Biodiesel is an alternative fuel similar to conventional or ‘fossil’ diesel. One of the new ideas of producing diesel from the animal and plant sources. The process used to convert these oils to Biodiesel is called transesterification. Most biodiesel produced at present is produced from waste, vegetable oil sourced from restaurants, chip shops, industrial food producers such as Birdseye etc.
Benefits of Biodiesel.
The main benefit of biodiesel is that it can be described as ‘carbon neutral’. This means that the fuel produces no net output of carbon in the form of carbon dioxide (CO2).Only waste required.Not costly.As diesel is very important
§ Lab scale (small scale)
§ Industrial scale (large scale)
There are different approaches
Focussed on the process which is applicable to both aspects
Animals ---- fat, Plants---- oils
Methanol (it will react with the animal or plant source and will produce biodiesel).
Why animal fat.
Consisted of glycerol and normal fatty acids
Glycerol + fatty acids = fats
Fatty acids are hydrocarbon chains if we break them from glycerol, they will be converted into some hydrocarbon-rich elements and that will be diesel.
Just separate the glycerol backbone from fatty acids and two things will be generated:
Glycerol---- glycerine + bio-diesel
Mixing of alcohol and catalyst
Catalyst is dissolved in the alcohol using a standard agitator or mixer. Reaction. The alcohol/catalyst mix is then charged into a closed reaction vessel and the oil or fat is added. The system from here on is totally closed to the atmosphere to prevent the loss of alcohol. The reaction mix is kept just above the boiling point of the alcohol (around 160 °F) to speed up the reaction and the reaction takes place.
Once the reaction is complete, two major products exist glycerine and biodiesel. Each has a substantial amount of the excess methanol that was used in the reaction. The reacted mixture is sometimes neutralized at this step if needed. The glycerine phase is much denser than the biodiesel phase and the two can be gravity separated with glycerine simply drawn off the bottom of the settling vessel.
The glycerine by-product contains unused catalyst and soaps that are neutralized with an acid and sent to storage as crude glycerine. In some cases, the salt formed during this phase is recovered for use as fertilizer. In most cases, the salt is left in glycerine. Water and alcohol are removed to produce 80-88% pure glycerine that is ready to be sold as crude glycerine. In more sophisticated operations, the glycerine is distilled to 99% or higher purity and sold into the cosmetic and pharmaceutical markets.
Methyl Ester Wash
once separated from the glycerine, the biodiesel is sometimes purified by washing gently with warm water to remove residual catalyst or soaps, dried, and sent to storage. In some processes this step is unnecessary. This is normally the end of the production process resulting in a clear amber-yellow liquid with a viscosity similar to petrodiesel. In some systems, the biodiesel is distilled in an additional step to remove small amounts of color bodies to produce colorless biodiesel.
High Cost of Production, Monoculture, Use of Fertilizers, Shortage of Food, Water Use, Future Rise in Price, Degradation during long term storage.