CO2 Separation From Combined Cycles Using Molten Carbonate Fuel Cells

Author(s):  
G. Manzolini ◽  
S. Campanari ◽  
P. Chiesa ◽  
A. Giannotti ◽  
P. Bedont ◽  
...  

This paper presents an analysis of advanced cycles with limited CO2 emissions based onthe integration of molten carbonate fuel cells (MCFCs) in natural gas fired combined cycles (NGCC) in order to efficiently capture CO2 from the exhaust of the gas turbine. In the proposed cycles, the gas turbine flue gases are used as cathode feeding for a MCFC, where CO2 is transferred from the cathode to anode side, concentrating the CO2 in the anode exhaust. At the anode side, the MCFCs are fed with natural gas, processed by an external reformer which is thermally integrated within the FC module; the corresponding CO2 production is completely concentrated at the anode. The resulting anode exhaust stream is then sent to a CO2 removal section which is based on a cryogenic CO2 removal process, based on internal or external refrigeration cycles, cooling the exhaust stream in the heat recovery steam generator and recycling residual fuel compounds to the power cycle. In all cases, a high purity CO2 stream is obtained after condensation of water and pumped in liquid form for subsequent storage. The possibility to arrange the MCFC section with different configurations and operating parameters of the fuel cell modules is investigated, and the option to include two fuel cell modules in series connection, with intermediate cooling of the cathode stream, in order to enhance the plant CO2 separation effectiveness, is also examined. The MCFC section behavior is simulated taking into account Ansaldo Fuel Cells experience and reference data based on a dedicated simulation tool. Detailed energy and material balances of the most promising cycle configurations are presented; fuel cell and conventional components’ working parameters are described and discussed, carrying out a sensitivity analysis on the fuel cell CO2 utilization factor. The plant shows the potential to achieve a CO2 avoided fraction approaching 70–80%, depending on the CO2 concentration limit at cathode outlet, with overall electric efficiency only 1–2% points lower than the reference combined cycle. The plant power output increases by over 40%, thanks to the contributions of the MCFC section which acts as an active CO2 concentrator, giving a potentially relevant advantage with respect to competitive carbon capture technologies.

Author(s):  
G. Manzolini ◽  
S. Campanari ◽  
P. Chiesa ◽  
A. Giannotti ◽  
P. Bedont ◽  
...  

This paper presents an analysis of advanced cycles with limited CO2 emissions based on the integration of Molten Carbonate Fuel Cells (MCFC) in natural gas fired combined cycles (NGCC) in order to efficiently capture CO2 from the exhaust of the gas turbine. In the proposed cycles, the gas turbine flue gases are used as cathode feeding for a MCFC, where CO2 is transferred from the cathode to anode side, concentrating the CO2 in the anode exhaust. At the anode side the MCFCs are fed with natural gas, processed by an external reformer which is thermally integrated within the FC module; the corresponding CO2 production is completely concentrated at the anode. The resulting anode exhaust stream is then sent to a CO2 removal section which is based on a cryogenic CO2 removal process, based on internal or external refrigeration cycles, cooling the exhaust stream in the heat recovery steam generator, and recycling residual fuel compounds to the power cycle. In all cases, a high purity CO2 stream is obtained after condensation of water and pumped in liquid form for subsequent storage. It is investigated the possibility to arrange the MCFC section with different configurations and operating parameters of the fuel cell modules, and the option to include two fuel cell modules in series connection, with intermediate cooling of the cathode stream, in order to enhance the plant CO2 separation effectiveness. The MCFC section behavior is simulated taking into account Ansaldo Fuel Cells experience and reference data, based on a dedicated simulation tool. Detailed energy and material balances of the most promising cycle configurations are presented; fuel cell and conventional components working parameters are described and discussed, carrying out a sensitivity analysis on the fuel cell CO2 utilization factor. The plant shows the potential to achieve a CO2 avoided fraction approaching 70–80%, depending on the CO2 concentration limit at cathode outlet, with an overall electric efficiency only 1–2% point lower than reference combined cycle. The plant power output increases by over 40%, thanks to the contribute of the MCFC section which acts as an active CO2 concentrator, giving a potentially relevant advantage with respect to competitive carbon capture technologies.


Author(s):  
Maurizio Spinelli ◽  
Stefano Campanari ◽  
Matteo C. Romano ◽  
Stefano Consonni ◽  
Thomas G. Kreutz ◽  
...  

The state-of-the-art conventional technology for post combustion capture of CO2 from fossil-fuelled power plants is based on chemical solvents, which requires substantial energy consumption for regeneration. Apromising alternative, available in the near future, is the application of Molten Carbonate Fuel Cells (MCFC) for CO2 separation from post-combustion flue gases. Previous studies related to this technology showed both high efficiency and high carbon capture rates, especially when the fuel cell is thermally integrated in the flue gas path of a natural gas-fired combined cycle or an integrated gasification combined cycle plant. This work compares the application of MCFC based CO2 separation process to pulverized coal fired steam cycles (PCC) and natural gas combined cycles (NGCC) as a ‘retrofit’ to the original power plant. Mass and energy balances are calculated through detailed models for both power plants, with fuel cell behaviour simulated using a 0D model calibrated against manufacturers’ specifications and based on experimental measurements, specifically carried out to support this study. The resulting analysis includes a comparison of the energy efficiency and CO2 separation efficiency as well as an economic comparison of the cost of CO2 avoided under several economic scenarios. The proposed configurations reveal promising performance, exhibiting very competitive efficiency and economic metrics in comparison with conventional CO2 capture technologies. Application as a MCFC retrofit yields a very limited (<3%) decrease in efficiency for both power plants (PCC and NGCC), a strong reduction (>80%) in CO2 emission and a competitive cost for CO2 avoided (25–40 €/ton).


Author(s):  
Maurizio Spinelli ◽  
Stefano Campanari ◽  
Stefano Consonni ◽  
Matteo C. Romano ◽  
Thomas Kreutz ◽  
...  

The state-of-the-art conventional technology for postcombustion capture of CO2 from fossil-fueled power plants is based on chemical solvents, which requires substantial energy consumption for regeneration. A promising alternative, available in the near future, is the application of molten carbonate fuel cells (MCFC) for CO2 separation from postcombustion flue gases. Previous studies related to this technology showed both high efficiency and high carbon capture rates, especially when the fuel cell is thermally integrated in the flue gas path of a natural gas-fired combined cycle or an integrated gasification combined cycle plant. This work compares the application of MCFC-based CO2 separation process to pulverized coal fired steam cycles (PCC) and natural gas combined cycles (NGCC) as a “retrofit” to the original power plant. Mass and energy balances are calculated through detailed models for both power plants, with fuel cell behavior simulated using a 0D model calibrated against manufacturers' specifications and based on experimental measurements, specifically carried out to support this study. The resulting analysis includes a comparison of the energy efficiency and CO2 separation efficiency as well as an economic comparison of the cost of CO2 avoided (CCA) under several economic scenarios. The proposed configurations reveal promising performance, exhibiting very competitive efficiency and economic metrics in comparison with conventional CO2 capture technologies. Application as a MCFC retrofit yields a very limited (<3%) decrease in efficiency for both power plants (PCC and NGCC), a strong reduction (>80%) in CO2 emission and a competitive cost for CO2 avoided (25–40 €/ton).


Author(s):  
Vincenzo Spallina ◽  
Matteo C. Romano ◽  
Stefano Campanari ◽  
Giovanni Lozza

Integrated gasification combined cycles (IGCCs) are considered the reference technology for high efficiency and low emission power generation from coal. In recent years, several theoretical and experimental studies in this field have been oriented toward capturing CO2 from IGCCs through the integration of solid oxide fuel cells (SOFCs) for coal-syngas oxidation, investigating the so-called integrated gasification fuel cell cycles (IGFC). However, molten carbonate fuel cells (MCFCs) can also be a promising technology in IGFCs. After rather comprehensive research carried out by the authors on modeling and simulation of SOFC-based IGFC plants, an interesting IGFC cycle based on MCFC is assessed in this work, where plant layout is designed to exploit the capability of MCFCs of transferring CO2 and O2 from the oxidant side to the fuel side. Syngas produced in a high efficiency Shell gasifier is cleaned and mainly burned in a combustion turbine as in conventional IGCCs. Turbine flue gas, rich with oxygen and carbon dioxide, are then used as oxidant stream for the fuel cell at the cathode side, while the remaining clean syngas is oxidized at the anode side. In this way, the MCFC, while efficiently producing electricity, separates CO2 from the gas turbine flue gas as in a post-combustion configuration; oxygen is also transported toward the anode side, oxidizing the remaining syngas as in an oxy-combustion mode. A CO2-rich stream is hence obtained at anode outlet, which can be cooled and compressed for long term storage. This configuration allows production of power from coal with high efficiency and low emission. In addition, as already highlighted in a previous study where a similar concept has been applied to natural gas-fired combined cycles, a limited fraction of the power output is generated by the fuel cell (the most expensive component), highlighting its potential also from an economic point of view. Detailed results are presented in terms of energy and material balances of the proposed cycle.


Author(s):  
Vincenzo Spallina ◽  
Matteo C. Romano ◽  
Stefano Campanari ◽  
Giovanni Lozza

Integrated gasification combined cycles (IGCCs) are considered the reference technology for high efficiency and low emission power generation from coal. In recent years, several theoretical and experimental studies in this field have been oriented towards capturing CO2 from IGCCs through the integration of Solid Oxide Fuel Cells (SOFC) for coal-syngas oxidation, investigating the so-called Integrated Gasification Fuel Cell cycles (IGFC). However, Molten Carbonate Fuel Cells (MCFC) can also be a promising technology in IGFCs. After a rather comprehensive research carried out by the authors on modeling and simulation of SOFC-based IGFC plants, an interesting IGFC cycle based on MCFC is assessed in this work, where plant layout is designed to exploit the capability of MCFCs of transferring CO2 and O2 from the oxidant side to the fuel side. Syngas produced in a high efficiency Shell gasifier is cleaned and mainly burned in a combustion turbine as in conventional IGCCs. Turbine flue gas, rich of oxygen and carbon dioxide, are then used as oxidant stream for the fuel cell at the cathode side, while the remaining clean syngas is oxidized at the anode side. In this way the MCFC, while efficiently producing electricity, separates CO2 from the gas turbine flue gas as in a post-combustion configuration; oxygen is also transported towards the anode side, oxidizing the remaining syngas as in an oxy-combustion mode. A CO2-rich stream is hence obtained at anode outlet, which can be cooled and compressed for long term storage. This configuration allows to produce power from coal with high efficiency and low emission. In addition, as already highlighted in a previous study where a similar concept has been applied to natural gas-fired combined cycles, a limited fraction of the power output is generated by the fuel cell (the most expensive component), highlighting its potential also from an economic point of view. Detailed results are presented in terms of energy and material balances of the proposed cycle.


Energies ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 1361 ◽  
Author(s):  
Jae-Hyeong Yu ◽  
Chang-Whan Lee

Molten carbonate fuel cells (MCFCs) are high-operating-temperature fuel cells with high efficiency and fuel diversity. Electrochemical reactions in MCFCs are exothermic. As the size of the fuel cells increases, the amount of the heat from the fuel cells and the temperature of the fuel cells increase. In this work, we investigated the relationship between the fuel cell stack size and performance by applying computational fluid dynamics (CFD). Three flow types, namely co-flow, cross-flow, and counter-flow, were studied. We found that when the size of the fuel cells increased beyond a certain value, the size of the fuel cell no longer affected the cell performance. The maximum fuel cell temperature converged as the size of the fuel cell increased. The temperature and current density distribution with respect to the size showed a very similar distribution. The converged maximum temperature of the fuel cells depended on the gas flow condition. The maximum temperature of the fuel cell decreased as the amount of gas in the cathode size increased.


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