The article presents an operation planning optimisation approach using a genetic algorithm for CHPPs in an urban heat supply zone. Changes in market environment will result in a significant change in energy system planning and operation. For efficient production planning in the liberalized power markets, it is paramount to determine the optimal strategies over a time horizon. Solution of an optimization task of such complexity requires a well-crafted set of tailored modelling, simulation, optimization, and forecasting tools. A well-designed solution is unthinkable without a great number of production units, such as gas turbines, steam turbines, heat-only boilers, and thermal storages, reflected by the optimization model.