In recent years, the global energy landscape has been undergoing a significant transformation, driven by the urgent need to address environmental concerns, energy security, and sustainable development. The traditional reliance on conventional fossil fuels has led to numerous challenges, including greenhouse gas emissions, climate change, and resource depletion. As a result, there is a growing emphasis on the development and utilization of non-conventional energy sources, which offer cleaner, more sustainable alternatives. This comprehensive text, "Non-Conventional Energy Sources," is designed to provide an in-depth exploration of the various non-conventional and renewable energy options available today. The book is structured to offer a holistic understanding of the energy sector, from basic concepts and terminology to advanced technologies and their applications. It aims to serve as a valuable resource for students, researchers, industry professionals, policymakers, and anyone interested in the future of energy. Chapter 1: An Overview of Energy Sources introduces fundamental concepts related to energy, including key terminologies, the physical and thermodynamic properties of power, and methods for measuring energy. It also discusses strategies for energy efficiency, the role of energy audits, and the significance of decentralized and distributed generation, cogeneration, and various energy categories. Chapter 2: The Present World Map for Recyclable and Non-Conventional Energy provides a global perspective on the adoption and impact of renewable energy sources. It examines solar power's expansion, climate change policies, the International Solar Alliance, and the transformation of power systems worldwide. The chapter also addresses global energy investments and the job creation potential of renewable energy sectors, alongside the effects of COVID-19 on the energy landscape. Chapter 3: Current World Scenario for Renewable Energy delves into specific renewable energy technologies, including photovoltaic cells, solar thermal panels, wind power, and water power. Detailed discussions on materials, technical considerations, and advancements in these fields highlight the progress and potential of renewable energy solutions. Chapter 4: Energy from Non-Conventional Sources focuses on biomass and geothermal energy, exploring their sources, characteristics, and conversion methods. The chapter covers various forms of biomass, such as wood, grasses, algae, and waste, and examines hydrogen energy, including production, storage, and fuel cell applications. Chapter 5: Storage of Energy addresses the critical issue of energy storage, detailing the working principles, types, and applications of rechargeable batteries, capacitors, supercapacitors, and hybrid capacitors. It also discusses carbon capture, storage, and conversion technologies. Chapter 6: Policy and Environmental Considerations Related to Energy Generation explores the environmental impacts of different power generation methods, including pollution control in thermal and nuclear power plants, and the environmental effects of solar and hydroelectric power stations. It also covers waste management strategies, the conversion of plastic waste to reusable power, and the circular economy's role in waste-to-energy processes. This book aims to equip readers with a thorough understanding of non-conventional energy sources, their technological advancements, environmental implications, and the policies shaping their development. By exploring these diverse topics, we hope to contribute to the global discourse on sustainable energy solutions and the transition towards a more resilient and environmentally friendly energy future.