Biodiesel production systems: real-world reactor technologies and processes

Biodiesel is a promising substitution for diesel for solving greenhouse gas emissions and traffic-related air pollution. If well-developed, switching to biodiesel can have other socioeconomic advantages, including energy security, job growth, and eco-friendly conversion of used-cooking oil. However, the biodiesel production industry currently has much lower economic feasibility than that of the petrochemical diesel industry. Some countries have been trying to encourage biodiesel production and consumption by providing subsidies or increasing the price of diesel through higher taxation. These types of incentives may not be sustainable as they have a great economic burden on both the governments and civilians. Together with the current sophisticated condition of the world (e.g., wars, sanctions, pandemic), the need for quicker developments of the biodiesel industry to decrease the capital and production costs is more significantly felt than before. Therefore, this review scrutinizes the current development stages of the biodiesel industry from a production systems viewpoint. The chapter starts with an introduction justifying the need for this study and the general knowledge of biodiesel production technologies. This is followed by three separate sections scrutinizing rotating reactors (stirred tank reactors, spinning tube-in-tube reactors), simultaneous reaction-separation reactors, and cavitation reactors (sonochemical/ultrasonic reactors, hydrodynamic cavitation reactors, shockwave power reactors). By presenting real-world reactor technologies and processes, and their advantages and limitations, this chapter tries to gain the attention of a wider audience familiar with the biodiesel industry to stimulate further ideas and research in this field.