This numerical and experimental study aims at finding the how the application of exhaust gas recirculation affects the performance of a single cylinder direct injection (DI) diesel engine using different blends of waste plastic oil while using conventional diesel oil as the base fuel. This oil is obtained through a process of pyrolysis from a commercial processing plant. This book is aimed bringing theory and practice together so that the role of recycling in the use of energy and alternative sources of energy can be collaborated in engineering studies to offer solutions to the long term standing issue of environmental pollution which was the motivation behind this work.Waste to green energy has become paramount as biodiesel from waste plastic municipal solid waste landfills can be used effectively to fill this gap and provide energy for propulsion, heating and power generation. This will provide and create employment while reducing environmental degradation sustainably.