Biodiesel Production PDF

I.GREEN CONCEPT Nowadays, the word “Green” does not only represent the green color but is also a symbol of saving the environment which is surrounding us. A green concept is concerned with any approach to decrease Greenhouse gas (GHG) resulting from human or industrial activities, such as burning of...

I.GREEN CONCEPT Nowadays, the word “Green” does not only represent the green color but is also a symbol of saving the environment which is surrounding us. A green concept is concerned with any approach to decrease Greenhouse gas (GHG) resulting from human or industrial activities, such as burning of fossil fuel to meet the energy requirements which are the major contributor to temperature rise. It is signposted that by 2050, minimum 40% reduction in (GHG), emissions, mainly CO2, is obligatory to sustain the average increase < 1.5°C. This phenomenon continuously compels the community to search for Green Alternatives both in energy resources and platform chemicals, from the available substitutes to conventional fuels as: BIODIESEL, GREEN HYDROGEN and GREEN CONCRETE. 1. BIODIESEL The overwhelming concerns due to over exploitation of fossil resources and increases of (GHG) necessitate the utilization of alternative energy resources. Biodiesel has been considered as one of the most adaptable alternatives to fossil- derived diesel with similar properties and numerous environmental benefits. There are various approaches for biodiesel production, development of cost-effective and robust catalyst with efficient production methods and utilization of a variety of feedstock could be the optimum solution to bring down the production cost. The alternative biodiesel fuel should be found to compensate the future fuel demand and reduce pollution. 1.1 Production of Biodiesel Biodiesel is a renewable fuel that can be produced from vegetable oils, animal fats, and other sources of biomass. There are many methods for producing biodiesel such as: Transesterification: It is the most commonly used method for producing biodiesel. In this process, the triglycerides in the vegetable oils or animal fats are reacting with an alcohol (usually methanol or ethanol) in presence of a catalyst 1  (potassium or sodium hydroxide) to produce Fatty Acid Methyl Ester (FAMEs), which are the main components of biodiesel. Pyrolysis: It is a process that involves heating of biomass in the absence of oxygen to produce a bio-oil, which can be further refined into biodiesel. Supercritical-Transesterification: It is a process that uses supercritical fluids (usually CO2) instead of traditional solvents to extract and convert the triglycerides into biodiesel. Microbial fermentation: The process involves using micro-organisms (such as bacteria or yeast) to convert sugars and other organic compounds into fatty acids, which can be converted into biodiesel. Enzymatic catalysis: The process involves using enzymes to catalyze the conversion of triglycerides into biodiesel. Production of Biodiesel using Transesterification Biodiesel manufacture is a process of producing the biofuel from chemical reactions of transesterification and esterification. This involves vegetable or animal fats and oils or algae being reacted with short chain alcohols (methanol or ethanol). The alcohols used should be of low molecular weight. Ethanol is the most used alcohol because of its low cost. However, greater conversions into biodiesel can be reached using methanol. Although the transesterification reaction can be catalyzed by either bases or acids, the base catalyzed reaction is more common. This path has lower reaction times and catalyst cost less than using acid catalyst. However, alkaline catalysis has the disadvantage of high sensitivity to both water and free fatty acids present in the oils. The main reaction involved is: Triglycerides + Alcohol → biodiesel + Glycerol The major steps required are illustrated in the following flowsheet: 2  Triglycerides, Alcohol Pre-treatment Reaction “catalyst” Separation By - products Water Washing impurities Drying Storge and Distribution FAMEs Simplified Block Flowsheet for Production of Biodiesel 3 a) Feedstock pre-treatment Used oil is processed to remove impurities from storage and handling, such as dirt, charred food, ………through filtration. Moisture must also be removed because its presence during base – catalyzed transesterification results in the saponification (hydrolysis of the triglycerides), producing soap instead of biodiesel. b) Transesterification reaction The feedstock is mixed with methanol or ethanol and a catalyst (such as Na or K hydroxide) in a reaction vessel. The mixture is agitated and heated to promote the transesterification reaction to produce biodiesel and glycerol as byproduct. c) Separation After the reaction is complete, products include not only biodiesel but also byproducts such as glycerol, soap, excess alcohol and traces of water. All of these by products must be removed to meet the standards. The density of glycerol is greater than that of biodiesel (Fatty Acid Methyl Esters FAMEs ) , and this property difference is exploited to separate the bulk of the glycerol coproducts. d) Washing The FAMEs are washed with water to remove any remaining impurities or catalyst. e) Drying The washed FAMEs are dried to remove any remaining water. f) Storage and Distribution Additional processes may be used depending on methods of producing Biodiesel and regulatory requirements. 1.2 Biodiesel Blends Biodiesel is a diesel fuel made from vegetable oil, animal fats or restaurants greases. It is safe, biodegradable, and produces less air pollutants than petroleum – based diesel. 4 Biodiesel is produced in a pure form referred to as “ B100 “ or “ neat Biodiesel “ and is typically blended with petroleum – based diesel fuel. Such biodiesel blends are designated as BXX , where XX represents the percentage by volume of pure biodiesel contained in the blend e.g. B10 is 10% biodiesel and 90% petroleum diesel. Common blends include B2 ,B5 and B20. Blend of 20% or B20 significantly reduces GHG emissions that contribute to global warming. It can be used as a 20% blend in most diesel equipment with no modifications.