Optimizing Biogas Plants - Modeling and Simulation of Dark Fermentation for Enhanced Hydrogen Production

This paper presents a simulation-based approach to evaluate the integration potential of dark fermentation into existing biogas plants for bio-hydrogen production. The original modeling concept involved validating two mechanistically distinct models—a batch and a continuous stirred anaerobic bioreactor model—using experimental data from the HyPerFerment project. Both models were designed to simulate hydrogen production from the same microbial culture and substrate under controlled conditions. Initially, a hydrolysis-coupled kinetic model was implemented to account for substrate degradation, microbial growth, and hydrogen formation. However, the absence of key experimental parameters (e.g., glucose and biomass concentrations) hindered full validation. Parameter uncertainty and model overfitting limited its predictive reliability. As a result, the modeling strategy was revised to a simplified Monod-based approach, which treats the substrate as directly bioavailable and reduces the number of required parameters. This model was successfully validated against batch experiment data and subsequently extended to simulate continuous operation. The study highlights the practical limitations of comprehensive modeling under data scarce conditions and proposes a robust alternative that is well-suited for experimental calibration. It contributes to the methodological foundation for integrating DF into bioenergy systems, aiming to enhance the hydrogen yield and overall efficiency of biogas plants.