scholarly journals Challenges in developing direct carbon fuel cells

2017 ◽  
Vol 46 (10) ◽  
pp. 2889-2912 ◽  
Author(s):  
Cairong Jiang ◽  
Jianjun Ma ◽  
Gael Corre ◽  
Sneh L. Jain ◽  
John T. S. Irvine
Keyword(s):  
Fuel Cells ◽  
Fuel Cell ◽  
Electrical Efficiency ◽  
Direct Carbon Fuel Cell ◽  
Direct Carbon Fuel Cells

A direct carbon fuel cell (DCFC) can produce electricity with both superior electrical efficiency and fuel utilisation compared to all other types of fuel cells.

A direct carbon fuel cell with a CuO–ZnO–SDC composite anode

RSC Advances ◽  
2016 ◽  
Vol 6 (55) ◽  
pp. 50201-50208 ◽  
Author(s):  
Wenbin Hao ◽  
Yongli Mi
Keyword(s):  
Fuel Cells ◽  
Fuel Cell ◽  
Power Density ◽  
Anode Material ◽  
Maximum Power ◽  
Maximum Power Density ◽  
Composite Anode ◽  
Direct Carbon Fuel Cell ◽  
Direct Carbon Fuel Cells

A direct carbon fuel cell with a CuO–ZnO–SDC composite anode was demonstrated. The maximum power density was 130 mW cm−2 at 700 °C. The results indicate that CuO–ZnO can be used as a nickel-free anode material for direct carbon fuel cells.

scholarly journals The Use of Direct Carbon Fuel Cells in Compact Energy Systems for the Generation of Electricity, Heat and Cold

Energies ◽  
2018 ◽  
Vol 11 (11) ◽  
pp. 3061 ◽  
Author(s):  
Robert Zarzycki ◽  
Andrzej Kacprzak ◽  
Zbigniew Bis
Keyword(s):  
Fuel Cells ◽  
Fuel Cell ◽  
High Efficiency ◽  
Hot Water ◽  
Maximum Heat ◽  
Absorption Chillers ◽  
Heating And Cooling ◽  
Direct Carbon Fuel Cell ◽  
Basic Source ◽  
Direct Carbon Fuel Cells

The study presents a concept and calculations concerning the operation of the direct carbon fuel cell (DCFC) with molten hydroxide electrolyte (MH-DCFC) as the basic source of electricity integrated with heat and cool air generation systems. The technology of direct carbon fuel cells assumes the direct use of a carbon fuel (such as fossil coal, carbonized biomass, graphite, coke etc.) to generate electricity with high efficiency and low impact on the environment. These cells operate by utilizing carbon fuel in the range of temperatures of 673–973 K and allow for generation of electricity with an efficiency of about 56%. In order to improve the fuel conversion efficiency, the heat generated in the process of cell cooling can be used to prepare hot water, for heating during the heating season, while during the summer period, heat from cooling of the direct carbon fuel cells can be utilized in the process of cool air production (chilled air) using absorption chillers for e.g. air conditioning. This paper presents a case study and simulation calculations of the system composed of MH-DCFC that generates electricity, and runs heat exchangers and an absorption chiller, integrated with the fuel cell to generate heating and cooling for improving the efficiency of the whole system. The maximum heat and cool streams that can be obtained during the operation of the cell were also evaluated. The results obtained in the study can be helpful in the design of autonomous buildings equipped in direct carbon fuel cells as sources of electricity integrated with the systems of heat and cool generation.

Modeling of a Methane Fuelled Direct Carbon Fuel Cell System

2005 ◽  
Author(s):  
K. Hemmes ◽  
M. Houwing ◽  
N. Woudstra
Keyword(s):  
Fuel Cells ◽  
Fuel Cell ◽  
Production Efficiency ◽  
Cell System ◽  
Total System ◽  
Carbon Particles ◽  
Direct Carbon Fuel Cell ◽  
Air Stream ◽  
Reactive Carbon ◽  
Outlet Stream

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 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 efficiency is 22.9 % (based on methane LHV) and 20.7 % (HHV). The hydrogen production efficiency is 65.5 % (based on methane LHV) and 59.1 % (HHV), which leads to a total system efficiency 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 a 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 reuse.

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.

Fuel Cells: What’s Up Next?

2003 ◽  
Author(s):  
Kas Hemmes
Keyword(s):  
Fuel Cells ◽  
Fuel Cell ◽  
Chemical Process ◽  
Waste Heat ◽  
Exothermic Reaction ◽  
Process Industry ◽  
Chemical Process Industry ◽  
Cell Technology ◽  
Fuel Cell Technology ◽  
Direct Carbon Fuel Cell

Fuel cells are defined as devices that convert chemical energy into heat and electric power. However, depending on their type, fuel cells have special features that can be used advantageously in for instance the chemical process industry of which examples will be given. Nevertheless these new applications use existing fuel cells like the MCFC. This is very exiting and many new possibilities are yet to be explored. However there is no principle reason why we should limit fuel cell technology to present types and the well known fuels like hydrogen, methane and methanol and air as oxidant. Recently interest in the direct conversion of carbon as a fuel has revived which has led to the development of a DCFC (direct carbon fuel cell) based on MCFC technology. Lawrence Livermore National Lab has demonstrated the DCFC successfully on a bench scale size. Also H2S is considered as a fuel. Further ahead opportunities are to be explored by replacing exothermic reaction in the chemical process industry such as partial oxidation reactions by their electrochemical counterpart. Thereby electricity is generated instead of excessive waste heat. Now that fuel cell technology is getting mature we can think of adopting this technology in new dedicated fuel cell types, with relatively short development trajectories, for application in totally new fields where electricity may just be a by-product.

Modeling of a Methane Fuelled Direct Carbon Fuel Cell System

2005 ◽  
Author(s):  
N. Woudstra ◽  
T. P. van der Stelt ◽  
K. Hemmes
Keyword(s):  
Heat Transfer ◽  
Fuel Cells ◽  
High Temperature ◽  
Fuel Cell ◽  
Energy Conversion ◽  
Fuel Conversion ◽  
Cell Systems ◽  
Electrochemical Conversion ◽  
Direct Carbon Fuel Cell ◽  
Conversion Efficiencies

Energy conversion today is subject to high thermodynamic losses. About 50 to 90 % of the exergy of primary fuels is lost during conversion into power or heat. The fast increasing world energy demand makes a further increase of conversion efficiencies inevitable. The substantial thermodynamic losses (exergy losses of 20 to 30 %) of thermal fuel conversion will limit future improvements of power plant efficiencies. Electrochemical conversion of fuel enables fuel conversion with minimum losses. Various fuel cell systems have been investigated at the Delft University of Technology during the past twenty years. It appeared that exergy analyses can be very helpful in understanding the extent and causes of thermodynamic losses in fuel cell systems. More than 50 % of the losses in high temperature fuel cell (MCFC and SOFC) systems can be caused by heat transfer. Therefore system optimisation must focus on reducing the need for heat transfer as well as improving the conditions for the unavoidable heat transfer. Various options for reducing the need for heat transfer are discussed in this paper. High temperature fuel cells, eventually integrated into gas turbine processes, can replace the combustion process in future power plants. High temperature fuel cells will be necessary to obtain conversion efficiencies up to 80 % in case of large scale electricity production in the future. The introduction of fuel cells is considered to be a first step in the integration of electrochemical conversion in future energy conversion systems.

Direct Conversion of Coal and Coal-Derived Carbon in Fuel Cells

2004 ◽  
Author(s):  
John F. Cooper
Keyword(s):  
Fuel Cells ◽  
Fuel Cell ◽  
Conversion Efficiency ◽  
Carbon Materials ◽  
Energy Resource ◽  
Direct Conversion ◽  
Atomic Scale ◽  
Molten Carbonate Fuel Cell ◽  
Molten Carbonate ◽  
Direct Carbon Fuel Cell

A direct carbon fuel cell (DCFC) using a carbon-rich derivative of coal would maximize the conversion efficiency of this vast energy resource by avoiding the efficiency limitations of heat engines. A total conversion efficiency of 80% (based on heat of combustion of carbon) has been achieved at 30–120 mA/cm2 using carbon materials extracted from coal and other fossil resources. High experimental efficiency is grounded in two favorable aspects of the reaction thermodynamics. The net fuel cell reaction (C + O2 = CO2) has a nearly zero entropy change and therefore a theoretical efficiency of 100%. The fixed chemical potentials of carbon reactant and CO2 product make possible the full utilization of fuel in a single pass through the cell. The pure CO2 product can be used directly in enhanced oil and gas recovery, or sequestered. Historically, the development of carbon fuel cells have been limited by low anode rates, accumulation of impurities in the electrolyte, logistics of refueling, and lack of suitable cathodes. These problems are being addressed by recent developments of highly reactive carbon materials, low-cost techniques for separation of coal from ash, the possibility of pneumatic distribution of solid particulate fuel to the cells, and availability of cathodes from the molten carbonate fuel cell technology. Rate depends on atomic scale disorder and accessibility of reactive sites, but not on purity. Sources of suitable anode fuel include thermally decomposed products of (1) mechanical and chemical coal/ash separation or (2) solvent extraction. With current understanding of the cell basics, the next steps are demonstration of an engineering scale fuel cell stack (∼1 kW), supported by development of coal-to-carbon processes and techniques of electrolyte management. Successful development of a direct conversion fuel cell for coal (or coal-derived carbon) has extraordinary implications in extending the energy reserves of coal-producing nations, easing the control of regulated emissions at the plant, and expanding the use the earth’s greatest fossil resource while decreasing emissions of greenhouse gas.

Basic Electrochemical Thermodynamic Studies of Fuel Cells Using MALT2

2009 ◽  
Vol 6 (2) ◽  
Author(s):  
M. Williams ◽  
T. Horita ◽  
K. Yamagi ◽  
N. Sakai ◽  
H. Yokokawa
Keyword(s):  
Fuel Cells ◽  
Fuel Cell ◽  
Thermal Efficiency ◽  
Hydrogen Oxidation ◽  
Polymer Electrolyte Fuel Cell ◽  
Direct Oxidation ◽  
Oxidation Of Methane ◽  
Direct Carbon Fuel Cell ◽  
Direct Methanol ◽  
Lower Temperature

There are at least four basic fuel cell thermodynamic features: maximum intrinsic thermal efficiency (electrical efficiency), reversible potential, and two new ones—intrinsic cooling requirement and intrinsic exergetic efficiency. A basic electrochemical thermodynamic analysis of fuel cells using MALT reveals that it is probably for thermodynamic reasons that cooling strategies other than excess oxidant, such as water cooling, have generally been adopted for lower temperature fuel cells such as polymer electrolyte fuel cell (PEFC) and phosphoric acid fuel cell (PAFC). One can mathematically demonstrate that for a simple hybrid system, any fuel cell, any operating temperature, and any pressure, the maximum reversible work is equal to the free energy of reaction at the standard state. This study gives information of new opportunity fuels having increasing importance is all future energy scenarios. The results of this analysis show that ammonia and direct methanol give greater maximum intrinsic thermal efficiency than hydrogen oxidation. From these simple studies alone, one would conclude that the great payoff in terms of theoretical efficiency potential for research is direct carbon fuel cell (DCFT), PEFC, and direct oxidation of methane, intermediate temperature solid oxide fuel cell (SOFC), and simple fuel cell turbine hybrids.

scholarly journals Progress and Challenges in the Direct Carbon Fuel Cell Technology

2015 ◽  
Vol 49 ◽  
pp. 109-129
Author(s):  
Jun Jie Chen ◽  
Xu Hui Gao ◽  
Long Fei Yan ◽  
De Guang Xu
Keyword(s):  
Fuel Cells ◽  
Fuel Cell ◽  
Power Plants ◽  
Current Status ◽  
Solid Carbon ◽  
Fuel Utilization ◽  
Cell Technology ◽  
Fuel Cell Technology ◽  
Stage Of Development ◽  
Direct Carbon Fuel Cell

Fuel cells are under development for a range of applications for transport, stationary and portable power appliances. Fuel cell technology has advanced to the stage where commercial field trials for both transport and stationary applications are in progress. Direct Carbon Fuel Cells (DCFC) utilize solid carbon as the fuel and have historically attracted less investment than other types of gas or liquid fed fuel cells. However, volatility in gas and oil commodity prices and the increasing concern about the environmental impact of burning heavy fossil fuels for power generation has led to DCFCs gaining more attention within the global study community. A DCFC converts the chemical energy in solid carbon directly into electricity through its direct electrochemical oxidation. The fuel utilization can be almost 100% as the fuel feed and product gases are distinct phases and thus can be easily separated. This is not the case with other fuel cell types for which the fuel utilization within the cell is typically limited to below 85%. The theoretical efficiency is also high, around 100%. The combination of these two factors, lead to the projected electric efficiency of DCFC approaching 80% - approximately twice the efficiency of current generation coal fired power plants, thus leading to a 50% reduction in greenhouse gas emissions. The amount of CO2 for storage/sequestration is also halved. Moreover, the exit gas is an almost pure CO2 stream, requiring little or no gas separation before compression for sequestration. Therefore, the energy and cost penalties to capture the CO2 will also be significantly less than for other technologies. Furthermore, a variety of abundant fuels such as coal, coke, tar, biomass and organic waste can be used. Despite these advantages, the technology is at an early stage of development requiring solutions to many complex challenges related to materials degradation, fuel delivery, reaction kinetics, stack fabrication and system design, before it can be considered for commercialization. This paper, following a brief introduction to other fuel cells, reviews in detail the current status of the direct carbon fuel cell technology, recent progress, technical challenges and discusses the future of the technology.

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