Deornwulf
Member
- Nov 10, 2004
- 153
- 28
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With the latest advances in Bio-fuels, the worries over the declining supply of oil in the world should disappear.
So why isn't use more widespread? A dramatic switch to biofuels would be too disruptive to world markets, for both the oil trade and the trade of the organic materials used in the fuels. Cost is also a factor, coming in at approximately $3 per gallon to the consumer. However, it is comforting to know that an oil crisis would not be crippling.
Biodiesel is not a new fuel in North America. In fact, biodiesel activities date back to the late 70's and early 80's. Since the oil embargo of 1973 by the Organization of Petroleum Exporting Countries (OPEC), a significant amount of research on biodiesel and other domestically produced fuel has been conducted by various universities, government agencies, and research organizations. The general conclusion is that biodiesel is a technically acceptable blending stock for conventional petroleum diesel. The cost of using biodiesel is quite economical when compared to the total cost to use other alternative fuels.
Energy Policy Act (EPACT) regulations require certain fleets to purchase alternative fueled vehicles and to consume alternative fuels. Now fleets can receive one vehicle compliance credit for each 450 gallons of biodiesel consumed in medium and heavy duty diesel vehicles. This EPACT rule as well as concern over the health impacts of diesel fuel exhaust, and proposed regulations has spurred the recent activities to commercialize biodiesel in North America. A new partial excise tax exemption approved in October 2004 will also spur consumer acceptance.
WHAT IS BIODIESEL?
Biodiesel is defined as the mono alkyl esters of long chain fatty acids derived from renewable lipid sources. Biodiesel is typically produced through the reaction of a vegetable oil or animal fat with methanol in the presence of a catalyst to yield glycerin and biodiesel (chemically called methyl esters). Biodiesel is registered with the US Environmental Protection Agency as a pure fuel or as a fuel additive and is a legal fuel for commerce. Biodiesel is an alternative fuel which is typically blended with petroleum diesel for use in compression ignition (diesel) engines. Its physical and chemical properties as it relates to operation of diesel engines are similar to petroleum based diesel fuel.
BIODIESEL ATTRIBUTES
Emissions Reductions
The use of biodiesel in a conventional diesel engine results in substantial reduction of unburned hydrocarbons, carbon monoxide, and particulate matter. Emissions of nitrogen oxides are either slightly reduced or slightly increased depending on the duty cycle and testing methods. Particulate emissions from conventional diesel engines can be divided into three components. Each component is present in varying degrees depending on fuel properties, engine design and operating parameters. Also, the use of biodiesel reduces CO2 in the atmosphere, since growing soybeans consumes nearly four times as much CO2 as the amount of CO2 produced from biodiesel exhaust.
Lubricity
With the lubricity of conventional diesel fuel being scrutinized due to processing changes required to reduce the sulfur and aromatic content of diesel fuel, biodiesel use can be demonstrated to be a benefit. Lubricity test utilizing both the High Frequency Reciprocating Rig (HFRR) and the Ball On Cylinder Lubricity Evaluator (BOCLE) have demonstrated the lubricity advantage of biodiesel.
Tests have also been conducted on Jet A-1 fuel. These test results from a leading independent research institute concluded that biodiesel shows significant lubricity improvement compared to diesel fuel.
Biodegradability
Biodiesel also has desirable degradation attributes. Studies at the University of Idaho have been conducted to determine the biodegradation of biodiesel in an aqueous solution. biodiesel was compared to diesel fuel and dextrose. Biodiesel samples degraded more rapidly than the dextrose control and were 95 percent degraded at the end of 28 days. The diesel fuel was approximately 40 percent degraded after 28 days.
Another study conducted at the University of Idaho tested the "Biodegradability of Biodiesel in the Aquatic Environment" by the CO2 evolution method and gas chromatography (GC), comparing the results with regular diesel. According to the University of Idaho's report, under aerobic conditions and nutrient supply (N, P), microorganisms will metabolize a substance to two final products, CO2 and water. Therefore, CO2 is presumed to be the prevalent indicator of organic substance breakdown. If the substrate is the only carbon source, the amount of CO2 evolved will be proportional to the carbons consumed by microorganisms from the test substrate. Thus, the percentage of CO2 evolution is proportional to the percentage of substrate degradation.
The maximum percent CO2 evolution from several samples of biodiesel produced were between 85.54-88.49 percent in 28 days, the same as that of dextrose, indicating there is no difference in their biodegradability. Yet, the CO2 evolution from the diesel flasks was only 26.24 percent. It should also be noted that biodiesel blends accelerate the biodegradability of No. 2 diesel. For example a 20% biodiesel blend degrades twice as fast as No. 2 diesel. This illustrates that biodiesel use has demonstrated biodegradability benefits at levels lower than 100%.
Toxicity
Impacts on human health represent a significant criteria as to the suitability of a fuel for commercial applications. Health effects can be measure in terms of fuel toxicity to the human body as well as health impacts due to exhaust emissions. Tests conducted by Wil Research Laboratories, Inc. investigated the acute oral toxicity of pure biodiesel fuel as well as a 20% blend of biodiesel with No. 2 diesel (B20) in a single-dose study on rats. the LD50 of pure biodiesel, as well as B20, was found to be greater than 5000 mg/kg, although hair loss was noted on one sample in the B20 group. The acute dermal toxicity of neat biodiesel was evaluated in a single dose study involving rabbits. The LD50 of biodiesel was found to be greater than 2000 mg/kg and the 2000 mg/kg dose level was found to be a No Observable Effect Level (NOEL) for systemic toxicity.
Acute aquatic toxicity tests with Daphnia Magna have also been conducted. Table salt (NaCl), diesel and biodiesel were compared to each other. The LC50 count (the concentration where 50 percent of the Daphnia Magna have died and 50 percent were still alive) for table salt was 3.7 parts per million (ppm). Fifty percent of the Daphnia Magna were dead at 1.43 ppm for diesel fuel. The LC50 number varied for biodiesel from 23 ppm to 332 ppm. There biodiesel is less toxic than diesel fuel.
So why isn't use more widespread? A dramatic switch to biofuels would be too disruptive to world markets, for both the oil trade and the trade of the organic materials used in the fuels. Cost is also a factor, coming in at approximately $3 per gallon to the consumer. However, it is comforting to know that an oil crisis would not be crippling.