In advancing fuel cell technology, METC is building the capability to simulate the performance of phosphoric acid, molten carbonate, and solid oxide fuel cell systems using computer models. Computer models are capable of predicting various aspects of the performance, economics, and environmental intrusion of both individual cells and complete fuel cell power generation systems. Performance models have been developed which predict operating characteristics such as heat and mass transfer, fuel utilization, current density, and the effect of contaminants on cell operation. There are both steady-state and transient models, with the transient models being used to simulate the dynamic response of the system during load-following maneuvers. Some of the performance models are based on fundamental principles of thermodynamics and mass transfer. Because of this theoretical nature, these models provide analytical insight into the optimization of overall system operation. Other empirical performance models use correlations derived from experimental data. Complementing the performance models, other codes have been developed to provide an economic analysis of fuel cell systems and to identify the ultimate use of these systems in a variety of marketing conditions scenarios. Models provide insight into the technical and economic issues that must be addressed to develop and commercialize the various fuel cell technologies. These models must be continuously updated to improve their predictive capabilities as the technology progresses. Many of the models examined are potentially applicable to fuel cell systems analysis. METC will employ some or parts of these codes along with the Advanced System for Process Engineering (ASPEN) to develop stimulation capabilities for the performance and economics of fuel cell systems.