COMPARISON TO PETROL FUELS
CAN BIODIESEL BE PRODUCED
RESULT AND DISCUSSION
Need for biodiesel:
In this advancing age, the importance of fuels is tremendous. The world runs on fuels such as petroleum and diesel. Every year, billions of tones of coal and natural gas are extracted and used up. But these, being natural resources, are nearing depletion levels. The search is on for alternative sources of fuel. This is where Biodiesel comes into the picture. Biodiesel has been around for about 100 years or so. But it is not used widely like petrol and diesel.
However, the petroleum industries were able to make inroads in fuel markets because their fuel was much cheaper to produce than the biomass alternatives. The result, for many years, was a near elimination of the biomass fuel production infrastructure.
Only recently, have environmental impact concerns and a decreasing price differential made biomass fuels such as biodiesel a growing alternative.
What is biodiesel?
Biodiesel is a renewable fuel that can be manufactured from algae, vegetable oils, animal fats or recycled restaurant greases; it can be produced locally in most countries.
Biodiesel refers to a diesel-equivalent processed fuel derived from biological sources (such as vegetable oils) which can be used in unmodified diesel-engine vehicles.
Chemically, transesterified biodiesel comprises a mix of mono-alkyl esters of long chain fatty acids.
It is distinguished from the straight vegetable oils (SVO) or waste vegetable oils (WVO) used as fuels in some diesel vehicles.
It is safe, biodegradable, non-toxic and reduces air pollutants, such as particulates, carbon monoxide and hydrocarbons.
- Biodiesel is a liquid which varies in color — between golden and dark brown — depending on the production feedstock.
- Biodiesel uncontaminated with starting material can be regarded as non-toxic.
- It is practically immiscible with water, has a high boiling point and low vapor pressure. Typical methyl ester biodiesel has a flash point of ~ 150 °C (300 °F).
- Biodiesel has a density of ~ 0.88 g/cm³, less than that of water..
- Biodiesel has about 5–8% less energy density , but better lubricity and more complete combustion can make the energy output of a diesel engine only 2% less per volume when compared to petro-diesel — or about 35 MJ/L
- The flash point of biodiesel (>150 °C) is significantly higher than that of petroleum diesel (64 °C) or gasoline (−45 °C). The gel point of biodiesel varies depending on the proportion of different types of esters contained.
- However, most biodiesel, including that made from soybean oil, has a somewhat higher gel and cloud point than petroleum diesel. In practice this often requires the heating of storage tanks, especially in cooler climates.
- Biodiesel can be used in pure form (B100) or may be blended with petroleum diesel at any concentration in most modern diesel engines.
- Blends of 20 percent biodiesel with 80 percent petroleum diesel (B20) can generally be used in unmodified diesel engines. Biodiesel can also be used in its pure form (B100), but may require certain engine modifications to avoid maintenance and performance problems.
- Biodiesel can also be used as a heating fuel in domestic and commercial boilers.
Existing oil boilers may contain rubber parts and may require conversion to run on biodiesel, but the conversion process is usually relatively simple– involving the exchanging of rubber parts for synthetic ones due to biodiesel being a strong solvent.
Biodiesel will degrade natural rubber gaskets and hoses in vehicles. They should be replaced with FKM, which is nonreactive to biodiesel. However, this is more likely to occur where methanol used to catalyse the transesterification process has not been properly removed afterwards.
One should not burn B100 (pure 100% biodiesel) in an existing home heater without breaking it in, as biodiesel will dissolve coagulated heating oil, which can break off in chunks and cause problems.
The presence of water is a problem because:
- Water reduces the heat of combustion of the bulk fuel. This means more smoke, harder starting, less power.
- Water causes corrosion of vital fuel system components: fuel pumps, injector pumps, fuel lines, etc.
- Water & microbes cause the paper element filters in the system to fail ( rot), which in turn results in premature failure of the fuel pump due to ingestion of large particles.
- Water freezes to form ice crystals near 0 °C (32 °F). These crystals provide sites for nucleation and accelerate the gelling of the residual fuel.
- Water accelerates the growth of microbe colonies, which can plug up a fuel system. Biodiesel users who have heated fuel tanks, therefore, face a year-round microbe problem.
When compared to petroleum fuels:
Biodiesel typically produces about 60% less net-lifecycle carbon dioxide emissions, as it is itself produced from atmospheric carbon dioxide via photosynthesis in plants.
However, the smog forming hydrocarbon emissions are 35% greater, and the Nitrogen Oxide emissions are also greater than those from petroleum-based diesel.
Some vehicle manufacturers are positive about the use of biodiesel, citing lower engine wear as one of the fuel’s benefits.
Biodiesel’s higher lubricity index compared to petrodiesel is an advantage and can contribute to longer fuel injector life.
Biodiesel is a better solvent than standard diesel, as it ‘cleans’ the engine, removing deposits in the fuel lines. It has been known to break down deposits of residue in the fuel lines of vehicles that have previously been run on petrodiesel.
However, this may cause blockages in the fuel injectors if an engine has been previously run on petroleum diesel for years.
Conversion to Biodiesel:
Some operational problems were reported due to the high viscosity of vegetable oils compared to petroleum diesel fuel, which result in poor atomization of the fuel in the fuel spray and often leads to deposits and coking of the injectors, combustion chamber and valves.
Attempts to overcome these problems included heating of the vegetable oil, blending it with petroleum-derived diesel fuel or ethanol, pyrolysis and cracking of the oils.
Some International standards were set in order to regulate the quality of Biodiesel produced around the world.The standards ensure that the following important factors in the fuel production process are satisfied:
- Complete reaction.
- Removal of glycerin.
- Removal of catalyst.
- Removal of alcohol.
- Absence of free fatty acids.
- Low sulfur content.
Basic industrial tests to determine whether the products conform to the standards typically include gas chromatography, a test that verifies only the more important of the variables above.
Tests that are more complete are more expensive. Fuel meeting the quality standards is very non-toxic, with a toxicity rating (LD50) of greater than 50 mL/kg.
Importance of Biodiesel today:
Biodiesel is used by millions of car owners in Europe (particularly Germany).
Research sponsored by petroleum producers has found petroleum diesel better for car engines than biodiesel. This has been disputed by independent bodies, including for example the Volkswagen environmental awareness division, who note that biodiesel reduces engine wear.
Pure biodiesel produced ‘at home’ is in use by thousands of drivers who have not experienced failure, however, the fact remains that biodiesel has been widely available at gas stations for less than a decade, and will hence carry more risk than older fuels.
Many municipalities have started using 5% biodiesel (B5) in snow-removal equipment and other systems.
Biodiesel sold publicly is held to high standards set by national standards bodies.
Global biodiesel production reached 3.8 million tons in 2005. Approximately 85% of biodiesel production came from the European Union.
In the United States, biodiesel is the only alternative fuel to have successfully completed the Health Effects Testing requirements (Tier I and Tier II) of the Clean Air Act (1990).
Biodiesel is considered readily biodegradable under ideal conditions and non-toxic.
A University of Idaho study compared biodegradation rates of biodiesel, neat vegetable oils, biodiesel and petroleum diesel blends, and neat 2-D diesel fuel.
Using low concentrations of the product to be degraded (10 ppm) in nutrient and sewage sludge amended solutions, they demonstrated
Separation of droplets and solids at phase separation profiles
that biodiesel degraded at the same rate as a dextrose control and 5 times as quickly as petroleum diesel over a period of 28 days, and that biodiesel blends doubled the rate of petroleum diesel degradation through co-metabolism.
The same study examined soil degradation using 10 000 ppm of biodiesel and petroleum diesel, and found biodiesel degraded at twice the rate of petroleum diesel in soil.
In all cases, it was determined biodiesel also degraded more completely than petroleum diesel, which produced poorly degradable undetermined intermediates.
Toxicity studies for the same project demonstrated no mortalities and few toxic effects on rats and rabbits with up to 5000 mg/kg of biodiesel.
Petroleum diesel showed no mortalities at the same concentration either, however toxic effects such as hair loss and urinary discolouring were noted with concentrations of >2000 mg/l in rabbits.
Since biodiesel is more often used in a blend with petroleum diesel, there are fewer formal studies about the effects on pure biodiesel in unmodified engines and vehicles in day-to-day use.
Can Biodiesel be produced?
Chemically, transesterified biodiesel comprises a mix of mono-alkyl esters of long chain fatty acids.
The most common form uses methanol to produce methyl esters as it is the cheapest alcohol available, though ethanol can be used to produce an ethyl ester biodiesel and higher alcohols such as isopropanol and butanol have also been used. Using alcohols of higher molecular weights improves the cold flow properties of the resulting ester, at the cost of a less efficient transesterification reaction.
A lipid transesterification production process is used to convert the base oil to the desired esters. Any Free fatty acids (FFAs) in the base oil are either converted to soap and removed from the process, or they are esterified (yielding more biodiesel) using an acidic catalyst.
After this processing, unlike straight vegetable oil, biodiesel has combustion properties very similar to those of petroleum diesel, and can replace it in most current uses.
A byproduct of the transesterification process is the production of glycerol. For every 1 tonne of biodiesel that is manufactured, 100 kg of glycerol are produced. Originally, there was a valuable market for the glycerol, which assisted the economics of the process as a whole. However, with the increase in global biodiesel production, the market price for this crude glycerol (containing 20% water and catalyst residues) has crashed.
- Raw material needed for production of Biodiesel:
A variety of oils can be used to produce biodiesel. These include:
- Virgin oil feedstock; rapeseed and soybean oils are most commonly used, soybean oil alone accounting for about ninety percent of all fuel stocks; It also can be obtained from field pennycress and Jatropha other crops such as mustard, flax, sunflower, canola, palm oil, hemp, and even algae show promise.
- Waste vegetable oil (WVO);
- Animal fats including tallow, lard, yellow grease, chicken fat, and the by-products of the production of Omega-3 fatty acids from fish oil.
- Sewage. A company in New Zealand has successfully developed a system for using sewage waste as a substrate for algae and then producing bio-diesel.
Worldwide production of vegetable oil and animal fat is not yet sufficient to replace liquid fossil fuel use.
Furthermore, some environmental groups object to the vast amount of farming and the resulting over-fertilization, pesticide use, and land use conversion that they say would be needed to produce the additional vegetable oil.
- Many advocates suggest that waste vegetable oil is the best source of oil to produce biodiesel. However, the available supply is drastically less than the amount of petroleum-based fuel that is burned for transportation and home heating in the world.
- It is important to note that one gallon of waste oil is not equivalent to one gallon of biodiesel
- Although it is economically profitable to use WVO to produce biodiesel, it is even more profitable to convert WVO into other products such as soap. Therefore, most WVO that is not dumped into landfills is used for these other purposes.
- Animal fats are similarly limited in supply, and it would not be efficient to raise animals simply for their fat. However, producing biodiesel with animal fat that would have otherwise been discarded could replace a small percentage of petroleum diesel usage.
- Advantages of Biodiesel:
Biodiesel feedstock plants utilize photosynthesis to convert solar energy into chemical energy. The stored chemical energy is released when it is burned, therefore plants can offer a sustainable oil source for biodiesel production.
Most of the carbon dioxide emitted when burning biodiesel is simply recycling that which was absorbed during plant growth. So the net production of greenhouse gases is small. However, Biodiesel produces more NOx emissions than standard diesel fuel.
At the tailpipe, biodiesel emits 4.7% more CO2 than petroleum diesel”. However, if “biomass carbon [is] accounted for separately from fossil-derived carbon”, one can conclude that biodiesel reduces emissions of carbon monoxide (CO) by approximately 50% and carbon dioxide by 78% on a net lifecycle basis because the carbon in biodiesel emissions is recycled from carbon that was in the atmosphere, rather than the carbon introduced from petroleum that was sequestered in the earth’s crust.
Biodiesel contains fewer aromatic hydrocarbons:
benzofluoranthene: 56% reduction; Benzopyrenes: 71% reduction.
Biodiesel can reduce by as much as 20% the direct (tailpipe) emission of particulates, small particles of solid combustion products, on vehicles with particulate filters, compared with low-sulfur (<50 ppm) diesel.
Particulate emissions as the result of production are reduced by around 50%, compared with fossil-sourced diesel.
Biodiesel has a higher cetane rating than petrodiesel, which can improve performance and clean up emissions compared to crude petro-diesel (with cetane lower than 40).
Laboratory Synthesis of Bioediesel
Aim: Making Biodiesel from French fries oil
- Examine the container of waste fryer oil and note its appearance. Depending upon the oil, it may also be more or less solidified, because frying oils vary widely from “lard” which is an animal fat, to lighter oils such as corn or soy oil.
- Waste material in the used oil must be removed. For this purpose, a filter made of a piece of cloth may be used. Filter out about 200ml of the oil. Examine the filtered oil and note down its appearance.
- Carefully pour 1 mL of the oil into a graduated cylinder. Add enough isopropanol to it to make 10 mL, cover with a piece of parafilm and invert several times to mix. Pour the resulting solution into a 25 mL Erlenmeyer flask and cover it with parafilm, too.
- Use a small piece of pH paper to measure the pH of the solution, and note the pH in your notebook as well.
- A solution containing 1 gram of alkali per liter of water has been made and will be put in a buret. Use this buret to add 1 mL of this alkali solution to the contents of your 25 mL Erlenmeyer, cover and mix carefully by swirling. Measure the pH with pH paper. Repeat as often as necessary to cause the pH to change to around 8 or 9. Note the total volume of alkali needed.
- The concentration of the titrant was chosen so that the number of ml of titrant equals the number of extra grams of alkali needed to neutralize the free fatty acids. To this must be added the amount of alkali needed to catalyze the reaction.
- If the alkali used is to be sodium hydroxide, this will be 3.5 g of NaOH per liter of oil. If potassium hydroxide is to be used, we will need 9.0 g of KOH per liter of oil.
Add the required amount of alkali.
- Measure the amount of methanol you will need in a graduated cylinder. You’ll be assigned an amount from 10% to 20% of the oil by volume. Add that amount to a 250 mL Erlenmeyer flask and immediately cover it with a piece of parafilm so it doesn’t evaporate.
- Carefully slide a stirring bar down the side of the flask, add the alkali from your weighing boat, and cover with the parafilm. Put the flask on the stirrer and start it mixing to dissolve the alkali. It will take a few minutes to dissolve.
- Using a graduated cylinder, measure 200 mL of filtered oil and add it to the 250 mL flask while stirring. Re-cover with parafilm, and let it stir for 1 hour.Remove from the stirrer and pour your mix into a separatory funnel and cap. Be careful not to let the stirring bar drop into the separatory funnel. Let the mixture settle at least overnight.
- Use the separatory funnel to drain as much of the glycerin as you can into a graduated cylinder. It tends to coat the sides of the funnel, so it may take several minutes to get it out. Note how much you have. If there is a soap layer, drain it into a separate graduated cylinder and note its volume as well. Pour the biodiesel from the top of the funnel into another graduated cylinder and note its volume.
Intelligent micro fine filtration
- Use pH paper to check the pH of both the top biodiesel layer and the bottom glycerin layer. If there was a soap layer, check its pH as well.
- Fryer oils will have a specific gravity generally around 0.94-0.96, while biodiesel will have a specific gravity in the 0.86-0.89 range. We generally consider biodiesel specific gravities above 0.9 to be incompletely transesterified. you can weigh a small amount of the biodiesel using a volumetric flask to calculate the density, and from that the specific gravity.
- Viscosity is also an important property since most applications such as diesel engines and oil furnaces use a pump to spray the fuel into the combustion chamber. Biodiesel must have a viscosity similar to petroleum diesel to be useful in the same equipment.
- The chemicals should be handled with care to avoid any mishaps.
- Sodium hydroxide and potassium hydroxide can cause chemical burns, either from the solid form or the alcohol solutions. Therefore these must be used with caution.
- Place the esters and the glycerin in the containers provided.
- Any excess or left over vegetable oil can be put back into the Waste Fryer Oil container.
- Any excess alcohol or lye can be thrown away.
Result and Conclusion
The oil sample thus obtained is put in a small oil lamp. It is observed that the lamp burns well with less smoke. Therefore the synthesis of biodiesel has been completed successfully.
The biodiesel produced was found to be releasing very less smoke. Therefore it is less polluting. It can even be used in the common diesel engines. This will greatly reduce the emission of CO2 and other poisonous gases as exhaust from automobiles. Mass production of biodiesel from waste oil will also reduce the amount of waste oil that is dumped in pits causing a lot of pollution.
- www.franken filtertechnik kg.com/
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