**Abstract**

Since the world is gradually drifting toward sustainable development, renewable energy technologies are gaining traction and gasification technology is one of many renewable energy technologies that have gained popularity in recent times. The gasification technology is one of three main (combustion and pyrolysis) thermochemical conversion pathways that can be used to recover energy from biomass materials. Although the gasification technology has been in existence for centuries, it has not been exploited to its full potential mainly because the fundamental principles underpinning its operation are still vague, particularly with regard to feedstock flexibility and the type of gasification system. Furthermore, due to the many types of gasification systems, the mechanisms involved in their feedstock conversion processes are still under debate and require further research to clearly establish the optimum conditions of performance of each type of gasifier. Therefore, this chapter presents an overview of the gasification technology and discusses the different types of gasification systems that are commonly used today for the recovery of energy. The limitations of each type of gasifier in relation to performance and feedstock conversion are also discussed, including research priority areas that will allow for system optimization in terms of efficiency.

**Keywords:** energy recovery, gasifiers, combustion kinetics, feedstock, gasification efficiency
