The paper introduces the concept of Thermoeconomic Environment and discusses how the Constructal Theory can be applied to the productive structure of an energy system. In this way, the optimal criterion of minimum energy cost of the product, generally assumed by the Thermoeconomic Optimization, can be regarded as derived from the Constructal Law, when the flow of useful product through the productive structure is considered as the characteristic flow of the system. In consequence of the evolution prescribed by the Constructal Law, it can be highlighted that recycling flows may arise in the productive structure and that residues and sub-products cannot be indefinitely accumulated. In this process, a crucial role is played by the framework of the Thermoeconomic Environment. In the outlined context, the evolution of energy systems toward highly interrelated productive structures can be regarded as a consequence of the Constructal Law.