Signal-screening-guided response-contribution-correlation framework reveals instability evolution in biogas system...

The biogas system plays a crucial role in sustainable waste-to-energy strategies. However, instability in practical urban applications hinders its promotion and development. To deepen understanding of this instability, we employed a multi-dimensional dynamic indicator early-warning platform to screen instability signals based on a simulated biogas system. Key indicators were selected as instability factors, and their reliability as signals was confirmed. Thus, we analyzed the onset and evolution of instability by integrating response-contribution-correlation analysis, and proposed an instability curve to describe system instability. The results revealed a three-stage evolution process in biogas system instability: an initial lag phase, followed by mid-term acceleration, and eventual stabilization. The sustained response of the dominant instability factor to other instability factors marked the formal onset of system instability, while the subsequent response path maintained the system in a low-efficiency state. Additionally, we found that shifts in the contribution of instability factors to methane production accelerated instability progression, whereas the gradually increasing correlation among instability factors stabilized and reinforced the instability process. Overall, the findings revealed underlying mechanisms and staged evolution patterns of instability in the biogas system, offering insights and technical support for the stable application of sustainable waste-to-energy systems.