I feel happy to introduce a Special Issue on Renewable Energy Systems for Sustainable Environment in Environmental Science and Pollution Research. This special issue is dedicated to the research studies reported on Environmental impacts of Renewable Energy Systems presented in the International Conference on Thermal Analysis of Energy Systems 2021 organized by Heat Pump Research Institute and Department of Mechanics, Al-Farabi Kazakh National University, Almaty, Republic of Kazakhstan during the 22nd, 23rd and 24th of December 2022 through online mode. More than 100 technical papers were presented through Online. About 25 papers were shortlisted. The research papers shortlisted for this special issue mainly focus on bio-fuels and environment impact reduction in diesel engines. The papers were reviewed by subject experts and revised accordingly to meet the requirements of the Journal. I express my gratitude to Dr. Philippe Garrigues, Editor in Chief and Fanny Creusot, Editorial Assistant, Environmental Science and Pollution Research for providing this opportunity to compile this special issue. I would like to thank all the authors for their research contributions to this special issue. The support provided by the subject experts in reviewing the research articles are gratefully acknowledged. I extend my heartfelt thanks to the conference co-organizers: Dr. S. Jayaraj, former Professor in Mechanical Engineering, National Institute of Technology, Calicut, India; Dr. Ye. Belyayev and Dr. Zaure Rakisheva, Department of Mechanics, Al-Farabi Kazakh National University, Kazakhstan. Dr. K. Sopian, Director, Solar Energy Research Institute, Malaysia, Dr. R. M. Singh, Professor in Geotechnical Engineering, NTNU, Norway, and Dr. Arun K Raj, Post-doctoral researcher, University of California, USA are thanked for their active support in organizing this conference.