A review on feedstocks, production processes, and yield for different generations of biodiesel

Continuous increase in world's population, rapid industrialization, urbanization, and economic growth force for continuously increase in fossil fuel consumption to meet growing energy demand. Continuous emissions from burning of fossil fuel will create the need to find the appropriate and sustainable replacement for fossil fuels. Biodiesel is appropriate alternate solution for diesel engine due to its renewable, non-toxic and eco-friendly nature. According to EASAC biodiesel evolution is classified into four generations. Cultivation in arid and semi arid land or water, crop yield, effect on food supply, yield of biodiesel, energy content, carbon-neutral economy, easy availability, and economic viable are the main factors behind the evolution of biodiesel generations. This article highlights a comprehensive assessment of various feedstocks used for different generation biodiesel production with their advantages and disadvantages. Different production methods for biodiesel with yield calculation are also explained. Algae based third generation feedstocks are better in comparison with first and second generation due to their high energy content, high oil content and less polluting nature. Forth generation of biodiesel produced from synthetic biology, which will enhance the various physiochemical properties of biodiesel to achieve carbon neutral economy. Among the all biodiesel production processes; transesterification is the most suitable process, because it produces biodiesel of high yield, comparable properties with diesel. This process is also feasible as per economic point of view. The energy demand of future can be met by the blending of different generation oil feedstocks.