NOVELTY - The system or apparatus comprises a cartridge to receive a mixture comprising a first reactant and a second reactant, and a unit to control an operation condition of the system based on the identifier on the cartridge. The cartridge includes an enzyme e.g. lipase to facilitate a reaction between the first and second reactants to generate alkyl ester, and an identifier. The unit controls a speed of a pump based on the identifier in which the speed of the pump affects the speed of the solution passing through the cartridge, and controls a heater based on the identifier.    USE - The system or apparatus is useful for generating alkyl ester from vegetable oils and animal fats, where the alkyl ester is useful as bio-diesel fuel for internal combustion diesel engine and a gas turbine diesel engine.    ADVANTAGE - The system is capable of simply, easily and economically generating the alkyl ester with high purity and productivity and less waste and pollution and without any impurities, and reduces the amount of inert solvent for dissolving the oil source and reactant alcohol during production of alkyl ester.    DETAILED DESCRIPTION - The system or apparatus comprises a cartridge to receive a mixture comprising a first reactant and a second reactant, and a unit to control an operation condition of the system based on the identifier on the cartridge. The cartridge includes an enzyme e.g. lipase to facilitate a reaction between the first and second reactants to generate alkyl ester, and an identifier. The unit controls a speed of a pump based on the identifier in which the speed of the pump affects the speed of the solution passing through the cartridge, and controls a heater based on the identifier in which the heater affects a temperature of the solution. The controller determines when send a signal indicating the cartridge to be replaced based on the identifier. The cartridge is configured to be coupled to an alkyl ester generator that comprises a mixer to mix an oil source (110) and a primary alcohol or secondary alcohol in an organic solvent (120) to form solution that is passed through the cartridge, an evaporator to remove the organic solvent and unreacted primary alcohol or secondary alcohol, a first phase unit to separate the alkyl ester from the glycerol, and a second unit to separate the alkyl ester from unreacted oil source. The lipase facilitates a reaction between the oil source and the primary alcohol or the secondary alcohol to generate an alkyl ester. The solution does not undergo phase separation throughout the reaction. An INDEPENDENT CLAIM is included for a method for generating alkyl ester.    DESCRIPTION OF DRAWING(S) - The figure shows a block diagram of a fuel production system.    Oil source (110)    Solvent (120)    Reactant (130)    Reactor (140)    Co-product. (160)