Engine Test of Bio-Diesel Manufactured from Waste Cooking Oil and Reward Preferential Benefit Analyses for Its Promotion

Abstract

The main problem for current biodiesel is high cost. According to the statistics, 70% of manufacturing cost of biodiesel is from feedstock. So using cheep feedstock and raise the transerification rate to reduce cost is the key for the manufacturing biodiesel. But there are following shortcomings for adopting chemical method to synthesize biodiesel: complicated manufacturing process, excess of alcohol; the follow-up process must have corresponding alcohol retrieval device, high energy-consuming, dark colour because the quality of the unsaturated fatty acid is easy to change under high temperature; difficult to retrieve esterified products, high cost; there is waste alkali liquid emission in the manufacturing process. To solve above-mentioned problems, some researcher have begun to use bio-enzyme to synthesize biodiesel, that is, use animal and plant fatty and low carbon alcohol to conduct transerification reaction through fatty acid and manufacture corresponding fatty acid: methyl and ethyl. The biodiesel synthesized by enzyme method has moderate condition, that is, low transerification rate, 40% to 60% in general. At present time, the fatty acid is effective in the esterificaiton or transerification of long chain fatty alcohol and low esterification rate for short chain fatty alcohol such as methanol and ethanol. Besides, short chain alcohol is poisonous to enzyme that the enzyme life is short. The difficulty to retrieve its by-products glycerol and water constrains the product. The glycerol is poisonous to immobilized enzyme that shortens the life of immobilized enzyme. So it is necessary to develop new immobilization method for fatty enzyme and esterification process to manufacture high quality and low cost biodiesel. Developing biodiesel by biocatalyst transerificaiton is one of new process that is developing in the world. Using biocatalyst to conduct the esterification production of biodiesel could essentially be divided into extracellular enzyme and intracellular enzyme. There already had many researches on the extracellular reaction. Akoh et al., Who had tested many fatties to dissolve enzyme, found that dissolving enzyme had the best effectiveness [1]. Knothe et al (2000) also offered pre-processing method for fatty ester composition [2]. Wu, W.T. et al. also conducted researches on the enhancement of activity of enzyme in commercialized enzyme Novozyme435 [3]. The biggest shortcoming of extracellular reaction is that the enzyme has to go through the process of isolation and purification that is complicated in