About Biodiesel

Biodiesel refers to a non-petroleum-based diesel fuel consisting of short chain alkyl (methyl or ethyl) esters, made by transesterification of vegetable oil, which can be used (alone, or blended with conventional petrodiesel) in unmodified diesel-engine vehicles. Biodiesel is distinguished from the straight vegetable oil (SVO) (aka "waste vegetable oil", "WVO", "used vegetable oil", "UVO", "unwashed biodiesel", "pure plant oil", "PPO") used (alone, or blended) as fuels in some converted diesel vehicles. "Biodiesel" is standardized as mono-alkyl ester and other kinds of diesel-grade fuels of biological origin are not included.[1]

Blends

Blends of biodiesel and conventional hydrocarbon-based diesel are products most commonly distributed for use in the retail diesel fuel marketplace. Much of the world uses a system known as the "B" factor to state the amount of biodiesel in any fuel mix: fuel containing 20% biodiesel is labeled B20, while pure biodiesel is referred to as B100. It is common to see B99, since 1% petrodiesel is sufficiently toxic to retard mold. 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. Blending B100 with petro diesel may be accomplished by:

• Mixing in tanks at manufacturing point prior to delivery to tanker truck

• Splash mixing in the tanker truck (adding specific percentages of Biodiesel and Petro Diesel)

• In-line mixing, two components arrive at tanker truck simultaneously.

Origin

On August 31, 1937, G. Chavanne of the University of Brussels (Belgium) was granted a patent for a 'Procedure for the transformation of vegetable oils for their uses as fuels' (fr. 'Procédé de Transformation d’Huiles Végétales en Vue de Leur Utilisation comme Carburants') Belgian Patent 422,877. This patent described the alcoholysis (often referred to as transesterification) of vegetable oils using ethanol (and mentions methanol) in order to separate the fatty acids from the glycerol by replacing the glycerol with short linear alcohols. This appears to be the first account of the production of what is known as 'biodiesel' today.[2]

Applications

Biodiesel can be used in pure form (B100) or may be blended with petroleum diesel at any concentration in most modern diesel engines. Biodiesel has different solvent properties than petrodiesel, and will degrade natural rubber gaskets and hoses in vehicles (mostly found in vehicles manufactured before 1992), although these tend to wear out naturally and most likely will have already been replaced with FKM, which is nonreactive to biodiesel. Biodiesel has been known to break down deposits of residue in the fuel lines where petrodiesel has been used.[3] As a result, fuel filters may become clogged with particulates if a quick transition to pure biodiesel is made. Therefore, it is recommended to change the fuel filters on engines and heaters shortly after first switching to a biodiesel blend.

As a Heating Oil

Biodiesel can also be used as a heating fuel in domestic and commercial boilers, sometimes known as bioheat. Older furnaces may contain rubber parts that would be affected by biodiesel's solvent properties, but can otherwise burn biodiesel without any conversion required. Care must be taken at first, however, given that varnishes left behind by petrodiesel will be released and can clog pipes- fuel filtering and prompt filter replacement is required. Another approach is to start using biodiesel as blend, and decreasing the petroleum proportion over time can allow the varnishes to come off more gradually and be less likely to clog. Thanks to its strong solvent properties, however, the furnace is cleaned out and generally becomes more efficient. A technical research paper (4) describes laboratory research and field trials project using pure biodiesel and biodiesel blends as a heating fuel in oil fired boilers. During the Biodiesel Expo 2006 in the UK, Andrew J. Robertson presented his biodiesel heating oil research from his technical paper and suggested that B20 biodiesel could reduce UK household CO2 emissions by 1.5 million tons per year.

Physical Properties

Biodiesel has better lubricant than that of today's diesel fuels. During the manufacture of these, to comply with low SO2 engine emission limits set in modern standards, severe hydrotreatment is included. Biodiesel addition reduces wear[5] increasing the life of the fuel injection equipment that relies on the fuel for its lubrication, such as high pressure injection pumps, pump injectors (also called unit injectors) and fuel injectors.

The calorific value of biodiesel is about 33 MJ/L. This is 9 % lower than regular Number 2 petrodiesel. Variations in biodiesel energy density is more dependent on the feedstock used than the production process. Still these variations are less than for petrodiesel.[6] It has been claimed biodiesel gives better lubricity and more complete combustion thus increasing the engine energy output and partially compensating for the higher energy density of petrodiesel.[7]

Biodiesel is a liquid which varies in color — between golden and dark brown — depending on the production feedstock. It is immiscible with water, has a high boiling point and low vapor pressure. *The flash point of biodiesel (>130 °C, >266 °F)[8] is significantly higher than that of petroleum diesel (64 °C, 147 °F) or gasoline (−45 °C, -52 °F). Biodiesel has a density of ~ 0.88 g/cm³, less than that of water.

Biodiesel has a viscosity similar to petrodiesel, the current industry term for diesel produced from petroleum. Biodiesel has high lubricity and virtually no sulfur content, and it is often used as an additive to Ultra-Low Sulfur Diesel (ULSD) fuel.

Biodiesel is 3 1/2 times more energy efficient than bioethanol[9].

References

1. ^ Biodiesel 101 - Biodiesel Definitions (?). National Biodiesel Board. Retrieved on 2008-02-16.
2. ^ Knothe, G.. Historical Perspectives on Vegetable Oil-Based Diesel Fuels (PDF). INFORM, Vol. 12(11), p. 1103-1107 (2001). Retrieved on 2007-07-11.
3. ^ McCormick, R.L.. 2006 Biodiesel Handling and Use Guide Third Edition (PDF). Retrieved on 2006-12-18.
4. ^ Robertson, Andrew. Biodiesel Heating Oil: Sustainable Heating for the future. Institute of Plumbing and Heating Engineering. Retrieved on 2008-01-07.
5. ^ Biodiesel
6. ^ National Biodiesel Board (2005-10). "Energy Content".: 1. Retrieved on 2007-11-20. 
7. ^ UNH Biodiesel Group
8. ^ Generic biodiesel material safety data sheet (MSDS)
9. ^ http://www.silsbeebee.com/news.php?viewStory=283