against low-income food consumers.
Placing greater emphasis on land efficiency—that is, maximizing
energy yield per acre—will be essential to making the best use of
ethanol. Though corn has broad political support as a feedstock in the
United States, it is one of the least efficient sources of ethanol. For
example, ethanol yields per acre for French sugar beets and Brazilian
sugarcane are roughly double those for American corn.
Also important is the amount of energy used to produce ethanol. Growing,
transporting, and distilling corn to make a gallon of ethanol uses almost
as much energy as is contained in the ethanol itself. Sugar beets are
a better source, producing nearly two units of energy for every unit used
in production.
Sugarcane, though, is by far the most efficient of the current feedstocks
— yielding eight times as much energy as is needed to produce the
ethanol. Given their positive energy balances and higher yields, it makes
more sense to produce ethanol from sugar crops than from grains. Ethanol
could quickly take off in sugarcane-producing tropical countries, which
have the advantage of year-round growing seasons, large labor supplies,
and low production costs. As fuel demand rises in these developing nations,
biofuel production could check oil imports while bolstering rural economies.
Brazil, for example, could produce enough ethanol to meet total domestic
fuel demand by increasing the area used to grow sugarcane for alcohol
from 6.6 million acres to 13.8 million acres (5.6 million hectares) or
by shifting all current sugarcane acreage to ethanol production. Unfortunately,
new fields may cut further into already shrinking rainforests, making
them a serious environmental liability.
If ethanol is to become a major part of the world fuel supply without
competing with food and forests, its primary source will not be grains
or even sugar crops; it will be more abundant and land efficient cellulosic
feedstocks, such as agricultural and forest residues, grasses, and fast-growing
trees.
Promising new technologies are being developed that use enzymes to break
down cellulose and release the plants’ sugars for fermentation into
ethanol. A demonstration plant using this technology opened in Canada
last year, and large-scale production is expected to be commercially viable
by 2015.
Agricultural residues, such as corn stalks, wheat straw, and rice stalks,
are normally left on the field, plowed under, or burned. Collecting just
a third of these for biofuel production would allow farmers to reap a
sort of second harvest, increasing farm income while leaving enough organic
matter to maintain soil health and prevent erosion. The agricultural residues
that could be harvested sustainably in the United States today, for example,
could yield 14.5 billion gallons of ethanol — four times the current
output—with no additional land demands.
"Energy crops," such as hardy grasses and fast growing trees,
have higher ethanol yields and better energy balances than conventional
starch crops.
One likely candidate is switchgrass, a tall perennial grass used by farmers
to protect land from erosion. It requires minimal irrigation, fertilizer,
or herbicides but yields 2-3 times more ethanol per acre than corn does.
Such crops could potentially be harvested on marginal land, avoiding the
conversion of healthy cropland or forests to energy-crop production.
Still, with world energy demands rising, biofuels will meet only a fraction
of fuel needs unless there are substantial improvements in vehicle fuel
economy.
Fortunately, the technologies required are available and affordable.
Shifting vehicle production to gas-electric hybrids, like those on the
market today, and reducing weight and drag would decrease fuel use several
fold.
Adding an extra battery and plug-in capability to hybrid vehicles would
allow short trips to be made using only electric power – preferably
produced from wind – decreasing fuel demand to levels that could
be met with ethanol alone.
Increasing the role of ethanol in meeting fuel demand will require ongoing
research and development to improve biomass-ethanol conversion technologies,
along with consistent legislative support for biofuel production and greater
fuel efficiency in the automotive industry.
Shifting government energy subsidies, such as from oil exploration to
biofuel development, is a clear choice as new oil fields prove increasingly
elusive. With improved vehicle fuel economy and the use of more efficient
cellulosic feedstocks, biofuel has the potential to supply a substantial
share of the world’s automotive fuel.
For more examples of ethanol production by country, see data at: http://earth-policy.org/Updates/2005/Update49_data.htm
{Published in cooperation with the Earth Policy Institute, online at:
http://earth-policy.org}
Questions or Comments: editor@ens-news.com
http://www.ens-newswire.com/ens/jul2005/2005-07-01-02.asp
|
