This proceedings contains peer-reviewed papers from International Conference on Renewable and Clean Energy 2025 which was held in Fukuoka, Japan, Feb 15-17, 2025. This book presents innovative grid integration technologies for techno-economic operation of renewable and clean energy technologies (e.g., solar photovoltaic, wind energy, hydrogen technologies including electrolyzer and fuel cell, energy storage technologies, etc.). It covers key aspects on energy conversion systems related to renewable energy technologies and their grid integration, techno-economic power dispatching from the distributed environmental-friendly energy sources considering combined heat and power applications, electrical energy network operation with increasing penetration of renewable energy sources, energy efficiency and demand side management, e-mobility, including machine learning applications for intelligent operation of energy systems, etc. The key objective of book is to educate the readers on how sustainable energy technologies can be integrated with energy conversion processes for achieving net zero targets in real-world applications. The book is able to serve as a useful reference for graduate students, academicians, industry professionals and policy makers interested in exploring the potential of energy technologies in development of sustainable energy system.