Environmental Engineering Reference
In-Depth Information
http://www.freetherm.de/rapseng.html) which have been designed to be operated exclusively on
canola/rapeseed oil. The most exciting prospect for canola/rapeseed oil lies in its role as a renewable
energy source in temperate regions. With the decline in the Earth's petroleum resources, individuals,
the public sector, and industries are under pressure to reduce their consumption of fossil fuels. This
pressure is the driving force for advanced technological solutions. These will make use of renewable
energy resources and thus maximize the efficient use of remaining nonrenewable energy resources.
On the basis of this concept, canola/rapeseed oil has been studied or used to replace mineral oils for
manufacturing products such as plastics (http://news.mongabay.com/bioenergy/2007/07/scientists-
develop-polyurethane.html), engine oils (Glamser and Widmann 2001), lubricants (Wightman et al.
1999), and surfactants (BioMatNet).
The most important use of Brassica oil as a renewable energy source is in the manufacturing of
biodiesel for powering motor vehicles. In general, oil from canola/rapeseed has 90% of the calorific
value of mineral oil. However, being 10% heavier than mineral oil, its heat content per liter is similar
to mineral oil. Biodiesel from canola/rapeseed oil is obtained by the process called methanolysis
(Vicente et al. 2004) which yields a renewable fuel and a glycerol byproduct. Canola/rapeseed
oil-derived biodiesel is a renewable and biodegradable fuel which is compatible with commercial
diesel engines and has environment friendly properties such as reduced toxicity and lower emissions
(Mittelbach et al. 1983). Biodiesel derived from Brassica oil (including rapeseed and canola oil)
has been successfully used in pure form in newer diesel engines without engine damage and is
also frequently mixed with standard diesel in varying ratios (2-20%). The diesel fuel derived from
canola/rapeseed is also used to generate heat, power, and electricity.
The simple extraction process includes mechanical pressing of seeds with mild heating to recover
90% of the oil; titration and washing with hydrocarbon solvents (hexane or heptane); heating to
150°C to evaporate the solvent; filtration to remove gummy fats and carbohydrates; mixing with
caustic soda to lower acidity and remove free fatty acids molecules and refining. The refined oil
obtained in this way is similar to common diesel fuel except for its 10% higher viscosity. It is
suitable for use in power stations to generate electricity. In addition, the seed press cake obtained as a
byproduct in the above process can be used as a source of energy in an incineration plant to produce
electricity. A privately held company in the United States (http://www.biofuelpowerandlight.com)
designs and builds biofuel power plants based on vegetable oil feed stocks including canola/rapeseed
oil. The company owns one biodiesel plant that produces 70 million gal/year of B100 biodiesel,
some of which is sent to biofuel power plants in Texas that generate green electricity. Combined
heat and power units (CHP) fuelled with canola/rapeseed oil are also of interest to industry due to
efficient utilization of renewable agricultural energy sources, and feasibility/research studies point
to their advantages with possible improvements including a list of these advantages (Glamser and
Widmann 2001; Klaus et al. 2005; Pantaleo et al. 2008). The concept of energy cabins heated by
biofuels or biodiesel is also emerging and some people are experimenting in this area (http://www.
motherearthnews.com/Renewable-Energy/2003-12-01/Heat-Your-Home-with-Biodiesel.aspx;
http://www.juwi.com/fileadmin/user_upload/en/pdf/JUWI_Bereichsbrosch%C3%BCre_Bio_EN_
1Aufl.pdf). Feasibility studies are also being conducted concerning the use of biodiesel in low-speed
diesel engines, gas turbines, and steam generation boilers for generation of electricity (Bolszoa and
Mcdonell 2008; http://mydocs.epri.com/docs/public/000000000001014867.pdf).
18.1.6 d
omEStic
and
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Oil obtained from Brassica seeds (rapeseed, mustard or canola) is 40% of the total seed weight on
average, generating approximately 80% of the cash value of the crop, and is now considered an
important feedstock for renewable energy products, mainly biodiesel. A recent study (Johnston and
Hollowway 2007) revealed that there are 109 countries in the world which can produce biodiesel
on a profitable basis. However, it is now well recognized that profitability in the bioenergy sector
depends on the availability of a particular feedstock, its yield potential, and cost of production.
