This paper attempts to bring out the performance of the alternative fuel “BIODIESEL A DERIVATIVE FROM JATROPHA OIL”. The onset of Industrial Revolution led to the exploitation of fossil fuels, which results in environmental problems such as pollution and green house effect. Due to the constant increase in depletion of fossil fuels and its consequent effect on the environment and ecology, there is awareness around the world for the importance of saving them.
In recent years, several initiatives are being taken in India to bring this fuel from the fields to the wheels. The efficacy of biodiesel as an automotive fuel is well recognized. Several countries including U.S.A. are substituting the conventional mineral diesel by biodiesel to address the issues of air quality and energy security. The availability of wastelands, presence of a variety of non-edible oil seeds and plants, prospects of development of rural economy, biodegradability and emission benefits are some of the positive attributes which qualify biodiesel especially its blends to be a prominent contender for substituting petrodiesel in India. Moreover, the technological requirements for process and production of biodiesel being comparatively less bulky and its ability to fuel an existing diesel vehicle with no or minor modifications also make it a promising alternate fuel. This paper also contains the results on the comparison of biodiesel with conventional diesel on the basis of brake efficiency, combustion duration, emission test etc.
With the stock of fossil fuels diminishing throughout the world and demand for energy based comforts and mobility ever increasing, time is ripe that we strike a balance between energy security and energy usage. However, technology cannot bring back an extinct animal resource but, can only extend the supply of some resources by improving them, using them more efficiently or recycling them. Our case study involves results from a famous research institute, TNAU – Coimbatore, and from our institute – KCT.
1. Introduction
Imported of petroleum products constitutes a major drain on our foreign exchange reserves, which involved a cost of approximately Rs. 90,000 crores/annum. Even 5% replacement of petroleum fuel by bio-fuel can help India save Rs.4000 crores per year in foreign exchange. It is utmost important that the options for substitution of petroleum fuels be explored to control this burgeoning import bill. The degrading air qualities in our cities further warrant the quest for alternate cleaner fuels. With the stock of fossil fuels diminishing throughout the world and demand for energy based comforts and mobility ever increasing, time is ripe that we strike a balance between energy security and energy usage. Moreover having uplifted to such a sphere of engineering excellence, reverting back to the ages of the bull carts will prove next to impossible thereby compelling us to search for a basket of alternative fuels to derive energy to cater to our needs. Several sources of energy, especially for driving the automotives are being developed and tested. This report presents detailed information on Biodiesel together with its emission benefits. The prospect of biodiesel as an alternative to conventional fuels like gasoline and diesel and the experience of other countries is also outlined
1.2 BIO-DIESEL -- AN ALTERNATIVE FUEL FOR FUTURE
1.2.1 What is Bio-diesel?
- A substitute for or an additive to diesel fuel that is derived from the oils and fats of plants.
- An alternative fuel that requires no engine modifications and provides power similar to conventional diesel fuel.
- A biodegradable transportation fuel that contributes no net carbon dioxide or sulfur to the atmosphere, and is low in particulate emissions.
- A renewable, domestically produced liquid fuel that can help reduce Indian dependence on foreign oil imports.
1.3 JATROPHA CURCAS
Various low value vegetable oils, which are not suitable for human consumption, can be used for the purpose of production of bio-diesel. Non-edible oils like Jatropha, Pongamia, Argemone, Mohua, Castor, Salvadora, etc. all can be used for the production of bio-diesel. However, Jatropha has got tremendous potential in the country because of the following reasons.
1.3.1 Why Jatropha?
- The plant is a small bush, grows fast and starts yielding from 2nd year itself.
- Highly adaptable to various agro climatic conditions. Can thrive well even in adverse soil conditions, hot and dry ecosystem.
- Wastelands with gravel / stones, undulated lands can also be utilized.
- Can be a profitable in sub marginal dry lands.
- Not browsed by cattle
- Oil can be extracted easily from the seeds by expellers
1.3.2 What is Jatropha?
- It is a cross-pollinated crop and yield starts in 2nd year. Productivity stabilizes in 7-8 years. Economic life can be up to 40 years also if cultured and maintained well.
- It is propagated by seeds, can also be propagated vegetatively from cuttings.
- In commercial plantations, a crop of Jatropha can be raised as a block plantation at a space of 2-3 meters from plant to plant depending upon the fertility of the soil and rainfall of the area.
1.3.3 Potential of Jatropha:
The Jatropha Curcas plant has the potential, 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. It can grow in areas of low rainfall (250 mm per year minimum, 900-1,200 mm optimal) and is drought resistant and is not browsed by animals.
§ Planting density - 1,000 plants per Acre
§ Productivity - Starts yielding after on year, but the maximum productivity from 5th year onwards
§ Life Span - 50 years
§ Yield per Acre/ year
§ Market Price -The seed can be sold around Rs.5 to 6 per kg.
1.3.4 Limitations:
The plant has some limitations. It does not tolerate water logged and marshy conditions. Hence, suitable lands only should be selected; also innovative methods are needed to reduce the cost of cultivation.
1.4 The Process
Biodiesel can be produced through "TRANSESTERIFICATION"; a process that combines vegetable oils, animal fats, and/or micro algal oils with alcohol in the presence of a catalyst to form fatty esters. Product recovery is separated into phases which provides for easy removal of glycerol, a valuable industrial by-product, in the first phase. The remaining alcohol/ester mixture is then separated and the excess alcohol is recycled. Then the esters are sent to the clean-up or purification process which consists of water washing, vacuum drying, and filtration.
1.5 Characteristics of BioDiesel
Biodiesel as automotive fuel has similar properties to petrodiesel and as such can be directly used in existing diesel engines with no or minor modifications. It can be used alone or mixed in any ratio with petrodiesel. The most common blend is B20, a mix of 20% biodiesel with 80% petroleum diesel. Biodiesel has 11% oxygen by weight and essentially contains no sulphur or aromatics
Values
Specific gravity 0.88
Viscosity @ 20 Ċ (centistokes) 7.5
Cetane Index 49
Cold filter Plugging Point (Ċ) -12
Net Heating Value (Kilojoules/Liter) 33,300
Physical properties of Biodiesel
1.5.1 Facts about BIO-DIESEL:
Biodiesel is the first and only alternative fuel to have a complete evaluation of emission results and potential health effects submitted to the U.S. Environmental Protection Agency (EPA) under the Clean Air Act Section 211 (b).
Biodiesel is biodegradable.
Biodiesel is non-toxic (less toxic than table salt).
Biodiesel reduces air toxics by up to 90%.
Biodiesel is safer to handle than diesel or gasoline.
Reduces cancer-causing particulates by up to 94% compared to petroleum diesel.
Biodiesel contains no sulfur and emits no sulfur dioxide, the primary cause of acid rain.
1.5.2 Toxicity of Biodiesel
Impacts on human health represent significant criteria as to the suitability of the fuel for commercial applications. Health effects can be measured in terms of fuel toxicity to the human body as well as health impacts due to exhaust emissions. Tests conducted by the Wil Research Laboratories investigated the acute oral toxicity of pure biodiesel fuel as well as B20 in a single dose study on rats, which concluded that biodiesel is not a toxic and there is no hazards anticipated from ingestion incidental to industrial exposure. The acute oral LD50 (lethal dose) is greater than 17.4-g/kg-body weight, which by comparison is far safer then even table salt. According to NIOSH (National Institute for Occupational Safety & Human Health), a 96-hr. lethal concentration of biodiesel for bluegills was greater than 1000 mg/l and this aquatic toxicity is deemed as insignificant. Other related effects of biodiesel are given below:
- Very mild human skin irritation. It is less than the irritation produced by 4% soap and water solution.
- It is biodegradable. It degrades at least 4 to 5 times faster then conventional diesel fuel.
- Biodiesel has a flash point of about 300 F well above conventional diesel fuel.
- Spills of biodiesel can decolorize any painted surface if left for long.
- There is no tendency for the mutagenicity of exhaust gas to increase for a vehicle running on biodiesel.
1.6 Case Study
1.6.1 Operation & Performance Results (from TNAU – CBE)
- Horsepower, fuel economy and torque are similar to those of conventional diesel fuel engines.
- Cetane number is comparatively lower than that of conventional diesel fuel.
- Improved lubricity.
- No engine modification required when used in compression ignition engines.
- Range of vehicle akin to that of conventional diesel vehicles.
1.6.1.1 Performance
The variation of brake thermal output is shown in the graph for both conventional diesel and biodiesel the brake thermal efficiency of conventional diesel is 30.3 % where as for bio-diesel is 29%. The bio-diesel has lower viscosity and density than Jatropha oil but higher than conventional diesel. Lower the viscosity results in improved atomization, fuel vaporization and combustion. In addition, the ignition delay is closer to that of diesel with bio-diesel due to its high Cetane rating.
The variation of volumetric efficiency with power output is shown in the below graph the volumetric efficiency of biodiesel is lower than conventional diesel. This is due to the higher temperature of the retained exhaust, which will preheat the incoming fresh air and lowers volumetric efficiency.
Exhaust gas temperature of biodiesel is higher than conventional diesel which is shown in the below graph. The maximum exhaust temperature for conventional diesel is 402▫C where as for bio-diesel is 415▫C. The reduction in exhaust gas temperature is due to the higher latent heat of vaporization of methanol.
1.6.1.2 Exhaust Emissions:
The variation in smoke emission with power output is shown in the below graph. The smoke level with diesel is 3.8 BSU at maximum power. With bio-diesel the smoke level is found to be 4 BSU.
The HC concentration found in the exhaust is shown in the below graph. The HC emission is 100 ppm for conventional diesel and 110 ppm with bio-diesel. CO emission level is also higher for biodiesel compared to conventional diesel. The lower brake thermal efficiency and calorific value of bio-diesel has lead to the injection of higher quantities of fuel for same power output compared to diesel. The nitrogen oxide (NO) emissions are low compared to standard diesel due to lowered premixed burning rate following delay period. This is due to lower entrainment and fuel air mixing rates. The NO level for bio-diesel is higher than normal mode and is lower than diesel values.
1.6.1.3 Combustions Parameters:
The variation of ignition delay is shown in the below graph. Biodiesel shows longer ignition delay as compared to diesel due to low Cetane number. It is just 10▫ CA for biodiesel which is due to the cooling effect produced due to methanol as it vaporizes resulting in increased ignition delay. The higher viscosities, poor atomization, mixture preparation with air are few reasons for ignition delay. The graph shows the variation of peak pressure with brake power.
The combustion duration increases with rise in power output with all fuels due to increase in quantity of fuel injected. It is comparatively higher than conventional diesel. The increase in combustion duration of biodiesel is only due to the slow combustion of the injected fuel.
1.6.2 Performance & Emission Results (from KCT – CBE)
1.6.2.1 Performance Results
1.6.2.1.1 BRAKE POWER Vs SFC:
The specific fuel consumption of BioDiesel with Diesel blends is comparable with Diesel Fuel, whereas for 100% BioDiesel the specific Fuel consumption increases from 8 % to 9%.
1.6.2.1.2 BRAKE POWER Vs EXHAUST HEAT LOSS:
The exhaust Heat Loss has seemed to be the same for Diesel and all the Blends.
1.6.2.1.3 BRAKE POWER Vs EXHAUST GAS TEMPERATURE
An increase of 6.6% (ie., 10 ºC) in exhaust gas temperature is found Bio diesel in comparison with Diesel
1.6.2.1.4 BRAKE POWER Vs AIR FUEL RATIO
A decrese of 24% is found in the air fuel ratio of BioDiesel on comparison with Diesel.
1.6.2.1.5 BRAKE POWER Vs BRAKE THERMAL EFFICIENCY
The brake thermal efficiency of BioDiesel has a decrease of 2% with that of Diesel
1.6.2.2 DISCUSSION ON EMISSION RESULTS:
1.6.2.2.1 Oxygen % vs (bio-diesel & diesel)
An increase of 2% is observed in the Biodiesel blends on comparison with Diesel.
1.6.2.2.2 Combustion effciency % vs (bio-diesel & diesel)
The Combustion Efficiency of BioDiesel is found to be better than Diesel. An increase of 2%(approx) is observed.
1.6.2.2.3 Co2 % vs (bio-diesel & diesel)
The CO2 (%) from the exhaust gases is also found to be less than that of conventional Diesel by 0.5%
1.6.2.2.4 Co(ppm) vs (bio-diesel & diesel)
The CO(ppm) emission from the exhaust gases is found to have decreased by 7% when compared with that of conventional Diesel fuel.
1.7 Advantages of BIODIESEL
The benefits of biodiesel are:
- The lifecycle production and use of biodiesel produces approximately 80% less carbon dioxide emissions, and almost 100% less sulphur dioxide. Combustion of biodiesel alone produces over a 90% reduction in total unburned hydrocarbons, and a 75-90% reduction in aromatic hydrocarbons. Biodiesel further provides significant reductions in particulates and carbon monoxide than conventional diesel fuel.
- Biodiesel is the only alternative fuel that runs in any conventional, unmodified diesel engine.
- Needs no change in refueling infrastructures and spare part inventories.
- Maintains the payload capacity and range of conventional diesel engines.
- Diesel skilled mechanics can easily attend to biodiesel engines.
- 100% domestic fuel.
- Neat biodiesel fuel is non-toxic and biodegradable. Based on Ames Mutagenicity tests, biodiesel provides a 90% reduction in cancer risks.
- Cetane number is significantly higher than that of conventional diesel fuel.
- Lubricity is improved over that of conventional diesel fuel.
- Has a high flash point of about 300 F compared to that of conventional diesel, which has a flash point of 125 F.
1.8 Disadvantages of BIODIESEL
Some of the disadvantages of biodiesel are:
- Quality of biodiesel depends on the blend thus quality can be tampered.
- There may be problems of winter operatibility.
- Spills of biodiesel can decolorize any painted surface if left for long.
- Neat biodiesel demands compatible elastomers (hoses, gaskets, etc.)
- Biodiesel has excellent solvent properties. Any deposits in the filters and in the delivery systems may be dissolved by biodiesel and result in need for replacement of the filters.
1.9 Conclusion
Biodiesel is the only alternative fuel to have fully completed the health effects testing requirements of the Clean Air Act. The use of biodiesel in a conventional diesel engine results in substantial reduction of unburned hydrocarbons, carbon monoxide, and particulate matter compared to emissions from diesel fuel. The estimated increase of demand for diesel from the 2001-02 level of 38.815 Million tons to 52.324 Million tons is supposed to 66.095 million tons in 2006-7 which shows a massive hike of 34% to 70% respectively over 2001-02 level in physical terms which will lead to increase of crude oil import. While the country is short of petroleum reserve, it has large arable land as well as good climatic conditions (tropical) with adequate rainfall in large parts of the area to account for large crop production each year. The Indian Administration is now taking up cultivation of Jatropha Curcas in many sites of the country, especially due to its use for the fuel manufacture. So there is a bright future for this alternative fuel.
References
Technical paper on BIO-Diesel from Jatropha Oil
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