This book explores the scientific and technological relevance of rare earth elements in energy and sustainability. It covers their roles in clean energy systems, including electric vehicles, wind turbines, and energy storage. Emphasis is placed on material properties, extraction processes, and sector-specific applications. The book also discusses market trends, environmental concerns, and supply chain issues, making it valuable for researchers, students, and professionals in energy and materials science fields. This book explores the vital role of rare earth elements in driving clean energy and sustainable development. Covering topics from mining impacts and global resource distribution to applications in wind energy, solar power, batteries, electric vehicles, and fuel cells, it provides a comprehensive overview of current and emerging technologies. It also examines recycling methods, the circular economy, and potential alternatives to rare earths. Designed for researchers, engineers, and students, the book offers both foundational insights and forward-looking perspectives on rare earth applications in the evolving energy landscape. This book is applicable across various industries, including production, design engineering, automotive, aviation, and defense. It supports researchers in these fields by highlighting the role of rare earth elements in enhancing battery performance, improving energy efficiency, and advancing sustainable technologies such as electric vehicles, wind turbines, and energy storage systems.