Book excerpt: This book derives an explicit analytical pattern (or framework) that permits the examination and optimization of biogas production systems. It provides a concise overview of the current status of biogas and biogas coupled agricultural systems in China, and introduces evaluation methods for energy efficiency, environmental emissions, economic performance and sustainability assessment approaches. Based on empirical studies, it also explores future options for the system development by focusing on emissions mitigation, biogas energy efficiency and system sustainability. Systematic methods of life cycle assessment and thermodynamic analysis may provide new angles for biogas system evaluation. The system discussed is not only a biogas producer, but also a biogas-linked ecological agricultural system, which has the potential to broaden the applicable scopes of renewable energy and eco-agricultural management. The comprehensive, in-depth knowledge and experience presented provide new analytical approaches for researchers in relevant fields and shed light on the construction and operation of emerging anaerobic digestion and biogas industries. This book is a valuable resource for researchers focusing on biogas system modeling, project managers and policymakers.