Modeling of a Direct Carbon Fuel Cell System

2010 ◽  
Vol 7 (5) ◽  
Author(s):  
K. Hemmes ◽  
M. Houwing ◽  
N. Woudstra
Keyword(s):  
Fuel Cells ◽  
Solid Oxide Fuel Cells ◽  
Exergy Analysis ◽  
Cell System ◽  
System Model ◽  
System Level ◽  
Molten Carbonate ◽  
Bench Scale ◽  
Direct Carbon Fuel Cell ◽  
Molten Carbonate Fuel Cells

Direct carbon fuel cells (DCFCs) have great thermodynamic advantages over other high temperature fuel cells such as molten carbonate fuel cells (MCFCs) and solid oxide fuel cells. They can have 100% fuel utilization, no Nernst loss (at the anode), and the CO2 produced at the anode is not mixed with other gases and is ready for re-use or sequestration. So far, only studies have been reported on cell development. In this paper, we study the performance of a CO2-producing DCFC system model. The theoretically predicted advantages that are confirmed on a bench scale are also confirmed on a system level, except for the production of pure CO2. Net system efficiencies of around 78% were found for the developed system. An exergy analysis of the system shows where the losses in the system occur. If the cathode of the DCFC must be operated as a standard MCFC cathode, the required CO2 at the cathode is the reason why a large part of the pure CO2 from the anode is recycled and mixed with the incoming air and cannot be used directly for sequestration. Bench scale studies should be performed to test the minimum amount of CO2 needed at the cathode. This might be lower than in a standard MCFC operation due to the pure CO2 at the anode side that enhances diffusion toward the cathode.

Modeling of a Direct Carbon Fuel Cell System

2005 ◽  
Author(s):  
K. Hemmes ◽  
M. Houwing ◽  
N. Woudstra
Keyword(s):  
Fuel Cells ◽  
Exergy Analysis ◽  
Cell System ◽  
System Model ◽  
System Level ◽  
Anode Side ◽  
Fuel Utilization ◽  
Fuel Cell System ◽  
Bench Scale ◽  
Direct Carbon Fuel Cell

Direct Carbon Fuel Cells (DCFCs) have great thermodynamic advantages over other high temperature fuel cells such as MCFC and SOFC. They can have 100% fuel utilization, no Nernst loss (at the anode) and the CO2 produced at the anode is not mixed with other gases and is ready for reuse or sequestration. So far only studies have been reported on cell development. In this paper we study the performance of a CO2-producing DCFC system model. The theoretically predicted advantages that are confirmed on a bench scale are also confirmed on a system level, except for the production of pure CO2. Net system efficiencies of around 78 % were found for the developed system. An exergy analysis of the system shows where the losses in the system occur. If the cathode of the DCFC must be operated as a standard MCFC cathode the required CO2 at the cathode is the reason why a large part of the pure CO2 from the anode is recycled and mixed with the incoming air and cannot be used directly for sequestration. Bench scale studies should be performed to test the minimum amount of CO2 needed at the cathode. This might be lower than in standard MCFC operation due to the pure CO2 at the anode side that enhances diffusion towards the cathode.

Modeling of a Methane Fuelled Direct Carbon Fuel Cell System

2010 ◽  
Vol 7 (6) ◽  
Author(s):  
K. Hemmes ◽  
M. Houwing ◽  
N. Woudstra
Keyword(s):  
Fuel Cells ◽  
Fuel Cell ◽  
Cell System ◽  
Molten Carbonate Fuel Cell ◽  
Total System ◽  
Molten Carbonate ◽  
Heating Value ◽  
Carbon Particles ◽  
Direct Carbon Fuel Cell ◽  
Air Stream

Direct Carbon Fuel Cells (DCFCs) have great thermodynamic advantages over other high temperature fuel cells such as molten carbonate fuel cell (MCFC) and solid oxide fuel cell. They can have 100% fuel utilization, no Nernst loss (at the anode), and the CO2 produced at the anode is not mixed with other gases and is ready for re-use or sequestration. So far only studies have been reported on cell development. In this paper we study in particular the integration of the production of clean and reactive carbon particles from methane as a fuel for the direct carbon fuel cell. In the thermal decomposition process heat is upgraded to chemical energy in the carbon and hydrogen produced. The hydrogen is seen as a product as well as the power and heat. Under the assumptions given the net system electric efficiencies are 22.9% (based on methane lower heating value, LHV) and 20.7% (higher heating value, HHV). The hydrogen production efficiencies are 65.5% (based on methane LHV) and 59.1% (HHV), which leads to total system efficiencies of 88.4% (LHV) and 79.8% (HHV). Although a pure CO2 stream is produced at the anode outlet, which is seen as a large advantage of DCFC systems, this advantage is unfortunately reduced due to the need for CO2 in the cathode air stream. Due to the applied assumed constraint that the cathode outlet stream should at least contain 4% CO2 for the proper functioning of the cathode, similar to MCFC cathodes, a major part of the pure CO2 has to be mixed with incoming air. Further optimization of the DCFC and the system is needed to obtain a larger fraction of the output streams as pure CO2 for sequestration or re-use.

Operation of Carbonate Fuel Cell (MCFC) Using Syngas

2011 ◽  
Author(s):  
Joseph McInerney ◽  
Hossein Ghezel-Ayagh ◽  
Robert Sanderson ◽  
Jennifer Hunt
Keyword(s):  
Power Generation ◽  
Fuel Cells ◽  
Fuel Cell ◽  
Natural Gas ◽  
High Efficiency ◽  
Cell System ◽  
System Level ◽  
Molten Carbonate ◽  
Fuel Cell Stack ◽  
Internal Reforming

High temperature fuel cells, such as Molten Carbonate Fuel Cells (MCFC), are prime candidates for power generation using natural gas. Currently MCFC-based products are available for on-site power generation using natural gas and methane-rich biogas. These systems use the most advanced stack configuration utilizing internal reforming of methane. The in-situ reforming within the fuel cell anode provides many operational benefits including stack cooling at high current densities. Syngas from a variety of sources such as coal, biomass and renewables are anticipated to play a key role in the future landscape of power generation. MCFC is capable of utilizing syngss to produce electric power at a very high efficiency. However, because of the differences in the gas compositions between natural-gas and syngas, the fuel cell stack and system designs need to be modified for syngas fuels. The purpose of this study is to develop the design modifications at both the stack and system level needed for operation of internal reforming MCFC using low-methane content syngas without major design changes from the commercial product design. The net outcome of the investigation is a fuel cell system which meets the goals of being able to operate on low methane syngas within thermo-mechanical requirements of the fuel cell stack components. In this paper, we will describe the approach for modification of MCFC design and operating parameters for operation under syngas using both system level modeling and stack level mathematical modeling.

A Matlab-Simulink Analysis of Hybrid SOFC Dynamic Behavior

2005 ◽  
Author(s):  
Umberto Desideri ◽  
Gheorghe Lazaroiu ◽  
Dario Zaninelli ◽  
Cristian Lazaroiu
Keyword(s):  
Fuel Cells ◽  
Solid Oxide Fuel Cells ◽  
Hybrid System ◽  
Solid Oxide ◽  
Oxide Fuel ◽  
Molten Carbonate ◽  
High Hydrogen ◽  
Matlab Simulink ◽  
Fuel Flow ◽  
Molten Carbonate Fuel Cells

Fuel cells are more and more used in hybrid systems with micro-turbines for electricity and heat delivery. Two types of fuel cells are mostly used for cogeneration: solid-oxide fuel cells (SOFC) and molten carbonate fuel cells (MCFC). Solid oxide fuel cells (SOFC) are operating at high temperatures that make them well suited for cogeneration process, but influence the entire system due to their dynamic character. The hybrid system requires a pre-reforming process in order to convert the fuels, such as natural gas, in a gas with a high hydrogen content for the electrochemically oxidation with air. In this paper the dynamic model of the SOFC and of the hybrid system is developed in Matlab-Simulink environment. The comprehensive model is based on the electrochemical and thermal equations and on the temperature dynamics. The response of the SOFC and of the hybrid system to the variation of fuel flow and other parameters is investigated.

Status and Challenges of Molten Carbonate Fuel Cells

2010 ◽  
Vol 72 ◽  
pp. 283-290 ◽  
Author(s):  
Stephen J. McPhail
Keyword(s):  
Fuel Cells ◽  
Energy Supply ◽  
Nuclear Power ◽  
System Level ◽  
Molten Carbonate ◽  
Technical Status ◽  
Molten Carbonate Fuel Cells

By analogy with the development of nuclear power and photovoltaics, the position of MCFC technology is evaluated in the context of today’s energy supply. A brief review is presented of the technical status of MCFC materials and challenges left open. At system level, a number of more or less niche applications prove to be promising for approaching early markets and an update is given of some important figures on construction and deployment of MCFC systems worldwide.

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