From the standpoint of an energetically and economically efficient waste elimination, the design and operation of optimized incineration power plants with the cogeneration of electricity and heat has become today an important issue. Decision models developed to minimize the total costs associated with such systems only partially respond to the problems associated with the choice of the synthesis (configuration, technology), the design, and the operation of the waste treatment unit. In fact, the time factor which greatly affects certain key parameters such as the amount of wastes, the electrical and heating demands placed on the system, and the economic parameters (to name just three) render the problem of synthesis, design and operation very complex. The methodology and tools require first defining a unified objective function which represents the total cost of the system, integrated over its economic lifetime. Based on a flexible (in time) superconfiguration which includes all potential technical alternatives, the system is then mathematically optimized, accounting for a set of given constraints. This paper presents an application of these methodology and tools to a future waste incineration plant. The main results have been used in the decision making process for the conception of the plant which is currently under construction.