**3. Biodiesel production technologies**

Several efforts have been made to produce derivatives of vegetable oil that can approximate the performance and properties of hydrocarbon-based diesel fuels. The problems associated with the vegetable oil to be used as diesel fuel are high viscosity, low stability against oxidation and the subsequent reactions of polymerization,

low volatility due to which incomplete combustion occurs, resulting in the formation of high amount of ash [12]. Different process can be used in order to change these properties such as direct use or blending, micro emulsion, pyrolysis (thermal cracking) and the most conventional process is the transesterification.
