**5. Conclusion**

An idealized reference model was needed for an accurate efficiency evaluation of dark fermentation. A PN was chosen, which was modeled based on the thermodynamics of the relevant reaction pathways. A total of 27 reactions and 21 components were considered to calculate the reactor's idealized concentration of H2 and CH4. Comparing the results of the PN and the experimental data showed a qualitative agreement of the graphs, which support the model's suitability as an ideal reference state.

The model was validated using initial experimental data at a laboratory scale. Divergences between the expected and the observed reaction turnover were found. These are mainly due to experimental uncertainties. The authors plan to validate the model based on further experimental data, which will be obtained during the operation of a newly constructed demonstration plant.

Based on the existing experimental data, a substantial fluctuation in the efficiency becomes visible during the reaction. The efficiency evaluation based on the developed model suggests an optimization potential of 21–56%. Since the model is a purely theoretical idealized reference process, it can be assumed that this optimization potential cannot be achieved technically. However, the assessment method gives a better idea of where the biological process can be optimized due to the detailed analysis of separate reaction steps. By monitoring the concentrations of the reactants, intermediates, and end products in the reactor, the model can be used to identify which process steps need to be optimized in detail.

## **Acknowledgements**

We want to extend our heartfelt appreciation to our project partners of MicroPro GmbH and Streicher Anlagenbau GmbH & Co. KG for their valuable contribution of *Optimizability of Biogenic Hydrogen Production DOI: http://dx.doi.org/10.5772/intechopen.111853*

expertise and experimental data, which greatly enhanced the quality and significance of this research. Without their support and collaboration, this study would not have been possible. We are grateful for their dedication and commitment to advancing scientific knowledge in this field.
