Without a computer-aided tool for planning and load distributing, it is nearly impossible to optimize complex planning processes due to their continuously changing requirements and large amounts of data within the power plant systems. A planning and optimization tool for cogeneration systems has been developed at the Bayer Research Center. This tool is based on mixed integer linear programming. The production system is separated into individual components to enable mathematical operations to be performed. There are technical components, such as boilers, turbines and heat exchangers, plus contracts, duties and conditions. The mathematical description of these, defined as the behaviour of components and the interaction between them, leads to a linear system of equations with mixed integer values. The aim of operational planning is to minimize the total cost, which includes the production and startup costs of all components and all purchase costs.