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Global warming, environmental and sustainability aspects of a geothermal energy based biodigester integrated SOFC system

2020    Inac, Selcuk; Unverdi, Salih Ozen; Midilli, Adnan

In this study, global warming, environmental and sustainability aspects of a geothermal energy based biodigester integrated SOFC system are parametrically analyzed. In this regard, a system is designed, consisting of three main subsystems such as Solid Oxide Fuel Cell, Anaerobic Digester, and a Heat Recovery Steam Generator. In order to investigate the global warming, environmental and sustainability aspects of the system, the energy and exergy analyses are performed, and the following indicators are taken into consideration, which are i) unit CO2 emission, ii) environmental effect factor, iii) waste exergy ratio, iv) exergy destruction ratio, v) exergy recovery ratio, vi) exergetic sustainability index. Accordingly, the maximum exergetic sustainability index and exergy efficiency of the integrated system are calculated to be 0.486 and 0.367, respectively, in case the SOFC inlet temperature is equal to 633.3 degrees C while electric current density is 5500 A/m(2). On the other hand, the minimum exergy destruction ratio and the minimum environmental effect factor are obtained to be 0.74 and 2.33 while SOFC inlet temperature is 633.3 degrees C and SOFC current density is 8000 A/m(2). The minimum unit CO2 emission of the whole system is determined to be 368.4 kg/MWh at 5500 A/m(2) of SOFC current density and 727 degrees C of SOFC inlet temperature while determined as 258.3 kg/MWh at 8000 A/m(2) of SOFC current density and 680 degrees C of SOFC inlet temperature. Thus, it can be said that such a system may be applied for reducing the CO2 based global warming effects and improving the environmental sustainability. (c) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.