This book explores the use of recent advanced multiple stage conversion technologies. These applications combine conventional fluidised bed systems with new plasma technologies to efficiently generate different energy outputs from waste materials with minimum cleaning effort. Using a mix of modelling and experimental approaches, the author provides fundamental insights into how the key operating variables of the two-stage process may impact the final quality of syngas. This thesis serves as a useful reference guide on the modelling and design of single and multiple-stage systems for thermal waste treatment. Its extended section on plant configuration and operation of waste gasification plants identifies the main technical challenges, and is of use to researchers entering the field.