Algae Bio-fuel With the population of the world about to reach 7 ...

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Feb 20, 2013 (4 years and 7 months ago)

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Algae Bio
-
fuel


With the population of the world about to reach 7 Billion and the
reality of petroleum as a exhaustible resource becomes apparent, new
avenues for renewable energy are being quickly investigated. Mos
t of
these new sources such as
thermonuclear energy, nuclear breeders, solar
energy, wind energy, hydropower, geothermal energy, ocean currents,
ti
des and waves,

are also being researched but most of these sources
can only be used in a passive form of energy such as electricity (Lee
et.
a
l. 187)
. This means

that they cannot be directly
used for
combustion like gasoline in a vehicle. A renewable energy source that
can be synthesized into a liquid fuel for vehicles is algae. Algae was
first used by humans as a source of protein but over the

last 50 years
has been used to create a variety of fuels similar to how corn can be
used to create ethanol (Demirbas 2742). Algae have many benefits as a
source for bio
-
fuel such as high growth rate, low land and water use,
versatility in different enviro
nments, recycling
wastewater
, and high
production of oils

(Demirbas 2742)
. Along with the advantages of algae
as a bio
-
fuel come disadvantages such as
light penetration issues for
optimum growth, costly setups, high harvest cost, high costs to
synthesize f
uels and less research than needed for optimum efficiency.
All these factors come into play when looking at the world of renewable
algae bio
-
fuel.


First, the actual process and variations of algae bio
-
fuel
creation should be examined. There

are two basic

systems
: closed and
open.
A closed system involves a tank or photobioreactor that holds the
algae and the environment the algae lives in is completely controlled
(Demirbas 2740). The open system is basically created from a plastic or
cement lined pool tha
t is open to the environment. These systems tend
to be cheaper but outside factors such as contamination by foreign
algae and more difficult pH control need to be considered (Demirbas
2739). Closed systems are more expensive but factors such as pH,
nutrien
ts, and invasive species are more easily controlled. These two
systems are how the algae are raised but the harvesting and
synthesizing are more difficult.


Methods for the
harvesting of algae include concentration through
centrifugation, foam fractionatio
n, flocculation, membrane filtration
and ultrasonic separation (Demirbas 2740). All these harvesting methods
“may contribute 20
-
30% to the total cost of algae biomass,” (Demirbas
2740
-
2741). Once the algae are harvested they can be used to produce
“bioetha
nol, vegetable oils, biodiesel, bio
-
oil, bio
-
syngas, and bio
-
hydrogen,” (Demirbas 2741). This clearly shows the versatility and
importance for the

research of algae as bio
-
fuel. Especially since most
of these fuels could be used directly for combustion in
transportation
vehicles unlike
wind power, for example, which must be turned into
electricity and stored to be viable. One well researched use of algae
as fuel is in the production of biodiesel.


Bio
-
diesel has many benefits such as low sulfur content, lo
w
metal content, can be used by any vehicle that runs on a diesel engine,
higher flash point, and many sources such as algae and waste frying
oils (Vasudevan and Briggs 421
-
422).
Algae are

a viable r
esource for
bio
-
diesel because of their aquatic environme
nt, which gives better
access to water, CO
2

and nutrients than a land
-
based crop. Even though
bio
-
diesel has its benefits it also has many issues that need further
inspection. One example of an issue with biodiesel production is the
balance between oil pro
duction capacity and the rate at which the oil
is produced. Basically, strains of algae that produce higher oil
contents tend to mature much slower than the strains that produce less
oil (Vasudevan and Briggs 427).
One solution to this problem was
proposed

by Huntley and Redalje, which used a combination of open and
closed systems where one system promotes cell growth and the other
promotes oil production

(Vasudevan and Briggs 428)
. This shows the
ingenuity and research that is going into algae bio
-
fuels. T
he last
things to be examined are

the pros and cons of algae as
a source of
bio
-
fuel.


A few advantages of using algae as a bio
-
fuel are non
-
competitive

with food crops, ability to recycle wastewater and
sustainability
.
Other ways of producing bio
-
fuels,
such as using corn to produce
ethanol, “adversely affects habitat conversion, water and air quality,
carbon sequestration in the soil and

soil fertility,” (Fargione et.a
l.
2). Algae
bio
-
fuel production
doesn’t compete with food crops because
they don’t req
uire soil for growth and can be grown with salt or
freshwater (Fargione et.
a
l. 11). Wastewater can also be used to provide
nutrients to such as phosphorous and nitrogen. “This allows for algae
production to be improved cheaply, while simultaneously
treatin
g
wastewater,” (Demirbas 2741). Both of these advantages lead to the
production of algae bio
-
fuel being a sustainable practice because it
can be used for water remediation and does not take up valuable
resources such as fresh water and quality soil. Algae
bio
-
fuel seems
like a good choice for alternative energy but doesn’t come without its
disadvantages.


Some disadvantages include high initial costs, light penetration
issues and inadequate research.
Photobioreactors are relatively more
expensive than open

systems because they require large amounts of
mechanical and metal pieces rather than a plastic or cement coating
that is required for an open system (Demirbars 2739
-
2740). Light
penetration is also an issue because the equipment to agitate the algae
is r
ather expensive and without it, yields decrease because of less
biomass produce from the algae (Demirbas 2740). All of these issues can
be explained from research in this field. Even though research has been
ongoing for 50 years, it still has many problems

to solve.


All in all, the use of algae as a bio
-
fuel seems like a
sustainable and worthwhile fuel choice for the future. It will be
worthwhile because it does not have to be directly converted into
electricity but can be combined with diesel or synthesi
zed into ethanol
for transportation uses. With the population ever increasing, algae
could be the replacement for the depleting fossil fuels.


Literature Cited



Demirbas, A., 2010. Use of Algae as Biofuel Sources. Energy
Conversion and Management, Turkey,

Issue 51,
p.
2738
-
2749.



Lee, J.H., Lee, D.G., Park, J.I., and Kim, J.Y. 2009. Bio
-
Hydrogen Production From a Marine Brown Algae and its Bacterial
Diversity. Korean Journal of Chemistry and Engineering, Korea,
Issue 27,
p.
187
-
192.



Fargione, J.E., Nelson,
E.J., McLeod, S., Tillman, D.,
Oberhauser, K.S., McCoy, T., Flaspohler, D.J., Cooper, T.R.,
Lehman, C., Hill, J., 2009. Bioenergy and Wildlife: Threats and
Opportunities for Grassland Conservation. Bioscience, Washington,
Issue 9, p. 767
-
777.



Vasudevan, P.
T., Briggs, M., 2008. Biodiesel Production

Current
State of the Art and Challenges. Journal of Industrial
Microbiology and Biotechnology, United States, v. 35, no. 5, p
421
-
430.