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A few simple “cleansing” steps are required for the catalyst to be reused. The reaction isessentially similar to the traditional process in that the raw feed (vegetable oil) is reactedwith a primary alcohol (usually methanol) to produce methyl esters and a by­productglycerol.2.3.3 Potential Problems and SolutionsUsing the more expensive enzymatic catalyst in place of NaOH poses a few potentialproblems. These problems are briefly described below.· Methanol (used for esterification) is known to deactivate the lipase,greatly hindering its catalytic capabilities.· Lipases are expensive, and must be reusable to be cost effective.· Glycerol, the by­product of esterification reaction, seems to reduce theconversion of methyl esters, possibly due to unwanted side reactions.· No reliable continuous process of esterification using lipase has beendeveloped yet. A continuous process for biodiesel production is highlydesirable to keep production costs low.To improve the economics of biodiesel production using a lipase as the catalyst we arelooking into the following process improvements:· A step­wise addition of methanol to reduce the deactivation of the lipaseby the alcohol. This may be done in a three part process; one molarequivalent being added every few hours a total of three times, resulting inthe required 3:1 methanol to oil ratio. While this is effective, catalystdeactivation tends to be inevitable at some point. A good process seems torun about 10 batches before noticeable deactivation occurs.· Different “carriers” of the lipase have been investigated to maximizeconversion. One common carrier is polypropylene 100EP forP.flouroscens.· Glycerol adsorbing compounds have been investigated to consume theglycerol and allow for a higher conversion. This incurs the loss of avaluable by­product and may require additional steps to deal with theadditives.· Alternate alcohols have been used to improve miscibility and/or lower thedeactivation rate of the lipase caused by methanol.2.3.4 A Novel Biodiesel Production MethodWe believe that a new biodiesel production process, based on the work of Xu et al. [22]that addresses the above­mentioned problem areas, could significantly increase the fuel’scompetitiveness. In this process, methyl acetate is used as the reacting alcohol withsoybean oil, and immobilized Candida Antarctica as the lipase catalyst. Methyl acetatehas negligible effect on the catalyst. The main by­product, triacetylglycerol (instead ofglycerol), is not absorbed on the catalyst surface, alleviating the catalyst deactivationproblem. In addition, the recent work of Cortright [23] shows the promise of low costhydrogen production from triacetylglycerol [24].8