Modelling the Degradation Kinetics of Substrates Rich in Lignocellulose for a Flexible Biogas Process in Practical Application

Biogas represents a considerable share of the renewable electrical and thermal net energy in Germany. Beyond that it can be stored in gas storages, or it can be supplied to the natural gas grid after conditioning. Because of its storage capacity, biogas is also well-suited to balance the fluctuating supply of other renewable energy sources. Besides that, the process of biogas formation itself can be made flexible, too. At the moment, the production of biogas is mainly based on energy crops. However, the substantial available potential of agricultural waste biomass is currently not full used.

In contrast to energy crops, agricultural waste biomass is generally characterized by a markedly higher content of lignocellulose. Lignocellulose is a complex component of biomass that can only be converted very slowly or partially in the biogas process due to its structure and composition. As a result, the biogas process reacts comparatively slowly to substrate additions and the biogas yield is reduced. In order to make the biogas production flexible and to be able to plan the biogas production, it is necessary to make predictions. These are to be made possible by means of a model that is capable of describing the degradation kinetics of agricultural residues.

In order to define this model, existing work will be followed up, in which a correlation between the composition of energy crops and their degradation kinetics as well as their specific methane potential could already be demonstrated. In this context, the effectiveness of different pre-treatment methods on the degradation kinetics and methane potential of agricultural residues will also be investigated. Furthermore, it is planned to develop an application based on the model in order to make the results usable in practice. This should enable operators of biogas plants to plan the use of agricultural residues for biogas production.