Edible and nonedible biodiesel feedstocks: Microalgae and future of biodiesel

Biodiesel is a renewable, clean-burning diesel replacement that reduces the dependence on petroleum fuels, creating local jobs and improving the environment. Biodiesel can be synthesized from a diverse mix of feedstocks, such as waste cooking oil, soybean oil, animal fats, and Jatropha curcas. It can be used in existing diesel engines without modification and is covered by all major engine manufacturers' warranties, most often in blends of up to 5% or 20% biodiesel. In fact, thousands of research articles have been published on this research area since mid-1980s. This proves its importance and impact. Therefore, this chapter aims to promote the work on biodiesel industry. Some important aspects related to this research area, such as types of feedstocks, oil extraction, biodiesel production and optimization, physicochemical properties, fuel blending, engine performance, and effect of additives and microalgae, have been highlighted in this chapter. The author has selected some of the best (about 170) available articles to come up with this report. Moreover, the author has concluded the chapter with some important features that may promote biodiesel future. It can be concluded from this chapter that biodiesel is still a promising alternative fuel in research area. However, work should continue on biodiesel production from microalgae and wastes, such as food waste, plastic waste, and waste cooking oil. Moreover, development of novel catalyst that can convert high free fatty acid oils into biodiesel in one/two-step process can open a huge area for biodiesel production from waste cooking oil and improve its economic aspect. In addition to that, biobutanol production from glycerin as by-product of biodiesel production process is another good choice that resulted in the production of two renewable fuels instead of one. Finally, the authors suggest that integration of ternary fuel blends, such as biodiesel-ethanol-hydrogen, biodiesel-butanol-hydrogen, or biodiesel-methanol-hydrogen, in internal combustion engine is an excellent option to overcome the negative effect of each fuel to improve the blend properties and thus better engine and emission performances.