Exergetic Analysis of a Natural Gas Combined-Cycle Power Plant with a Molten Carbonate Fuel Cell for Carbon Capture

Alberto Fichera,Rosaria Volpe,Samiran Samanta

doi:10.3390/su14010533

Alberto Fichera, Rosaria Volpe + Show 1 more

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https://doi.org/10.3390/su14010533

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Journal: Sustainability	Publication Date: Jan 4, 2022
Citations: 5	License type: CC BY 4.0

Affiliation: University of Catania, KIIT University

Abstract

This study aims to propose the repowering of an existing Italian natural-gas fired combined cycle power plant through the integration of Molten Carbonate Fuel Cells (MCFC) downstream of the gas turbine for CO2 capture and to pursuit an exergetic analysis of the two schemes. The flue gases of the turbine are used to feed the cathode of the MCFC, where CO2 is captured and transported to the anode while generating electric power. The retrofitted plant produces 787.454 MW, in particular, 435.29 MW from the gas turbine, 248.9 MW from the steam cycle, and 135.283 MW from the MCFC. Around 42.4% of the exergy destruction has been obtained, the majority belonging to the combustion chamber and, in minor percentages, to the gas turbine and the MCFC. The overall net plant efficiency and net exergy efficiency are estimated to be around 55.34 and 53.34%, respectively. Finally, the specific CO2 emission is around 66.67 kg/MWh, with around 2 million tons of carbon dioxide sequestrated.

Highlights

Cell for Carbon Capture.In recent years, the need to address the environmental issues associated with the exploitation of fossil sources in power plants has been largely debated
The existing plant has been simulated in the cycle Tempo software and the major operating parameters are listed in Table 1 and compared with the data published in the reference study [4] for validation purposes
Exergy due to the stack loss is reduced and the exergy loss related to the capture system is 3.22%

Summary

Introduction

One way to couple the needs for both reducing emissions and satisfying the global energy demand can be represented by carbon capture and storage technologies integrated into existing power plants, capable of reducing the release of carbon dioxide into the atmosphere. Carbon capture can be achieved by integrating either oxy-fuel or precombustion or post-combustion capture technologies. Oxy-fuel and precombustion allow for higher energy efficiencies of the power plants, but, on the other side, post-combustion technologies can be more integrated into existing plants [4]. With a view of enabling the repowering of existing plants, and focusing on post-combustion solutions, Molten Carbonate Fuel Cell (MCFC) may be considered a suitable candidate technology to capture carbon dioxide from flue gases deriving from the gas turbine of the power plant [5].

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