Petroleum and Coal Pet Coal (2021); 63(2): 284-291 ISSN 1337-7027 an open access journal Review Open Access The Sustainability of Biodiesel Synthesis from Different Feedstocks: A Review Katlego Bombo 1 , Tumeletso Lekgoba 1* , Oluwatosin Azeez 1,2 and Edison Muzenda 1,3 1 Department of Chemical, Materials and Metallurgical Engineering, Botswana International University of Science and Technology, Palapye, Botswana 2 Department of Chemical Engineering, Federal University of Technology, Minna, Nigeria 3 Department of Chemical Engineering Technology, Faculty of Engineering and the Built Environment, University of Johannesburg, Johannesburg, South Africa Received October 7, 2020; Accepted December 22, 2020 Abstract Currently, the world is facing an energy crisis due to an increase in the global energy demand and this has led to an increased dependence on fossil fuels for energy generation and transportation. The steady rise in the world population which is more than seven billion currently is met with an increase in fossil fuel consumption thereby increasing the threat of fossil depletion and an apparent energy deficit. Fossil fuel emissions pose a threat to the environment and the general human population due to risks posed by greenhouse gases they produce. Biodiesel is recognized as a suitable alternative to fossil fuels due to its biodegradable, renewable and environmentally friendly nature. Biodiesel sources are classified into first, second and third generation based on their origin and type of feedstocks used. There are fourth-generation feedstocks which are biologically man-made resources that are currently at the embryotic stage of research. This paper reviews the sustainability of using Jatropha curcas seeds and microalgae for the production of biodiesel. It highlights an evaluation of the oil yield, composition and performance of the biodiesel derived from both sources whilst assessing the viability of individual feedstocks in biodiesel production. Additionally, different methods of biodiesel production are also assessed. Keywords: Biofuel; Jatropha curcas; Microalgae; Transesterification; Triglycerides. 1. Introduction Today, modern lives have come to depend on energy for its profusion, convenience and potential with fossil fuel energy largely contributing to the worldwide energy consumption. With factors such as the increase in world population and rapid industrialization, the global energy demand has also increased [1] . Therefore, increased demands for fossil fuels has led to the depletion of fossil fuel reserves [2] . The continuous use of fossil fuels mainly in trans- portation, electricity and thermal energy generation has largely contributed to the anthropo- genic greenhouse gas (GHG) emissions. These emissions pose the threat of global climate change due to global warming [3] . Whilst GHGs largely contribute to global warming and cli- mate change, GHGs and harmful matter released from the transportation industries pose a threat to human life and the environment in general [4] . In order to explore more sustainable means of meeting the global energy demand, biofuels have been explored in past decades as practical alternative sources to fossil fuels and this has opened the doors to explore the dif- ferent biofuel sources and the feasibility of the fuels produced. Biofuels are liquid or gaseous fuels that are made from biomass feedstock and these feedstocks are biological resources from edible crops, non-edible crops, animal fats, wastes and microbes. The types of biofuel include, biodiesel, bio-methanol, biogas, bioethanol and bio-dimethyl-ether [5] . Biodiesel, which is the main diesel fuel alternative in the EU is mainly produced from oils derived from the aforementioned feedstocks [4] . Unlike fossil fuels, biofuels are biodegradable, renewable, relatively clean and environmentally safe fuels derived from biological sources such as plants, 284