BioDiesel is clean fuel for Diesel engines. It can be manufactured from renewable source such as vegetable oil, animal fat, recycled food oil, organic gas like methane and CO, etc. BioDiesel can be used as 100% fuel oil or mixed with fossil Diesel using in Diesel engines. For the physical and chemical characteristics of bioDiesel and fossil Diesel is similar, it can be used in Diesel engines.
The major reasons for the use of bioDiesel and bio-mixed Diesel is that, without affecting the functions, it fulfills the three essential requirements for meeting energy demand, being environment friendly, and being safely used. There are outstanding features for bioDiesel but till today for automobile industry, the most promising features are the similar use efficiency and no need for facility or maintenance procedures change. The other characteristics of bioDiesel and bio-mixed Diesel are described in details below.
Comparing the biodegradation of bioDiesel and the normal Diesel in clean water, the results show that 95% bioDiesel is degraded while Diesel is degraded 40% in 28 days. In addition, the degradation effect is increased for the mixture of bioDiesel and Diesel. A good example is that mixing 20% bioDiesel with 80% Diesel, the degradation speed is twice as fast as No. 2 Diesel. BioDiesel is thus proved superior biodegradability.
The flash point of pure bioDiesel is over 100oC while that of fossil Diesel is 50-80oC. The flash point of the mixture of bioDiesel and fossil Diesel will be higher as increasing the addition of pure bioDiesel. It therefore shows that pure bioDiesel and bio-mixed Diesel are safer than traditional fossil Diesel in storage, management and use.
The tests on mice for intake toxicity study by Wil Research Laboratories, Inc. on pure bioDiesel and B20 mixture of 20%v/v bioDiesel and 80%v/v fossil Diesel. The results show that LD50 of higher than 5,000mg/kg for both pure bioDiesel and B20. The aquatic animals Daphnia Magma are tested for toxicity tests by using edible salt, fossil Diesel, and bioDiesel. The LC50 is 3.7ppm for edible salt, 1.43ppm for fossil Diesel, and 23-332ppm for bioDiesel. It thus shows bioDiesel is much less toxic than Diesel.
Due to the requirements of low-sulfur Diesel, sulfur content limit of 0.05 w/w% by EPA of United States, the problems that automobile industry facing are out of date or unsuitable for injection pumps. The pump manufacturers start to suggest use additive lubricant in order to reduce the damage of injection pumps by low-sulfur Diesel. There are engine tests made by Southwest Research Institute and Stanaddyne Corporation of US. The results indicate that if only the addition of small amount of esterified bioDiesel, lower than 1%, significant improvement for lubrication effects will be obtained.
Because oxygen contained in bioDiesel can help complete oxidation and CO2 production, the hydrocarbon compounds and carbon oxide emission is both reduced significantly. Hence the use of bioDiesel can decrease the production of suspended carbon particles. In addition, if the soluble organic particles or hydrocarbon contained in the suspended particles remain the same or increase, use of bioDiesel can further prevent from sulfate production. Thus the benefits of bioDiesel is, besides reducing contaminate and carbon emission, less damage to human health than fossil Diesel. Furthermore, the polycyclic aromatic hydrocarbon (PAH) and nitropolycyclic aromatic hydrocarbon of Diesel exhaust have been considered potential carcinogen. In comparison to fossil Diesel from other studies, bioDiesel can reduce up to 75-85% of PAH, with the exception of benzo(a)anthracene, which was reduced by 50%. The nPAH compounds of 2-nitrofluorene and 1-nitropyrene can be reduced to 90%, leaving the rest of the nPAH trace amount. All the reduction performance is contributed to bioDiesel containing no aromatic compounds. Likewise bioDiesel has similar reduction effects on NOx with exception of esterified bioDiesel. Additionally comparing the hydrocarbon contained in all types of bioDiesel and fossil Diesel, the former can be decreased by almost 50% and the corresponding ozone is reduced by the same amount.
In general, the storage and management for fossil Diesel can be applied to bioDiesel. Fuel should be stored in clean, dry, and dark environment with extreme temperature prevention. The material for storage tank is stainless steel, polyvinyl chloride, poly propylene chloride, etc. BioDiesel has solubility to other materials, causing the sediment in the tanks and piping to block the filters which prevention is needed.