Gas from Grass
Ethanol production has sparked a hot debate
among environmental scientists and farmers. It's
true that ethanol burns cleaner than
conventional gasoline, emitting less carbon
dioxide and benzene into the air. It's also true
that corn and other plants used as ethanol
feedstock absorb atmospheric carbon dioxide in
their growth stage, greatly reducing carbon
dioxide levels over the entire fuel life cycle
[source:
U.S. Department of Energy]. But the
dependence on corn as an ethanol feedstock in
the United States has created problems, both
with the food supply and fossil fuel
consumption.
Humans directly consume only two out of every
10 ears of corn grown in the U.S., either as
fresh corn, corn syrup, corn meal or other corn
derivatives. The other eight ears traditionally
became feed for livestock like cows, pigs and
chickens, but that was before the ethanol boom.
Thanks in part to government subsidies, more
corn was grown for ethanol from August 2011 to
July 2012 than for livestock [source:
Lott]. That was a first in American farming
history. In a year when drought conditions
lowered total corn yield, critics blame ethanol
production for even higher food prices [source:
McDonald].
Corn and soybeans, another popular ethanol
feedstock, also require large amounts of fossil
fuel energy to produce. Tractors burn up their
fair share of
fossil fuels, but the biggest culprit is
synthetic fertilizer. Nitrogen fertilizer, for
example, requires 1.5 tons (1360.7 kilograms) of
fossil fuels -- usually coal and natural gas --
to produce one ton (907.18 kilograms) of
nitrogen [source:
Oliver].
Thankfully, researchers and farmers have
identified a number of non-food sources of
ethanol feedstock that can grow just about
anywhere without any additional fertilizers. In
the U.S., the best options are tall grasses like
switchgrass and miscanthus. These grasses grow
more than 10 feet (3.05 meters) high in thick
strands, and they're perennials,
which means they can be harvested in the fall
and grow back in the spring. Fewer plantings
means less fossil fuel burnt in the tractor. In
tropical climates like Hawaii and Southeast
Asia, researchers are experimenting with bana
grass, sweet sorghum and an inedible oil nut
called jatropha [source:
Smith].
These grasses can grow in poor soils with
little irrigation or fertilizer input. And they
pack a biomass punch. According to tests by the
Argonne National Laboratory, switchgrass has an
energy output ratio of 1 to 10, meaning every
unit of energy consumed to produce switchgrass
ethanol results in 10 units of available energy.
Corn ethanol, on the other hand, produces only
1.36 units of energy output for every unit of
energy input [source:
Wang].
The switch to "grassoline"
is ingenious because it doesn't compete with
existing food crops, can be grown on marginal
land, doesn't rely on synthetic fertilizers and
produces a far greater amount of energy per unit
of biomass. That helps to keep food prices down,
fuel costs down, and pollution levels low -- a
win for everyone!
Fill 'Er Up with Pond Scum
Starting as early as the 1950s,
alternative energy researchers have had
their eyes on algae [source:
Keune]. Mature
algae -- that slimy green goo also known
as pond scum -- are rich
with lipids, a type of
molecule that includes fats. Those lipids
can be extracted and turned into biodiesel.
The remaining dry algal matter can be
fermented and processed into ethanol
[source:
Haag]. Two fuels for the price of one!
Algae need three things to grow: water,
sunlight and carbon dioxide. Otherwise,
they're not very picky. Algae can grow in
salt or fresh water, even in wastewater from
sewage treatment facilities or dairy farms.
The key to growing great algae is lots of
available carbon dioxide in the water.
Naturally occurring ponds don't usually
contain enough carbon dioxide to maintain
healthy growth rates, but researchers have
figured out an ingenious solution:
redirecting carbon dioxideemissions from
coal-fired power plants into the algal
ponds. Not only does algal biodiesel burn
cleaner than conventional gas, but it eats
up coal emissions.
Under the right conditions, algal
colonies can double in mass overnight, and
an impressive 50 percent of that mass is
oil. To compare, the second best
oil-producing plant is the oil-palm tree,
which is only 20 percent oil [source:
Haag]. The U.S. government has invested
tens of millions of dollars to help bring
algal fuels to market, but current
production methods still cost a prohibitive
$8 a gallon at the pump. The hope is that
with further investment by the United States
military and energy giants like Exxon Mobil
and Chevron, algae will become both an
environmental and economic
superfuel.
Flying High (And Cheap) With Biofuels
The U.S. military is the world's largest
gas guzzler, buying and burning through more
than 8 billion gallons of fuel per year
[source:
National Energy Technology Laboratory].
Jet fuel is a particularly expensive
resource and the military is always looking
for ways to cut the cost of maintaining its
airborne fleet. One exciting possibility is
the increased use of
biofuels in the jet fuel mix.
During
World War II, German scientists
developed a process of making liquid fuel
from coal. Known as Fischer-Tropsch (F-T)
fuels, they can be made from coal, natural
gas or biomass [source:
Ryan]. The U.S. military is particularly
interested in biomass as a fuel source
because it decreases reliance on foreign
oil, thereby increasing energy security in
the event of an international crisis.
But the focus on biofuels is about more
than energy security or "greening up" the
military. It's also a smart business
decision. In a 2012 press conference,
Assistant Secretary of the Air Force Terry
Yonkers explained that military testing
shows that biofuels burn cleaner and cooler
in jet engines. That increases overall
engine life by a factor of ten, greatly
reducing repair and replacement costs
[source:
Ryan].
Another benefit of biofuels is that they
have less mass than fossil fuels, meaning
that bio-based jet fuel weighs less than
conventional jet fuel. This could have big
implications for commercial aircraft, where
the weight of the airplane is reflected in
ticket prices. A greener, more secure
military plus cheaper flights to Cleveland?
Another biofuel win for everyone.
Putting the "Eco" in Economic Impact
Slightly less than half of the world's
population lives in rural areas, but they
make up 70 percent of the world's poor
[source:
The World Bank]. For decades, the plight
of poor rural farmers has been exacerbated
by low food prices. The global market for
food staples like wheat and corn was
dominated by the United States and Europe,
where government subsidies kept prices
unnaturally low. A country like Mexico,
which used to feed itself on its own corn,
now imports 12 million tons (10.88 billion
kilograms) a year from the U.S., where corn
prices are lower [source:
Rodriguez].
Oil is the same. Of the world's 47
poorest countries, 38 import more oil than
they produce domestically and 25 of those 38
countries import every drop of oil they
consume [source:
Worldwatch Institute]. With an
overreliance on both foreign-grown food and
foreign oil, the rural poor in developing
nations are dangerously exposed to price
spikes. When food and oil prices go up, as
they have dramatically in recent years, they
suffer the consequences without any of the
benefits.
Homegrown
biofuels have the potential to reverse
the poverty rate in developing nations.
Think of the hundreds of millions of farmers
who can barely subsist on the market price
of their food crops. By growing
ethanol and biodiesel feedstock, they
will receive a fair price for a hot
commodity. At the same time, energy
entrepreneurs in their same country can
build the biofuels infrastructure to
generate homegrown energy. A 2010 report
from the International Food Policy Research
Institute concluded that increased biofuel
production in countries like Tanzania and
Mozambique could decrease the poverty rate
in those countries by 5 percent by 2020
[source:
Arndt et al].
Lower energy costs, better wages and
reduced rural poverty -- another biofuel win
for everyone.
Garbage Cars
The average American generates 4.43
pounds (2 kilograms) of garbage every day.
As a nation, we tossed out roughly 250
million tons (227 billion kilograms) of
trash in 2010, from food waste to
construction debris to outdated iPhones
[source:
EPA]. What if we could divert all of
that waste from the landfill and convert it
into usable energy? Doc Brown did it in
"Back to the Future" -- feeding his
DeLorean's cold fusion reactor with banana
peels and beer -- and thanks to a process
called gasification, so can
we.
Gasification uses heat and pressure to
crack the molecular compounds of almost any
carbon-based material into a substance
called synthetic gas, or
syngas. All around the
world, cities are replacing their landfills
with gasification plants. In Edmonton, the
capital of the Canadian province of Alberta,
the city is building a facility that will
convert 100,000 tons (90 million kilograms)
of municipal waste into 9.5 million gallons
(35,961 cubic liters) of biofuel annually
[source:
City of Edmonton].
Inside the Edmonton facility, scheduled
to open in 2013, municipal waste (garbage)
will be sorted by type: compostable organic
waste, recyclable material and waste
products that would normally be sent to the
landfill. Those leftovers will be
shredded into a fine pulp and fed into the
gasifier, where incredible heat — not fire —
liquefies the material into carbon monoxide
(CO) and hydrogen (H2), the major elements
of syngas. The syngas will then pass through
a catalytic converter where the molecules
are rearranged to form ethanol, a standard
biofuel, and methanol [source:
Edmonton Biofuels].
From California to Finland, more of these
plants are popping up to process wood-based
waste and plain old garbage. Could Doc's
DeLorean be far off? Well, yes. But when
millions of tons of trash become millions of
gallons of gas, that's another biofuel win
for everyone.
For lots more information on biofuel,
grassoline, garbage cars and other
alternative fuels, explore the related links
on the next page.
© 1998-2013 HowStuffWorks, Inc
http://auto.howstuffworks.com/fuel-efficiency/biofuels/5-responsibly-produced-biofuel.htm#page=3