Comparison of Molten Carbonate and Solid Oxide Fuel Cells for Integration in a Hybrid System for Cogeneration or Tri-Generation

2004 ◽  
Author(s):  
Georgia C. Karvountzi ◽  
Clifford M. Price ◽  
Paul F. Duby
Keyword(s):  
Fuel Cells ◽  
Fuel Cell ◽  
Solid Oxide Fuel Cells ◽  
Steam Turbine ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Solid Oxide ◽  
Oxide Fuel ◽  
Molten Carbonate ◽  
Hybrid Cycle

High temperature fuel cells, such as molten carbonate fuel cells (MCFC) and solid oxide fuel cells (SOFC) can be integrated in a hybrid cycle with a gas turbine and a steam turbine and achieve overall lower heating value (LHV) efficiencies of about 70%. A hybrid cycle designed for cogeneration or tri-generation applications could lead to even higher overall LHV efficiencies. Tri-generation is the combined generation of power, heat and cooling from the same fuel source. The purpose of the present paper is to compare the performance of a 20MW MCFC system and a 20MW tubular SOFC system and assess their potential to cogeneration and tri-generation applications. The system includes a fuel cell, a gas turbine, a multiple pressure heat recovery steam generator (HRSG), a steam turbine and an absorption chiller (for cooling). The systems were designed and sized using GatecycleTM heat balance software by GE Enter Software, LLC. In order to optimize each system we developed curves showing LHV “electric” and “cogeneration” efficiency versus power for different ratios of “MCFC and SOFC fuel cell-to-gas turbines size.” At atmospheric pressure and at 675°C (1247°F) the 20MW MCFC system achieves “electric” efficiency of 69.5%. The SOFC at the same pressure and at 980°C achieves 67.3% “electric” efficiency. The MCFC alone is more efficient (58%) than the SOFC alone (56%). However the SOFC produces more heat than the MCFC leading to slightly higher cogeneration and tri-generation efficiencies. Pressurized operation at 9atm boosts the performance of the SOFC system to higher efficiencies (70.5%). Pressurized operation is problematic for the MCFC due to increased cathode corrosion leading to cathode dissolution as well as sealant and interconnection problems. However we can pressurize the MCFC system independently of the fuel cell with the integration of a gas turbine with a compressor pressure ratio of 10 to 16. Thus we achieve efficiencies close to 69%. In conclusion SOFC is more efficiently integrated in a hybrid configuration with gas turbine and a steam turbine for trigeneration applications when pressurized. MCFC is more efficiently integrated at atmospheric and pressures below 6 atm.

Effect of Fuel Cell Operation Pressure on the Optimization of a Hybrid System SOFC/Turbine for Cogeneration

2004 ◽  
Author(s):  
Georgia C. Karvountzi ◽  
Clifford M. Price ◽  
Paul F. Duby
Keyword(s):  
Fuel Cells ◽  
Fuel Cell ◽  
Solid Oxide Fuel Cell ◽  
Steam Turbine ◽  
Gas Turbine ◽  
Hybrid System ◽  
Heat Balance ◽  
Gas Turbines ◽  
Solid Oxide ◽  
Oxide Fuel

A solid oxide fuel cell (SOFC) integrated in a hybrid system with a gas turbine can achieve lower heating value (LHV) power of efficiencies of about 70%. Given the high operating temperature of the SOFC, it produces high grade heat, and a hybrid system designed for cogeneration may achieve total LHV efficiencies of 78% of 80% without post combustion and 85%–88% with post combustion. The present paper illustrates the optimum integration of a tubular solid oxide fuel cell in a cogeneration cycle with a multiple pressure heat recovery steam generator (HRSG) and a back pressure steam turbine. We considered fuel cells of 7.5 MW, 9 MW, 15 MW, 15 MW, 18 MW, 22.5 MW and 27 MW by scaling up published data for a 1.2 MW tubular solid oxide fuel cell. The operating pressures were 3 and 9atm. We used GateCycle™ heat balance software by GE Enter Software, LLC, to design a 20–40 MW high efficiency cogeneration plant. We performed a calculation of the heat balance of the fuel cell stack in Microsoft® Excel and then we imported the results into GateCycle™. We developed curves showing LHV “electric” efficiency versus power for different ratios of “fuel cell-to-gas turbine size”. Pressurization has a positive impact on the fuel cell polarization curve leading to higher power output. The gain in electric power, however, is offset by the additional power requirement of the compressor at higher pressures. Our analysis shows that an optimum pressure of about 9 atmospheres results in an overall hybrid system power efficiency of about 70% and a LHV “cogeneration” efficiency of about 80%. In conclusion, high efficiencies are obtained by optimization of a hybrid system consisting of pressurized high temperature fuel cells with gas turbines and a steam turbine.

scholarly journals Parametric Study of Fuel Cell and Gas Turbine Combined Cycle Performance

1997 ◽  
Author(s):  
Dawn Stephenson ◽  
Ian Ritchey
Keyword(s):  
Fuel Cells ◽  
Fuel Cell ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Combined Cycle ◽  
Solid Oxide ◽  
Simple Cycle ◽  
Cycle Performance ◽  
Oxide Fuel ◽  
Combined Cycles

A number of cycles have been proposed in which a solid oxide fuel cell is used as the topping cycle to a gas turbine, including those recently described by Beve et al. (1996). Such proposals frequently focus on the combination of particular gas turbines with particular fuel cells. In this paper, the development of more general models for a number of alternative cycles is described. These models incorporate variations of component performance with key cycle parameters such as gas turbine pressure ratio, fuel cell operating temperature and air flow. Parametric studies are conducted using these models to produce performance maps, giving overall cycle performance in terms of both gas turbine and fuel cell design point operating conditions. The location of potential gas turbine and fuel cell combinations on these maps is then used to identify which of these combinations are most likely to be appropriate for optimum efficiency and power output. It is well known, for example, that the design point of a gas turbine optimised for simple cycle performance is not generally optimal for combined cycle gas turbine performance. The same phenomenon may be observed in combined fuel cell and gas turbine cycles, where both the fuel cell and the gas turbine are likely to differ from those which would be selected for peak simple cycle efficiency. The implications of this for practical fuel cell and gas turbine combined cycles and for development targets for solid oxide fuel cells are discussed. Finally, a brief comparison of the economics of simple cycle fuel cells, simple cycle gas turbines and fuel cell and gas turbine combined cycles is presented, illustrating the benefits which could result.

Comparative Analysis of Hybrid Cycles Based on Molten Carbonate and Solid Oxide Fuel Cells

2001 ◽  
Author(s):  
Stefano Campanari ◽  
Ennio Macchi
Keyword(s):  
Fuel Cells ◽  
Fuel Cell ◽  
Gas Turbines ◽  
Solid Oxide ◽  
Molten Carbonate Fuel Cell ◽  
Small Scale ◽  
Oxide Fuel ◽  
Molten Carbonate ◽  
Successful Operation ◽  
Hybrid Plants

High temperature fuel cells are experiencing an increasing amount of attention thanks to the successful operation of prototype plants, including a multi-MW Molten Carbonate Fuel Cell (MCFC) demonstration plant and a hybrid Solid Oxide Fuel Cell (SOFC) gas turbine power plant. Both MCFCs and SOFCs are currently considered attractive for the integration with gas turbines in more complex “hybrid” plants, with projected performances that largely exceed combined cycles efficiencies even at a small-scale size and with an extremely low environmental impact. This paper compares the performances of MCFC and SOFC hybrid cycles. The comparison shows some advantages for the SOFC hybrid cycle in terms of plant simplicity and moderately higher efficiency.

Optimization of a MCFC/Turbine Hybrid System for Cogeneration

2003 ◽  
Author(s):  
Georgia C. Karvountzi ◽  
Clifford M. Price ◽  
Paul F. Duby
Keyword(s):  
Fuel Cells ◽  
High Temperature ◽  
Fuel Cell ◽  
Steam Turbine ◽  
Gas Turbine ◽  
Hybrid System ◽  
Heat Balance ◽  
Gas Turbines ◽  
Cogeneration Plant ◽  
Hybrid Cycle

High temperature fuel cells can be integrated in a hybrid cycle with a gas turbine and achieve lower heating value (LHV) efficiencies of about 70%. A hybrid cycle designed for cogeneration applications could lead to even higher LHV efficiencies such as 78% to 80% without post combustion and 85%–90% with post combustion. The purpose of the present paper is to optimize the integration of a high temperature fuel cell in a cogeneration cycle. We used Gatecycle™ heat balance software by GE Enter Software, LLC, to design a 20–80 MW high efficiency cogeneration plant. Since Gatecycle™ does not have an icon for the fuel cell, we calculated the heat balance for the fuel cell stack in Microsoft® Excel and we imported the results into Gatecycle™. We considered a 8.5 MW, a 17 MW and a 34 MW fuel cell by scaling up of the commercially available 3MW molten carbonate fuel cell (MCFC). Our goal was to evaluate the optimum ratio between the fuel cell size and gas turbine size using a family of curves we developed showing LHV “electric” efficiency versus power for different ratios of “fuel cell–to–gas turbines size”. Similar curves showing LHV “cogeneration” efficiency are also presented. In addition configurations with a back pressure steam turbine and with a condensing steam turbine are evaluated. The influence of steam generation pressure in the overall system efficiency is discussed, as well as the performance of the hybrid system for different temperatures (0°F–80°F) and elevations (0 ft–3000 ft). Our conclusion is that high temperature fuel cells in a hybrid configuration with gas turbines could be successfully integrated into a cogeneration plant to achieve very high efficiencies.

Gas Turbine Cycles With Solid Oxide Fuel Cells—Part II: A Detailed Study of a Gas Turbine Cycle With an Integrated Internal Reforming Solid Oxide Fuel Cell

1994 ◽  
Vol 116 (4) ◽  
pp. 312-318 ◽  
Author(s):  
S. P. Harvey ◽  
H. J. Richter
Keyword(s):  
Power Generation ◽  
Fuel Cells ◽  
High Temperature ◽  
Fuel Cell ◽  
Solid Oxide Fuel Cells ◽  
Solid Oxide Fuel Cell ◽  
Energy Conversion ◽  
Gas Turbine ◽  
Solid Oxide ◽  
Oxide Fuel

In conventional energy conversion processes, the fuel combustion is usually highly irreversible, and is thus responsible for the low overall efficiency of the power generation process. The energy conversion efficiency can be improved if immediate contact of air and fuel is prevented. One means to prevent this immediate contact is the use of fuel cell technology. Significant research is currently being undertaken to develop fuel cells for large-scale power production. High-temperature solid oxide fuel cells (SOFC) have many features that make them attractive for utility and industrial applications. However, in view of their high operating temperatures and the incomplete nature of the fuel oxidation process, such fuel cells must be combined with conventional power generation technology to develop power plant configurations that are both functional and efficient. Most fuel cell cycles proposed in the literature use a high-temperature fuel cell running at ambient pressure and a steam bottoming cycle to recover the waste heat generated by the fuel cell. With such cycles, the inherent flexibility and shorter start-up time characteristics of the fuel cell are lost. In Part I of this paper (Harvey and Richter, 1994), a pressurized cycle using a solid oxide fuel cell and an integrated gas turbine bottoming cycle was presented. The cycle is simpler than most cycles with steam bottoming cycles and more suited to flexible power generation. In this paper, we will discuss this cycle in more detail, with an in-depth discussion of all cycle component characteristics and losses. In particular, we will make use of the fuel cell’s internal fuel reforming capability. The optimal cycle parameters were obtained based on calculations performed using Aspen Technology’s ASPEN PLUS process simulation software and a fuel cell simulator developed by Argonne National Laboratory (Ahmed et al., 1991). The efficiency of the proposed cycle is 68.1 percent. A preliminary economic assessment of the cycle shows that it should compare favorably with a state-of-the-art combined cycle plant on a cost per MWe basis.

Gas Turbine Cycles With Solid Oxide Fuel Cells—Part I: Improved Gas Turbine Power Plant Efficiency by Use of Recycled Exhaust Gases and Fuel Cell Technology

1994 ◽  
Vol 116 (4) ◽  
pp. 305-311 ◽  
Author(s):  
S. P. Harvey ◽  
H. J. Richter
Keyword(s):  
Power Generation ◽  
Fuel Cells ◽  
Fuel Cell ◽  
Power Plant ◽  
Solid Oxide Fuel Cells ◽  
Gas Turbine ◽  
Solid Oxide ◽  
Oxide Fuel ◽  
Exhaust Gases ◽  
Gas Turbine Cycle

In conventional energy conversion processes, the fuel combustion is usually highly irreversible, and is thus responsible for the low overall efficiency of the power generation process. The energy conversion efficiency of the combustion process can be improved if immediate contact of fuel and oxygen is prevented and an oxygen carrier is used. In a previous paper (Harvey et al., 1992), a gas turbine cycle was investigated in which part of the exhaust gases—consisting mainly of CO2, H2O, and N2—are recycled and used as oxygen-carrying components. For the optimized process, a theoretical thermal efficiency of 66.3 percent was achieved, based on the lower heating value (LHV) of the methane fuel. A detailed second-law analysis of the cycle revealed that, although the exergy losses associated with the fuel oxidation were significantly less than those associated with conventional direct fuel combustion methods, these losses were still a major contributor to the overall losses of the system. One means to further improve the exergetic efficiency of a power cycle is to utilize fuel cell technology. Significant research is currently being undertaken to develop fuel cells for large-scale power production. High-efficiency fuel cells currently being investigated use high-temperature electrolytes, such as molten carbonates (~ 650°C) and solid oxides (usually doped zirconia, ~1000°C). Solid oxide fuel cells (SOFC) have many features that make them attractive for utility and industrial applications. In this paper, we will therefore consider SOFC technology. In view of their high operating temperatures and the incomplete nature of the fuel oxidation process, fuel cells must be combined with conventional power generation technology to develop power plant configurations that are both functional and efficient. In this paper, we will show how monolithic SOFC (MSOFC) technology may be integrated into the previously described gas turbine cycle using recycled exhaust gases as oxygen carriers. An optimized cycle configuration will be presented based upon a detailed cycle analysis performed using Aspen Plus™ process simulation software (Aspen Technology, 1991) and a MSOFC fuel cell simulator developed by Argonne National Labs (Ahmed et al., 1991). The optimized cycle achieves a theoretical thermal efficiency of 77.7 percent, based on the LHV of the fuel.

scholarly journals Integrated Cr and S poisoning of a La0.6Sr0.4Co0.2Fe0.8O3−δ (LSCF) cathode for solid oxide fuel cells

RSC Advances ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 7-14
Author(s):  
Cheng Cheng Wang ◽  
Mortaza Gholizadeh ◽  
Bingxue Hou ◽  
Xincan Fan
Keyword(s):  
Fuel Cells ◽  
Fuel Cell ◽  
Solid Oxide Fuel Cells ◽  
Solid Oxide Fuel Cell ◽  
Solid Oxide ◽  
Cell Performance ◽  
Oxide Fuel ◽  
Performance Deterioration

Strontium segregation in a La0.6Sr0.4Co0.2Fe0.8O3−δ (LSCF) electrode reacts with Cr and S in a solid oxide fuel cell (SOFC), which can cause cell performance deterioration.

Thermodynamic model and analysis of hybrid power installations built around solid-oxide fuel cells and gas-turbine units

2008 ◽  
Vol 55 (9) ◽  
pp. 790-794 ◽  
Author(s):  
R. R. Grigor’yants ◽  
V. I. Zalkind ◽  
P. P. Ivanov ◽  
D. A. Lyalin ◽  
V. I. Miroshnichenko
Keyword(s):  
Fuel Cells ◽  
Solid Oxide Fuel Cells ◽  
Gas Turbine ◽  
Thermodynamic Model ◽  
Solid Oxide ◽  
Oxide Fuel ◽  
Hybrid Power ◽  
Power Installations
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