The subjects of green energy and sustainability have never been more important, as governments around the world wrestle with the problem of how to protect the planet from the damage being caused to the environment by climate change. This book presents the proceedings of GEESD2023, the 4th International Conference on Green Energy, Environment and Sustainable Development, held in Mianyang, China from 15-17 June 2023 and online via Zoom. The conference aims to gather innovative academicians and industry experts in the fields of green energy, environment, and sustainable development in a common forum, providing a platform for the exchange of the latest research developments in related fields. This year, the call for papers attracted more than 280 submissions, 138 of which were accepted for inclusion in this collection. The process of evaluation and peer-review took place over six months and involved more than 100 TPC members and reviewers. The book is divided into 7 sections: green energy and systems; computer methods in the environment; chemistry and the environment; ecology and the rural environment; energy, environment and economy; environment and pollution; and water and mineral resources. Papers deal with the most up-to-date findings and technologies. The book provides a valuable overview of the latest research and developments and will be of interest to all those working in the fields of green energy and sustainable development.