A Theoretical and Experimental Study of Controllable Electricity Production via Biogas Plants

With the expansion of renewable but fluctuating power generation from wind and solar energy, the demand placed on the security and reliability of supply is increasing. To en-sure grid stability in the future, controllable power production via biogas plants has great technical and economic potential. The main aim of this thesis is a new system design for controlled, demand oriented elec-tricity production via biogas plants, based on system analyses and parameter studies. Derived aims are the analysis of new control strategies and required hardware modifica-tions, e.g. storage capacities and CHP units. Therefore the role of biogas in a future renewable based electricity system is discussed and different overall concepts for a controlled flexible electricity production via biogas are compared. Within a system analysis the current state of technology of biogas plant components, which are affected by a controllable electricity production is described. Building on this, technical requirements are characterised and technical recommenda-tions are given. Since for the realisation of plant concepts for a controlled electricity pro-duction monetary incentive systems are needed. As a potential market the Day-Ahead Auction of the EPEX Spot Se were identified. The concept development takes place via a parameter study, thereby various plant con-cepts are defined by varying the plant sizes, the additional electricity production capaci-ties and the gas storage capacities. Before the actual economic analysis is carried out, different feasible control strategies and the associated earnings, based on different gas storage and electricity production capacities, are presented. Within the economic analysis the necessary additional investment and operating costs for the controllable electricity are discussed and the costs are compared with possible higher revenues. Based on the results of the concept development an existing biogas plant was modified in order to demonstrate the operation of the controllable electricity production via biogas plants. Within the monitoring, the ability of biogas plants to act as a controllable electrici-ty producer were demonstrated. Also practical experiences with respect to the plant and component operation were made.