Sustainable biodiesel: A comprehensive review on feedstock, production methods, applications, challenges and opportunities

Abstract

Due to economic and demographic expansion, energy consumption is rising, increasing our dependence on fossil fuels. Burning fossil fuels generates excessive greenhouse gases and particulate matter. However, governments, scientists, and researchers are trying to develop new and renewable resources of energy that can either replace or reduce the dependency on fossil fuels significantly. Biodiesel has greater lubrication efficiency, high cetane number, lower pour point, low aromatics, and sulfur contents. Biodiesel can be synthesized by catalyzing the transesterification of triglycerides with alcohols. Both types of oils, edible and non-edible, along with third-generation sources like algae, can be used as feedstock for producing biodiesel. Supercritical fluids, heterogeneous nanocatalysts, solid alkali/solid acid catalysts, acids, and bases are heterogeneous agents. These catalysts are beneficial. Biodiesel can be used at different concentrations. Most biodiesel blends are B5 (up to 5%) and B20 (6% to 20%). B100 (pure biodiesel) is often used as a blendstock. Both types of oils, edible and non-edible, can be important biodiesel feedstock. This paper evaluates several biodiesel feedstocks, including their benefits and drawbacks. We are also examined biodiesel production and yield. The present review concludes with a discussion of the challenges, future outlook, and recommendations for selecting biodiesel feedstocks, catalysts, and production techniques to enhance sustainability.