The text comprehensively highlights the latest methodologies, models, techniques, and applications along with a description of modeling, optimization, and experimental works in the energy sector. It further explains key concepts such as finite element analysis tools, hybrid energy systems, mechanical components design, and optimization, solar coupled systems, and vertical heat exchanger.This book• Discusses the role and integration of solar, geothermal, and hydrogen‑based thermal energy storage (TES) technologies in different sectors for space heating and cooling applications.• Covers mechanical modeling and optimization of hybrid energy storage systems for performance improvement and focuses on hydrogen production, storage, and safety measures.• Explores the integration of IoT and global energy interaction technologies, highlighting their potential benefits in driving the transition toward a sustainable and resilient global energy system.• Explains different aspects of clean technologies such as batteries, fuel cells, ground energy storage, solar thermal system, and the role of green hydrogen in decarbonizing sectors like transportation and energy.• Showcases a clear idea of sustainable development using renewable energy, focusing on policymaking, challenges in transition from conventional to renewable energy, and future directions in energy sector.It is primarily written for senior undergraduates and graduate students, and academic researchers in the fields of mechanical engineering, production engineering, industrial engineering, and environmental engineering.