Biodiesel - Environmental Benefits of Biodiesel
Environmental Benefits of Biodiesel
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Environmental Benefits in comparison to petroleum based fuels include:
Biodiesel reduces emissions of carbon monoxide (CO) by approximately 50% and carbon dioxide by 78.45% on a net basis because the carbon in biodiesel emissions is recycled from carbon that was already in the atmosphere, rather than being new carbon from petroleum that was sequestered in the earth's crust.
Biodiesel contains fewer aromatic hydrocarbons: benzofluoranthene: 56% reduction; Benzopyrenes: 71% reduction. It also eliminates sulfur emissions (SO2), because biodiesel doesn't include sulfur. Biodiesel reduces by as much as 65% the emission of particulates (small particles of solid combustion products).
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. The increase in NOx emmisions may also be due to the higher cetane rating of biodiesel. Properly designed and tuned engines may eliminate this increase. It has a higher cetane rating than petrodiesel, and therefore ignites more rapidly when injected into the engine.
Pure biodiesel (BD100 or B100) can be used in any petroleum diesel engine, though it is more commonly used in lower concentrations. Some areas have mandated ultra-low sulfur diesel (ULSD) petroleum, which reduces the natural viscosity and lubricity of the fuel because the sulfur and certain other materials have been removed. Additives are required to make it properly flow in engines, and biodiesel is one popular alternative. Ranges as low as 2% (BD2 or B2) have been shown to restore lubricity. Also, many municipalities have started using 5% biodiesel (BD5 or B5) in snow-removal equipment and other systems.
Since biodiesel is more often used in a blend with petroleum diesel, there is less information and formal studies about the effects on pure biodiesel in unmodified engines and vehicles in actual use. Fuel meeting the standards and engine parts that can withstand the greater solvent properties of biodiesel is expected to, and in reported cases does, run without any additional problems over petroleum diesel.
The gel point of biodiesel varies depending on the proportion of different types of esters that it contains. However, most biodiesel including that made from soybean oil has a somewhat higher gel and cloud point than petroleum diesel. In practice this often requires the heating of storage tanks, especially in colder climates.
From Wikipedia.