In the design and/or performance analysis of an energy conversion system, there are two factors other than the thermodynamic operation of the system which play an important role. They are the economis of the capital equipment used in the cycle and the past effects of the cycle (i.e., the construction of the capital equipment) and present and future effects of the cycle (i.e., its operation and the recycling of any used-up capital equipment) on the environment. All three factors - the thermodynamics, the economics and the environmental effects - are presently taken into account to some degree or another at different stages in the analysis of such a system. However, they are only considered separately or in some limited combination or not at all, since a consistent methodoligy which combines all of them into a single entity or tool is lacking. The purpose of our proposal is to develop such a methodology, providing a framework simple enough to be practical yet sufficiently consistent with good engineering practice and the complexities involved in this type of modelling. As a base, we will use some of the extensive work which has already been done in the literature by the authors themselves and others.