Biomedical Engineering Reference
In-Depth Information
Table 1. Regional Actors in Biodiesel sector
Actor
Need
Benefits
Problems
Alternatives
Farmer
Crops with value
added use
Good rotation
crops: breaks
disease cycles
Market price
below breakeven
cost
Growing barley,
peas, lentils
Crusher
Oil and meal
market
n/a
Difficult to find
local crushers
Involvement in
another ag
enterprise
Meal user
Regional
alternative for
livestock feed
Good for dairies
More than 12%
canola mean in
feed is not
applicable
Importing
alternative meals
Biodiesel producer Low cost of
regional
feedstocks
Oil feedstock; low
pour point
Oil extraction
efficiency
Biolubricants as
potentially
candidates
Blender
/Distributor
Meet market
demand for
biodiesel
Tax credit; easily
blended
Minimal economic
incentive to
expand storage
facilites
Synthetic lubricity
additives probably
cheaper
End user
Warranties for fuel
and engines
Regional
alternative fuel
source
Engine warranties,
fuel price
Petroleum diesel
2.1. Biodiesel Reaction Chemistry
Biodiesel is produced from the catalytic transesterification, a type of alcoholysis of
vegetable oils, animal fats, or waste cooking oils with an alkyl alcohol group. During
transesterification, an alkoxy is exchanged between an ester compound and an alcohol to
produce a different ester and alcohol. As shown in Figure 4, the transesterification of
biodiesel produces three moles of fatty acid methyl esters (FAMEs) from one mole of
triglyceride and methanol. This reaction actually occurs in three steps as shown in Figure 5.
In the reaction mechanism, the methanol forms a tetrahedral intermediate at an ester group on
the triglyceride (TG) and then detaches to form a diglyceride (DG) and a FAME. [10] This is
repeated stepwise until the monoglyceride (MG) is converted to glycerine (GL). Excess
alcohol should be used to drive the reaction forward, for which a 6:1 molar ratio of alcohol to
oil is most commonly the case. [10-12]
