Thermoeconomic Analysis of a Combined Cycle and an IRSOFC Plant and Carbon Exergy Tax Influence on Advanced Systems Economic Competitiveness Available to Purchase

In the paper, a Thermoeconomic Analysis of two advanced energy systems, using different procedures for the electric power generation, has been performed. The first system is a three pressure level combined cycle of 335 MW, with an electricity production efficiency in the order of 54%. The second system is a model of advanced plant of 142 MW proposed by Massardo, composed by a pressurised Internal Reforming Solid Oxide Fuel Cell (IRSOFC) combined with a Gas Turbine; the plant can reach efficiencies at the order of 70%. A preliminary exergy analysis has been performed, which has outlined the irreversibilities generation. Then, a Thermoeconomic Analysis, evaluating the unit exergetic cost and unit thermoeconomic costs of all the energy flows of the two plants has been done. The results in terms of unit thermoeconomic costs obtained have outlined that a typology of plant like the FCGT4 is not yet competitive in economic terms with the advanced combined cycle plants, even if it represents a new high-efficiency technology, and especially An effective method for the reduction of CO₂ emissions. Therefore, the second aim of the paper is to utilise a procedure of evaluation of an economic penalty applied to the CO₂ emissions: the Carbon Exergy Tax (CET), based on the Second Law efficiency of the plant. It is discussed how the use of CET can contribute to the promotion and adoption of an advanced energy system such as the FCGT4 plant, reducing its economic gap with a standard technology represented by the combined cycle plant.