The development of new environmental technologies plays a critical role in making environmental protection more effective and economically viable. This book opens a truly innovative perspective for understanding environmental innovation essential to a sustainable society, and develops tools for analyzing shifts in research and development (R&D) strategies and technology development priorities through quantitative patent data analysis. Using a patent decomposition framework, the book systematically examines three critical environmental technology domains across the world's major patent offices: renewable energy, environmentally friendly vehicles, and pollution control. Technologies covered include solar power, offshore wind, electric vehicles, plug-in hybrid vehicles, and waste management and recycling. A key finding is that apparent declines in patent activity often reflect rational strategic reallocation rather than innovation stagnation, revealing how market forces, policy incentives, and national industrial structures collectively reshape R&D priorities. Thus, this book creates a new quantitative understanding of R&D strategies for environmental technology innovation.