Environmental Engineering Reference
In-Depth Information
be able to substitute for traditional fossil fuels. The Hubert Peak Theory (http://www.hubbertpeak.
com/summary.htm) for oil reserves suggests that fossil oil production is dropping and it will cease
to exist sometime in the future, therefore it is necessary that alternate energy sources are found to
supply the world's growing energy demands. In light of these speculations, new concepts, theories,
and methods are being developed to utilize vegetable oil as an alternate energy to fossil oil.
Vegetable oil can be used effectively to replace conventional fuel in diesel engines and heating
oil burners. The first person to introduce the idea of using vegetable oil in the diesel engines was
Rudolf Diesel, who in the early 1900s investigated the idea and presented his theory in front of
British Institute of Mechanical Engineers. He remarked, “The fact that fat oils from vegetable
sources can be used may seem insignificant today, but such oils may perhaps become in course of
time of the same importance as some natural mineral oils and the coal tar products are now” (http://
www.biodiesel.org/resources/reportsdatabase/reports/gen/20011101_gen-346.pdf). Whenever there
has been a fossil oil crisis in the world due to reduced production and variations in demand/
supply as witnessed in 1930s, 1940s, and 1970s, interest in vegetable oil as a potential source of
energy resurfaced. Presently, the concept is taken very seriously by numerous countries as well
as by the private industrial sector, chiefly driven by energy security issues and environmental
concerns. Commercialization of fuels derived from vegetable oils (“biofuels”) is being adopted in
numerous countries around the world by developing fuels that meet quality standards and putting
the appropriate legislation in place. A good example of such adoption is in the transport sector and
includes such names as Elsbett AG (http://en.wikipedia.org/wiki/Elsbett), a well-known German-
based company, which produces a variant of a diesel engine that can run on pure vegetable oil. An
award winning documentary released in 2002,
The Coconut Revolution
, provided evidence of the
successful survival of Bougainville people in Papua New Guinea by effectively utilizing coconut oil
to replace traditional fuel in their Jeeps (Gerhard 2001). Publicly available information on biofuels
is increasing and the list of publications on vegetable oil based fuels is rapidly growing. This article
is the result of an effort to synthesize the current knowledge of vegetable oils as sources of energy,
with a focus on the oilseed Brassicas.
18.1.2 B
iofuElS
and
B
iodiESEl
18.1.2.1 straight vegetable oil and Waste vegetable oil
Although research on vegetable oil as an alternative form of energy has been an ongoing process
for at least a century, it is only now that scientists have been able to understand the necessary
engine parameters and related fuel properties for its reliable long-term usage in vehicles. The
most basic form of vegetable oil is straight vegetable oil (SVO), which is used primarily for
cooking purposes. Although the term generally refers to new, not previously used oils, it has also
been used for the cleaned waste vegetable oil discussed later. It is readily available, but it is not
recommended as an effective replacement for vehicle fuel due to its viscosity. Published research
(U.S. Department of Energy 2006) on the issue indicates that the high viscosity of SVO promotes
the deposition of carbon and results in the accumulation of SVO in the engine crankcase. Over
time, this can cause diesel engine malfunction. From recent research, it can safely be concluded
that SVO is acceptable for short term use but its long term usage will harm diesel engines (Babu
and Devaradjane 2003).
To solve this problem, engineers have devised a kit (http://www.journeytoforever.org/biodiesel_
svo.html) that preheats the SVO to reduce its viscosity before using it as a fuel in diesel engines.
The kit is usually sold at approximately U.S.$1,200 but the prices may vary. This after-market
kit normally contains three sections: a heat exchanger, an original diesel fuel tank, and an SVO
tank. Initially, the driver has to start the car and wait for the vegetable oil to be heated before
switching the engine to the SVO tank. The process is reversed and the power is switched back to
diesel before parking the vehicle. These two-tank, SVO systems were the first to be developed.
Optimization of this system is not complete. Preheating of the vegetable oil in these systems takes
