The process of producing biodiesel is called transesterification whereby the ester chains in the vegetable oil are separated from the glycerine. This is achieved by replacing each molecule of glycerine with three molecules of methanol in the presence of a catalyst, i.e. transesterifying the neutral glycerides into Methyl Ester. The product, biodiesel is also commonly known as Fatty Acid Methyl Ester.
It is possible to use bases or acids as catalyst for this transesterification process. Common catalyst used is “bases” as base – catalyzed reaction has higher reaction rate.
It can be seen that the result of the reaction with 1 mole of vegetable oil and 3 mole of methanol in the presence of catalyst is 3 moles of biodiesel and 1 mole of glycerol. The reason is that the reaction is desired to proceed in the direction of the arrow (i.e. to the right) easily and completely. The excess of methanol can be recovered at a later stage in the production process.
Biodegradable
Nontoxic
Renewable
Provides 3.2 times more energy than is used to produce it
Lower greenhouse gas (CO2) emissions by nearly 80%
Very high flash point at 150 degrees C (petroleum diesel at 70 degrees C)
Safest fuel to store and handle
Improve ignition and engine efficiency
Better solvent than standard diesel as it removes deposits in the fuel line
Less dependence on petroleum derived fuels
Reduction of particulates emission by nearly half
These benefits occur while requiring virtually no engine modifications or costly infrastructural additions. Biodiesel can also be used as a heating fuel in domestic and commercial boilers. Existing oil boilers only require a relatively simple conversion to run on biodiesel.
Biodiesel can be distributed using today's infrastructure, and its use and production are increasing rapidly. Fuel stations are beginning to make biodiesel available to consumers, and a growing number of transport fleets use it as an additive in their fuel.
Glycerine is a 10% by-product of biodiesel production via the tranesterification of vegetable oils. It is a central components of lipids. This colorless, odorless, viscous liquid is widely used in pharmaceutical formulations and it is a very valuable product having applications in various products of daily human requirements.
Glycerine is used in a variety of applications -
Medicine and pharmaceutical technology
Food and beverages
Personal care
Animal feed
Dietary supplements (Medium chain triglycerides)
Surface coatings & paints
Inks
Lubricants & greases
Adhesives
Textile chemicals
Tobacco additives
Plastics additives & lubricants
Some potential uses for glycerine include the following:
Hydrogen gas production
Potential fuel additive
Compost additive
Citric acid production
Conversion to ethanol
Conversion to raw material for epoxy resins.
Ethanol is the most common biofuel worldwide. It is an alcohol fuel. It is produced by fermentation of sugars derived from wheat, corn, sugar beet and sugar cane. The production methods used are enzymatic digestion (to release sugars from stored starches e.g. from wheat and corn), fermentation of the sugars, distillation and drying.
The fermentation process yields both ethanol and water. This water must be removed if ethanol is to be utilized as fuel. Purification to 95%-96% (known as hydrated ethyl alcohol) is adequate for ethanol-only engines, whereas blending with gasoline requires a purity of 99.5% to 99.9%, and is known as anhydrous ethanol.
All petrol engines can run on blends of up to 15% bioethanol with petroleum/gasoline. For higher percentage blends, engine modifications are needed. Many car manufacturers are now producing flex-fuel vehicles, which can run on any combination of ethanol and petrol.
