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Ethanol combustion in a solid oxide fuel cell for electrical power generation aided study

Ziel

To perform technical and economic analysis of ethanol utilization for power production using solid oxide fuel cells.

To simulate process of ethanol steam reforming and ethanol partial oxidation in a chemical reactor depending on molar ethanol/steam, ethanol/carbon dioxide and ethanol/oxygen ratios and temperature.

To select materials which can have high catalytic activity with respect to ethanol steam reforming, ethanol/carbon dioxide and ethanol partial oxidation and to investigate the chosen materials at temperatures 600-9000C with respect to their catalytic activity on the one hand and stability against poisoning and carbonisation on the other hand at acceptable molar ethanol/oxidant and temperature as found 2.

To select electrode materials which can have high electrochemical activity to electrochemical oxidation of ethanol and/or products of ethanol oxidation and to investigate them in semi-cells with different electrolytes (zirconia- and ceria-based) in respect to their activity to electrochemical oxidation of ethanol and/or products of ethanol oxidation.

To stimulate processes occurred in solid oxide fuel cell fed by ethanol-steam, ethanol-carbon dioxide and ethanol-air mixture.

To study a solid oxide fuel cell with appropriate working area (50- 60 cm2) fed by ethanol-oxidant system of the optimum composition to prove a concept elaborated. To measure electrochemical and electrical characteristics of the solid oxide fuel cell, output anode gas composition as well as to monitor the solid oxide fuel cell stability during long-term test (up to 1000 hours).

Background & Justification for Undertaking the Project

During the last 150 years, the global industrial revolution based on power production processes using mainly fossil fuels such as coal, oil natural gas. In this certain time period large political and economical evolutions in combination with the unequal geographical distribution of the global oil and natural gas reserves forced the governments of many countries to the exploitation of alternative fuels minimizing their national dependence on fuel imports. Such alternative fuels are various alcohols (methanol, ethanol), their ethers, biogas, and biodiesel. Among these, ethanol has been proposed in many cases for a number of reasons such as its high availability and its ecological security. The basic difference of ethanol in comparison with all the rest alternative fuels is the feasibility of its production from plants and biological matter with biochemical processes like fermentation. Raw matter for ethanol production is every form of cellular biomass like agricultural and forest residues, urban wastes and various modes of agricultural products containing sugar or starch. Ethanol is considered an important solution for the problems of the environmental pollution of urban and industrial areas. In many countries, it is used as a light-duty vehicle fuel component (up to 90% per volume in mixtures with gasoline) giving oxygenated fuel blends for automobile applications. Like all alcohols its molecule contains oxygen that improves combustion in vehicle engines and lowers carbon monoxide (CO) emissions. Similarly, all others emissions of pollutants such as nitrogen oxides (NOx) and carbon dioxide (CO2) are found reduced in comparison with the amounts emitted from gasoline engines. Finally, the absence of sulfur (S) in ethanol molecule minimizes sulfur oxides (SOx) emissions that are responsible for potentially devastating phenomena like acetic rain.
Concerning with the economical im-pact of ethanol use, the substitution of oil amounts imported with nationally manufactured ethanol can provide not only the obvious advantage of the reduction of the exported financial exchange but also many other profits in all national sectors. The increase of ethanol demand results to the intensification of the national agricultural activity, to the increase of the agricultural income and to the establishment of new work positions. These will further increase due to the increase of the investments for agricultural equipment and also because of the construction of ethanol fuelled power plants. As a result, the rational scientific and technological programming of the ethanol exploitation for power production can significantly contribute to the reduction of the national economic lack, to the stabilization of the import-export trade balance and finally to the improvement of the national macroeconomic indices.
During the last decades, alternative fuels such as biogas, methanol and ethanol have been under serious consideration by many governments intending the continuous replacement of petroleum-based transportation and power plant fuels. Especially ethanol, which had been used as a fuel since the classical combustion experiments of A. Otto in 1897, is considered a promising alternative due to its high thermal content and its ecological characteristics.
In Greece, the advantages of the alternative fuels and especially ethanol framed with an appropriate national program can help significantly the energy adequacy and the national economical level. The agricultural nature of the Greek population combined with the challenges of the energy, economic and environmental problems can make ethanol an ideal fuel for its future.
The most promising technology of energy production during the 21st century is the technology of fuel cells. The increasing interest for environmental protection, the need for safe energy supply and the demand for clean and more efficient energy conversion technologies render fuel cells as reliable energy conversion systems. Fuel cells are a revolutionary tech-nology that is widely applied for electricity production without any dangerous emissions through the electrochemical oxidation of a fuel such as hydrogen, hydrocarbons, alcohols. A fuel cell is a chemical reactor of continuous operation and produces electrical energy as long as it is fed with the fuel and oxidant. It consists of the electrolyte, which is in touch from both sides with the electrodes. The electrodes consist of appropriate materials so as to catalyse both the anodic and cathodic reactions. The fuel is inserted in the anode and oxygen in the cathode. The exhaust gas contains steam and carbon dioxide. The fuel cell efficiency can approach the 70% of the heat produced during the combustion of the fuel with oxygen. This is about by two times larger compared to the efficiencies of the conventional thermal en-gines.
Among other types of fuel cells, solid oxide fuel cell (SOFC) has some advantages over other fuel cells especially when is fed with organic fuels. Its structure is hard and stable because it consists solely of solid components: an electrolyte is a ceramic material, which is an oxygen ion conductor in high temperatures of 700-1000oC, an anode is metal or cermet (Ni- or Co-based), a cathode is an electron oxide conductor. It can utilize any organic fuel or products of its reforming or partial oxidation, e.g. any H2- and CO-containing gases. Within the inlet part of the SOFC (up to 25% depending on fuel), the direct electrochemical oxidation of gaseous organic fuel can occur when the anode consists of (or include) appropriate materials. Also, in this part, an organic fuel is reformed into H2- and CO-containing mixture. Within the rest part of the SOFC, electrochemical oxidation of H2 and CO occurs. If the anode does not provide an acceptable rate of electrochemical oxidation of organic fuel the latter must be reformed into H2- and CO-containing mixture out of the anode. On the whole, various gas systems can be used in the SOFC: pure organic fuel, organic fuel + oxidant where oxidant are H2O, CO2, air or mixture hereof. In particular, fuel can be ethanol.
The main problem concerning the anode gas system in SOFC fed by organic fuel is as follows. The SOFC efficiency is the higher the higher concentration of fuel components is. On the other hand, the high concentration of the fuel components can lead to undesirable carbon formation due to thermodynamic or kinetic reasons. One of peculiarities of the anode gas system in SOFC fed by organic fuel is that it can be non-equilibrium but less or more close-to-equilibrium. In particular this means that although carbonisation is thermodynamically possible it does not occur due to kinetic reason. The hopeful information can be obtained only through experimental study of catalytic and electrocatalytic processes occurred in fuel-oxidant systems, in particular, in ethanol-oxidant systems.
The scientific information on the problem is very scanty:
only few papers were devoted to an analysis of possibility of ethanol utilization in fuel cells, in particular, in molten carbonate fuel cell and there are no papers on ethanol utilization in SOFCs;
few researchers considered compositions of equilibrium mixtures derived from ethanol steam reforming and there are no data on ethanol-CO2 and ethanol-air systems;
there no data on non-equilibrium gas compositions derived from ethanol-oxidant systems;
there is little (no) information on catalysts that provide forming necessary for SOFC H2- and CO-containing mixtures derived from initial ethanol-oxidant systems;
there little (no) experimental data on ethanol-oxidant catalytic transformation at the conditions close to SOFC ones;
there is no information on SOFC fed by ethanol research and development.
The proposed project has interdisciplinary character. On the whole, the project is devoted to energy conversion, namely, to bioethanol conversion into electric power. It is proposed that the tool for the mentioned energy conversion is a fuel cell, namely, the SOFC. So the project is connected with the electrochemistry and can give important information for solid-state electrochemistry, for the electrode kinetics in solids, for SOFC simulation and application. The study of ethanol transformation into various gaseous fuels occurring inside or/and outside of the SOFC is in a field of heterogeneous catalysis and electrocatalysis. The results obtained here can be important for catalytic and electrocatalytic technology, as well as for other types fuel cells applications as concern to derivation of H2- and CO-containing mixtures from various initial ethanol-oxidant systems.
The proposed research will lead mainly to extending our knowledge in the field of energy conversion, namely production of electric power from bioethanol using SOFC. Also, our knowledge will be extended in the fields of solid-state electrochemistry, heterogeneous catalysis and electrocatalysis. Some gaps will be filled in the field of thermodynamics of multi-component gas mixtures derived form ethanol-oxidant systems.
The results of the proposed research will lead to understanding possibility to produce electrical power bioethanol using SOFC. Especially, these results are of great importance for those countries that have scanty resources fuels and acceptable conditions for agriculture as concern elaboration of their strategy in energetic policy. Should the project be fulfilled it could influence both economy and social spheres. Some side results of the project could influence any technologies, for example, organic synthesis, heterogeneous catalysis and electrocatalysis. The results of the project could lead to the more complete understanding in the fields of solid state electrochemistry, catalysis, thermodynamics and kinetics in multi-component gas mixtures.
The results of the proposed research will lead to understanding possibility to produce electrical power bio-ethanol using SOFC. Especially, these results are of great importance for those countries that have scanty re-sources fuels and acceptable conditions for agriculture as concern elaboration of their strategy in energetic policy. Should the project be fulfilled it could influence both economy and social spheres. Some side results of the project could influence any technologies, for example, organic synthesis, heterogeneous catalysis and electrocatalysis. The results of the project could lead to the more complete understanding in the fields of solid state electrochemistry, catalysis, thermodynamics and kinetics in multi-component gas mixtures.

Aufforderung zur Vorschlagseinreichung

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Finanzierungsplan

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Koordinator

University of Thessaly
EU-Beitrag
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Adresse
Pedion Areos
38334 Volos
Griechenland

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