|
Biodiesel is the name of a clean burning
alternative fuel, produced from domestic, renewable resources. Biodiesel
contains no petroleum, but it can be blended at any level with petroleum
diesel to create a biodiesel blend. It can be used in compression-ignition
(diesel) engines with little or no modifications. It is likewise simple
to use, biodegradable, nontoxic, and essentially free of sulfur and aromatics.
Biodiesel has been involved in various tests in attempts to see if it is actually a better form of fuel than traditional diesel fuel. The real advantages of using biodiesel lie in the reduction of petroleum consumption and greenhouse gas emissions. These advantages are independent of blend level and are proportional to the amount of B100 consumed. B100 is the pure form of biodiesel. Use of biodiesel blends can significantly reduce toxic compound emissions, but may slightly increase NOx or nitrogen oxides.
Nitrogen oxides cause the brownish-yellow haze that are occasionally seen hovering over the top of some cities. These, however play a less significant role in global warming than the other Green House Gases (GHG).
Comparison test between biodiesel and petroleum based diesel reported that biodiesel reduces carbon dioxide (CO2) and sulfur dioxide (SO2) emissions by 100%, soot emissions by 40-60%, and carbon monoxide (CO) and hydrocarbon (HC) emissions by 10-50%.
Moreover, biodiesel reduces all polycyclic aromatic hydrocarbons (PAHs) and specifically the reduction of the following carcinogic PAHs:
- phenanthren by 97%
- benzofloroanthen by 56%
- benzapyren by 71% and
- aldehydes and aromatic compounds by 13%
The use of biodiesel and biodiesel blends results in a noticeable, less offensive change in exhaust odor, which can be a real benefit in confined spaces. In fact, equipment operators have compared it to the smell of French fries. Users also report having no eye irritation.
On the other hand, it is also important to consider the disadvantages of and problems with biodiesel. First, it is currently expensive. Second, the use of biodiesel produced from agricultural crops involve additional land use, as land area is taken up and various agricultural inputs with their environmental effects are inescapable. Even modest usages of biodiesel would consume almost all cropland in some countries in Europe. If the same thing will happen all over the world, the impact on global food supply could be a major problem. Third, biodiesel gives out more nitrogen oxide emissions but which can be reduced by blending kerosene or Fischer-Tropsch diesel to biodiesel. Fourth, biodiesel is less suitable for use in low temperatures than petrodiesel. The so-called 'cloud point' is the temperature at which a sample of the fuel starts to appear cloudy, indicating that wax crystals have begun to form. At even lower temperature, the fuel becomes a gel that cannot be pumped. The 'pour point' is the temperature below which the fuel will not flow. Vehicles running on biodiesel blends may therefore exhibit more problems in their driving ability at less severe winter temperatures than vehicles running on petroleum diesel. Lastly, biodiesel may tend to reduce fuel economy. The energy content per gallon of biodiesel is approximately 11% lower than that of petroleum diesel. Vehicles running on biodiesel are therefore expected to achieve about 10% fewer miles per gallon of fuel than petrodiesel.
|
