This paper describes a digital twin (DT) concept for a synthetic natural gas production pilot plant developed and implemented in a pilot plant at TU Wien. The process involves using a 100 kW dual fluidised bed (DFB) gasification plant and a 10 kW bubbling fluidised bed methanation reactor. The DT's goals are optimising and automating this pilot plant, thereby reducing operating costs and minimising CO2 emissions and other negative ecological influences in the long run. The DT's key tools include online process simulation, which approximates the value of variables that cannot be measured directly, and model predictive control (MPC). Live data from the plant is used in both tools to calculate the plant's current state and take over control tasks. Tests of the DT have been promising; holding operating points and switching between them was possible. Results from the implemented tools were visualised and aided operators in understanding the current state of the pilot plant.