1,720,958 research outputs found
A personal retrospect on three decades of high temperature fuel cell research: ideas and lessons learned
No full textIn 1986 the Dutch national fuel cell program started. Fuel cells were developed under the paradigm of replacing conventional technology. Coal-fired power plants were to be replaced by large-scale MCFC power plants fuelled by hydrogen in a full-scale future hydrogen economy. With today's knowledge we will reflect on these and other ideas with respect to high temperature fuel cell development including the choice for the type of high temperature fuel cell. It is explained that based on thermodynamics proton conducting fuel cells would have been a better choice and the direct carbon fuel cell even more so, with electrochemical gasification of carbon as the ultimate step. The specific characteristics of fuel cells and multisource multiproduct systems were not considered, whereas we understand now that these can provide huge driving forces for the implementation of fuel cells compared to just replacing conventional combined heat and power production technology.Economics of Technology and Innovatio
Electrochemical Gasification in a Direct Carbon Fuel Cell
No full textElectricity generation in a Direct Carbon Fuel Cell has thermodynamic advantages over conventional methods, because the DCFC is not limited by the Carnot efficiency. This thesis analyzes and models a DCFC where the electrochemical oxidation of carbon to carbon monoxide is taken into account, which is an endothermic reaction. The heat necessary for this reaction is converted directly into electricity, so the DCFC can achieve a theoretical reversible efficiency of >100%. The heat is provided by a solar reactor, which converts methane into hydrogen and solid carbon by thermal decomposition. The formed solid carbon particles is fuel for the DCFC. The produced CO at the anode of the DCFC is used in a WGS reactor where it reacts with steam to form hydrogen. In this way we present a Multi-Source Multi-Product energy system. The MSMP energy system is modelled in Cycle Tempo and we use the modelling results to perform a feasibility study and exergy analysis. The exergy analysis showed that the solar reactor contributes the most to the total exergy losses in the system. Considering the fact that the WGS reactor is a mature technology, the solar reactor is based on existing technology (CSP), and solutions to challenges in heat handling and mass transfer are available in the process industry, the MSMP energy system has high potential to be technically feasible. We calculated that the unknown costs of the MSMP energy system need to be lower than 29.8 €/MWhp to be competitive with conventional hydrogen production methods and need to be lower than 34.8 €/MWhp to be competitive with a gas fired plant. Based on current market prices for methane, hydrogen and electricity in Algeria and based on the fact that we were able to determine the costs of the majority of components in the MSMP energy system, it is likely that the unknown costs will not exceed our determined maximum unknown costs. This shows the economic feasibility potential. We calculated that the MSMP energy system emits 37% less CO2 than hydrogen production by steam reforming which indicates the sustainable potential. We concluded that the concept favors a geographical location with high solar density, good gas infrastructure and stable politics. Algeria seemed to meet all those demands. Therefore we conclude that our MSMP energy system has high potential to be socially feasible. We concluded that our MSMP energy system has high potential to be technically, economically and socially feasible.Electrical Engineering | Sustainable Energy Technolog
Comparison of the solid oxide fuel cell system for micro CHP using natural gas with a system using a mixture of natural gas and hydrogen
No full textSolid oxide fuel cell systems for combined heat and power production (SOFC μCHP) fueled by natural gas are attractive because of their high electrical and total efficiency even at small scale. The development of a hydrogen economy will increase the availability of distributed hydrogen as a pure gas. Alternatively, hydrogen may be blended with natural gas in the grid. This study investigates the performance of SOFC μCHP systems, while using a fuel varying from pure hydrogen to pure methane via mixtures of hydrogen and methane called Hythane. Flowsheet models of external as well as internal reforming fuel cell systems were developed in Cycle-Tempo simulation software. Results show that both the external as well as the internal reforming system can operated on all fuel gas compositions varying from pure hydrogen to pure methane, thus allowing for a transition towards a hydrogen economy via the mixing of hydrogen into the natural gas grid. Although the natural gas based systems have a higher electrical efficiency, the introduction of hydrogen into the gas leads to a higher total efficiency of the combined heat and power system. The addition of hydrogen into the fuel minimizes the problems of thermal stress and thermal shock associated with the use of methane in internal reforming fuel cell systems. The internal reforming system showed a higher performance compared to the external reforming system for all Hythane gas mixtures in terms of not only electrical efficiency but also in terms of thermal and total efficiency.Economics of Technology and Innovatio
Synergies in the offshore domain: A case study of the WINWIN concept
No full textSince the ratification of and commitments made under the COP 21 summit, we have witnessed an increase towards implementing and utilizing renewable technologies in our energy mix. The global cumulative installed wind energy capacity in 2017 surpassed 540 GW, which is an increase of over 173% compared to 2010 levels. At the same time, Solar PV technology has also experienced a significant cost reduction, and the global installed capacity was 500 GW in 2018. Despite rapid development and growth, the overall contribution on the global energy scene is still limited. Fossil fuels still dominates the global energy supply, and are likely to do so in the coming years. This thesis explores the potential upside of considering synergies in the offshore domain, in order to further expand the diffusion of renewable technologies.Electrical Engineering | Sustainable Energy Technolog
Multi-Level Energy Focused Integration of Sectors For Rural Development: An Indian Context
No full textIndia is a country constantly grappling with problems of impeded rural development. Energy, in particular sustainable energy can be seen as key to attain the Sustainable Development Goals set out by the U.N. Integration of rural sectors can be seen as a methodology to broaden the potential achievement of the targetted Sustainable Development Goals. This thesis report aims at providing multi-purpose systems as a result of energy focused integration of sectors for augmenting rural development in India. The main research question of the thesis was ’Having recognized the importance of systems thinking, how can energy focussed Integration of Sectors provide directions to overcome the problem of impeded rural development in India?’. Top-Down knowledge gaps are prevalent in India for such integrative techniques, thus requiring attention to primarily to make integration of sectors a reality in India, thus the thesis has a core around marking out potential barriers which could be faced by such sector integrated techniques to break into the Indian market and policy while discussing the obstacles to implementation of such solutions. Furthermore another important aspect of the thesis lays out some plausible solutions to these barriers and obstacles.Electrical Engineering | Sustainable Energy Technolog
Optimizing the preparation phase to a tender phase that is conducive for sustainable product innovations: An exploratory study to identify influential (external) factors
No full textContractors can be stimulated to offer sustainable product innovations through tenders in the GWW sector. But despite the sustainability ambitions of clients to achieve a 100% circular economy by 2050 and sustainably generated energy in the Netherlands, contractors are hindered from being able to offer sustainable product innovations by clients. To make recommendations to clients to optimize the preparation phase of public procurement. In order to contribute to this, it is made clear how contractors can be stimulated by investigating the influential (external) factors of the tender phase that can stimulate contractors to offer sustainable product innovations with a TRL level 7-9 during the tender phase. Offshore and Dredging Engineerin
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
The integration of molten carbonate fuel cells with coal fired steam power plants for CO2 capture
No full textLAUREA SPECIALISTICAConsiderando che la riduzione delle emissioni dei gas serra è un delle più grandi sfide dell’epoca moderna, questo lavoro è volto a ridurre lo scarico di anidride carbonica nell’atmosfera da parte di centrali elettriche attraverso l’utilizzo di celle a combustibile ad alta temperatura. Infatti, le celle ad alta temperatura, in particolare del tipo a carbonati fusi oltre a produrre elettricità, possono essere utilizzate per concentrare e successivamente catturare la CO2. Aggiungendo una cella a combustibile a carbonati fusi (MCFC) all’interno di una centrale a carbone si prova a conciliare un metodo economico per catturare l’anidride carbonica con una fonte di produzione di energia di grossa scala. Lo scopo dell’analisi è quello di ridurre i costi elevati che caratterizzano le tecniche di cattura della CO2 convenzionali sfruttando le caratteristiche della cella a combustibile. Inoltre, il calore presente allo scarico della cella può essere recuperato nel ciclo a vapore aumentandone l’efficienza. Il lavoro di tesi punta a valutare i benefici legati all’integrazione di una cella a combustibile relativamente piccola rispetto alle dimensioni della centrale a carbone, in modo da trovare una tecnologia per catturare la CO2 fattibile sul breve-medio periodo. Nello studio viene assunto che una porzione di gas di scarico sia estratta dal generatore di vapore, pulito dalle sostanze dannose per il funzionamento della cella e mandato all’ingresso del catodo, dopo una diluizione con aria, per assicurarsi la proporzione ossidante/combustibile corretta. Dal lato opposto, l’anodo viene alimentato a gas naturale precedentemente riscaldato fino alla temperatura richiesta. Grazie alle condizioni di funzionamento della cella, allo scarico anodo il gas sarà composto principalmente da CO2 e in percentuali minori da idrogeno e monossido di carbonio. Dopo la combustione in ossigeno dei residui di questi ultimi, il flusso viene raffreddato per condensare l’acqua e rimuovere il contenuto di CO2. Il calore contenuto nel flusso uscente dal lato catodo è inviato al ciclo a vapore che, per mezzo di uno scambiatore, riscalda una porzione di vapore in maniera da permettere un incremento di efficienza e di potenza della centrale originaria. Il lavoro è stato svolto durante un periodo di stage presso TU Delft, considerata una delle università più importanti a livello mondiale nel campo di tecnologie energetiche sostenibili. La tesi è stata sviluppata sotto la guida del Dr. Kas Hemmes che ha definito le linee guida e gli argomenti del progetto, contribuendo attivamente all’esecuzione per l’intero svolgimento del progetto, in collaborazione con il Group of Energy Convesion Systems (Gecos) del Politecnico di Milano.Considering that the mitigation of greenhouse emission is one of the biggest challenges of the modern age, this work aims to reduce the carbon dioxide emission from a pre-existing power plant by means the integration of high temperature fuel cells. In fact, high temperature fuel cells of the molten carbonate type can produce electricity while also acting as carbon dioxide concentrator. The addition of Molten Carbonate Fuel Cell (MCFC) in a standard coal-fired power plant might represent an economic way for capturing CO2 from a large scale power plant. The analysis proposes to reduce the typical high costs of conventional techniques for capturing carbon dioxide, exploiting the properties of MCFCs. Moreover, the heat excess coming out from the cell can be recovered in the steam cycle increasing the plant efficiency.
The work aims to evaluate the potential benefits obtained by integrating a relatively small size fuel cell (with respect to the power plant size) in order to find a technology for capturing CO2 which could be applied in the short or medium term. The study assumes that a portion of flue gases is extracted from the steam generator, cleaned up from detrimental elements for the MCFC and then sent to the cathode inlet. Before feeding the cathode the flue gas is diluted with air in order to respect oxidant requirements of the fuel cell. On the other side, preheated natural gas is used as fuel for the anode. Due to MCFC operating conditions, the out coming gas from the anode side is mainly composed by carbon dioxide, water, hydrogen and carbon monoxide in smaller percentage. After the combustion with oxygen of residual fuels (namely H2 and CO) for preheating the cell system, the flow is cooled down in order to separate the carbon dioxide content from water by condensation. The heat contained in the flow exiting from cathode side is recovered in the steam cycle by means of a heat exchanger which preheat a portion of steam flow in order to increase plant efficiency and electric power output.
The work has been developed during a stage period at TU Delft considered one of the most prestigious universities in the world in the field of Sustainable Energy Technology. The thesis has been carried out thanks to the guidance of Dr. Kas Hemmes that defined the guidelines and the main topics of the project, supporting us during the entire development of the work, in cooperation with the Group of Energy COnversion Systems (GECOS) at Politecnico di Milano
Role of Fuel assisted Solid oxide Electrolysis in the Renewable Energy Scenario: A Feasibility Study
No full textFuel assisted electrolysis has the advantage of reducing the power demand of hydrogen production by solid oxide electrolysis with the help of assisting fuel. This thesis presents a feasibility study on the use of biogas fuelled solid oxide fuel assisted electrolysis (SOFEC) for hydrogen production on an industrial scale. The biogas is supplied as a source of hydrogen to the anode of the solid oxide electrolyser where hydrogen gets oxidised and provides electrons for the steam splitting taking place at the cathode. This results in upgrading of biogas to hydrogen and reduction in the electrical power demand. However, steam reforming of biogas (methane) is an endothermic reaction and hence,heat has to be supplied externally.The SOFEC system is modelled in Cycle Tempo and the modelling results are used to perform the feasibility study based on technical, economic and social aspects. Further, to corroborate the results from the study, a case study scenario of integration of SOFEC in a steelmill is presented.With regard to technical aspects, the SOFEC cathode and electrolyte materialswere found to be in practice commercially, adequate biogas supply could be ensured by biogas production at waste water treatment plants and heat supply from high temperature waste heat sources was proposed to meet heat demand of methane reforming. Based on these conditions, the SOFEC system has high prospect of being technically feasible.Further, for economic analysis, the net production cost of SOFEC was estimated to be less than 4.5 Eur/kg H2 which is lower than that of low temperature (7.32 Eur/kg H2) and high temperature electrolysis (5.54Eur/kg H2). Considering high temperature heat, recovered from molten slags in steel mills, being used as heat supply followed by a predicted drop in electrolyser capital costs, the SOFEC is able to compete with lower production costs of steam methane reforming (3 Eur/kg H2). Thus, low electrolyser capital costs and availability of low cost waste heat supply are the main driving factors for SOFEC to be economical.In social aspects, the operational safety and social acceptance of SOFEC were investigated. It was concluded that for hydrogen storage challenges, existing commercial hydrogen storage solutions can work and with hydrogen fuel cells being socially accepted, the SOFEC was assumed to be accepted the same. Also the SOFEC was shown to have low CO2 (2 kg CO2 equivalent / kg H2) and low SO2 emissions provided sufficient desulfurisation of biogas is done. Therefore, it is concluded that the SOFEC has high potential to be socially feasible.Although, the SOFEC has been presented to be a feasible technology, uncertaintiessuch as degradation in performance due to interruptions in biogas supply, absence of anode materials which can withstand reducing environments, absence of low cost high temperature heat and high costs of electrolyser systems are obstacles which have to be resolved
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