Exergoeconomic analysis of cogeneration thermal power plants

The method of the exergoeconomic analysis consists in combining the exergetic and economical analysis of the thermal power systems. Through the exergetic analysis imperfections of the processes are revealed by evaluating the destructions and loses of exergy. Combining both exergetic analysis and economical analysis we can establish the costs of the flows of exergy, meaning that operating with the costs of the useful part of exergy will be possible. This means that through exergoeconomic analysis direct relations between costs and irreversibilities of that system are established. In fact, these relations are economical in essence, but they create a direct link between costs and technical and functional parameters of the systems in discussion. During economical optimization obvious priorities and trends of modifying those parameters having purpose the minimization of the costs for the final products will result. On the other side, for those systems that provide more final products, exergoeconomical analysis allows to establish the real costs of each product by his utility rate, measured by his exergy. In the costs balance equations, referred to exergetic flows, unavoidable appear some series of non exergetic costs, represented by the cost rates associated with capital investment and operating and maintenance. This fact allows to distinctly highlight the costs on which technical and organizational measures of environment protection are implied and to establish the specific parameters of economical efficiency of the application of those measures. This way, it can be compared different methods of abating the pollution produced by the system in discussion in order to limit this pollution below the restrictions asked by operative legislation. According to the equations given in the paper the cost of heat from the cogeneration power station will be not only a true value from thermodynamic point of view, but also low enough value. Thus, after adding distribution costs, the sale price to final consumers will remain lower than for the case of individual heating systems, without cogeneration. This way of calculating the heat price could be a support of reconsidering the cogeneration plants in Romania. Another aspect, beside those shown, for reconsidering the cogeneration plants in Romania, is the higher efficiency for the distribution systems, by eliminating the loses and reducing the administrative costs. By the exergoeconomic analysis of the cogeneration plants, it can be highlighted also other aspects, such as the weight of loses of exergy in the costs for the final products, which characterizes the internal and external irreversibilities of the processes. This way the priorities of action for decreasing these irreversibilities, in order to increase the efficiency of the cogeneration plants can be established