What is biodiesel?
From the word bio, we refer to the meaning of organic mass obtained from plants and animals. Fat like matter which is obtained as oil from seeds of crops and fatty stuff from animals are called biomaterials and this type of materials are used to produce a diesel form of fuel and in overall, the so obtained fuel is called biodiesel. It is simple to make biodiesel in the laboratory.
In case of its properties, it is much more near to blended diesel obtained from crude petroleum. The word biodiesel became much valuable when concerned with alternative energy sources. As per the European Council by 2020 it made the decision to bring the effort to use 10% of biofuels in automobile fuel system.
How biodiesel is available in the market
Biodiesel is obtained with the blend of a petrodiesel fuel mixed with it. A pure 100% biodiesel is meant to be rated as B100, based on the biodiesel percentage the fuel gets rated for example for 20% biodiesel the fuel is specified as B20 which contain the remaining 80% petro-diesel. These brands are used based on the engine and methods that companies make biodiesel.
How to make biodiesel
The raw materials are any vegetable oil mostly is soya bean, mustard, jojoba, and coconut. The second ingredient is potassium hydroxide or sodium hydroxide whatever, and the last is methanol.
Equipments required: a beaker and a stirrer and if not you can use a home blender or mixer with the regulator. A separating funnel and pet bottles. A thermometer and heater (heating mantle).
The process to make biodiesel:
Add 200 ml pure methanol to 1-litre vegetable oil, sodium hydroxide of 3.5 to 4 grams (or KOH 5 gm). Start the stirrer and heat the mixture up to 55 to 60oC range temperature. After obtaining the temperature maintain it for 30 min then stop the process and pour the solution into the separating funnel allowing it to settle.
Two layers will form, at the bottom glycerine settles down and the top layer is now called biodiesel.
Drawback of biodiesel
- Poor atomization
- Coking of injectors
- However, bioethanol is safer than fossil fuel like gasoline and diesel, it also has some of the drawbacks of incomplete combustion and production of acetaldehyde. The increase of acetaldehyde levels in the atmosphere due to bioethanol fuel consumption. Modern vehicles that use bioethanol as fuel are increasing the cities to control the pollution due to the combustion. Utilising the bioethanol is one of the solutions for climate change problems. By blending the bioethanol in petrol and diesel, European countries want to reduce the greenhouse gas emission from the transportation vehicles that developed by Flexi fuel technology.The scientific fact is that when the bioethanol fuel undergoes incomplete combustion. The unburned ethanol escapes into the atmosphere and oxidises to form acetaldehyde and to acetic acid.
- Lubricating properties
- High cetane number
- No sulphur
- Calorific value= 37.72 MJ/kg
- Immiscible with water
- Flashpoint 130oC
- Density 0.88 g/cm3
Compounds that catalyze transesterification based on pH
- acidic-catalysts (e.g. HCl and H2SO4)
- basic-catalysts (e.g. KOH and NaOH)
The commonly preferred catalyst used for transesterification
- Sodium hydroxide
- Potassium hydroxide
- Natural Zeolite (Clinoptilolite)
- Modified natural zeolite
- Synthetic zeolite Y
- Modified synthetic zeolite
Due to drawbacks in bioethanol, it is mixed with a petro derived diesel to form a Bioethanol-diesel emulsion for use in direct injection diesel engines. The best emulsion is 5% of bioethanol in petrodiesel, pollutants from engine exhaust are tested to be less from all other composition trails ( maintaining the same out power ).
To make biodiesel better and to know it quality, the produced emulsion should be tested with an experiment set up given below :
- Four stork engine
- Fuel consumption system (Automatic solenoid control buret)
- Airflow calculation system
- Thermocouples for temperature measurement in the exhaust opening
- Flue gas analyzer (to measure nitric oxide, carbon monoxide and dioxide)
- Sensing meters: smoke meter, pressure transducer
Data to be obtained from the experiment:
- Pressure crank angle diagram (this give an idea of initiation of ignition)
- Ignition interruption
- Heat discharge rate
- Maximum cylinder pressure
- Combustion duration
Engine performance analysis
- Brake specific energy utilization
- Exhaust gas temperature
- Thermal energy balance
Engine emission analysis
- Brake specific hydrocarbon and nitric oxide emission
- Smoke emissions
Upgradation to make biodiesel, meet the fossil fuel petrol composition
By using the technology of fluid catalyst cracking, biodiesel upgradation is possible to yield gasoline composition. The streams like vacuum gas oil when mixed with biodiesel, FCC column cracks the heavy molecule without any change in operating temperature and catalyst composition. This type of technological upgradation makes biodiesel more environmentally friendly.