There is a need for a text book containing practical case studies in the subject of energy conservation and associated CO2 emission mitigation for UG & PG level engineering and science students. This book is written keeping in mind the application part of engineering knowledge and skills so that learners and practicing engineers can really apply the techniques in the field. Application of engineering principles and the methodology of integrating with practice in reducing CO2 emission are presented in this maiden edition. The first chapter provides an insight into the nexus between energy consumption and CO2 emission and the needed for mitigation. In Chapter-2 a detailed survey is presented to highlight the need of energy conservation and the achievements made. The application of numerical tools for critical analysis of energy systems to quantify energy consumption and CO2 emission mitigation potential are reviewed and presented. Detailed discussions on energy Audit, emission estimation methodology are enumerated in Chapter 3 to motivate the readers to understand and apply these strategies in the industrial environment. The cases of paper based industry, cement, spice powder and electronic contactors manufacturing industry are discussed for better understanding in chapters 4, 5, 6 & 7. In chapter 8, the application of numerical method-Computational Fluid Dynamics (CFD) to pressure drop analysis in compressed air pipe junctions T and elbow are discussed with simulation results for energy and CO2 emission reduction. A brief introduction is presented on carbon capture in chapter 9. This book will be an eye opener for the readers looking for a career in the domain of Green Manufacturing and serve as a hand book for practicing engineers.