This book delves into the novel theory of supercritical adsorption and its practical applications in energy storage and environmental management. It is divided into two parts. The first part provides a comprehensive theory of supercritical adsorption, illustrated with examples that showcase significant progress in both applied and theoretical research due to advancements in adsorption theory. Building on this theoretical foundation, the second part demonstrates how supercritical adsorption theory can address research questions in the fields of energy and environmental science. It explores how the ideas, chemical reactions, and materials/adsorbents used in supercritical adsorption research can transform approaches to environmental challenges. Additionally, it highlights how adsorptive technology enhances natural gas sweetening and methane enrichment from low-quality gas. More importantly, it presents an efficient and feasible strategy for achieving carbon circulation within the energy consumption and generation cycle. Overall, this book has the potential to make a substantial contribution to the fields of chemical engineering, energy, and environmental science.