Flexible methane production using PI Controller with simulation based soft sensor

Anaerobic digestion plants have the potential to produce biogas on demand to help balance renewable energy production and energy demand by consumers. A proportional integral (PI) controller is constructed and tuned with a novel tuning method to control biogas production in an optimal manner. In this approach, the proportional part of the controller is a function of the feeding rate and system's degree of stability. To estimate the degree of stability, a simulation‐based soft sensor is developed. By means of the PI controller, the requirement for gas storage capacity of the digester is reduced by approximately 30 % compared to a constant, continuous feeding regime of the digester.