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Rowlands, Stephen E. "Electrochemical supercapacitors for energy storage applications." Thesis, De Montfort University, 2002. http://hdl.handle.net/2086/4077.
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Du, Yanping. "Cold energy storage : fundamentals and applications." Thesis, University of Leeds, 2014. http://etheses.whiterose.ac.uk/8622/.
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This thesis concerns cold energy storage (CES) technology. Such a technology produces cold energy by consuming electricity in a refrigerator and stores cold energy in an eutectic phase change material (PCM) in a temperature range of (TPCM is the PCM storage temperature and Ta is the environmental temperature), resulting in a cold exergy efficiency less than 100%. The stored cold energy can be either directly extracted by a cold discharge process or utilized through a Rankine cycle at peak hours for electricity generation. The aim of the research is to study fundamental aspects and address the scientific and technological challenges associated with the CES technology. Methods for storing high grade, high energy density and temperature-adaptive cold energy are to be developed. Another objective is to develop innovative solutions for enhancing charge/ discharge processes. Particular attention is paid to the use of a prototype CO2 based CES system to investigate the feasibility of CES technology for small scale systems. In this work, a criteria for PCM selection for high grade and high energy density cold storage is established. For enhancing charging/ discharging rate of a PCM device, metal foams are embedded in PCM to form a PCM composite. Parametric study on the CES system is done based on a CO2 Rankine cycle for achieving an optimal cold storage efficiency. Investigations have been carried out on the performance of a small scale CES system. These include CES with an open and a close Rankine cycle and a piston based engine for cold to power conversion in the cycle. A method for improving grade of stored cold energy is using eutectic salt-water solutions for forming a binary/ ternary cold storage system, by which the eutectic temperature is lowered. PCMs with lower freezing temperature and smaller molecular weight are selected as components in the binary/ ternary system. However, due to the potential issue of compatibility of PCM molecular structures, it is critical to select PCMs which have comparable melting temperatures and compatible molecular structures. PCM composite is formed by embedding metal foams in PCM solutions. Cold discharging rate, defined as the power transfer of cold energy per unit time during the discharge process, is greatly affected by thermal diffusivity and thermal conductivity of the PCM composite. Combined effect of cold radiation and convection is to be considered for assessing the value of cold discharging rate, which becomes more significant for large PCM capsules under low PCM temperatures and low Reynolds number (Re). Cold utilisation in a CES system using Rankine cycles is theoretically studied. Storage efficiency of the CES system is a round trip efficiency of electricity, which is defined as ratio of output electricity to the input electricity. A storage efficiency as high as 43.9% has been shown to be possible for the CES system. However, the storage efficiency is generally between 30%~40% in consideration of the actual efficiencies of cryogen pump, regenerator, engine and refrigerator. Piston based engines with a new valve scheme is experimentally investigated. Compared with small engine, large engine system has apparently larger capacity for power generation, but the engine efficiency is reduced due to the block of the exhaust gas in the chamber. In the presented case study, the efficiency of the large engine is 38.5% while the storage efficiency of the CES system is approximately 22.0%. In the point view of net electricity output for peak-shifting, CES is a feasible technology that need to be further developed. In brief, the work of the CES research are summarized as follows: • Improvement of cold charging/ discharging rate by embedding open-cell metal foams in PCM; • Assessment of cold discharging rate by considering the combined effect of cold radiation and convection; • Optimization of cold storage efficiency by developing computer program based on sub-critical CO2 properties; • Cold to power conversion by using a piston based engine coupled with a new valve scheme.
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Yang, Hao. "Graphene-based Supercapacitors for Energy Storage Applications." The Ohio State University, 2013. http://rave.ohiolink.edu/etdc/view?acc_num=osu1376918924.
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Edwards, Jacob N. "Thermal energy storage for nuclear power applications." Thesis, Kansas State University, 2017. http://hdl.handle.net/2097/36238.
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Master of ScienceDepartment of Mechanical and Nuclear Engineering
Hitesh Bindra
Storing excess thermal energy in a storage media that can later be extracted during peak-load times is one of the better economical options for nuclear power in future. Thermal energy storage integration with light water-cooled and advanced nuclear power plants is analyzed to assess technical feasibility of different storage media options. Various choices are considered in this study; molten salts, synthetic heat transfer fluids, and packed beds of solid rocks or ceramics. In-depth quantitative assessment of these integration possibilities are then analyzed using exergy analysis and energy density models. The exergy efficiency of thermal energy storage systems is quantified based on second law thermodynamics. The packed bed of solid rocks is identified as one of the only options which can be integrated with upcoming small modular reactors. Directly storing thermal energy from saturated steam into packed bed of rocks is a very complex physical process due to phase transformation, two phase flow in irregular geometries and percolating irregular condensate flow. In order to examine the integrated physical aspects of this process, the energy transport during direct steam injection and condensation in the dry cold randomly packed bed of spherical alumina particles was experimentally and theoretically studied. This experimental setup ensures controlled condensation process without introducing significant changes in the thermal state or material characteristics of heat sink. Steam fronts at different flow rates were introduced in a cylindrical packed bed and thermal response of the media was observed. The governing heat transfer modes in the media are completely dependent upon the rate of steam injection into the system. A distinct differentiation between the effects of heat conduction and advection in the bed were observed with slower steam injection rates. A phenomenological semi-analytical model is developed for predicting quantitative thermal behavior of the packed bed and understanding physics. The semi-analytical model results are compared with the experimental data for the validation purposes. The steam condensation process in packed beds is very stable under all circumstances and there is no effect of flow fluctuations on thermal stratification in packed beds. With these experimental and analytical studies, it can be concluded that packed beds have potential for thermal storage applications with steam as heat transfer fluid. The stable stratification and condensation process in packed beds led to design of a novel passive safety heat removal system for advanced boiling water reactors.
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Nagar, Bhawna. "Printed Graphene for energy storage and sensing applications." Doctoral thesis, Universitat Autònoma de Barcelona, 2019. http://hdl.handle.net/10803/667240.
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El objetivo de esta tesis ha sido el diseño y la preparación de electrodos flexibles basados en grafeno utilizando diferentes técnicas de impresión para aplicaciones de almacenamiento de energía, específicamente supercondensadores y sensores electroquímicos. Se han empleado diferentes estrategias teniendo en cuenta la aplicación final y, por consiguiente, el grafeno o sus híbridos se prepararon utilizando diferentes rutas sintéticas junto con una selección cuidadosa de las técnicas de impresión disponible, así como los sustratos. Para la parte de almacenamiento de energía (Capítulo 2), se han demostrado dispositivos de tipo supercondensador con alta capacidad, energía y densidad de potencia sobre tela (tela de carbono), papel (papel A4 común) y sustratos plásticos utilizando diferentes técnicas de impresión, híbridos de grafeno y electrolitos híbridos. En el caso de las aplicaciones de sensores (Capítulo 3), se han demostrado dos sensores sobre sustratos plásticos. Se muestra un (bio)sensor de ADN de alta sensibilidad para virus que utiliza la impresión fácil en un solo paso, y cuyo principio de operación y estructura se pueden extender a otros bioanalitos con interés para aplicaciones en diversas áreas. En otro estudio, se preparó una tinta inyectable de grafeno muy estable y de muy alta concentración y se demostró su uso como sensor bacteriano como prueba de concepto. La tinta de grafeno preparada podría producir impresiones altamente conductoras que, en principio, pueden ser aplicables a otros sensores bio- o químicos con alta sensibilidad. Se llevaron a cabo estudios de diferentes técnicas de impresión y se formularon y probaron las tintas adecuadas para cada técnica con la optimización de los parámetros de impresión para obtener películas reproducibles y, por lo tanto, la fabricación del dispositivo reproducible ha sido el objetivo final. Las principales técnicas de impresión / recubrimiento utilizadas en esta Tesis son el recubrimiento tipo Doctor blade, la impresión por chorro de tinta (inkjet), la serigrafía (screen printing y la novedosa técnica de estampado con cera. El proyecto implicó, por lo tanto, una parte muy importante de síntesis y caracterización del grafeno y derivados, la formulación de tintas y, finalmente, la integración y ensayo de dispositivos.The focus of this thesis has been the design and preparation of flexible graphene-based electrodesand their printing using different techniques for applications in energy storage, specifically supercapacitors and electrochemical sensing devices. Different strategies have been employed keeping in mind the end application and accordingly graphene or its hybrids wereprepared using different synthetic routes along with careful selection of the available printing techniques as well as the substrates. For energy storage part(Chapter 2), Supercapacitor devices with high capacitances, energy and power density have been demonstrated over Cloth (Carbon), Paper (Common A4 paper) and Plastic substrates using different printing techniques, graphene hybrids as well as hybrid electrolytes. In the case of Sensing applications(Chapter 3),two sensors have been demonstrated over plastic substrates. A high sensitivity DNA (Bio)sensor for viruses using one step facile printing is shown, which structure and operation principle can be extended to other bio-analytes with interest for applications in various areas. In another study, extremely high concentration yet stable graphene inkjet printable ink has been prepared and its use as a bacterial sensor has been demonstrated as a proof of concept. The graphene ink prepared could produce highly conducting patterns that in principle can offer other bio or chemical sensing with high sensitivities. Studies of different printing techniques were carried out and suitable inks were formulated and tested for each technique with optimization of the printing parameters in order to obtain reproducible films and hence reproducible device fabrication has been the focus. The main printing/coating techniques used in this Thesis are Doctor blade coating, Inkjet printing, screen printing and wax stamping technique. The project therefore involved a very important part of synthesis and characterization of graphene and derivatives, formulation of inks and finally device integration and testing
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Mangu, Raghu. "NANOSTRUCTURED ARRAYS FOR SENSING AND ENERGY STORAGE APPLICATIONS." UKnowledge, 2011. http://uknowledge.uky.edu/gradschool_diss/207.
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Vertically aligned multi walled carbon nanotube (MWCNT) arrays fabricated by xylene pyrolysis in anodized aluminum oxide (AAO) templates without the use of a catalyst, were integrated into a resistive sensor design. The steady state sensitivities as high as 5% and 10% for 100 ppm of NH3 and NO2 respectively at a flow rate of 750 sccm were observed. A study was undertaken to elucidate (i) the dependence of sensitivity on the thickness of amorphous carbon layers, (ii) the effect of UV light on gas desorption characteristics and (iii) the dependence of room temperature sensitivity on different NH3 and NO2 flow rates. An equivalent circuit model was developed to understand the operation and propose design changes for increased sensitivity.
Multi Walled Carbon NanoTubes (MWCNTs) – Polymer composite based hybrid sensors were fabricated and integrated into a resistive sensor design for gas sensing applications. Thin films of MWCNTs were grown onto Si/SiO2 substrates via xylene pyrolysis using chemical vapor deposition technique. Polymers like PEDOT:PSS and Polyaniline (PANI) mixed with various solvents like DMSO, DMF, 2-Propanol and Ethylene Glycol were used to synthesize the composite films. These sensors exhibited excellent response and selectivity at room temperature when exposed to low concentrations (100ppm) of gases like NH3 and NO2. Effect of various solvents on the sensor response imparting selectivity to CNT – Polymer nanocomposites was investigated extensively. Sensitivities as high as 28% was observed for a MWCNT – PEDOT:PSS composite sensor when exposed to 100ppm of NH3 and -29.8% sensitivity for a MWCNT-PANI composite sensor to 100ppm of NO2.
A novel nanostructured electrode design for Li based batteries and electrochemical capacitor applications was developed and tested. High density and highly aligned metal oxide nanowire arrays were fabricated via template assisted electrochemical deposition. Nickel and Molybdenum nanowires fabricated via cathodic deposition process were converted into respective oxides via thermal treatments and were evaluated as electrodes for batteries and capacitor applications via Cyclic Voltammetery (CV). Several chemical baths were formulated for the deposition of pristine molybdenum nanowires. Superior electrochemical performance of metal (Ni and Mo) oxide nanowires was observed in comparison to the previously reported nano-particle based electrodes.
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Parra, Mendoza David. "Optimum community energy storage for end user applications." Thesis, University of Nottingham, 2014. http://eprints.nottingham.ac.uk/27708/.
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The UK government determined that 30% of the total electricity and 15% of the total energy should be generated from renewable sources by 2020 according to the Low Carbon Transition Plan. However, most renewable energy technologies are intermittent because they depend on weather conditions and they do not offer matching capability. Energy storage is attracting intensive attention as a technology which converts renewable energy technologies into a dispatchable product which meets variable demand loads. There is increasing interest for energy storage located very close to consumers which is able to augment the amount of local renewable generation consumed on site, provides demand side flexibility and helps to decarbonise the heating sector. This thesis optimises community energy storage (CES) for end user applications including battery, hydrogen and thermal storage performing PV energy time-shift, load shifting and the combination of them. The optimisation method obtains the economic benefits of CES by quantifying the levelised cost, levelised value and internal rate of return. The method follows a community approach and the optimum CES system was calculated as a function of the size of the community, from a single home to a 100-home community. A complimentary methodology was developed including three reference years (2012, 2020 and zero carbon year) to show the evolution of the economic benefits during the low carbon transition. Additionally, a sensitivity analysis including the key parameters which affect the performance and the economic benefits was developed. The community approach reduced the levelised cost down to 0.30 £/kWh and 0.14 £/kWh for PV energy time shift and load shifting respectively when projected to the year 2020. These values meant a cost reduction by 37% and 55% regarding a single home. A cost of the storage medium of 275 £/kWh for Li-ion batteries (equivalent to a 10% subsidy over the assumed cost, 310 £/kWh) is the break-even point for Li-ion batteries by 2020 for an electricity price equal to 16.3 p/kWh (R^2=0.6). Secondly, this thesis presents a new community hydrogen storage system integrated in a low carbon community and the experimental results when performing PV energy time-shift, load shifting and the combination of them. Long term ES was demonstrated when the community storage hydrogen system performed load shifting and the capacity factor of the electrolyser increased by 116% when PV energy time-shift was performed in addition to load shifting. This system was designed in collaboration with industrial partners and the key findings obtained during the construction and testing phases are shared.
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Roberts, Aled Deakin. "Ice-templated porous carbons for energy storage applications." Thesis, University of Liverpool, 2016. http://livrepository.liverpool.ac.uk/3006170/.
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Porous carbons prepared via templating methodologies have shown excellent performance for various energy storage applications, such as electrodes in batteries, supercapacitors and as gas storage materials. Despite the impressive performances often reported, various issues such as complex and multi-step synthesis strategies have impeded their implementation in practical devices, and so there is a need to develop new, low-cost and commercially viable strategies for their fabrication. This thesis explores an unconventional method for the preparation of templated carbons - a process termed ice-templating. Ice-templating, as will be discussed in the forthcoming chapters, is a relatively simple technique holds several advantages over more conventional templating strategies. Having its own difficulties and shortcomings, only a few papers had been published on ice-templated porous carbons (ITPCs) prior to the commencement of this PhD. This thesis describes the ways in which we explored and overcame these difficulties to successfully prepare a number of ice-templated porous carbons, before evaluating their performance as materials for various energy storage devices.
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Mistry, Priyen C. "Coated metal hydrides for stationary energy storage applications." Thesis, University of Nottingham, 2016. http://eprints.nottingham.ac.uk/38798/.
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This thesis explores suitable materials for energy stores for stationary applications, specifically a prototype hydrogen store, domestic thermal store operating between 25-100 C and a moderate thermal store for a concentrated solar power (CSP) plant operating at 400 C. The approach incorporated a unique coating technique to deliver prototype hydrogen and thermal storage media, where the coating could offer commercial advantages, for example, in the form of hydride activation and enhanced kinetics during successive cycling. The highly reversible Mg-MgH2 system is particularly promising for thermal storage, obtaining an enthalpy of reaction of 74.5 kJ/mol H2 that translates to a thermal energy capacity of approximately 2800 kJ/kg of MgH2. Nevertheless, magnesium is hindered by slow activation and poor kinetics of (de)hydrogenation, even when approaching temperatures ideal for concentrated solar power applications (in the region 400 C). Elevated temperature cycling studies were performed on commercial atomised Mg powder with magnetron sputtered catalysts (chromium, iron, vanadium and stainless steel) applied to their surfaces; the aim of which was to fabricate hydrogen storage materials that possess (de)hydrogenation characteristics equal to or even bettering their nanocrystalline equivalents, yet in a potentially economic and scalable manner. Following 50 cycles at 400 C, the coatings were found to have little to no positive impact on the behaviour of the atomised Mg powders. In addition, for both uncoated and coated samples the effects of an activation process at 400 C are matched by cycling the material 5 times from the outset, after which identical behaviour is observed during subsequent cycles. At 350 C, the benefits of catalyst coatings on the hydrogen storage properties of atomised Mg powders are evident during activation and successive cycling up to 90 times. The material undergoes different microstructural evolution during cycling when in the presence of a surface catalyst, causing an enhancement of the `nucleation and growth' stage of (de)hydrogenation. This was attributed to particle reorientation dominating particle sintering, whereas the opposite occurs for the uncoated material. For the domestic thermal and prototype hydrogen stores a selection of AB and AB2 intermetallic hydrides enhanced through catalysis or thermodynamic modification were investigated. TiFe produced via powder atomisation obtained thermodynamic properties (dehydrogenation H = 28.9 kJ/mol H2 and S = 105 J/K.mol H2) in line with published results. The minor substitution of Ni into TiFe1-xNix resulted in different hydrogenation characteristics to TiFe, for example, TiFe0:96Ni0:04 possessed a dehydrogenation of H = 29.9 kJ/mol H2 and S = 107 J/K.mol H2. Discrepancies between maximum achieved and theoretical capacities were observed for both atomised TiFe and TiFe0:96Ni0:04 and a range of possible contributing factors are discussed. A minor addition of Pd (1.17 wt.%) magnetron sputtered to the surface of TiFe0:96Ni0:04 enabled successful room temperature hydrogenation with no activation treatment required. Characterisation (SEM and TEM) confirmed it is not necessary to have complete Pd coverage in the form of a uniform coating and XPS was utilised to derive a theory for the activation mechanism. The AB2 alloy comparison between the commercially available Hydralloy C5 and in house fabricated Ti0:9Zr0:2Mn1:5V0:2Cr0:3 showed that Hydralloy C5 was the most promising alloy for the hydrogen store application with the higher working capacity (ca. 0.96 wt.%) in the pressure range of 4-15 bar at 22 C, despite Ti0:9Zr0:2Mn1:5V0:2Cr0:3 obtaining a higher maximum storage capacity (1.82 wt.%). The hydrogenation kinetics of both alloys were studied with corresponding activation energies and hydrogen diffusion coefficients determined. The kinetics of hydrogenation for both alloys is sufficiently fast that only the heat transfer of the storage system is the rate limiting parameter for hydrogen exchange for most technical applications.
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Ek, Ludvig, and Tim Ottosson. "Optimization of energy storage use for solar applications." Thesis, Linköpings universitet, Elektroniska Kretsar och System, 2018. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-149305.
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Energy storage systems is very useful to use in solar panel systems to save money, but also tobe more environment-friendly. The project was given by the solar energy companyPerpetuum Automobile (PPAM) and the project is for their customer, the condominiumcompound Ekoxen. The task is to make a energy regulation for Ekoxen's energy storage sothey can save more money. The energy storage primary task is to shave the top-peaks of theconsumption for Ekoxen. Which means that the battery will supply the household instead forthe three-phase grid. This will make the electric bill for Ekoxen cheaper. Thesimulation/analysis of the energy regulation is done in a spreadsheet tool, where one partworks as a Time-of-Use program and the other work as a modbus feature. Time-of-Use is aweb-based program for PV systems with battery storage, where time-periods can be set toaffect the battery behavior. The modbus feature simulates a system where an algorithm can beimplemented. The results will show that the time-periods for charging the battery with theTime-of-Use program needs to be changed two times per year. One time for the summermonths and a second time for the rest of the months. The results will also show that themodbus feature is better on peak shaving than the time-of-use program.
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Sarwar, Wasim. "Hybridised energy storage systems for automotive powertrain applications." Thesis, Imperial College London, 2016. http://hdl.handle.net/10044/1/44975.
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This study explores whether the requirements of the Energy Storage System (ESS) in electrified automotive powertrains can be more effectively met by Hybridised Energy Storage Systems (HESS) than by batteries alone, and aims to quantify the benefits. Given their complementary characteristics, this study focuses upon combinations of Lithium-ion Batteries (LIBs) and Supercapacitors (SCs). In order to develop a comprehensive understanding of HESS operation and capabilities, a literature review is conducted and experiments and modelling tools are designed to address knowledge gaps. The electrochemical and thermal performance of SCs and LIBs is examined in detail, and the amassed knowledge is used to generate modelling tools. Following a review of HESS topologies, a model of a passive HESS is developed through combination of the SC and LIB models. The developed models are validated using experimental data for automotive drive-cycles. The degradation of a HESS is assessed using experimental analysis. The main findings of this study are split into three chapters: Supercapacitors This chapter explores the electrochemical and thermal characteristics of SCs and demonstrates how they vary with the operating conditions relevant for latter comparison with LIBs. Particular focus has been placed upon the attributes of SCs which affect their performance in a HESS, namely capacity and resistance variation with operating conditions, heat generation during operation, low temperature performance and performance degradation following extended use. An understanding of these factors is used to develop a model capable of predicting SC performance over an array of operating conditions, enabling latter combination with a lithium ion battery model to predict HESS behaviour in both cell-level and high voltage systems. An emphasis was placed upon the development of a high fidelity thermal model as the academic literature provided a limited understanding of thermal management and the effect of thermal gradients within SCs. The development of a high fidelity thermal model led to novel findings with respect to heat generation with SCs during operation. Lithium-ion Batteries An understanding of the performance and characteristics of LIBs relative to SCs is necessary for the development of an understanding of a HESS. This chapter briefly explains why LIBs are the dominant form of energy storage in electrified passenger vehicles, and subsequently discusses how LIBs function. The relationship between each component within the LIB and its performance is reviewed, and common internal design trade-offs such as material selection and thicknesses are explained. LIB performance variation as a function of operating conditions is subsequently presented and described analytically. This knowledge is used to generate a model to predict battery performance over a range of operating conditions, with a particular focus placed upon performance over an automotive drive-cycle. The developed model enables estimation of internal temperature during use. The causes of long term performance degradation are examined and a summary of degradation methods and their causes is provided. Hybridised Energy Storage Systems This chapter investigates whether it is possible to combine supercapacitors suitable for a micro hybrid electric vehicle (mHEV) with high-energy batteries suitable for use in a battery electric vehicle (BEV) to create a Hybridised Energy Storage System (HESS) suitable for use in a hybrid electric vehicle (HEV). A passive HESS topology is investigated due to its low cost and complexity and therefore high reliability. A low cost HESS is found to be capable of meeting the electrical demands of a HEV during a drive cycle. The operating principles of HESSs are discussed and factors limiting system performance are explored. The performance of the HESS is found to be significantly less temperature dependent than battery-only systems, however the heat generated suggests a requirement for thermal management. A correctly sized HESS is shown to generate less heat than a specialised HPB ESS. The HESS degrades at a similar rate to a specialised HPB. In a HESS, battery resistance rises faster than supercapacitor resistance; as a result, the supercapacitor provides a greater current contribution over time, therefore the energy throughput, temperature rise and rate of degradation of the batteries is reduced.
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Quan, Ting. "Hollow MoSx nanomaterials for aqueous energy storage applications." Doctoral thesis, Humboldt-Universität zu Berlin, 2021. http://dx.doi.org/10.18452/22909.
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Die vorliegende Arbeit konzentriert sich auf die Synthese von neuartigen hohlen MoSx-Nanomaterialien mit kontrollierbarer Größe und Form durch die kolloidale Template Methode. Ihre möglichen Anwendungen in wässrigen Energiespeichersystemen, einschließlich Superkondensatoren und Li-Ionen-Batterien (LIBs), wurden untersucht.
Im ersten Teil wurde eine neue Nanostruktur aus hohlen Kohlenstoff-MoS2-Kohlenstoff-nanoplättchen erfolgreich durch eine L-Cystein unterstützte hydrothermale Methode unter Verwendung von Gibbsit als Templat und Polydopamin (PDA) als Kohlenstoffvorläufer synthetisiert. Nach dem Kalzinieren und Ätzen des Gibbsit Templates wurden gleichförmige Hohlplättchen erhalten, die aus einer sandwichartigen Anordnung von teilweise graphitischem Kohlenstoff und zweidimensional geschichteten MoS2 Flocken bestehen. Die Plättchen haben eine ausgezeichnete Dispergierbarkeit und Stabilität in Wasser sowie eine gute elektrische Leitfähigkeit aufgrund des durch die Kalzinierung von Polydopaminbeschichtungen erzeugten Kohlenstoffs gezeigt. Das Material wird dann in einem symmetrischen Superkondensator mit 1 M Li2SO4 als Elektrolyt aufgebracht, der eine spezifische Kapazität von 248 F/g (0.12 F/cm2) bei einer konstanten Stromdichte von 0.1 A/g und eine ausgezeichnete elektrochemische Stabilität über 3000 Zyklen aufweist, was darauf hindeutet, dass hohle Kohlenstoff-MoS2-Kohlenstoffnanoplättchen vielversprechende Materialien als Kandidaten für Superkondensatoren sind.
Im zweiten Teil wurde 21 molare LiTFSI, das sogenannte "Wasser-in-Salz" (WIS) Elektrolyt, in Superkondensatoren mit hohlen Kohlenstoffnanoplättchen als Elektrodenmaterial untersucht. Im Vergleich zu dem im ersten Teil verwendeten 1 molaren Li2SO4-Elektrolyten wurden bei dem vorliegenden WIS Elektrolyt signifikante Verbesserungen in einem breiteren und stabilen Potentialfenster festgestellt, das durch die geringere Leitfähigkeit mit dem Gegenstück leicht beeinflusst wird. Die elektrochemische Impedanzspektroskopie (EIS) wurde ausgiebig eingesetzt, um einen Einblick in die Reaktionsmechanismen der WIS-Superkondensatoren zu erhalten. Zusätzlich wurde auch der Einfluss der Temperatur auf die elektrochemische Leistung im Temperaturbereich zwischen 15 und 55 °C untersucht, was eine hervorragende spezifische Kapazität von 128 F/g bei dem optimierten Zustand von 55 °C ergab. Die EIS-Messungen deckten die Abnahme der angepassten Widerstände mit der Temperaturerhöhung und umgekehrt auf und beleuchteten direkt die Beziehung zwischen elektrochemischer Leistung und Arbeitstemperatur von Superkondensatoren für zuverlässige praktische Anwendungen.
Im dritten Teil wurde MoS3, ein amorphes, kettenförmig strukturiertes Übergangsmetall Trichalcogenid, als vielversprechende Anode in "Wasser-in-Salz" Li-Ionen-Batterien (WIS-LIBs) nachgewiesen. Die in diesem Teil verwendeten hohlen MoS3-Nanosphären wurden mittels einer skalierbaren Säurefällungsmethode bei Raumtemperatur synthetisiert, wobei sphärische Polyelektrolytbürsten (SPB) als Schablonen verwendet wurden. Beim Einsatz in WIS-LIBs mit LiMn2O4 als Kathodenmaterial erreicht das präparierte MoS3 eine hohe spezifische Kapazität von 127 mAh/g bei einer Stromdichte von 0.1 A/g und eine gute Stabilität über 1000 Zyklen sowohl in Knopf- als auch in Pouch-Zellen. Der Arbeitsmechanismus von MoS3 in WIS-LIBs wurde auch durch Ex-situ-Röntgenbeugungsmessungen (XRD) untersucht. Während des Betriebs wird MoS3 während der anfänglichen Li-Ionen-Aufnahme irreversibel in Li2MoO4 umgewandelt und dann allmählich in eine stabilere und reversible LixMoOy-Phase (2≤y≤4)) entlang der Zyklen umgewandelt. Amorphes Li-defizientes Lix-mMoOy/MoOz wird bei der Delithiierung gebildet.
Die Ergebnisse der vorliegenden Studie zeigen einfache Ansätze zur Synthese hohler MoSx-Nanomaterialien mit kontrollierbarer Morphologie unter Verwendung einer Template-basierten Methode, die auf die vielversprechende Leistung von MoSx für wässrige Energiespeicheranwendungen zurückzuführen sind. Die elektrochemischen Untersuchungen von hohlen MoSx-Nanomaterialien in wässrigen Elektrolyten geben Einblick in die Reaktionsmechanismen von wässrigen Energiespeichersystemen und treiben die Entwicklung von Metallsulfiden für wässrige Energiespeicheranwendungen voran.The present thesis focuses on the synthesis of novel hollow MoSx nanomaterials with controllable size and shape through the colloidal template method. Their possible applications in aqueous energy storage systems, including supercapacitors and Li-ion batteries (LIBs), have been studied. In the first part, hollow carbon-MoS2-carbon nanoplates have been successfully synthesized through an L-cysteine-assisted hydrothermal method by using gibbsite as the template and polydopamine (PDA) as the carbon precursor. After calcination and etching of the gibbsite template, uniform hollow platelets, which are made of a sandwich-like assembly of partial graphitic carbon and two-dimensional layered MoS2 flakes, have been obtained. The platelets have shown excellent dispersibility and stability in water, and good electrical conductivity due to carbon coating generated by the calcination of polydopamine. The material is then applied in a symmetric supercapacitor using 1 M Li2SO4 as the electrolyte, which exhibits a specific capacitance of 248 F/g (0.12 F/cm2) at a constant current density of 0.1 A/g and an excellent electrochemical stability over 3000 cycles, suggesting that hollow carbon-MoS2-carbon nanoplates are promising candidate materials for supercapacitors. In the second part, 21 m LiTFSI, so-called “water-in-salt” (WIS) electrolyte, has been studied in supercapacitors with hollow carbon nanoplates as electrode materials. In comparison with 1 M Li2SO4 electrolyte used in the first part, significant improvements on a broader and stable potential window have been revealed in the present WISE, which is slightly influenced by the lower conductivity with the counterpart. The electrochemical impedance spectroscopy (EIS) has been extensively employed to provide an insight look on the formation of solid electrolyte interphase in the WIS-supercapacitors. Additionally, the effect of temperature on the electrochemical performance has also been investigated in the temperature range between 15 and 55 °C, yielding eminent specific capacitance of 128 F/g at the optimized condition of 55 °C. The EIS measurements disclosed the decrease of fitted resistances with the increase of temperature and vise versa, directly illuminating the relationship between electrochemical output and working temperature of supercapacitors for reliable practical applications. In the third part, MoS3, an amorphous chain-like structured transitional metal trichalcogenide, has been demonstrated as a promising anode in the “water-in-salt” Li-ion batteries (WIS-LIBs). Hollow MoS3 nanospheres used in this part have been synthesized via a scalable room-temperature acid precipitation method using spherical polyelectrolyte brushes (SPB) as the template. When applied in WIS-LIBs with LiMn2O4 as the cathode material, the prepared MoS3 achieves a high specific capacity of 127 mAh/g at the current density of 0.1 A/g and good stability over 1000 cycles in both coin cells and pouch cells. The working mechanism of MoS3 in WIS-LIBs has also been studied by ex-situ X-ray diffraction (XRD) measurements. During operation, MoS3 undergoes irreversible conversion to Li2MoO4 during the initial Li ion uptake, and is then gradually converted to a more stable and reversible LixMoOy (2≤y≤4)) phase along cycling. Amorphous Li-deficient Lix-mMoOy/MoOz is formed upon delithiation. The results in the present thesis demonstrate facile approaches for synthesizing hollow MoSx nanomaterials with controllable morphologies using a template-based method, which attribute to the promising performance of MoSx for aqueous energy storage applications. The electrochemical studies of hollow MoSx nanomaterials in aqueous electrolytes provide insight into the reaction mechanisms of aqueous energy storage systems and push forward the development of metal sulfides for aqueous energy storage applications.
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Tang, PengYi. "Semiconductor composite materials for energy storage and conversion applications." Doctoral thesis, Universitat Autònoma de Barcelona, 2018. http://hdl.handle.net/10803/664734.
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L’energia que s’origina de combustibles fòssils ha permés avenços molt remarcables a la nostra civilització durant el segle passat. No obstant, els combustibles fòssils no son il·limitats i suposen una font d’increment del diòxid de carboni a l’atmòsfera, amb els seus conseqüents efectes ambientals nocius. Millorar la eficiencia dels dispositius d’enmagatzematge d’energia i la conversió d’energia solar a hidrògen mitjançant la dissociació de l’aigua són tecnologies clau per encarar problemes energètics i ambientals. Els semiconductors que es presenten en abundància i són beneficiosos pel medi ambient han estat en el punt de mira durant els últims anys donades les seves característiques especifiques com a supercapacitors i dispositius per la dissociació de l’aigua.
És conegut que les propietats capacitives dels semiconductors están molt afectades per la seva estructura a la nanoescala i la seva baixa conductivitat, limitant les densitats d’energia i potencia. Així doncs, entendre i manipular l’estructura jeràrquica a la nanoescala és essencial per dissenyar materials nanocompostos per l’emmagatzematge d’energia amb millores en la transferència de càrrega i habilitat de transportar ions electrolítics. Per la dissociació d’aigua fotoelectroquímica (PEC), la recombinació electró-forat al “bulk” i les interfícies juguen un paper molt determinant en l’actuació catalítica. La investigació sobre la modulació de la dinámica de transferencia de càrrega així com el nivell d’energia i la densitat d’estats de superfície sobre la modificació d’un segon semiconductor o catalitzadors per dissociació de l’oxígen (OEV) podrien ser de gran interés. Per altra banda, pels catalitzadors de evolució d’hidrògen (HEC), com la identificació de defectes estructurals, transmisió de fase i les vacants presents en materials 2D juguen un paper de vital interès per optimitzar els catalitzadors per la reacció d’evolució de l’hidrògen (HER) en la dissociació de l’aigua.
Aquest treball està dividit en 7 capítols: El Capítol 1 és la part introductòria, que inclou els principis bàsics dels supercapacitors i la dissociació de l’aigua i comenta els factors limitants de les propietats electroquímiques dels semiconductors per aplicacions en supercapacitors i dissociació de l’aigua. El Capítol 2 resumeix les metodologies emprades en aquest treball. Aquest capítol inclou els detalls sobre les configuracions experimentals del TEM, STEM i EELS, processament de dades, simulacions i una introducció a les tècniques electroquímiques com la voltimetria cíclica, espectre d’impedància electroquímica i els models de circuits electrònics per il·lustrar els estats de superficie.
La síntesi i els resultats experimentals es presenten en els Capítols 3-6. El Capítol 3 tracta sobre la fabricació de nuclis embrancats de nanocompostos de Fe2O3/PPy com a electrodes negatius per aplicacions en supercapacitors, així com la investigació dels mecanismes de creixement de nanofulles de PPy sobre flocs d’hematita. Al Capítol 4, hem optimitzat les condicions de síntesi, incloent el gruix de ITO, gruix de TiO2, càrrega de dipòsit de FeNiOOH i la temperatura de post-sinterització dels nanofils de ITO/Fe2O3/Fe2TiO5/FeNiOOH com a fotoànodes per la dissociació de l’aigua en electrolits alcalins. Els detalls de l’estructura s’han investigat principalment mitjançant TEM i STEM-EELS, mentre que la transferència de càrrega i els mecanismes de la dinàmica de reacció han estat investigats sistemàticament per PEIS. Al Capítol 5 hem optimitzat les condicions del bany químic per sintetitzar CoFe PBA suportat sobre fotoànodes basats en nanofils de Fe2O3/Fe2TiO5 per la dissociació de l’aigua en electròlits àcids. Els detalls de l’estructura han estat investigats principalment per TEM i STEM-EELS mentre que la transferència de càrrega i els mecanismes de la dinàmica de reacció han sigut investigats sistemàticament per PEIS. Al Capítol 6, ens hem centrat en la caracterització de defectes estructurals, transmissió de fase, vacants en materials 2D per HER per la dissociació de l’aigua amb un STEM dedicat amb correcció d’aberracions, incloent HAADF, ABF, EELS-STEM, GPA i simulacions d’HAADF. Finalment, al Capítol 7 es resumeixen les conclusions generals d’aquest treball, juntament amb les projeccions futures d’aquests.The energy originated from fossil fuels has enabled the remarkable advancement of civilization over the past century. However, fossil fuels are not infinite in supply and they are a source of increasing atmospheric carbon dioxide and the associated abominable environmental effects. Improving the efficiency of the energy storage devices and conversion of solar energy into hydrogen energy via water splitting are key technologies to tackle the serious energy and environmental problems. Earth-abundant, environmental-friendly semiconductors for supercapacitor and water splitting applications have received great attention due to their specific characteristics. It is well established that the capacitive properties of semiconductors are greatly affected by their nanostructure and poor conductivity, leading to a limited energy and power densities. Thus, understanding and manipulating the hierarchical structure at the nanoscale is essential to design composite materials for energy storage with enhanced charge transfer and electrolyte ions transportation abilities. On one hand, in photoelectrochemical water splitting (PEC), the electron-hole recombination in the bulk interfaces plays a determinative role in the catalytic performance. The investigation about modulation of the charge transfer kinetics as well as the energy level and density of surface state upon the modification of a second semiconductor or oxygen evolution catalysts (OEC) could be of great interest. On the other hand, for hydrogen evolution catalysts (HEC), as the identification of structural defects, phase transmission and vacancies presented in the 2D materials play a vital role in optimizing the catalyst for hydrogen evolution reaction (HER) in water splitting. This dissertation is divided into 7 chapters: Chapter 1 is the introduction part, which includes the background of supercapacitors and water splitting and reviews the limited factors affecting the electrochemical properties of semiconductors for supercapacitor and water splitting applications. In Chapter 2 summarizes the applied methodologies in this dissertation. This chapter includes the details about the TEM, STEM, EELS experimental setups, data processing, simulations and general introductions to the electrochemical techniques, such as cyclic voltammetry, electrochemical impedance spectrum as well the electrical circuit model for illustrating the surface states. Specific synthesis procedures and experimental results for every one of the studied nanosystems are presented in Chapters 3-6. Chapter 3 deals with the fabrication of core-branch Fe2O3/PPy nanocomposites as negative electrode for supercapacitor applications as well as the investigation of PPy nanoleaves growth mechanism onto the hematite nanoflakes. In Chapter 4, we have optimized the synthesis conditions, including the ITO thickness, TiO2 thickness, FeNiOOH deposition charge and the post-sintering temperature of ITO/Fe2O3/Fe2TiO5/FeNiOOH nanowire-based photoanodes for water splitting in alkaline electrolyte. The detailed structure has been mainly investigated by TEM and STEM-EELS, while, the charge transfer and reaction kinetic mechanisms were systematically investigated by PEIS. In Chapter 5, we have optimized the chemical bath conditions for synthesising CoFe PBA supported onto Fe2O3/Fe2TiO5 nanowire-based photoanodes for water splitting in acidic electrolyte. The detailed structure has been mainly investigated by TEM and STEM-EELS, while, the charge transfer and reaction kinetic mechanisms were investigated by PEIS. In Chapter 6, we moved the characterization of structural defects, phase transmission, vacancies in 2D materials for HER in water splitting with advanced aberration-corrected dedicated STEM, including HAADF, ABF, EELS-STEM, GPA and HAADF simulation. Finally, Chapter 7 summarizes the general conclusions of this dissertation, along with a brief outlook.
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Abrahamsson, Johan. "Kinetic Energy Storage and Magnetic Bearings : for Vehicular Applications." Doctoral thesis, Uppsala universitet, Elektricitetslära, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-212106.
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One of the main challenges in order to make electric cars competitive with gas-powered cars is in the improvement of the electric power system. Although many of the energy sources currently used in electric vehicles have sufficientlyhigh specific energy, their applicability is limited due to low specific power. It would therefore be advantageous to create a driveline with the main energy storage separated from a smaller energy buffer, designed to have high power capabilities and to withstand frequent and deep discharge cycles. It has been found that rotating kinetic energy storage in flywheels is very well suited for this type of application. A composite shell, comprising an inner part made of glassfiber and an outer part made of carbonfiber, was analyzed analytically and numerically, designed, and constructed. The shell was fitted onto a metallic rotor using shrinkfitting. The cost of the shell, and the complexity of assembly, was reduced by winding the glass- and carbonfiber consecutively on a mandrel, and curing the complete assembly simultaneously. Thereby, the shell obtained an internal segmentation, without the need for fitting several concentric parts onto each other. The radial stress inside the composite shell was kept compressive thanks to a novel approach of using the permanent magnets of the integrated electric machine to provide radial mechanical load during rotation. Two thrust bearing units (one upper and one lower) comprising one segmented unit with the permanent magnets in a cylindrical Halbach configuration and one non-segmented unit in a up/down configuration were optimized, constructed and tested. Each thrust bearing unit generated 1040 N of repelling force, and a positive axial stiffness of 169 N/mm at the nominal airgap of 5 mm. Two radial active magnetic bearings (one upper and one lower) were optimized, constructed and tested. By parameterizing the shape of the actuators, a numerical optimization of force over resistive loss from the bias currentcould be performed. The optimized shape of the electromagnets was produced by watercutting sheets of laminated steel. A maximum current stiffness of120 N/A at a bias current of 1.5 A was achieved.
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Hasnain, Syed Mahmood. "Latent heat thermal energy storage for solar heating applications." Thesis, University of Leeds, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.252924.
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Roscow, James. "Composite ferroelectric materials for energy harvesting and storage applications." Thesis, University of Bath, 2018. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.761037.
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In this study composite ferroelectric materials have been investigated for their ability to harvest energy from mechanical vibrations via the piezoelectric effect, and store electrical energy as capacitor materials. A combination of modelling and experimental techniques have been used to understand the consequences of using multiphase materials for energy harvesting and storage applications, with particular focus on the significance of interactions between composite structure, electric field distributions and the effective material properties. A detailed investigation into the properties of ferroelectric ceramic-air composites, such as porous barium titanate, is presented. Introducing isotropic, randomly distributed porosity into barium titanate was found to increase the energy harvesting figure of merit from ~1.40 pm^2/N for the dense material to ~2.85 pm^2/N at 60 vol.% porosity. Finite element modelling was used to better understand the poling behaviour of barium titanate with different porous structures (uniform, porous sandwich layer and aligned), enabling the design of materials with improved energy harvesting capabilities. Complex porous structures were found to have enhanced energy harvesting figures of merit, with maximum values achieved of 3.74 pm^2/N and 3.79 pm^2/Nin barium titanate with a 60 vol.% porosity sandwich layer (overall porosity ~34 vol.%) and highly aligned freeze cast barium titanate with 45 vol.% porosity, respectively. Dense and porous barium titanate samples were mechanically excited and the derived electrical energy used to charge a capacitor. The porous barium titanate was found to charge the reference capacitor more effectively than the dense material, demonstrating the benefits of introducing porosity into ferroelectric materials for energy harvesting applications. Ferroelectric composites, in which either a conductive filler was added to a high permittivity ferroelectric matrix or a high permittivity ferroelectric phase was added to a low permittivity polymer matrix, were evaluated for their potential as a new generation of capacitor materials using finite element modelling. The studies suggested that the rise in effective permittivity due to the forming of composites is fundamentally linked to the rapid decline in dielectric breakdown strengths observed in composites, resulting in nearly all cases reported in the literature demonstrating a reduction in the energy storage figure of merit. It is concluded that future efforts into finding the next generation of energy storage materials should focus on single phase, or intrinsic, high permittivity materials rather than composite materials.
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Ahmad, Abdalqader Y. H. "Investigation of cryogenic energy storage for air conditioning applications." Thesis, University of Birmingham, 2018. http://etheses.bham.ac.uk//id/eprint/8255/.
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This research aims to develop an efficient air conditioning technology that exploits cold energy storage to reduce energy consumption and CO2 emissions and shift the cooling load to off peak times to achieve better national electricity grid stability. The investigation includes the use of commonly used cold storage materials (ice, Phase Change Materials PCM) to enhance the existing air conditioning systems and using cryogenic cold storage namely, liquid nitrogen/air (LN2/Lair) to provide air conditioning for domestic and office buildings. Computational Fluid Dynamic (CFD) modelling of the main two components in the cryogenic cooling system namely, cryogenic heat exchanger and expander were also carried out. An experimental test facility was developed to validate the CFD modelling of the liquid nitrogen evaporation process and assess its potential to provide cooling. Results showed that integrating existing Air Conditioning systems with cold storage tank can lead to energy saving of up to 26% and shifting the cooling load to off peak times, but this energy saving is highly dependent on the storage medium and its storage temperature. Also, using cryogenic fluids (LN2/Lair) to provide air conditioning for domestic and office buildings can recover up to 94% of the energy stored in LAir and up to 78% of the energy stored in LN2, and based on LN2/Lair prices of 3.5 pence per kg the system showed cost saving of the energy consumption of up to 73% when LAir is used and 67% when LN2 is used compared with the conventional system. The CFD modelling of cryogenic heat exchanger showed good agreement with the experimental work with maximum deviation 7.6%.
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Chen, Bingan. "Carbon nanotubes for adhesive, interconnect, and energy storage applications." Thesis, University of Cambridge, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.648440.
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Yang, Li. "Terephthalate-Functionalized Conducting Redox Polymers for Energy Storage Applications." Doctoral thesis, Uppsala universitet, Nanoteknologi och funktionella material, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-304628.
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Organic electrode materials, as sustainable and environmental benign alternatives to inorganic electrode materials, show great promise for achieving cheap, light, versatile and disposable devices for electrical energy storage applications. Conducting redox polymers (CRPs) are a new class of organic electrode materials where the charge storage capacity is provided by the redox chemistry of functional pendent groups and electronic conductivity is provided by the doped conducting polymer backbone, enabling the production of energy storage devices with high charge storage capacity and high power capability. This pendant-conducting polymer backbone combination can solve two of the main problems associated with organic molecule-based electrode materials, i.e. the dissolution of the active material and the sluggish charge transport within the material. In this thesis, diethyl terephthalate and polythiophenes were utilized as the pendant and the backbone, respectively. The choice of pendant-conducting polymer backbone combination was based on potential match between the two moieties, i.e. the redox reaction of terephthalate pendent groups and the n-doping of polythiophene backbone occur in the same potential region. The resulting CRPs exhibited fast charge transport within the polymer films and low activation energies involved charge propagation through these materials. In the design of these CRPs an unconjugated link between the pendant and the backbone was found to be advantageous in terms of the polymerizability of the monomers and for the preservation of individual redox activity of the pendants and the polymer chain in CRPs. The functionalized materials were specifically designed as anode materials for energy storage applications and, although insufficient cycling stability was observed, the work presented in this thesis demonstrates that the combination of redox active functional groups with conducting polymers, forming CRPs, shows promise for the development of organic matter-based electrical energy storage materials.
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Kim, K. B., J. G. Kim, H. K. Kim, J. P. Jegal, K. H. Kim, J. Y. Kim, and S. H. Park. "Nanocomposites of Reduced Graphene Oxide for Energy Storage Applications." Thesis, Sumy State University, 2012. http://essuir.sumdu.edu.ua/handle/123456789/35266.
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A well-crystallized and nano-sized Metal oxide/reduced graphene oxide composite material for lithium
ion batteries has been successfully synthesized. The nano-sized metal oxide particles were evenly dispersed
on the reduced graphene oxide template without any agglomeration, which allows the inherent high active
surface area of individual metal oxide nano-particles in the composite. These unique structural and morphological
properties of metal oxide on the highly conductive reduced graphene oxide sheets in the composite
enable achieving the high specific capacity, and excellent high rate capability and stable cycling performance.
an analysis of the cyclic voltammogram data revealed that a large surface charge storage contribution
of the metal oxide/reduced graphene oxide nanocomposite plays an important role in achieving faster
charge/discharge.
When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/35266
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Zhang, Lu. "Study of Novel Graphene Structures for Energy Storage Applications." University of Cincinnati / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1479823012280305.
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Gong, Yifu. "Intelligent Energy-Efficient Storage System for Big-Data Applications." Diss., North Dakota State University, 2020. https://hdl.handle.net/10365/31752.
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Static Random Access Memory (SRAM) is a critical component in mobile video processing systems. Because of the large video data size, the memory is frequently accessed, which dominates the power consumption and limits battery life. In energy-efficient SRAM design, a substantial amount of research is presented to discuss the mechanisms of approximate storage, but the content and environment adaptations were never a part of the consideration in memory design. This dissertation focuses on optimization methods for the SRAM system, specifically addressing three areas of Intelligent Energy-Efficient Storage system design. First, the SRAM stability is discussed. The relationships among supply voltage, SRAM transistor sizes, and SRAM failure rate are derived in this section. The result of this study is applied to all of the later work. Second, intelligent voltage scaling techniques are detailed. This method utilizes the conventional voltage scaling technique by integrating self-correction and sizing techniques. Third, intelligent bit-truncation techniques are developed. Viewing environment and video content characteristics are considered in the memory design. The performance of all designed SRAMs are compared to published literature and are proven to have improvement.
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Martin, Benjamin Ryan. "Energy Harvesting Applications of Ionic Polymers." Thesis, Virginia Tech, 2005. http://hdl.handle.net/10919/32024.
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The purpose of this thesis is the development and analysis of applications for ionic polymers as energy harvesting devices. The specific need is a self-contained energy harvester to supply renewable power harvested from ambient vibrations to a wireless sensor. Ionic polymers were investigated as mechanical to electrical energy transducers. An ionic polymer device was designed to harvest energy from vibrations and supply power for a wireless structural health monitoring sensor.The ionic polymer energy harvester is tested to ascertain whether the idea is feasible. Transfer functions are constructed for both the open-circuit voltage and the closed-circuit current. The impedance of the device is also quantified. Using the voltage transfer function and the current transfer function it is possible to calculate the power being produced by the device.Power generation is not the only energy harvesting application of ionic polymers, energy storage is another possibility. The ionic polymer device is tested to characterize its charge and discharge capabilities. It is charged with both DC and AC currents. An energy storage comparison is performed between the ionic polymers and capacitors. While the polymers performed well, the electrolytic capacitors are able to store more energy. However, the ionic polymers show potential as capacitors and have the possibility of improved performance as energy storage devices. Current is measured across resistive loads and the supplied power is calculated. Although the power is small, the ionic polymers are able to discharge energy across a load proving that they are capable of supplying power.Master of Science
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Sze, Ngok Man. "Switching converter techniques for energy harvesting applications /." View abstract or full-text, 2007. http://library.ust.hk/cgi/db/thesis.pl?ECED%202007%20SZE.
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Bremner, Glen. "The electrochemical properties of conducting polymers for energy storage applications." Thesis, University of British Columbia, 2014. http://hdl.handle.net/2429/46550.
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Burpo, F. John (Fred John). "Three-dimensional virus scaffolds for energy storage and microdevice applications." Thesis, Massachusetts Institute of Technology, 2011. http://hdl.handle.net/1721.1/73776.
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Thesis (Sc. D.)--Massachusetts Institute of Technology, Dept. of Biological Engineering, February 2012.Cataloged from PDF version of thesis.
Includes bibliographical references.
With constantly increasing demand for lightweight power sources, electrode architectures that eliminate the need for conductive and organic additives will increase mass specific energy and power densities. The increased demand for lightweight power is coupled with increasing device miniaturization. As the scale of devices decreases, current battery technologies add mass on the same scale as the device itself. A dual functional electro-mechanical material that serves as both the device structural material and the power source would dramatically improve device integration and range for powered movement. To address the demand for lightweight power with the objective of a dual functional electro-mechanical material, the M 13 bacteriophage was used to create novel 3-dimensional nano-architectures. To synthesize 3-dimensional nanowire scaffolds, the M13 virus is covalently linked into a hydrogel that serves as a 3-dimensional bio-template for the mineralization of copper and nickel nanowires. Control of nanowire diameter, scaffold porosity, and film thickness is demonstrated. The nanowire scaffolds are found to be highly conductive and can be synthesized as free-standing films. To demonstrate the viability of the 3-dimensional nanowire networks for electrical energy storage, copper nanowires were galvanically displaced to a mixed phase copper-tin system. These tin based anodes were used for lithium rechargeable batteries and demonstrated a high storage capacity per square area and stable cycling approaching 100 cycles. To determine the viability of the 3-dimensional nanowire networks as dual functional electro-mechanical materials and the mechanical stability of processing intermediates, phage hydrogels, aerogels, and metal nanowire networks were examined with nano-indentation. The elastic moduli of the metal networks are in the range of open cell metal foams The demonstration of 3-dimensional virus-templated metal nanowire networks as electrically conductive and mechanically robust should facilitate their implementation across a broad array of device applications to include photovoltaics, catalysis, electrochromics, and fuel cells.
by F. John Burpo.
Sc.D.
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Ding, Yate. "Investigation of high capacity heat energy storage for building applications." Thesis, University of Nottingham, 2014. http://eprints.nottingham.ac.uk/30955/.
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The problems of excessive consumption of fossil resources, oil shortages and greenhouse gas emissions are becoming increasingly severe. Research and development work on new methods of thermal energy storage are imminently required. To effectively store seasonal renewable energy, a novel high capacity heat storage system has been designed and evaluated/validated through laboratory experiments and numerical simulations in this research. The system is driven by direct flow evacuated tube solar collector with enhanced PCM tank and intends to be applied in residential and commercial buildings. Theoretical and experimental approaches and numerical analysis have been employed in this study. Firstly, phase change materials (PCM) with specific heat density, melting point, melting and solidifying time have been investigated. This type of PCMs can maintain a considerable high internal temperature of environment chamber in a frozen ambient temperature. Numerical modelling has been conducted on a passive house (Nottingham H.O.U.S.E) to study whether proposed thermochemical materials can cover relative heating load and be power by solar panel in terms of roof size. Meanwhile, PCMs have been used to give a long duration for temperature-controlled chamber in laboratory, and thermochemical materials have been utilized in closed pumping pipe system for cooling and heating purpose. Secondly, characteristic experiments have been conducted on a modified solar collector working with an enhanced PCM tank that is integrated with a fan coil heat exchanger. The results show that light radiation of tungsten lamps (as a solar simulator) has approximately 70% efficiency to equate to solar radiation under the same Pyranometer reading value. At the same time, the solar system can supply over 50°C heating energy and the PCM tank within it can supply higher output temperature with longer duration than water tank. The efficiency of the whole solar collector heating system is over 50% as a heat absorption chamber in sunny days, while only approximately 10% under mostly cloudy weather. Lastly, proposed thermochemical materials (silica gel, calcium chloride, zeolite 13x, vermiculite and activated carbon) have been evaluated on designed thermochemical absorption chamber to supply fresh high temperature air for space heating. The results show that zeolite holds the highest reacted temperature (over 58°C) and vermiculite has really fast absorbing hydration duration, less than half hour. Silica gel possesses the biggest water absorbing capacity and vermiculite has a worse result. A comparison between experimental and numerical modelling results has been revealed. Considering the complexity of processes in cooling and heating system, the agreement of simulation and experimentation is satisfactory, thus the lumped numerical model is acceptable and significant for investigation of this scaled seasonal high capacity heat storage system. A full size seasonal heat storage system with a nominal heating capacity of 3kW has been proposed and illustrated in economic and environmental issues section. The results from net present value (NPV) and internal rate of return (IRR) sensitivity analysis both shows it is greatly attractive to develop this novel system for application in both household and commercial buildings in consideration of its about 9 years payback period, 20 years life span and zero gas (C02) emissions. An intelligent transpired solar collector system is also introduced and illustrated as future work.
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Afonso, Josiana Prado. "Towards cryogenic liquid –vapor energy storage units for space applications." Doctoral thesis, Faculdade de Ciências e Tecnologia, 2013. http://hdl.handle.net/10362/10158.
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Dissertation to obtain the Doctoral degree
in Physics EngineeringWith the development of mechanical coolers and very sensitive cryogenic sensors, it could be interesting to use Energy Storage Units (ESU) and turn off the cryocooler to operate in a free micro vibration environment. An ESU would also avoid cryogenic systems oversized to attenuate temperature fluctuations due to thermal load variations which is useful particularly for space applications. In both cases, the temperature drift must remain limited to keep good detector performances. In this thesis, ESUs based on the high latent heat associated to liquid-vapor phase change to store energy have been studied. To limit temperature drifts while keeping small size cell at low temperature, a potential solution consists in splitting the ESU in two volumes: a low temperature cell coupled to a cryocooler cold finger through a thermal heat switch and an expansion volume at room temperature to reduce the temperature increase occurring during liquid evaporation. To obtain a vanishing temperature drift, a new improvement has been tested using two-phase nitrogen: a controlled valve was inserted between the two volumes in order to control the cold cell pressure. In addition, a porous material was used inside the cell to turn the ESU gravity independent and suitable for space applications. In this case, experiments reveal not fully understood results concerning both energy storage and liquid-wall temperature difference. To capture the thermal influence of the porous media, a dedicated cell with poorly conductive lateral wall was built and operated with two-phase helium. After its characterization outside the saturation conditions (conduction, convection), experiments were performed, with and without porous media, heating at the top or the bottom of the cell with various heat fluxes and for different saturation temperatures. In parallel, a model describing the thermal response for a cell containing liquid and vapor with a porous medium heated at the top (“against gravity”) was developed. The experimental data were then used as a benchmark for this model based on a balance of three forces: capillarity force, gravity force and pressure drop induced by the liquid flow.
Fundação da Ciência e da Tecnologia - PhD scholarship(SFRH/BD/60357/2009); project “Cryogenic Temperature Stabilizers” (PTDC/EME-MFE/101448/2008)
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Pottathara, Yasir Beeran. "Graphene based Composites with Cellulose Nanofibrils for Energy storage applications." Thesis, Lorient, 2017. http://www.theses.fr/2017LORIS450/document.
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La recherche sur les matériaux diélectriques souples et biodégradable a été augmenté considérablement en raison de l'augmentation des exigences concernant l'énergie et les questions environnementales. Les composites polymériques, avec constante diélectrique élevée ont ainsi, été préférés par rapport aux composites à base de céramique pour les périphériques de stockage de l'énergie. L'objectif de cette thèse est de fabriquer une électrode biodégradable matériaux à base de nano-fibrilles de cellulose natives et oxydés (CNF) et de graphène pour améliorer le stockage diélectrique ainsi que les applications de stockage de charge électrochimique. La présente méthode de réduction, induite par les UV sur l'oxyde de graphène (GO) dans des matrices de cellulose, est une alternative prometteuse aux traitements à base de solvant en évitant la détérioration des propriétés des matériaux et l'utilisation de solvants organiques. Cette méthode pourrait être étendue à d’autres matériaux composites polymèresThe research on biodegradable and flexible dielectric materials has been increased widely because of increasing requirements about energy and environmental issues. Polymeric composites with high dielectric constant have, thus, been demanded increasingly compared to ceramic based composites for energy storage devices. The objective of this thesis is to fabricate a biodegradable electrode materials based on pristine and oxidized cellulose nanofibrils (CNF) with different graphene based fillers for enhanced dielectric storage as well as electrochemical charge storage applications. The presented dry method of UV induced reduction of graphene oxide (GO) in cellulose matrices are promising alternatives to solvent based treatments avoiding the deterioration of material properties and the use of organic solvents. This method could be extended to alternative polymer composite materials. In contrast to previous reports, the dielectric properties mainly focussed on the higher frequency regions to provide real, intrinsic material properties and obtained significant enhancement than reported studies. This approach gives a new insight to the exact performance of materials on dielectric charge storage applications. The current study gives more insight for the development of flexible, lightweight and biodegradable electrode materials for energy storage device applications
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Kumar, Prem. "Applications of superconducting magnetic energy storage systems in power systems." Thesis, Virginia Tech, 1989. http://hdl.handle.net/10919/44118.
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A Superconducting Magnetic Energy Storage (SMES) system is a very efficient storage device capable of storing large amounts of energy. The primary applications it has been considered till now are load-leveling and system stabilization.This thesis explores new applications/benefits of SMES in power systems. Three areas have been identified.
â ¢ Using SMES in conjunction with PV systems.SMES because of their excellent dynamic response and PV being an intermittent source complement one another.A scheme for this hybrid system is developed and simulation done accordingly.
Using SMES in an Asynchronous link between Power Systems. SMES when used in a series configuration between two or more systems combines the benefits of asynchronous connection, interconnection and energy storage. A model of such a scheme has been developed and the control of such a scheme is demonstrated using the EMTP. The economic benefits of this scheme over pure power interchange, SMES operation alone and a battery/dc link is shown.
Improvement of transmission through the use of SMES. SMES when used for diurnal load leveling provides additional benefits like reduced transmission losses, reduced peak loading and more effective utilization of transmission facility, the impact of size and location on these benefits were studied, and if used as an asynchronous link provides power flow control.Master of Science
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Persson, Fredrik. "Energy Storage for Stationary Applications – A Comparative, Techno-Economical Investigation." Thesis, KTH, Skolan för kemi, bioteknologi och hälsa (CBH), 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-280016.
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Power outages, electric-grid deficiencies and renewable energies are all examples where stationary energy storages are useful. In this master thesis, two types of stationary electrochemical energy storages are examined; vent-regulated lead-acid batteries (VRLA) and lithium iron phosphate batteries (LFP), to find out the more beneficial one in stationary uses. The techniques are examined for a large range of electric-grid services in a techno-economical investigation. The cost per delivered kWh of the energy storage is the basis of comparison which is calculated using battery degradation data with respect to C-rate, SoC, DoD, temperature, storage time and cycle frequency to estimate calendar and cyclic aging. Modelling presents neither alternative as superior although LFP is the more versatile alternative. VRLA-batteries can be a more cost-beneficial alternative for applications demanding less than 1 cycle/day, at temperatures lower than 30C, short project lifetimes and when utilizing storages beyond 80% EoL. The investment cost is lower for VRLA at equal C-rates. Cost items neglected will decrease the chances of VRLA being the cheapest technique. From a sustainability point of view, LFP is under almost all circumstances the less energy and CO2-intense technology, however recyclability is in clear favor for VRLA.Strömavbrott, underdimensionerade elnät och förnybar energi är tre exempel där ett stationärt energilager kan tillämpas. I den här masteruppsatsen undersöks två typer av stationära elektrokemiska energilager; ventilreglerade bly-syra-batterier och litium-järnfosfat-batterier (LFP), för att finna det mer fördelaktiga alternativet i stationära applikationer. De två teknikerna analyseras i ett stort antal elnätsapplikationer i en tekno-ekonomisk studie. Kostnaden per levererad kWh av energilagret används som jämförelsebas vilken beräknas utifrån batteridegraderingsdata med avseende på C-rate, SoC, DoD, temperatur, lagringstid och cykelfrekvens för att estimera kalender- och cyklisk åldring. Modellering visar att inget av batterialternativen är överlägset i alla situationer men LFP är det mångsidigare alternativet. Bly-syra-batterier kan vara mer kostnadseffektiva för applikationer som kräver mindre än 1 (full-ekvivalent) cykel/dag vid temperaturer lägre än 30C, korta projektlivstider samt när batterilagren används bortom 80% EoL. Investeringskostnaden är lägre för bly-syra-batterier när likadan C-rate appliceras. Negligerade kostnadsposter kommer minska chanserna att bly-syra-batterier är det billigaste alternativet. Från ett hållbarhetsperspektiv är LFP nästan uteslutande den mindre energikrävande och mindre CO2-intensiva tekniken. Bly-syra-batterier har dock en klar fördel när det kommer till återvinningsbarhet.
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Johnson, Douglas James. "Carbon Foam Infused with Pentaglycerine for Thermal Energy Storage Applications." University of Dayton / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1304086567.
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Hsieh, Yu-Yun. "Nanostructured Carbon-Based Composites for Energy Storage and Thermoelectric Applications." University of Cincinnati / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=ucin157322525150617.
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Quan, Ting [Verfasser]. "Hollow MoSx nanomaterials for aqueous energy storage applications / Ting Quan." Berlin : Humboldt-Universität zu Berlin, 2021. http://d-nb.info/1234451034/34.
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Dall'Agnese, Yohan. "Study of early transition metal carbides for energy storage applications." Thesis, Toulouse 3, 2016. http://www.theses.fr/2016TOU30025/document.
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La demande urgente d'innovations dans le domaine du stockage de l'énergie est liée au développement récent de la production d'énergie renouvelable ainsi qu'à la diversification des produits électroniques portables qui consomment de plus en plus d'énergie. Il existe plusieurs technologies pour le stockage et la conversion électrochimique de l'énergie, les plus notables étant les batteries aux ions lithium, les piles à combustible et les supercondensateurs. Ces systèmes sont utilisés de façon complémentaire des uns aux autres dans des applications différentes. Par exemple, les batteries sont plus facilement transportables que les piles à combustible et ont de bonne densité d'énergie alors que les supercondensateurs ont des densités de puissance plus élevés et une meilleure durée de vie. L'objectif principal de ces travaux est d'étudier les performances électrochimiques d'une nouvelle famille de matériaux bidimensionnel appelée MXène, en vue de proposer de nouvelles solutions pour le stockage de l'énergie. Pour y arriver, plusieurs directions ont été explorées. Dans un premier temps, la thèse se concentre sur les supercondensateurs dans des électrolytes aqueux et aux effets des groupes de surface. La seconde partie se concentre sur les systèmes de batterie et de capacités à ions sodium. Une cellule complète comportant une anode en carbone et une cathode de MXène a été développées. La dernière partie de la thèse présente l'étude des MXènes pour les supercondensateur en milieu organique. Une attention particulière est apportée à l'étude du mécanisme d'intercalation des ions entre les feuillets de MXène. Différentes techniques de caractérisations ont été utilisées, en particulier la voltampérométrie cyclique, le cyclage galvanostatique, la spectroscopie d'impédance, la microscopie électronique et la diffraction des rayons XAn increase in energy and power densities is needed to match the growing energy storage demands linked with the development of renewable energy production and portable electronics. Several energy storage technologies exist including lithium ion batteries, sodium ion batteries, fuel cells and electrochemical capacitors. These systems are complementary to each other. For example, electrochemical capacitors (ECs) can deliver high power densities whereas batteries are used for high energy densities applications. The first objective of this work is to investigate the electrochemical performances of a new family of 2-D material called MXene and propose new solutions to tackle the energy storage concern. To achieve this goal, several directions have been explored. The first part of the research focuses on MXene behavior as electrode material for electrochemical capacitors in aqueous electrolytes. The next part starts with sodium-ion batteries, and a new hybrid system of sodium ion capacitor is proposed. The last part is the study of MXene electrodes for supercapacitors is organic electrolytes. The energy storage mechanisms are thoroughly investigated. Different characterization techniques were used in this work, such as cyclic voltammetry, galvanostatic charge-discharge, electrochemical impedance spectroscopy, scanning electron microscopy and X-ray diffraction
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Aaronson, Barak D. B. "High resolution electrochemical imaging for energy conversion and storage applications." Thesis, University of Warwick, 2015. http://wrap.warwick.ac.uk/78415/.
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The work presented herein involves the development of the scanning electrochemical cell microscopy (SECCM) platform for visualizing electrochemical and (photo)electrochemical activity of processes at electrode surfaces relevant to energy applications. The use of complementary microscopy characterization techniques such as: field emission-scanning electron microscopy (FE-SEM), electron backscatter diffraction (EBSD), atomic force microscopy (AFM) and Raman microscopy provides a correlation between the localized (photo)electrochemical activity (obtained by SECCM) and physical properties of the investigated surfaces. SECCM studies of a polycrystalline platinum surface highlight the significant variations in electrochemical activity that can be measured at electrode surfaces due to variations in localized crystallographic orientation and the presence of grain boundaries. An ostensibly simple redox couple (Fe2+/3+) in two different acidic media on a polycrystalline platinum foil is utilized as a model system and the localized crystallographic orientation of the surface is determined by EBSD analysis. The approach is then extended to room temperature ionic liquids (RTILs) to study the reduction of triiodide (I3-) to iodide (I-) on polycrystalline platinum for the application of dye sensitized solar cells (DSSCs) as a counter electrode. The coupling of illumination with high sensitivity current followers and external lock-in amplifiers to the SECCM setup is described and the resulting platform is demonstrated to allow investigation of (photo)electrochemical systems. Two examples are provided: imaging photo-anodes in DSSCs and electrodeposition and characterization of conjugated polymers on a transparent electrode for organic photovoltaic devices. Finally, photo-SECCM is used for determining structure-activity relationships for (photo)electrocatalysts of conjugated organic polymers by coupling the technique with AFM and Raman spectroscopy, suggesting the technique as a potential high throughput screening platform. The approach is exemplified by investigating poly(3-hexylthiophene) and provides not only a correlation of film morphology and photo-activity but also extracts important information on film growth and aging.
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Fazlollahi, Farhad. "Dynamic Liquefied Natural Gas (LNG) Processing with Energy Storage Applications." BYU ScholarsArchive, 2016. https://scholarsarchive.byu.edu/etd/5956.
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The cryogenic carbon capture™ (CCC) process provides energy- and cost-efficient carbon capture and can be configured to provide an energy storage system using an open-loop natural gas (NG) refrigeration system, which is called energy storing cryogenic carbon capture (CCC-ES™). This investigation focuses on the transient operation and especially on the dynamic response of this energy storage system and explores its efficiency, effectiveness, design, and operation. This investigation included four tasks.The first task explores the steady-state design of four different natural gas liquefaction processes simulated by Aspen HYSYS. These processes differ from traditional LNG process in that the CCC process vaporizes the LNG and the cold vapors return through the LNG heat exchangers, exchanging sensible heat with the incoming flows. The comparisons include costs and energy performance with individually optimized processes, each operating at three operating conditions: energy storage, energy recovery, and balanced operation. The second task examines steady-state and transient models and optimization of natural gas liquefaction using Aspen HYSYS. Steady-state exergy and heat exchanger efficiency analyses characterize the performance of several potential systems. Transient analyses of the optimal steady-state model produced most of the results discussed here. The third task explores transient Aspen HYSYS modeling and optimization of two natural gas liquefaction processes and identifies the rate-limiting process components during load variations. Novel flowrate variations included in this investigation drive transient responses of all units, especially compressors and heat exchangers. Model-predictive controls (MPC) effectively manages such heat exchangers and compares favorably with results using traditional controls. The last task shows how an unprocessed natural gas (NG) pretreatment system can remove more than 90% of the CO2 from NG with CCC technology using Aspen Plus simulations and experimental data. This task shows how CCC-based technology can treat NG streams to prepare them for LNG use. Data from an experimental bench-scale apparatus verify simulation results. Simulated results on carbon (CO2) capture qualitatively and quantitatively agree with experimental results as a function of feedstock properties.
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Tian, Wenda. "Nanostructured electroactive polymeric composites for energy storage and separation applications." Thesis, Massachusetts Institute of Technology, 2018. https://hdl.handle.net/1721.1/121899.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Chemical Engineering, 2018Cataloged from PDF version of thesis.
Includes bibliographical references (pages 123-137).
Electroactive polymeric materials have garnered considerable interest due to their potential applications in advancing electrochemical energy storage, sensing, catalysis, and separations systems. Electroactive polymers include conducting polymers with a-conjugated backbones and redox polymers with localized redox-responsive moieties. The electro-responsive property of both conjugated and redox polymers is highly impacted by the efficient transport of counter-ions within polymers to maintain charge neutrality. The interactions at the molecular interface between the polymer and target entities ultimately dictate the performance of electroactive materials in the aforementioned applications. Nanostructures provide a shortened diffusion path for the transport of electrolyte ions or target molecules during a reversible redox process. The large interfacial area arising from an improved morphology allows efficient utilization of polymeric materials.
Consequently, the union of nanostructures and electro-responsiveness has proven to be a powerful strategy to enhance the merit of electroactive polymers in the design of next generation energy storage devices, sensors, catalysts and separation platforms. In this thesis, we focused on developing novel synthesis strategies for nanostructured electroactive polymeric composites. Two different synthesis approaches for the polymeric component were realized by exploiting the inter-molecular interactions between monomeric units and other entities during an electrochemical polymerization process. In the first approach, a nanostructured polyvinylferrocene /polypyrrole hybrid was fabricated via a co-deposition method as a result of the [pi]-[pi] stacking interactions between the aromatic pyrrole monomers and the metallocene moieties of polyvinylferrocene. The hybrid has a highly porous morphology with a significantly increased surface area compared to its bulk counterpart.
The synergistic effects between polyvinylferrocene and polypyrrole lead to enhanced ionic and electronic conductivity and, consequently, a higher specific capacitance as a supercapacitor electrode material. The second approach was a diffusion-controlled electrochemical method facilitated by the interactions between pyrrole monomers and the carbamate groups in CO₂-bound polyamines. As a result, a porous polypyrrole coating consisting of nanofibrous structures was synthesized and deposited on a carbon microfiber substrate. This composite material demonstrated enhanced electrochemical properties and adsorption capability towards aldehydes as a result of its porous morphology and high surface area. We later applied this composite material in achieving electrochemically modulated adsorption of polynucleotides.
The adsorption process was found to have a strong dependence on the oxidation states of the composite due to the electrostatic interactions between positively charged polypyrrole backbones and negatively charged phosphate groups in DNAs.
by Wenda Tian.
Ph. D.
Ph.D. Massachusetts Institute of Technology, Department of Chemical Engineering
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Miner, Elise Marie. "Energy storage and conversion applications of conductive metal-organic frameworks." Thesis, Massachusetts Institute of Technology, 2019. https://hdl.handle.net/1721.1/121783.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Chemistry, 2019Cataloged from PDF version of thesis.
Includes bibliographical references (pages 182-200).
Establishing catalytic structure-function relationships enables optimization of the catalyst structure for enhanced activity, selectivity, and durability against reaction conditions and prolonged catalysis. One class of catalysts that could benefit from systematic optimization is non-platinum group metal (non-PGM) electrocatalysts for the O₂ reduction reaction (ORR) to water (4e⁻ reduction) and / or hydrogen peroxide (2e⁻ reduction). The electrically conductive metal-organic frameworks (MOFs) M₃(HXTP)₂ (HXTP = 2,3,6,7,10,11-hexaimino or hexahydroxytriphenylene (HITP or HHTP, respectively)) feature a crystalline structure that contains homogeneously distributed, square planar transition metal sites reminiscent of those doped into carbonaceous media for ORR catalysis. Ni₃(HITP)2 functions as an active and stable ORR electrocatalyst in alkaline medium.
Experimental and computational techniques enabled elucidation of the kinetics, mechanism, and active site for ORR with Ni₃(HITP)₂, as well as understanding the essential nature of the extended MOF structure in providing catalytic activity. Varying the metal and ligand combinations within this class of MOFs afforded two distinct phases. Probing the stability, catalytic activity, product distribution, and electronic properties of the two phases of MOFs identified phase-dependent catalytic activity, regardless of the metal or chelating atom identity. Since the birth of the first rechargeable battery in 1860, emerging battery technologies have both provided answers to energy demands as well as additional obstacles to navigate.
Recent works have explored using MOFs as ionically conductive solid-state electrolytes which would eliminate the need for volatile organic liquids and potentially offer a wider electrolyte potential window and means of controlling the plating of alkali metals during charging. This work has taken advantage of the modular charge found in a Cu-azolate MOF, wherein guest Cl⁻ ions coordinated to Cu₄-lined clusters can be washed out of the structure, and stoichiometric loadings of anions varying in size can be reconstituted into the MOF when soaking the MOF in solutions containing alkali or alkaline earth metal salts. The anions are held in place through coordination to the Cu²⁺ centers, thus enabling the charge-balancing metal cations to achieve high transference numbers within this solid electrolyte. Further, the versatility regarding the identity of the guest metal salt provides a handle for modulating the cation transport activation energy and ionic conductivity.
by Elise Marie Miner.
Ph. D.
Ph.D. Massachusetts Institute of Technology, Department of Chemistry
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Li, Wenqi. "LIGNIN-DERIVED CARBON AND NANOCOMPOSITE MATERIALS FOR ENERGY STORAGE APPLICATIONS." UKnowledge, 2019. https://uknowledge.uky.edu/bae_etds/68.
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With a growing demand for electrical energy storage materials, lignin-derived carbon materials have received increasing attention in recent years. As a highly abundant renewable carbon source, lignin can be converted to a variety of advanced carbon materials with tailorable chemical, structural, mechanical and electrochemical properties through thermochemical conversion (e.g. pyrolysis). However, the non-uniformity in lignin structure, composition, inter-unit linkages and reactivity of diverse lignin sources greatly influence lignin fractionation from plant biomass, the pyrolysis chemistry, and property of the resulting carbon materials.
To introduce a better use of lignocellulosic biomass to biofuels and co-products, it is necessary to find novel ways to fractionate lignin and cellulose from the feedstock at high efficacy and low cost. Deep eutectic solvent (DES) was used to extract lignin from high lignin-content walnut and peach endocarps. Over 90% sugar yields were achieved during enzymatic hydrolysis of DES pretreated peach and walnut endocarps while lignins were extracted at high yields and purity. The molecular weights of the extracted lignin from DES pretreated endocarp biomass were significantly reduced. The native endocarp lignins were SGH type lignins with dominant G-unit. DES pretreatment decreased the S and H-unit which led to an increase in condensed G-units, which may contribute to a higher thermal stability of the isolated lignin.
Lignin slow pyrolysis was investigated using a commercial pyrolysis–GC/MS system for the first time to link pyrolysis chemistry and carbon material properties. The overall product distributions, including volatiles and solid product were tracked at different heating rates (2, 20, 40 ℃/min) and different temperature regions (100-200, 200-300 and 300-600 ℃). Results demonstrate that changes in reaction chemistry as a factor of pyrolysis conditions led to changes in yield and properties of the resulting carbon materials. Physical and chemical properties of the resulting carbon material, such as porosity, chemical composition and surface functional groups were greatly affected by lignin slow pyrolysis temperature and heating rate.
Lignin-derived activated carbons (AC) were synthesized from three different lignin sources: poplar, pine derived alkaline lignin and commercial kraft lignin under identical conditions. The poplar lignin-derived ACs exhibited a larger surface area and total mesopore volume than softwood lignin-derived AC, which contribute to a larger electrochemical capacitance over a range of scan rates. The presence of oxygen-containing functional groups in all lignin-derived ACs, which participated in redox reaction and thus contributed to an additional pseudo-capacitance. By delineating the carbonization and activation parameters, results from this study suggest that lignin structure and composition are important factors determining the pore structure and electrochemical properties of the derived carbon materials.
A 3-dimensional, interconnected carbon/silicon nanoparticles composite synthesized from kraft lignin (KL) and silicon nanoparticles (Si NPs) is shown to have a high starting specific capacity of 2932 mAh/g and a retaining capacity of 1760 mAh/g after 100 cycles at 0.72 A/g as negative electrode in a half-cell lithium-ion battery (LIB) test. It was found the elemental Si and C of the C/Si NPs were most likely linked via Si-O-C rather than direct Si-C bond, a feature that helps to alleviate the mechanical degradation from Si volume change and assure a sound electronic and ionic conductivity for enhanced electrochemical performance. EGA-MS and HC-GC/MS analyses suggest that the interaction of the Si, O and C can be tailored by controlling pyrolysis conditions.
This study systematically investigated the interconnecting aspects among lignin source, pyrolysis chemistry, characteristics of the derived carbon materials and electrochemical performance. Such knowledge on the processing-structure-function relationships serves as a basis for designing lignin-based carbon materials for electrochemical energy storage applications.
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Javadian-Deylami, Seyd Payam. "Metal Hydrides as Energy Storage for Concentrated Solar Thermal Applications." Thesis, Curtin University, 2017. http://hdl.handle.net/20.500.11937/58986.
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Hydrogen storage properties of LiBH4 may be changed by interaction with other complex hydrides due to an intimate interaction between the respective alkaline metals and boron which facilitate a relatively larger hydrogen storage capacity. The cyclic stability of the following binary complex hydride systems LiBH4-Ca(BH4)2, LiBH4-NaBH4 and LiBH4-NaAlH4 shows significant reversibility and due to their relative high gravimetric H2 storage capacity and specific heat storage capacity, they may potentially act as heat storage materials.
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Poupin, Lucas Michel Dominique. "Development of metal hydride systems for thermal energy storage applications." Thesis, Curtin University, 2020. http://hdl.handle.net/20.500.11937/84107.
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This thesis project furthers the development of innovative high temperature thermal energy storage using metal hydrides. The research greatly enhances the gravimetric energy density, which has the potential to lead to an increased efficiency of thermal energy storage. The project aimed at selecting suitable metal hydrides for scaling up and the investigation of heat storing reactors. Three systems were studied, including an autonomously operating thermal energy store of 1.8 MJ at 450 °C.
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Wasalathilake, Kimal Chandula. "Synthesis and characterization of modified graphene for energy storage applications." Thesis, Queensland University of Technology, 2018. https://eprints.qut.edu.au/123800/1/Kimal_Wasalathilake_Thesis.pdf.
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This thesis presents the synthesis and characterization of modified graphene materials and investigates their role in sustainable energy storage applications by using both experimental methods and density functional theory simulations. The outcomes obtained provide a better understanding of the structure-property relationship in modified graphene and its role in electrochemical process in rechargeable batteries, benefiting the development of high-performance electrode materials.
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Sebzali, Ahmad J. "A resonant DC link power converter for future drive applications." Thesis, University of Bristol, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.319019.
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Franzén, Kenzo, and Fredrik Jangelind. "States and Prospects of Hydrogen Storage Technologies in Aircraft Applications." Thesis, KTH, Energiteknik, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-298996.
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In recent years, more than 100 000 commercial flights have departed daily, and the number of passengers worldwide are expected to double within the next two decades, assuming there are no long-term impacts of the Covid-19 pandemic. Meanwhile, the aviation industry will need to undergo a shift to more sustainable fuels, due to the growing issue of climate change and implementation of policies that regulate the use of fossil-based fuels such as kerosene. Hydrogen has been established as one proposed fuel for aviation, due to its properties of high energy contents and the main emissions being water vapor. For hydrogen to be used as an aviation fuel, there is a need for efficient, safe and low-cost storage systems. Based on a set of quantifiable parameters the report aims to, based on technical, economical and safety perspectives as well as conclusions from previous studies, identify and quantify the current states and prospects of some of the most promising methods and technologies for hydrogen storage in commercial aircrafts. Furthermore, other important parameters are being identified and discussed after analyzing the viability of several physical and material storage technologies. The results show that although none of the technologies are sufficiently developed and ready for aircraft applications, cryogenic liquid hydrogen storage offers the best opportunities for the near future. Other forms of physical storage show some promise, whereas some material storage methods have large theoretical potential but require rapid development. While the other studied systems can’t be dismissed, a lot of research and development would have to be successful in order to reach technological and commercial viability. Further research is necessary for quantifying storage costs as well as prospects and targets for costs and gravimetric energy densities. All things considered, it is concluded that for hydrogen to be viable as an aviation fuel, hydrogen storage systems need to perform on a level much higher than today.Under de senaste åren har över 100 000 kommersiella flygningar avgått dagligen, och antalet passagerare världen över förväntas fördubblas inom de närmaste två decennierna, förutsatt att Covid-19-pandemin inte har några långvariga effekter på flygindustrin. Samtidigt behöver branschen genomföra en omställning till mer hållbara bränslen, till följd av det växande problemet med klimatförändringar och implementering av policy som reglerar användningen av fossilbaserade bränslen som Jet A1 (flygfotogen). Vätgas har etablerats som ett föreslaget flygbränsle tack vare sitt höga energiinnehåll och att dess utsläpp mestadels består av vattenånga. För att vätgas ska kunna användas som flygbränsle finns ett behov av effektiva, säkra och billiga lagringssystem. Baserat på en uppsättning av kvantifierbara parametrar syftar rapporten till, baserat på tekniska, ekonomiska och säkerhetsmässiga perspektiv, att identifiera och kvantifiera nuvarande tillstånd och framtidsutsikter hos flera av de mest lovande metoderna och teknologierna för vätgaslagring i kommersiella flygplan. Vidare identifieras och diskuteras andra viktiga parametrar efter att förutsättningarna för teknologier för fysisk lagring och materiallagring har analyserats. Resultaten visar att även om ingen av teknologierna är tillräckligt utvecklade eller redo att appliceras på flygplan, så erbjuder kryogen, flytande vätgaslagring de bästa möjligheterna för en nära framtid. Även andra former av fysisk lagring visar sig vara ganska lovande, medan vissa metoder för materiallagring har hög teoretisk potential men kräver en snabb utveckling i mognadsgrad. Även om de andra studerade systemen inte helt kan avfärdas så behöver mycket forskning och utveckling lyckas för att nå en teknologisk och kommersiell gångbarhet. Ytterligare forskning är nödvändig för att kvantifiera flyganpassade lagringskostnader samt utsikter och mål för kostnader och gravimetrisk lagringstäthet. Sammantaget dras slutsatsen att vätgaslagringssystem behöver prestera på en nivå långt över idag för att vätgas ska kunna bli lämpligt som flygbränsle.
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Zhou, Xin Zhang Qiming. "High energy/capacitance density poly(vinylidene fluoride) based polymers for energy storage capacitor applications." [University Park, Pa.] : Pennsylvania State University, 2009. http://etda.libraries.psu.edu/theses/approved/WorldWideIndex/ETD-4578/index.html.
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Manning, R. E. "An investigation of thermal energy storage and its applications to industrial systems." Thesis, Cranfield University, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.352684.
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Huang, Xiubing. "Transition-metal based oxides for oxygen storage and energy-related applications." Thesis, University of St Andrews, 2015. http://hdl.handle.net/10023/6817.
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The development of energy storage and conversion techniques with high efficiency and power density is of great importance for the sustainable development of our green world. Li-O₂ batteries with high theoretical energy density has attracted extensive attention. However there are still many issues waiting to be solved, such as low stability of cathode catalyst, as well as the deactivation of cathode by H₂O and CO₂ from air. Reversible solid oxide fuel cells can be used for electricity production by SOFCs and fuel production (H₂ and O₂) by SOECs. Thus, oxygen storage materials can bridge Li-O₂ batteries and reversible SOFCs with the purpose of increasing the whole efficiency of the system. The discovery of oxygen storage materials with reversible oxygen release/storage behaviours and high oxygen storage capacities dependent on temperature or oxygen partial pressures (e.g., inert and oxidation gases) still needs further research. The work in this thesis mainly focuses on the preparation of transition-metal based oxides (such as perovskite oxides, brownmillerite-type oxides, layered-perovskite oxides, coated β-MnO₂ nanorods, transition-metal doped CeO₂ nanocrystals) as oxygen storage materials and their energy-related applications, seeking to discover the principles for oxygen storage/release properties and their performance in energy conversion and storage applications. The prepared materials included nanostructured and bulk materials via various synthesis methods, including citrate-modified evaporation-induced self-assembly method, hydrothermal method, pechini method, as well as solid state method. This work investigated the oxygen storage capacities of several crystal structure types oxides based on transition-metals. Nanostructured La₀.₆Ca₀.₄Fe₁₋ₓCoₓO[sub](3-δ) and La₀.₆Ca₀.₄Mn₁₋ₓFeₓO[sub](3-δ) exhibit high oxygen storage capacities and stability under reductive 5%H₂/Ar, but the oxygen-storage content under inert argon is low, just about 0.2 wt%. Brownmillerite-type Ca₂AlMnO₅ is demonstrated to possess a large amount of oxygen release/storage capacities depending on temperature even under flowing oxygen, as well as high oxygen storage/release properties and reversibility under alternating inert and oxygen gases at 500 °C. Substituting Ga on the Al-site would reduce the oxygen storage capacities, even though these substituted samples still posses good reversibility. The effect of A-site species (Mg, Ca, Sr) have been also investigated and demonstrated. It can't obtain pure brownmillerite-type crystal structure when Ca is partially or totally substituted by Mg or Sr, resulting in poor reversibility and low oxygen storage capacities. Nanostructured layered-perovskite La₁.₇Ca₀.₃M₁₋ₓCuₓO[sub](4-δ) (M = Fe, Co, Ni, Cu) have also been investigated for oxygen storage and as potential cathodes for IT-SOFCs. Even though the as-prepared layered-perovskite oxides have been demonstrated to be good candidates as cathode materials for IT-SOFCs with high performance, they do not possess high amount of oxygen storage/release ability under inert atmospheres because of the robust phase stability. β-MnO₂ nanorods can release large amount of oxygen (ca. 9.2 wt%) with increasing temperature at about 560 °C under various gases (air, N₂). Coating β-MnO₂ nanorods with CeO₂ nanocrystals could result in lower temperatures for oxygen mobility and removal under N₂ because of the enhanced oxygen mobility between CeO₂₋ₓ and β-MnO₂, while coating β-MnO₂ nanorods with SnO₂ nanocrystals have no enhanced oxygen mobility behaviours. The results demonstrate the positive and negative synergetic effect between other metal oxides and β-MnO₂ on the oxygen migration. Cr- and Cu-doped CeO₂ nanocrystals (i.e. nanorods, nanocubes and nanoparticles) were chosen to investigate the effect of transition-metal doping on CeO₂ and their valence changes with temperature and various atmospheres, as well as their oxygen storage capacities. The effect of Cr- or Cu- doping on CeO₂ nanocrystal morphology and oxygen storage capacities have been investigated and demonstrated. This provides some basic information for transition-metals doped CeO₂ nanocrystal evolution and stability, as well as further applications in energy-related fields, such as three-way catalysts, electrode materials in solid oxide fuel cells and Li-air batteries.
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Görtz, Steffen. "Battery energy storage for intermittent renewable electricity production : A review and demonstration of energy storage applications permitting higher penetration of renewables." Thesis, Umeå universitet, Institutionen för tillämpad fysik och elektronik, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-104285.
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Driven by resource politics and climate change, the transition from conventional fossil fuel based and centralized energy generation to distributed renewables is increasing rapidly. Wind and solar power generation offer carbon dioxide neutral electricity but also present some integration difficulties for energy system operators and planners due to intermittent power output. A promising way of dealing with the intermittency from renewables is energy storage. The method of storing energy in the electricity grid, especially by the means of electrochemical storage, has gained a lot of attention over the last years in the energy sector. While most utilities and energy market stakeholders have the basic understanding of energy storage, a more profound knowledge of grid storage applications is often lacking. This thesis aims to highlight and explain possible energy storage applications with focus on renewables integration. Battery energy storage can allow higher amounts of renewable electricity generation to be integrated by smoothening power output, time shifting generated energy to follow demand and increase hosting capacities through peak shaving. Power quality related issues due to intermittency can be mitigated by controlling the storage’s charging patterns to respond to grid variables. For optimal utilization and maximum storage value, several applications should be within the operational repertoire of the storage unit. Other applications including arbitrage, grid investment deferral and load following are discussed. Several battery technologies which have been developed and tested for such applications including lead acid, sodium sulfate and lithium-ion are presented. The most promising battery energy storage technology is lithium-ion with exceptional storage characteristics and most importantly a favorable near term price development. Two case studies on two of Umeå Energy’s low voltage networks simulating high penetrations of solar generation have been carried out to demonstrate mitigation of overvoltage and peak shaving with battery energy storage systems. The simulations show that energy storage systems can successfully be used to aid the integration of renewables in the electricity grid. Present capital costs are still too high for energy storage to be feasible but falling pricing and a developing market is foreseen to lower the hurdles. The main obstacle for energy storage at grid scale besides high capital costs are, in principle, non-existing legal frameworks regulating the ownership of energy storage systems and system technology standardization. Further discussions on the matter in combination with testing and pilot projects are needed to gain national and international experience with battery energy storage for the successful high share integration of renewables.Sinande naturresurser och växthuseffekten driver på övergången från centraliserad kraftproduktion baserad på fossila bränslen till distribuerad förnyelsebar energiproduktion i rask takt. Vind- och solkraft levererar koldioxidneutral el men ställer samtidigt balansansvariga och elnätsplanerare inför en rad problem på grund av periodiskt återkommande och tidvis ostabil effektgenerering. Energilager presenteras som en lovande lösning på problemen orsakade av förnyelsebara energikällor Att lagra energi i elnätet, i synnerhet med batterier, har fått en hel del uppmärksamhet de senaste åren i energibranschen. De flesta elnätsbolag och intressenter på energimarknaden har en grundläggande förståelse kring energilagring i elnätet men saknar ofta mer djupgående kunskap. Detta examensarbete syftar att belysa och förklara användningsområden och potentialer för energilagring med fokus på integreringen av förnyelsebara energikällor. Teorin beskriver hur batterilager kan användas för tillåta integreringen av en hög andel förnyelsebar elproduktion. Några tillämpningar är; effektutjämning, lagring av producerad energi för senare bruk samt ökad nätkapacitet genom att kapa toppar. Problem relaterade till försämrad elkvalité orsakad av varierande kraftproduktion visas kunna pareras med hjälp av programmerbara energilagringssystem som läser av storheter på elnätet såsom spänning och frekvens. För att utnyttja energilagret optimalt och komma åt dess maximala värde bör flera användningsområden kombineras. Därför diskuteras även andra användningsområden såsom arbitrage, lagringskapacitet för att skjuta upp eller undvika förstärkning av elnätet och lastföljning. Ett flertal batteriteknologier aktuella för de diskuterade användningsområdena såsom bly-, natriumsulfat- och litium-jonbatterier presenteras. Den mest lovande teknologin är litium-jon tack vare dess utmärkta egenskaper och framförallt mycket gynnsamma förväntade prisutveckling. Två fallstudier av två av Umeå Energi´s nätområden med hög simulerad andel solenergiproduktion har utförts för att demonstrera utnyttjandet av energilager för reglering av överspänning och kapning av toppar. Simuleringarna visar att energilagringssystem med framgång kan underlätta integreringen av förnyelsebara energikällor. Dagens kapitalkostnader är fortfarande för höga för att energilagring ska vara ekonomiskt försvarbart men fallande priser och en växande marknad väntas verka till teknikens fördel. Det visar sig att regelverk gällande ägandeskapet och standardiseringen av energilager är i det närmaste obefintliga vilket utgör ytterligare hinder för tekniken. Fortsatta diskussioner gällande dessa punkter i kombinationen med test- och pilotanläggningar för att införskaffa erfarenhet av energilagring i elnätet krävs.
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Ren, Yu. "Applications of ordered mesoporous metal oxides : energy storage, adsorption, and catalysis." Thesis, University of St Andrews, 2010. http://hdl.handle.net/10023/1705.
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The experimental data and results demonstrated here illustrate the preparation and application of mesoporous metal oxides in energy storage, adsorption, and catalysis. First, a new method of controlling the pore size and wall thickness of mesoporous silica was developed by controlling the calcination temperature. A series of such silica were used as hard templates to prepare the mesoporous metal oxide Co₃O₄. Using other methods, such as varying the silica template hydrothermal treatment temperature, using colloid silica, varying the materials ratio etc., a series of mesoporous β-MnO₂ with different pore size and wall thickness were prepared. By using these materials it has been possible to explore the influence of pore size and wall thickness on the rate of lithium intercalation into mesoporous electrode. There is intense interest in lithium intercalation into titanates due to their potential advantages (safety, rate) replacing graphite for new generation Li-ion battery. After the preparation of an ordered 3D mesoporous anatase the lithium intercalation as anode material has been investigated. To the best of our knowledge, there are no reports of ordered crystalline mesoporous metal oxides with microporous walls. Here, for the first time, the preparation and characterization of three dimensional ordered crystalline mesoporous α-MnO₂ with microporous wall was described, in which K+ and KIT-6 mesoporous silica act to template the micropores and mesopores, respectively. It was used as a cathode material for Li-ion battery. Its adsorption behavior and magnetic property was also surveyed. Following this we described the preparation and characterization of mesoporous CuO and reduced Cu[subscript(x)]O, and demonstrated their application in NO adsorption and delivery. Finally a series of crystalline mesoporous metal oxides were prepared and evaluated as catalysts for the CO oxidation.