COMPARISON BETWEEN BIO-FUEL AND PETROLEUM DIESEL
The molecule size of biodiesel and petroleum diesel are similar, but they are different in chemical structure. Biodiesel molecules consist of chemicals known as fatty acid methyl esters, also known as FAME. FAME contains unsaturated un saturated olefin components. In contrast, the petroleum diesel consists of 95 percent of saturated hydrocarbons and 5 percent of aromatic compounds. This difference in chemical structure and composition between the two fuels causes variation in the physical properties of both the fuels.
One of the advantages of using biodiesel instead of petroleum diesel is biodiesel has higher lubricity than petroleum diesel. As a result, the lubricity reduces engine wear and friction which increases the lifespan of an engine. Biodiesel contains an ignorable small amount of sulphur, compared to petroleum diesel that contains a lot of sulphur. This also means it can reduce the pollution from engines that use biodiesels. Biodiesels are very much less toxic compared to petroleum diesel, this is an advantage when cleaning up the oil spills. In addition, Biodiesel has a higher oxygen content of 10 to 12 percent than the petroleum diesel which results in lower pollution emissions. However, this slight reduction in oxygen cont ent causes a reduced peak engine power of approximately 4 percent. Biodiesels can also reduce the greenhouse gas emissions by a tremendous amount. The burning of fossil fuels increases the carbon dioxide levels and other greenhouse gases that trap h eat in the Earth’s atmosphere. Greenhouse bene fits are very significant for 100% biodiesel fuels. There is a huge reduction of up to 90 percent of greenhouse gas emissions compared to petroleum-derived diesel. The air pollutants that are reduced includes particulate matter, carbon monoxide, hydrocarbons, sulfur oxides, nitrogen oxides and air toxics. The reduced particulate and unburned hydrocarbon emissions are a welcome relief in environment where workers and pedestrians are near to diesel engines, such as construction site or public transport. The biodiesel emission studies have been conduct ed for 20 years. Biodiesel is the first and only alternative fuel to be evaluated by the EPA under the Clean Air Act Section 211(b). This study examined the impact of hundreds hun dreds of exhaust emissions (regulated and non-regulated) and the potential health effects by these emissions. The results are shown below. According to
the table below, the biodiesel is better than the petro-diesel in every way as it is cleaner and have lesser emissions of hazardous gasses or particulate matters.
Average exhaust emissions for 100% Biodiesel compared to P etro-Diesel Fuel Regulated exhaust emissions B100 (100% biodiesel) Particulate Matter
-47%
Carbon Monoxide
-48%
Total unburned hydrocarbons
-67%
Nitrogen oxides
Almost the same
Non regulated emissions Sulfates
-100%
Polycyclic Aromatic Hydrocarbons
-80%
Nitrated polycyclic aromatic hydrocarbons
-90%
Speciated hydrocarbons ozone forming
-50%
potential
Moreover, when high blends of biodiesel are u sed, the gas from the exhaust of the diesel engines has been reportedly described to smell like fried food (especially French fries) which is a great relieve compared to the foul smell of diesel fuel exhaust. Furthermore, using biodiesel can reduce the dependence on foreign imported petroleum. For countries such as United States that has a great demand for gasoline and diesel fuel relies on petroleum for energ y. Biodiesel can be produced domestically from agricultural oils and waste fats and oils. In short, biodiesel is able to reduce their demand for petroleum. Biodiesel is also fairly easy to use, all diesel engines can use the biodiesel without modification, unlike other green fuels. Th e availability of the biodiesel is also increasing by the minute. More and more fueling stations in other countries are selling biodiesel. There is also the life cycle reduction of the carbon dioxide gases. Biodiesel helps to reduce the risk of the global warming. This is done by reducing the net carbon emission to the atmosphere. Biodiesels release carbon dioxide to the surrounding atmosphere when it is burned. However, considering the crops that are used to produce biodiesel absorbs carbon dioxide from
the atmosphere in their growth cycle. A joint study conducted by the U.S. Department of Agriculture and the U.S. Department of Energy concluded that biodiesel reduces the net carbon dioxide emissions to the atmosphere by a huge amount of 78.5% comparing with the petro-diesel fuel.
Of course, biodiesel is not completely perfect, it also has some weakness. One of the disadvantages is the Biodiesel would thicken and gel up at low temperatures more easily compared with petroleum diesel. This causes problems to the engines of the vehicle especially during the winter. But this problem can be overcome by blending the biodiesel with the winterized diesel fuel. Another problem of using biodiesel is that it tend to oxidize to form a semisolid gel-like mass. This causes problems for storing the fuels and using engines that are operated less frequently.
To reduce the problems faced by both the petroleum diesel and the bio-diesel, both the fuels are normally blended together. This is possible due to biodiesel and petroleum diesel blends easily with each other. In general, the properties of the blend will lie somewhere between the properties of both the fuels. These blends are generally used to improve the lubricity of the petroleum diesel and reduce its sulphur content. The blends are very useful to improve its coldoperating characteristics in the winter. For example, 70 percent of biodiesel mixed with 30 percent of petroleum diesel is very effective for winter conditions.
PERFORMANCE COMPARISON
Most alternative fuels introduced faced difficulty to gain acceptance or popularity due to the fact that they are not able to provide performance to the engine like the petroleum counterparts. Pure biodiesel or biodiesel blended with petro-diesel provides similar horsepower, torque and fuel mileage compared to the petro-diesel fuel. In pure biodiesel, they have energy content of 5% to 10% lower than the conventional petroleum diesel fuel. The only problem faced is that different biodiesel will have different quality that provides different level of performance and they can vary up to 15% from one supplier to the next. The lower energy content of the
biodiesel will only cause very slightly reduced performance when biodiesel is used in 100% pure form, even though users reported very little noticeable change in the performance of the engine or mileage. If the biodiesel are blended with petroleum at B20 level (20% biodiesel), there is less than 2% change in fuel energy content, users typically reported to have not noticed any change in mileage.
The injection system of most diesel engines depend on the fuel to lubricate itself. Lubricity is the degree to which the fuel can provide proper lubrication. Low lubricity petroleum diesel fuel can cause decreased performance of the engine and premature failure of injection system components. This is where biodiesel is advantageous, it p rovides excellent lubricity to the fuel injection system. Biodiesel blended with an amount as little as 5% can drastically improve the lu bricity of ultra low sulfur diesel and the engine’s fuel injection system life can be extended.
The ratio of the amount of energy required to produce, distribute and refine the fuel comparing to the amount of energy the fuel releases when its burned is identified as the energy balance of a fuel. The energy balance is used to determine how “renewable” a fuel is. A higher ratio of energy balance indicates a lower environmental impact because less fossil energy is needed to produce, distribute and refine the fuel. Biodiesel is found to be having a high energy balance compared to other alternative fuels. In the joint study, it is found that biodiesel releases 3.2units of energy for one unit of fossil fuel energy used to produce it. To compare with this value, the petro-diesel fuel has only a small 0.83 units of energy for every unit of fossil fuel energy that is used to produce it. This proves that biodiesel has really good energy balance compared to petro-diesel.
IMPORTANCE OF BIOFUEL Energy security is very important worldwide, in government and society. Every developing and advanced country depends on imports of various forms of energy which includes oil, natural gas and coal. A steady supply of energy is important for a country’s economy to develop, fuel for transportation, enough energy to run power plants, factory or heat homes. Biodiesel can improve the energy security in several ways.
When the crops are grown in the country where the fuel is consumed, each gallon of biodiesel displaces a gallon of imported crude oil from other countries. This can effectively reduce the country’s dependence on foreign oil supplies. Besides that, with the production of biodiesel that is distributed and used locally, it makes the country a much more difficult target for potential terrorist attack than large centralized facilities like oil refineries or pipelines used in the petroleum industry.
Biodiesel is much safer to handle compared to petroleum due to its low volatility. The high energy content of the liquid fuels makes it dangerous if an accidental ignition occurs when the fuel is being transferred or stored. The chance of an accidental ignition occurring is related to the temperature at which the fuel will create v apors to ignite, also known as the flash point temperature. The lower the flash point of the fuel, the lower the temperature at which the fuel can form a combustible mixture. As an example, gasoline has a flash point of -40 Fahrenheit, therefore gasoline can form combustible mixture at -40 Fa hrenheit. However, biodiesel has a really high flashpoint of more than 266 Fahrenheit. This also means that it cannot form a combustible mixture easily until it is heated so much more than the boiling point of the water. It is very rare for fuel to be subjected to these types of conditions, which makes biodiesel very much safer to store, handle and transport than the petro-diesel. Another importance of the bio-diesel is the biodiesel can recycle the waste products of many different oils and fats. Waste cooking oil c an be converted into high quality biodiesel using a process employed by various companies such as Pacific Biodiesel Technologies. As a result, the recycling of these oils are more cost effective, and their values were also increased significantly. The waste oils destined for sewers or landfills were also properly recycled to turn them into something useful.
The biodiesel that is created from local resources, it’s production and use can provide various economic benefits for the local communities. The locally available feedstocks are collected, converted to biodiesel, then they are distributed and used within the communit y. This process keeps energy dollars to stay in the community instead of sending them to foreign oil producers and refineries outside the community. There will also be a lot of job vacancies created for the feedstock farming and collection, skilled jobs for biodiesel produ ction and distribution. In addition, it will produce income for the local feedstock producers and refiners. To conclude, there will be multiple beneficiaries of the production of b iodiesel.
CONCLUSION In conclusion, the benefits for using the biodiesel fuel are so much better than petroleum diesel in every way. Besides the benefits to the environment and making our planet more green, it also creates a lot of job opportunities and improve our lives. Therefore, we should continue to develop the biodiesel technologies so that someday the whole world can use biodiesel instead of petroleum diesel.
REFERENCE http://biomass-sp.net/wp-content/uploads/2013/05/6B-Sime-Darby.pdf http://www.greenfuelonline.com/biofuel http://www.greenfuel.co.zw/index.php?option=com_content&view=article&id=3 http://en.wikipedia.org/wiki/Biofuel http://www.wisegeek.com/what-is-green-fuel.htm http://www.nrel.gov/docs/legosti/fy98/24772.pdf http://www.rta.nsw.gov.au/heavyvehicles/downloads/greentruck/case-study-biodiesel.pdf http://www.petrolprices.com/green-fuels.html http://www.biodiesel.com/index.php/biodiesel/biodiesel_benefits_why_use_biodiesel#easy
