A Critical Review of Croton as a Multipurpose Nonedible Tree Plant for Biodiesel Production towards Feedstock Diversification for Sustainable Energy

Oil demand has risen steadily due to the growing industrialization and modernization of the world. In addition to rising costs, the supply of fossil fuels is also declining. These and many other concerns couple with food shortages have drawn attention of scientists to a substitute fuel that is generated from feedstocks that can be renewed. Biodiesel as an alternative fuel with a lot of expectations is produced using edible grown conventional vegetable oils such as sunflower, rapeseed, palm, and soybean. The production of biodiesel from edible oils has, meanwhile, worsened the existing competitiveness of oil used for food and fuel. Emphasis on using nonedible feedstock is currently guided by research to discover more potential nonedible feedstock such as croton. Differences between perceptions and facts about these nonedible oils necessitate efforts to diversify feedstocks into sources that can warrant the production of energy without impacting on the security of food. Croton is a multipurpose evergreen plant that is nonedible and is commonly present and cultivated under environmental and socio-economic conditions, which are complex in nature. This plant, referred to as a golden tree, has various uses including fuels, medicinal, ornamentals, dyes, feed, enriching of soil, and afforestation. This research was therefore carried out to investigate the multipurpose use croton. Among the highlighted areas include croton (feedstock) used for biodiesel, the necessity for croton seed oil and its value chain, the process for the modifying croton oil to biodiesel, factors that influence the production of biodiesel, the application of croton biodiesel in engines for efficiency and emission characteristics, and prospects for croton biodiesel.