The benefits and hence the motivation for an operator to use such a system comes from the fact of being able to compare the actual state of the plant with an optimum state, currently adjusted to the boundary conditions, on a continuous basis, and thus have a tool for monitoring the quality of the process (quality visualization). The use of what-if – scenarios enables the specification of an optimum mode of operation under the valid actual conditions i.e. according to the current state. Typical quantities, which have a special effect, are the fuel temperature and the ambient conditions, such as cooling water temperature or air temperature and humidity.