Critical review: a standardized blueprint for green certificate integration in life cycle assessment

Green certificates (GCs), such as guarantees of origin (GOs), support renewable electricity tracking and corporate greenhouse gas reporting, but methodological inconsistencies, particularly in life cycle assessment (LCA) applications, undermine their credibility, transparency, and environmental benefits. This review critically evaluates current GC practices and their integration into LCA frameworks, identifying key challenges including double counting, insufficient geographic and temporal matching, and emission reallocation effects in residual electricity mixes. The review first examines global GC trading systems and associated policies, highlighting structural differences across regions such as the European Union, the United States, and China. It then explores how GCs are treated in market- and location-based accounting approaches for Scope 2 emissions. A multi-stage standardization framework is proposed, encompassing GC generation, trade, allocation, and application in LCA. Particular emphasis is placed on the need for harmonized certificate types, data traceability, and temporal alignment between energy use and certificate validity. Finally, policy and regulatory recommendations are presented to strengthen oversight, improve the reliability of market mechanisms, and foster international collaboration. This includes a call for reform in key protocols and a shift toward more granular, transparent tracking systems. The findings support more accurate environmental claims and promote a credible, standardized use of GCs in LCA and sustainability reporting.