Through a chemical process, oil from seeds (e.g., Jatropha and Pongamia) can be converted to a fuel commonly referred to as "biodiesel." No engine modifications are necessary to use biodiesel in place of petroleum-based diesel. Biodiesel can be mixed with petroleum-based diesel in any proportion.
Biodiesel is registered
as a fuel and fuel additive in US with the Environmental Protection Agency (EPA)
and is widely used in Europe. The use of Biodiesel results in a substantial
reduction of unburned hydrocarbons and the overall ozone forming potential of
the speciated hydrocarbon emissions from Biodiesel is nearly 50 percent less
than that measured for diesel fuel.
The flash point of biodiesel has been tested and reported by many sources. It has been concluded that the flash point of biodiesel blends rises as the percentage of biodiesel increases. Therefore, pure biodiesel or blends of biodiesel with petroleum diesel are safer to store, handle and use than conventional diesel fuel. In addition, it is essentially sulphur-free and eliminates the emission of sulphur dioxide and sulphate aerosols.
Two main forms of biodiesel, now sold in the US, are B20 and B100. B20 is a mixture of 20 percent biodiesel and 80 percent petrodiesel, a mixture that addresses diesel emissions problems (30 percent less unburned hydrocarbons, 20 percent less carbon monoxide, 22 percent less particulates and 20 percent fewer sulfates). Moreover, it achieves this reduction in pollution, while running in unmodified diesel engines.
B100 contains no petrochemicals -- it is 100 percent biodiesel and burns much cleaner (93 percent less unburned hydrocarbons , 50 percent less carbon monoxide, 30 percent less particulate matter and no sulfates) and it also improves performance.
Climate change is presently an important element of energy use and development. Biodiesel is considered "climate neutral" because all of the carbon dioxide released during consumption had been sequestered out of the atmosphere during crop growth. Combustion of one liter of diesel fuel results in the emission of about 2.6 kilograms of CO2. Therefore, the use of biodiesel will directly displace this amount of CO2 when used.
Combustion of biodiesel has been reported in a number of sources to have lower emissions compared with petroleum diesel. Lower emission of SO2, soot, carbon monoxide (CO), hydrocarbons (HC), polyaromatic hydrocarbons (PAH), and aromatics are presented in the following Diagram. NOX emissions from biodiesel are reported to range between plus or minus 10% as compared with petrodiesel depending on engine combustion characteristics.
Lower emissions of biodiesel compared with petrodiesel.
Source: Tickell, J., 1999. From the Fryer to the Fuel Tank., GreenTeach Publishing, Florida,U.S.A.
Production of Biodiesel involves growing the oil trees, pressing the seeds into oil and processing the oil into biodiesel by transesterification. The proposed project envisages use of Jatropha Curcas and Pongamia Pinnata Oils for production of Biodiesel.
Jatropha curcas Oil
Jatropha curcas plant shows promise for use as an oil crop for biodiesel. The Jatropha plant is Latin American in origin and is closely related to the castor plant. It is a large shrub/ small tree able to thrive in a number of climactic zones in arid and semi-arid tropical regions of the world. An easy to establish perennial, it can grow in areas of low rainfall (250 mm per year minimum, 900-1,200 mm optimal) and is drought resistant. In addition, it is valued for crop protection, prevents wind/water erosion, is not browsed by animals, will reach maximum productivity by year five, and has a 50 year life-span. The energy efficiency of the agricultural and industrial production process is between 1:3.75 and 1:5.
Pongamia pinnata is a native of the Western Ghats and is chiefly found along the banks of streams and rivers or near the sea on beaches and tidal forests. It also grows in dry places far in the interior and up to an elevation of 1000 mm. It is a hardy tree that mines water for its needs from 10 metre depths without competing with other crops. It grows all over the country, from the coastline to the hill slopes. It needs very little care and cattle do not browse it. It has rich leathery evergreen foliage that can be used as green manure. From year-5, the plant is expected to give economic yields and it may continue through to its life of 100 years. When in bloom, the Pongamia trees can be used for bee harvesting and honey production.
The most common derivatives of agricultural oil for fuels are methyl esters. These are formed by transesterification of the oil with methanol in the presence of a catalyst (usually basic) to give methyl ester and glycerol. Sodium hydroxide (NaOH) is the most common catalyst, though others such as potassium hydroxide (KOH) can also be used. The following Diagram presents a mass balance for transesterification:
100 kg oil+24 kg methanol+2.5 kg NaOH à 100 kg biodiesel+26 kg glycerine
R' R'' R''' = oil acids; R = (CH2)xCH3
Source: Feasibility of Biodiesel for Rural Electrification in India, Jeffrey L. Rosenblum, Carnegie Mellon University
The methanol and NaOH are premixed and added to the oil, mixed for a few hours, and allowed to gravity settle for about 8 hours. The glycerine settles to the bottom, leaving biodiesel on the top. The physical and chemical properties of the resulting biodiesel (Jatropha methyl esters) is presented in the following Table alongside those for petroleum diesel and European Union standards for biodiesel.
Jatropha Biodiesel properties compared with petro-diesel and EU standards
|Property||Units||Jatropha biodiesel||Petroleum diesel||E.U. standards for biodiesel|
|Density @ 30C||g/ml||0.88||0.85||> 0.8|
|Combustion point||C||192||55||> 55|
|Kinetic viscosity||cSt||4.84||2 - 8||5|
|Cetane number||-||52||47.5||> 48|
|Ester content||%||> 99||0||> 99|
|Sulfur content||%||0||< 0.5||< 0.55|
|Carbon residue||%||0.024||< 0.35||< 0.1|
Source: The Biomass Project, 2000. Curcas Oil Methyl Ester. Nicaragua.
The process of manufacture of Biodiesel and the properties of Biodiesel are more or less similar for Jatropha and Pongamia.
Advantages of Biodiesel
The higher cetane number of biodiesel compared to petro-diesel indicates potential for higher engine performance. Tests have shown that biodiesel has similar or better fuel consumption, horsepower, and torque and haulage rates as conventional diesel
The superior lubricating properties of biodiesel increases functional engine efficiency
Their higher flash point makes them safer to store
The biodiesel molecules are simple hydrocarbon chains, containing no sulfur, or aromatic substances associated with fossil fuels
They contain higher amount oxygen (up to 10%) that ensures more complete combustion of hydrocarbons
Biodiesel almost completely eliminates lifecycle carbon dioxide emissions. When compared to petro-diesel it reduces emission of particulate matter by 40%, unburned hydrocarbons by 68%, carbon monoxide by 44%, sulphates by 100%, polycyclic aromatic hydrocarbons (PAHs) by 80%, and the carcinogenic nitrated PAHs by 90% on an average. The use of biodiesel complements the working of the catalysator and can help a current EURO-1 motor attain the EURO-111 standards.
Fixation of up to 10 t/ha/yr CO2 that could be internationally traded
Production of 1 t/ ha/yr of high protein seed cake (60% crude protein) that can be potentially used as animal and fish feeds and organic matter that could be used as organic fertilizer particularly in remote areas
Various other products from the plant (leaf, bark and seed extracts) have various other industrial and pharmaceutical uses
Localised production and availability of quality fuel
Restoration of degraded land over a period of time
Rural employment generation
High cost of production: will eventually solve itself when large-scale production and use starts. Also, the price of petro-diesel does not take into account its actual cost (when environmental and military costs are included).
Modifications are required to the automobiles for use of biofuel: many automobile brands are currently marketed ready for use of bio diesel.
High CFPP (cold filter plugging point) values and hence solidification and clogging of the system at low temperatures: this problem occurs only in places where the temperature goes down to around 0°C, even here the problem is currently solved by adding additives.
Glycerine (glycerin, glycerol) is the by-product of making biodiesel. What sinks to the bottom of the biodiesel processor during the settling stage is a mixture of glycerine, methanol, soaps and the catalyst. Once separated from the biodiesel, adding phosphoric acid to the glycerine layer precipitates the catalyst out and also converts the soaps back to free fatty acids (FFAs), which float on top. The resultant products are light-colored precipitate on the bottom, glycerine/methanol/water in the middle, and FFA on top. The glycerine will be approx. 95% pure, a product to sell to refiners.
The residual crushed seed, known as de-oiled cake, is a good source of manure, which can be used locally, or for export. The seed husks can be used to make packaging materials.