Hi all,
Interesting David Suzuki column follows:
Vol. 10, No. 4
6 February 2008
Science Matters
by David Suzuki, with Faisal Moola
Fill 'er up with switchgrass
Not long ago, the question at the pump was always, "regular or unleaded?"
Today, leaded gasoline isn't even an option in most developed countries. And
with the need to drastically reduce our consumption of fossil fuels, the
question of the future just might be "switchgrass or algae?"
Of course, I'm being somewhat facetious. In their raw form you couldn't run
your car on either. However both organisms have the potential to be made into
biofuels such as ethanol or biodiesel. And that, if done in a careful and
sustainable way, could greatly reduce the greenhouse gas emissions that cause
global warming.
However, in spite of some of the hoopla about biofuels, there are still many
obstacles to overcome. Yes, you can already get ethanol mixed with your
gasoline or biodiesel mixed with your regular diesel in many North American
cities. In fact, in countries like Brazil, gasoline is always blended with at
least 20 per cent ethanol and you can easily get 100 per cent ethanol for your
car. So far, so good. But these biofuels have problems too.
As I discussed in a column last fall, a widespread adoption of biofuels, such
as biodiesel and ethanol could cause serious damage to the environment and
provide few benefits if the crop used to make the fuel isn't chosen carefully.
Corn, for example, is the largest source of ethanol in the United States, but
it is a poor choice for fuel because if you do a life-cycle analysis (looking
at all the energy needed to make the stuff), the energy obtained from
corn-based ethanol is only marginally better or worse than the energy you get
out of it. Plus, corn is heavily reliant on fertilizers and pesticides.
Thankfully, there are plenty of other options. Canola does better in a
lifecycle analysis, for example, and sugar cane - which is where Brazil gets
its ethanol from - better still. However, sugar cane requires a hot climate and
there are concerns that displacing Brazilian subsistence farmers to grow sugar
cane will push them into slashing and burning the rainforest for cropland. So
all biofuels still have an environmental, economic or social cost. If these
fuels are to be sustainable, such costs need to be minimized.
One promising biofuel that scores well in preliminary studies is cellulosic
ethanol made from switchgrass. According to results of a recent study published
in the prestigious journal Proceedings of the National Academy of Sciences,
switchgrass grown and managed for biofuel can produce 500 per cent more
renewable energy than the energy it needs to be grown and processed.
For the study, researchers conducted field trials (the first for switchgrass)
over five years on 10 farms in the Midwestern United States. Looking at all the
production and management information from each farm, they were able to
estimate greenhouse gas emissions and net energy inputs to outputs. After a
life-cycle analysis, the results were very positive: greenhouse gas emissions
from switchgrass-derived cellulosic ethanol on the farms were 94 per cent lower
than if the energy had come from gasoline.
Another benefit of switchgrass, and part of the reason for its success in the
trials, is that it is a native prairie grass that grows on agriculturally
marginal land. This means that fewer chemical inputs are required to maintain
the crop and makes it less likely that growing large crops of switchgrass would
take away land that would otherwise be used for food production.
Biofuels have the potential to help reduce pollution and global warming
emissions, as well as the regional conflicts caused by our dependence on fossil
fuels. But choosing the right fuel crop for the right geographic area is
critical, as is making sure that all social and environmental factors are
considered. If we can overcome those hurdles, you can look for more biofuels
made from waste wood, used vegetable oil, and yes, even algae, at our pumps in
the future.
Take David Suzuki's Nature Challenge and learn more at www.davidsuzuki.org.
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