Repowering of an Existing Cogeneration Plant Including Environmental Cost Internalization

In this paper an existing cogeneration plant (134 MWel and 225 MWth) based on gas turbine and steam cycle technology, has been investigated. The main goal of the work is to analyse different repowering options for the plant taking into account the capital cost of the new devices, the cost of the fuel and the cost related to the CO2 emissions. For the analysis of the repowering alternatives the Thermoeconomic Analysis has been utilised. Two different approaches have been used for the CO2 emissions cost evaluation: the classical Carbon Tax approach using political charges on the unit ton of emitted CO2, and one proposed by the Authors linked to the efficient utilization of energy resources in the plants, and based on the exergy analysis.In the paper the two procedures for the evaluation of the charges on the CO2 emissions and their influence on the choice of the repowering option, and how they promote the adoption of a high efficiency repowering solutions have been discussed.Copyright © 2000 by ASME