The energy crises, particularly the fear of depletion of mineral oils are becoming a very serious issue. Non-oil producing countries are becoming the victim of the scenario. On the other hand the environmental pollution, green house effect, global warming and acid rain are also threatening the life. Biodiesel is a promising alternative fuel which can cater the problems. Vegetable oils can be used to substitute mineral diesel after reducing their viscosity and specific gravity. For this purpose different techniques are used. Among these, transesterification is frequently used as it is the most reliable, most feasible, and can be used to produce biodiesel easily.
The conversion efficiency of biodiesel via transesterification depends upon the nature of feedstock, amount and type of alcohol and catalyst, operating temperature, and reaction time. In this study the performance of alkaline, acidic, and enzymatic catalysts have been reviewed. Modern techniques of development of biodiesel i.e., use of microwaves and super critical alcohol have also been discussed critically.
Ejaz M. Shahid and Younis Jamal
Renewable and Sustainable Energy Reviews Volume 15, Issue 9, December 2011, Pages 4732-4745
Biodiesel; Transesterification; Super critical methanol; Microwave irradiations