An evaluation of cassava as a biofuel crop focusing on crop yield, ethanol conversion rate, and water, soil and atmospheric contamination by Sarah Thompson An Undergraduate Thesis Submitted in Partial Fulfillment for the Requirement of Bachelor of Arts In Environmental Science: Policy Analysis Carthage College Kenosha, WI May, 2012
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An evaluation of cassava as a biofuel crop focusing on crop yield, ethanol
conversion rate, and water, soil and atmospheric contamination
by
Sarah Thompson
An Undergraduate Thesis
Submitted in Partial Fulfillment for the Requirement of
Bachelor of Arts
In
Environmental Science: Policy Analysis
Carthage College
Kenosha, WI
May, 2012
An evaluation of cassava as a biofuel crop focusing on crop yield, ethanol
conversion rate, and water, soil and atmospheric contamination
Sarah Thompson
May 12, 2012
____________________
Abstract:
An evaluation of biofuels is imperative to relieve human dependence on fossil fuels as
well as to reduce negative impacts on the environment that result from the burning
conventional fuels. Due to the exponentially growing global population, demands for fuel are
constantly on the rise. Biofuels are seemingly the perfect alternative to conventional fuels;
however it is important that their use is not creating more substantial issues than the ones they
are attempting to solve. Cassava is an energy crop that is becoming increasingly popular,
especially in China who purchased 98% of Nigeria’s cassava starch production in 2010 to
convert to ethanol. Cassava contains potentially toxic levels of cyanogenic glycosides which,
when disturbed, produce the toxic chemical hydrogen cyanide (HCN). Due to this toxic
release, I hypothesize that cassava production on a large scale for the purpose of
manufacturing biofuels will have a more so negative effect on both human and environmental
health with regard water, soil, and the atmosphere. This assessment was conducted by
compiling previous data from online sources and scholarly articles. The results support the
hypothesis that cassava production and processing for biofuel use is negatively impacting
environmental health however, further research is required to accurately address cassava as a
biofuel as production increases.
____________________
Introduction
The global human population has recently exceeded 7 billion. Of those alive today and
the 385 thousand more that will be here tomorrow (Bureau, 2010) there are countless opinions
about what should be done regarding everything from local politics to global environmental
affairs. The environment like all global systems is complex and in order to approach issues of
great complexity it is important to maintain a non biased ear by weighing all the options
presented globally to combat environmental degradation. Fuel is an ongoing source of global
environmental concern both because of high dependence levels and resulting negative
environmental impacts. Some impacts include air and water pollution as well as increases in
global temperature. U.S. society and industry rely on oil reserves to carry on life as we know it.
Following the events of September 11th the U.S. has put a halt on a majority of oil
imports from the Middle East. Because of this the U.S., as well as many other countries who
strive for independence in terms of energy, is turning to a greener option: biofuel. Typical food
crop biofuels are produced from the starchy portion of energy crops. One energy crop that
recently entered the biofuel market on a major scale is cassava. Many characteristics make it an
ideal energy crop however it also has a toxic chemical defense that classifies it an
environmental nuisance. If global goals include slowing environmental degradation and
reducing the population’s carbon imprint, investments in “greener” fuels are essential.
Cellulosic and food crop biofuels are a greener option than petroleum based fuels. The
political, biological, and chemical aspects of biofuels and an in depth exploration of cassava as
an energy crop will now be further discussed.
Literature Review
The United States alone consumes close to 20 million barrels of petroleum on average
per day. About 75% of this is used for transportation. Globally petroleum is consumed at a rate
of over 85 million barrels per day (Energy, 2011). Statistical evidence shows that the United
States, which in 2010 was home to only 4% of the global population, was responsible for 25%
of the total daily global petroleum consumption (Bureau, 2010). Based on statistical data there
is no denying that the United State’s dependence on petroleum fuel is substantially higher
than a majority of the world. The exponentially growing global human population
accompanied with development of underdeveloped nations means oil demands will continue
to soar; that is unless we adapt to alternative energy options or consume in a more sustainable
fashion.
There are two fundamental political viewpoints regarding this challenge to meet global
future fuel needs. The first is that of the “survivalists”. Survivalists like Lester Brown preach
that if we do not learn to use our non renewable resources sustainably (petroleum) while
strongly pursuing fuel alternatives, it is not only fuel shortages that we will be facing but also
major consequences resulting from harmful CO₂ emissions (global climate change) which may
lead to an increase in severe weather as well as global water shortages. Survivalists believe
that earth has a limited amount of resources and that humans need to reduce their
environmental imprint substantially in order to prevent population crash and further
deterioration of the globe (Dryzek, 2005).
On the opposite side of the spectrum are the “prometheans” who believe in the power
of technology to always overcome environmental challenges. In the face of “fuel shortages”,
they do not believe there is a need to worry because “fuel is only sought after when it is
needed, therefore we have no idea how much of it we have. We have always discovered more
fuel in the past, and even if we do run out, technology will adapt to create new fuels” (Dryzek,
2005).
Though their viewpoints differ greatly both discourses agree on the need for alternative
fuel sources (though the level of necessity may vary). Over the last couple of decades there has
been an enormous push toward biofuel development. Biofuels are fuels produced from
biological sources, like plant biomass, that are renewable. Biofuels can be produced from any
starchy plant material. Most biofuels are currently produced from food crops; however current
methods leave the majority of plant biomass behind as byproducts. An alternative is cellulosic
biofuel which converts cellulose into ethanol. This method can use any plant biomass as raw
products for ethanol production.
Why the push for alternatives
Though the prometheans believe that planet earth has no limits there are a great
number of individuals who see recent events as a sign that we are depleting resources at such
a highly unsustainable rate that if we do not change our ways we will suffer in a world lacking
it’s essential fuel source (Dryzek, 2005). Though through technology we have created great
amounts of renewable energy (solar, wind, hydro, and biofuels), none are currently enough to
completely stop using fossil fuel based energy. We must loosen our grip on oil and do so
before it is too late.
In America, the middle and lower classes have taken the hardest hit to their wallets. On
average, the price of gas in the United States has almost doubled since 2006 (Historical Price
Charts, 2011). Though prices tend to fluctuate some areas have seen prices soar to over $5.00 a
gallon. An assessment of U.S. average gas prices over the last 6 years show that since the
significant spike and decline in 2008, gas prices have been on an overall incline (Figure 1).
Figure 1: Average gas prices in the United States since 2006 to the present.
The 2008 spike was a result of natural disasters and political events that
indirectly caused an increase in the global oil market. As a result of such
events inflation took its course leading to price increases that peaked mid
2008. Following this peak, prices rather than global events became the fuel
selling determinant. High prices led to a recession that resulted in low
confidence in consumers and a decrease in demand, triggering the huge
drop off in gas prices seen in the figure.
Aside from price, there are other concerns that are common to many U.S. citizens and
other individuals worldwide. Are oil reserves really diminishing? Scientists can only
hypothesize but many agree that the global consumption of fossil fuels is far more demanding
than the earth can sustain for future generations. Since the BP Gulf oil spill the public has
become more aware of the depths we are going to in order to keep our national oil reserves
high. This accidental spill caused by high risk extraction has left hundreds of miles of beaches
disrupted, and has caused over 2,000 square miles of Louisiana’s wetlands to disappear (Golf
of Mexico Oil Spill (2010), 2011).
Repercussions like those of the BP oil spill have not had a significant enough impact for
oil companies to avoid similar high risk
projects. One currently of great political
conflict is the expansion of the Keystone XL
Pipeline. This venture will extend the current
pipeline an additional 1,700 miles through
U.S. soils (Figure 2). The XL pipeline will put
water and soil at a high risk for damaging
and undetectable potential leaks. Though the
pipeline’s design team has changed its
original coarse proposal to avoid some
environmentally sensitive areas, there is no
stopping this expansion project (Frosch,
2011). Our dependence on oil may prevail,
until the oil preserves run dry or prices soar to unaffordable heights.
Figure 2 (above): Original proposed rout of the Keystone XL Pipeline expansion.
Restructuring our nation
Though future oil projects are underway and more will continue to be proposed, there
is hope for a more sustainable future. The environmental discourse, “ecological
modernization” can be applied to support the production of biofuels. This discourse views
environmental problems as structural, and believes that the solving of such issues requires
economic reorganization of nations (Dryzek, 2005). Money is a key player both for
consumption and production of fuel. If governments can make greener fuels more cost
beneficial for business, then biofuels will be more embraced.
Thailand in particular has conducted multiple economic analyses regarding the
implementation of biofuel production into their culture. A study by David Bell (2011) found
that though pursuing alternative fuels would initially be more costly than importing
petroleum as they currently do, the Thai economy would benefit greatly because self
production would keep all fuel profits within their border (Bell, 2011). Economic assessments
are complex because they require views from all angles that are often difficult to see. When
considering biofuels versus fossil fuels it is not only production costs and sales that matter;
pollution, waste management, maintenance costs, and environmental impacts are all
important. As ecological modernization would suggest, “It pays to be green” (Dryzek, 2005).
Pollution cleanup, water treatment, and soil remediation are far more costly than pursuing
cleaner, greener practices.
Why Biofuels?
Besides being renewable, biofuels are more environmentally friendly than their fossil
fuel based counterparts because they reduce carbon dioxide emissions that lead to global
climate change. Climate change is a major global concern. This claim is not exclusively
supported, however when facing issues of such magnitude it is wise to implement
precautionary practices rather than continue to accelerate when possibly approaching a brick
wall (Dryzek, 2005). Scientists have found that the burning of fossil fuels results in major
carbon dioxide emissions that, due to their immense sum are slowly deteriorating parts of
earth’s ozone layer. Biofuels offer the advantage of being carbon dioxide neutral over their
production lifecycle; therefore biofuel consumption in combination with or in replacement of
fossil fuels would potentially reduce environmental atmospheric pollution (Wu, 2010).
Biofuel production would decrease fossil fuel imports while supporting the economy of
producing nations. Especially in developing nations, an increase in production would also
increase employment and rural development. Unfortunately, like all political issues, biofuel
implementation is complex; for every positive argument there is a counterargument.
Why not?
In kitchen cabinets throughout America (and much of the world) almost every food
label includes the ingredient corn (in one form or another). Whether aware of it or not, corn
products are a significant portion of our diet. Corn is a source of energy as well as food for
both humans and livestock. Statistics show that in America, four out of every ten ears of corn
are put towards ethanol production. That is 40% of our total corn production. Another 40% is
allocated to feed livestock while the remaining 20% is food for the human population (Rattner,
2011). This is the basis of the food versus fuel controversy. Our exponentially growing
population (Figure 3) is putting increasing pressure on agriculture to meet food demands for
both humans and livestock. As demands for food, fuel, exports, and livestock needs continue
to increase, pressures on farmers will also continue to rise. (Rattner, 2011). Due to the limited
amount of crop land available; any land used to grow energy crops is land that cannot be used
for food production. Ethanol production has and will continue to increase as the push for
alternative fuels becomes more intense (Figure 4).
Figure 3: This figure shows the global human population growth curve.
The human population is growing at an exponential rate and currently
totals over 7 billion people.
Figure 4: This figure shows the amount of ethanol the U.S. has produced in
millions of gallons from 1980 to 2010 (RFA, 2011).
Another matter of significant concern is water. Both food and energy crops alike require
large amounts of water for successful growth. For areas like the Midwest in the United States
water is not a concern because precipitation provides necessary irrigation. However, the
American west has reason to fear. The Colorado River is being used to irrigate over 4 million
acres of agricultural fields in Arizona and California. In 2006 about $1 billion dollars was spent
irrigating those western states (Pearce, 2006). The intense irrigation of dessert regions is
causing the depletion of underground aquifers as well as rivers to run dry. For example, the
once mighty Colorado no longer reaches the sea. Though not dry, the river is substantially
lower than in the past (Pearce, 2006). Prometheans may believe there isn’t a need to panic, but
if we do not pump the brakes on water use in the near future, that brick wall may be closer