Dynamic simulation of a biogas plant providing control energy reserves

Abstract

The increasing integration of renewable energy sources leads to challenges for the power grid balance. The share of power plants with intermittent energy production is rising. The increasing volatility of supply and demand has to be compensated by more flexibility in the energy system. Biomass-based plants are qualified for providing flexibility due to the almost infinite storability of the energy carrier. In this work dynamic models for the simulation of flexible operation of an Austrian biogas plant with biomethane production using the process simulation tool IPSEpro are presented. The models base on data collected during a one-year-monitoring. The plants main focus lies on biogas upgrading with two additional CHP units for production of heat and power on demand. For the simulation detailed models of the CHP units and various dynamic models including a gas storage model were developed and are described in this work. Additionally the effects of providing positive secondary control reserves on the needed gas and heat storage capacities were investigated in a case study. For this purpose one month of operation was simulated ex-post. The results show that the existing gas storage capacities are sufficient to provide control reserves while upgrading biogas steadily and simultaneously. Furthermore, the results of a cost efficiency analysis regarding optimal heat storage capacity are used to identify the most economic size of a hot water tank for short-term storage of heat for the investigated case.