History
Transesterification of a vegetable oil was conducted as early as
1853, by scientists E. Duffy and J. Patrick, many years before the first diesel engine became functional.
Rudolf Diesel's prime model, a single 10 ft (3 m) iron cylinder with a flywheel at its base, ran on its own power for the first time in Augsburg, Germany on August 10, 1893. In remembrance of this event, August 10 has been declared International Biodiesel Day. Diesel later demonstrated his engine at the World Fair in Paris, France in 1898. This engine stood as an example of Diesel's vision because it was powered by peanut oil—a biofuel. He believed that the utilization of a biomass fuel was the real future of his engine.
In a 1912 speech, Rudolf Diesel said, "the use of vegetable oils for engine fuels may seem insignificant today, but such oils may become, in the course of time, as important as petroleum and the coal-tar products of the present time."
During the 1920s, diesel engine manufacturers created a major challenge for the biofuel industry. Diesel engines were altered to utilize the lower viscosity of the fossil fuel (petrodiesel) rather than a biomass fuel (vegetable oil). The petroleum industries were growing and establishing themselves during this period.
Some see a conspiracy here and argue that the business tactics and the wealth that many of these "oil tycoons" already possessed greatly influenced the development of all engines and machinery. The alteration was the first step in the elimination of the production infrastructure for biomass fuels. Some see this as the first step in forcing the concept of biomass as a potential fuel base into obscurity, erasing the possibilities from the public awareness.
However, others have pointed out that fossil diesel is simply cheaper than vegetable oil, and that no conspiracy is necessary to explain the move toward fossil fuels.
In the 1990s, France launched the local production of biodiesel fuel (known locally as diester) obtained by the transesterification of rapeseed oil. It is mixed to the proportion of 5% into regular diesel fuel, and to the proportion of 30% into the diesel fuel used by some captive fleets (public transportation). Renault, Peugeot and other manufacturers have certified truck engines for use with up to this partial biodiesel. Experiments with 50% biodiesel are underway.
From 1978 to 1996, the U.S National Renewable Energy Laboratory experimented with using algae as a biodiesel source in the "Aquatic Species Program". A recent paper from the UNH Biodiesel Group, [1] offers calculations for the realistic replacement of all vehicular fuel with biodiesel by utilizing algae that has an over 50% natural oil content.
Fuel quality, standards and properties
Biodiesel is a clear amber-yellow liquid with a viscosity similar to petrodiesel (the industry term for diesel produced from petroleum). Much of the world uses a system known as the "BD factor" to state the amount of biodiesel in any fuel mix, in contrast to the "BA" system used for bioalcohol mixes. For example, 20% biodiesel is labeled BD20. Pure biodiesel, 100%, is referred to as BD100. In the United States, a similar system is used, but the "D" is dropped (B100, B20, B5, etc.).
The international standard for biodiesel is ISO 14214. In Germany, the requirements for biodiesels are fixed in a DIN standard. There are three different sorts of biodiesel, which is made of different oils:
- RME (rapeseed methyl ester, from rape products, according to DIN E 51606)
- PME (vegetable methylester, purely vegetable products entspr. DIN E 51606)
- FME (fat methyl ester, vegetable and animal products entsp. DIN V51606)
Biodiesel can be mixed with petroleum diesel at any concentration in most modern engines, although it has the disadvantage of degrading rubber gaskets and hoses in older vehicles (prior to 1992). Biodiesel is a better solvent than petrodiesel and has been known to break down deposits of residue in fuel lines of vehicles that usually run on petroleum. Fuel filters may become clogged with particulates if a quick transition to pure biodiesel is made, but the biodiesel cleans the engine in the process.
In a study at a U.S. military base, a biodiesel blend was used as a replacement for heating oil at housing on the base. Due to the solvent power of biodiesel, residues that had been present in fuel tanks for decades were dissolved. The particulate component of the residues caused repeated clogging of fuel strainers, requiring repeated replacement, cleaning, and in some cases installation of higher capacity filters. Due to the relatively smaller surface area and service life of fuel tanks in motor vehicles and mobile equipment, filter clogging is less prevalent but still a factor to be considered.
Properties necessary for biodiesel to ensure trouble-free operation in diesel engines are:
- Complete reaction.
- Removal of glycerin.
- Removal of catalyst.
- Removal of alcohol.
- Absence of free fatty acids.
The basic industrial tests includes gas chromatography that verifies only the really more important variables (glycerides,...). More complete testings cost more.
- Biodiesel reduces emissions carbon monoxide (CO) by approximately 50% and carbon dioxide by 78.45%.
- Biodiesel contains less aromatic hydrocarbons: benzofluoranthene: 56%; Benzopyrenes: 71%.
- It also eliminates sulfur emissions (SO2), because biodiesel doesn't include sulfur.
- Reduces by as much as 65% the emission of particulates (small particles).
- Biodiesel does produce more NOx emissions than petrodiesel, but these emissions can be reduced through the use of catalytic converters. Petrodiesel vehicles have generally not included catalytic converters because the sulfur content in that fuel destroys the devices, but biodiesel does not contain sulfur.
- It has a higher cetane rating (less knocking) than petrodiesel
Pure biodiesel (BD100 or B100) can be used in any petroleum 
