A simulation model of a power plant produces detailed information about every sub-process under all ambient and operational conditions. Linked to operational data of a power plant, the thermodynamic model can add or verify performance information, it can reconcile conflicting measurements, it can determine expected performance under current conditions, and it can predict performance in different operating modes. For plant operation, process simulation provides the opportunity to convert complex inter-relations of the process into an understandable format, or – by evaluating scenarios – to guide the plant operator to the optimum operating mode of the plant under given operating conditions. ENEXSA has long-term experience in the use but also in the development of heat balance codes. Through our know-how in software design, we can quickly adapt our tools to the requirements of the technical problem, and we can also integrate our models with other software applications of our clients. For power plant simulation, ENEXSA uses the heat balance software EBSILON®Professional by STEAG Energy Services GmbH, Germany. EBSILON excels through outstanding usability, a powerful and robust solver algorithm, and extraordinary flexibility in modelling options. Our cooperation with STEAG Energy Services also includes developing add-ons, new components and features for EBSILON, and we are also marketing the software globally under a brokerage agreement. ENEXSA developed the eneGrid Service that among other features enables the execution of EBSILON models in on-line or backfilling mode. This expands the capabilities of the PI System with in-depth heat balance analysis for performance evaluation and what-if calculations.