Risk Causation and Safety Governance Pathways for Very Large-Scale Biogas (Biomethane) Projects Under Dual-Carbon Goals: A DEMATEL-ISM-Based Empirical Study

Very large-scale biogas (biomethane) projects are important infrastructure systems for integrating organic waste treatment, renewable energy substitution, and carbon mitigation under China’s carbon peaking and carbon neutrality goals. However, their long process chains, concentrated hazardous media, and frequent confined-space operations create coupled safety risks that may undermine sustainable operation. To identify the dominant risk drivers and safety governance priorities, this study investigated five operating very large-scale biogas projects in Shanxi Province, China. On-site inspections, semi-structured interviews, and document reviews were used to identify ten safety-risk causative factors. The Decision-Making Trial and Evaluation Laboratory (DEMATEL) method was combined with Interpretive Structural Modeling (ISM) to quantify causal relationships and reveal the hierarchical transmission structure among the factors. The results show a structural imbalance between document-based compliance and operational implementation. Although basic safety documents were generally established, only 20% of the projects had scenario-specific emergency response plans for major accident scenarios; the compliance rate of explosion-proof electrical equipment, the configuration rate of fixed monitoring and alarm systems for combustible and toxic gases, and the effective operation rate of forced ventilation facilities were 40%, 60%, and 40%, respectively. Insufficient enterprise safety investment (M1) and unclear external regulatory responsibilities (M2) were the dominant root causes of system-level risk propagation, while inadequate control of high-risk operations (M9) and unsafe worker behavior (M10) were the final manifestations. A four-pillar governance pathway is proposed, including policy and standard improvement, technological support and equipment upgrading, personnel capacity enhancement, and sustainable funding mechanisms. The findings provide empirical evidence for risk-based supervision and indicate how operational safety governance can serve as an enabling condition for the long-term sustainability of the biomethane industry, rather than as a direct measurement of carbon-mitigation or energy-performance outcomes.