Biodiesel is a fatty acid methyl ester produced by transesterification of vegetable oils with methanol and is a clean biofuel, also known as "regenerated fuel". At present, Brazil is vigorously promoting the production of biodiesel to reduce oil imports. The US Department of Energy is raising funds to develop biomass, requiring that the use of biomass in the United States will increase by a factor of two by 2010, and biodiesel is also listed as one of the biomass.
At present, the international development of bio-diesel situation is optimistic, and the way to produce biodiesel there are three: First, the use of edible oil production of biodiesel; the second is the use of sugar cane fermentation production of diesel; third is the use of "engineering microalgae" production of diesel The Japan's annual consumption of edible oil is 2 million tons, resulting in the consumption of 40 million tons of waste oil for the production of biodiesel to provide raw materials. The effect of the free fatty acid and water on the catalytic effect of the enzyme in the reactants was not affected by the transesterification reaction of the enzymatic enzyme or the lipase. After the reaction solution is allowed to stand, the fatty acid methyl ester can be separated from glycerol, thereby obtaining a relatively pure diesel oil. The use of this method to produce biodiesel is somewhat worthy of attention and to be addressed: 1. Do not use organic solvents can not reach the high ester exchange rate; Reaction system of methanol to a certain amount, the lipase inactivation; Reaction time is relatively long; In general, the price of enzymes is higher. In order to improve the efficiency of diesel production, the use of enzyme immobilization technology, and in the reaction process to add methanol, more conducive to improving the production efficiency of diesel. This immobilized enzyme (lipase) is derived from a Candidaantaretica, which is made with a carrier for the production of diesel, the control temperature of 30 ° C, the conversion rate of 95%. This lipolytic enzyme used for 100 days without inactivation. After several reaction columns were passed through the reaction solution, the reaction was allowed to stand and the glycerol was separated and used as a biodiesel. In addition to vegetable oil production of bio-diesel, but also reported the use of sugar cane bagasse as raw material fermentation production of high-quality diesel research results, alleged 1 ton of bagasse energy and a barrel of oil equivalent (barrel is equal to 31.5 gallons per gallon equal to 3 .7853 liters). If a Canadian technology company is converting this result into productivity, a 6-barrel biodiesel plant has been set up to produce diesel fuel from bagasse as a raw material and plans to expand into a 25-ton industrial-scale production facility. But what microbial fermentation is used to produce diesel? How is the output rate? Did not see the specific report. The use of "engineering microalgae" to produce diesel is a noteworthy new trend in diesel production. The so-called "engineering microalgae", which is a microalgae constructed by genetic engineering technology, opens up a new technological approach for diesel production. The National Renewable Energy Laboratory (NREL) builds "engineering microalgae" through modern biotechnology, a "Cyclotellacryptica" of diatoms that increases lipid content to 60 in laboratory conditions % Of the above (generally natural state microalgae lipid content of 5% -20%), outdoor production can also be increased to more than 40%. This is due to the efficient expression of the acetyl-CoA carboxylase (ACC) gene in microalgae cells and plays an important role in controlling lipid accumulation levels.
Is currently studying the appropriate molecular vector to make the ACC gene fully expressed in bacteria, yeasts and plants, and further to modify the ACC in short, diesel is currently used in urban and rural areas is more common fuel, through the biological way to produce diesel is to expand the use of biological resources One of the most economical way, is one of the direction of bio-energy development. Energy biotechnology will be developed, "pollution-free biodiesel" will also be more widely used.