RE: biodiesel full report
BIO-DIESEL.DOC (Size: 264 KB / Downloads: 234)
BIODIESEL: A RENEWABLE AND SUSTAINABLE ENERGY RESOURCE
The Present world has been confronted with an energy crisis due to depletion of resources and increased environmental problems. Energy is consumed in different sectors like agriculture, commercial industry; transportation and domestic for the generation of power or mechanical energy. Current conventional resources are going to be exhausted in near future and hence alternative fuels like Biodiesel is to be used in place of diesel.Biodiesel is eco-friendly, renewable and hence sustainable. The Biodiesel production has not yet reached to the commercial level due to some technical and economical problems associated in its manufacture. Research is being conducted all over the world to make it a viable source of energy. This paper mainly focuses on its raw materials available, the process and the problems involved. The paper also explains about the various parameters that affect the process. Finally it concludes by highlighting its potential as a fuel of future providing energy security to India.
Biodiesel is a cleaner and environmental friendly fuel compared to diesel fuel which is obtained from petroleum processing. Biodiesel is a mono alkyl ester of long chain fatty acid derived from renewable lipid feed stock such as vegetable oil or animal fat. It is made from non-toxic, biodegradable, renewable resources such as new and used vegetable oils and animal fats. Fats and oils are chemically reacted with alcohols to produce chemical compounds called fatty acids(biodiesel).The by product glycerol is also commercially important product extensively used in pharmaceutical, soap and cosmetic industry. However the cost of biobiesel is yet to be made competent for its commercialization. The used vegetable oils can be the potential raw materials. Biodiesel can be used directly or mixed with petroleum based diesel.
India ranks high among the oil seed producing countries in the world with largest number of commercial varieties like rape seed, soyabean, cotton seed, pomgamia, palm, and jatropha etc.
MATERIALS AND METHODS OF PRODUCTION
Biodiesel is made from natural Resources. It is made from vegetable oils or animal fats. The raw materials that are used to extract oil in order to produce biodiesel are Jatropha, palm, soya bean, peanut, coconut. These crops can be grown for the production of biodiesel.
The below Graph shows the contribution of different vegetable oils towards biodiesel production
Methods of production
The other raw materials required are methanol and sodium hydroxide as catalyst.There are four methods to make biodiesel.
1. Blending with other fuels.
2. Micro emulsions
3. Thermal cracking or pyrolysis
Of these transesterification is seems to promising,hence described in detail in this paper.
The transesterification reaction is affected by the molar ratio of raw materials used, catalyst concentration, reaction temperature , reaction time and free fatty acids, water content of oils or fats. The process of transesterification and down stream operation are also addressed.
The transesterification process an alcohol (like methanol) reacts with the triglyceride oils contained in vegetable oils, animal fats, or recycled greases, forming fatty acid alkyl esters (biodiesel) and glycerin. The reaction requires heat and a strong base catalyst, such as sodium hydroxide or potassium hydroxide. The simplified transesterification reaction is shown below.
Triglycerides + Free Fatty Acids (<4%) + Alcohol ——> Alkyl esters + glycerin
Some feed stocks must be pretreated before they can go through the transesterification process. Feed stocks with less than 4% free fatty acids, which include vegetable oils and some food-grade animal fats, do not require pretreatment. Feed stocks with more than 4% free fatty acids, which include inedible animal fats and recycled greases, must be pretreated in an acid esterification process.
Triglycerides + Free Fatty Acids (>4%) + Alcohol ——> Alkyl esters + glycerin
• Acid Esterification. Oil feed stocks containing more than 4% free fatty acids go through an acid esterification process to increase the yield of biodiesel. These feed stocks are filtered and preprocessed to remove water and contaminants, and then fed to the acid esterification process. In this step, the feedstock is reacted with an alcohol (like methanol) in the presence of a strong acid catalyst (sulfuric acid), converting the free fatty acids into biodiesel. The remaining triglycerides are converted to biodiesel in the transesterification reaction.
• Transesterification. Oil feed stocks containing less than 4% free fatty acids are filtered and preprocessed to remove water and contaminants and then fed directly to the transesterification process along with any products of the acid esterification process. The catalyst, potassium hydroxide, is dissolved in methanol and then mixed with and the pretreated oil. If an acid esterification process is used, then extra base catalyst must be added to neutralize the acid added in that step. Once the reaction is complete, the major co-products, biodiesel and glycerin, are separated into two layers.
• Methanol recovery. The methanol is typically removed after the biodiesel and glycerin have been separated, to prevent the reaction from reversing itself and so the methanol is cleaned and recycled back.
• Biodiesel refining. Once separated from the glycerin, the biodiesel goes through a clean-up or purification process to remove excess alcohol, residual catalyst and soaps. This consists of one or more washings with clean water. It is then dried and sent to storage. Sometimes the biodiesel goes through an additional distillation step to produce a colorless, odorless, zero-sulfur biodiesel.
• Glycerin refining. The glycerin by-product contains unreacted catalyst and soaps that are neutralized with an acid. Water and alcohol are removed to produce 50%-80% crude glycerin. The remaining contaminants include unreacted fats and oils. In large biodiesel plants, the glycerin can be further purified, to 99% or higher purity, for sale to the pharmaceutical and cosmetic industries
The majority of the alkyl esters produced today are done with the base catalysed reaction because it is th most economic for several reasons:
Low temperature(150F) and pressure(20 psi)processing, high conversion(98%)with minimal side reactions and reaction time, direct conversion to methyl esters with no intermediate steps, exotic materials of construction are not necessary.
APPLICATIONS OF BIODIESEL
Biodiesel as self-contained renewable fuel has been applied in Diesel engines for decades.
Fuel additive / biocomponent
Biodiesel is used as fuel additive for several reasons. some of them are:
To increase and speed-up the deployment of vehicle. Biodiesel is used as an alternative fuel .
Diesel-powered equipment is used in underground mines because it is more powerful and mobile than electric-powered equipment. However, diesel emissions in the enclosed environments of underground mines pose a significant health hazard to mine workers.
oil spillage remediation
Biodiesel has excellent biodegradability in soil and ground water. It is even used to help clean up mineral oil slicks.
Biodiesel due to its unique properties has several uses in industries:
Chemical industry (paints, lubricants etc.)