Exergy and cost accounting of the UANE cogeneration plant

Abstract

In this paper, the concept of exergy is utilized for exergy and economic analysis of a cogeneration plant producing electric power and desalinated water. The objective is to obtain an idea about the exergy dissipation in each major plant component and to use the exergy-accounting method to obtain a fair and equitable cost allocation between electricity and water. Exergy and cost balance equations are written for each major plant component in terms of known and unknown unit exergy costs for the different streams. The resulting set of simultaneous equations is solved in association with a set of auxiliary equations. The exergy-balance equations revealed the amount of exergy dissipation for each component, and showed that the boilers and the distillers are the main offenders. The costs of electricity and water obtained using the exergy-accounting method are compared with a cost-allocation methodology that is currently used by some cogeneration utilities.