Advances in Biogas Technology Systems presents a consolidated, multi-scale reference for translating biogas innovation into reliable, commercially viable energy solutions. As biogas becomes increasingly important within the circular bioeconomy, it is being incorporated into energy systems through biomethane upgrading, grid injection, and transport-fuel applications. At the same time, advances in microbial engineering, process optimisation, and digital technologies-including artificial intelligence-are reshaping the monitoring, design, and scaling of anaerobic digestion systems. Nevertheless, literature remains fragmented across fundamentals, emerging technologies, and deployment-oriented topics, limiting end-to-end engineering decision making. The book assembles coverage across interconnected layers: substrate selection, pretreatment, and microbial dynamics; emerging and advanced technologies including metabolic engineering, kinetics, bioreactor design, and AI-enabled monitoring; and system-level implementation featuring upgrading and purification for high-quality biomethane, regulatory frameworks, circular economy integration, and industrial case studies. Chapters are designed to help readers connect lab-scale research to system optimisation and deployment challenges across regions and sectors. Advances in Biogas Technology Systems supports researchers, engineers, scientists, tertiary students, and biofuel professionals with practical, curated advances that address the full biogas value chain from feedstock to energy integration and climate-aligned performance.Integrates biogas fundamentals with system-level implementation across the full value chainUpdates upgrading and purification coverage for biomethane energy quality marketsLinks microbial dynamics, metabolic engineering, and kinetics to reactor and scale-up designApplies AI and digital monitoring approaches to improve predictability and performanceIncludes regulatory and circular-economy integration plus regional industrial case studies