Environmental Engineering Reference
In-Depth Information
Production of Rapeseed Methyl Ester (RME)
For the production of RME, rapeseed and methanol together with a catalyst such as
a caustic soda solution are placed in a reaction vessel at temperatures of about 50 °C
to 60 °C. This produces the desired rapeseed oil methyl ester as well as glycerine:
catalyst
(
)
rapseed oil
+
methanol
⎯
⎯⎯
→
glycerin
+
RME biodiesel
Biodiesel can be used as a substitute for fossil diesel fuels based on crude oil. It is
offered by many petrol stations in Germany. The engine manufacturer's specifi ca-
tions should stipulate whether a vehicle can run on pure biodiesel. If an engine is
not designed for use with this fuel, there is a danger that the biodiesel will eventu-
ally destroy the hoses and seals and cause engine damage. Small quantities of
biodiesel can be mixed with conventional diesel without a problem, even without a
release from the manufacturer. The European biofuel directive of May 2003 stipu-
lates that countries across the EU must institute national measures to replace 5.7%
of all transport fossil fuels (petrol and diesel) with biofuels by 2010.
However, the positive environmental impact of biodiesel is not undisputed.
■
www.ebb-eu.org
European Biodiesel Board
■
www.ieabioenergy.com
IEA Bioenergy
12.4.3 Bioethanol
Sugar, or glucose, starch and cellulose are used to produce bioethanol. The raw
materials include sugar beet, sugar cane and grains (Figure 12.14). Sugar can be
fermented directly into alcohol. On the other hand, starch and cellulose must fi rst
be broken down.
Production of Ethanol from Glucose
Glucose can be converted directly into ethanol in a hermetically sealed environment
through fermentation with yeast:
(
)
⎯→
fermentation
(
)
+
C H
O glucose
⎯⎯⎯⎯
2 CH CH OH ethanol
6 26
3
2
(
)
2
CO
2
carbon dioxide
Carbon dioxide is a by-product of this reaction. As plants absorb carbon dioxide
again during their growth, this reaction is actually not emitting any greenhouse
gases. The result of the fermentation is mash with an ethanol content of around 12%.
