An electrolytic cell was designed, built, and tested with several proof-of-concept experiments in which Zircaloy material was charged with hydrogen in order to generate zirconium hydride formations. The Electrolytic Charging with Hydrogen and a Thermal Gradient (ECH-TG) system has the ability to generate static 20°C to 120°C temperatures for a H2SO4 and H2O bath for isothermal experiment conditions. This system was designed to accommodate a molten salt bath in future experiments to achieve higher isothermal temperatures. Additionally, the design accommodates a cartridge heater, which when placed on the inside of the sample tube, can be set at temperatures up to 350 °C and create a thermal gradient across the sample. Finally, a custom LABVIEW VI, L2.vi, was developed to control components and record data during experimentation. This program, along with web cameras and the commercial StirPC software package, enables remote operation for extended periods of time with only minor maintenance during an experiment. While proving the concept for this design, 19 experiments where performed, which form the basis for a future parametric study. Initial results indicate formations of zirconium hydrides which formed rim structures between 8.690 +/- 0.982 μm and 12.365 +/- 0.635 μm thick. These electrolytically produced rims were compared with hydrides formed under a previous vapor diffusion experiment via Scanning Electron Microscope (SEM) imaging and Energy dispersive X-ray Spectroscopy (EDS) analysis. While the existing vapor diffusion method formed gradients of zirconium hydride, it failed to produce the gradient in the correct direction and also failed to create a hydride rim. The successful use of the ECH-TG system to create said rim, and some of the methods used to direct that rim to the OD of the tube can be used for future work with the vapor diffusion method in order to create zirconium hydrides of the correct geometry. The procedures and apparatus created for this project represent a reliable method for creating zirconium hydride rim structures.

Thesis (MScIng)--University of Stellenbosch, 2004. / ENGLISH ABSTRACT: Recent years have seen the development of various treatment methods for the purification of industrial waste waters due to the increased demand for reduced pollutant effluents. Aqueous waste streams containing toxic organic compounds are of special interest, since conventional treatment methods such as biological waste treatment can not always be used. Other popular treatment methods are often ineffective. Catalytic oxidation of organic wastes has been investigated since the 1960s with varying degrees of success. A major problem associated with this method is the high temperatures and pressures required to improve the activation energies involved. Electrochemical oxidation has become a popular method in the literature of treating these wastes, since the applied voltage determines the activation energy, and therefore the process can often be performed at ambient conditions. This thesis investigates the capability of a unique reactor system in the treatment of these wastes. The reactor utilises proton-exchange membrane technology to eliminate the requirement of conductivity in treated waste streams; thus the membrane serves as a solid electrolyte. The reactor system has therefore been referred to as a solid-polymer-electrolyte reactor. Novel metal oxide anodes are responsible for the oxidation of the organic molecules. These metal oxide catalysts show promise in the treatment of a wide variety of organic wastes. A SnO2 catalyst doped with ZrO2 is used as anode in this study. Dopants are added to the catalyst to improve properties such as catalytic activity and conductivity. Kinetic data was obtained on a wide range of values for the chosen experimental parameters (current density and flow rate). Phenol, an organic molecule often referred to in the literature as model contaminant due to its resistance to oxidation,was also used as contaminant in this study. The use of the reactor system in the disinfection of water containing selected pathogens, were included in the experimental work. This kinetic data served in the development of a simple model of the process, and provided the basis for a full analysis regarding potential scale-up and economic feasibility. A requirement of the study was the accurate determination of the various oxidation breakdown products of phenol. This led to the refinement of an HPLC analytical method in order to quantitatively determine these products. The full analysis showed that the current reactor system would not be economically viable — mainly due to very long reactor lengths required for the complete removal of all organic material. Both mass transfer and charge transfer at the chosen experimental conditions influenced the electrochemical oxidation of phenol. High pressure drops, causing low flow rates in the reactor, accounted for this because of the narrow flow channels required in the reactor. Some catalyst deactivation was also suspected to affect the overall reaction, but the full extent of the deactivation was not investigated thoroughly. There is still room for improvement in the electrochemical oxidation of organic wastes. The design of the flow channels, a factor that was not investigated, can significantly improve efficiency. Another aspect that was not investigated was the catalyst type. The catalyst has been identified in the literature as the main contributing factor to the success of the oxidation reaction. A wide variety of metal oxide catalysts are currently being researched and may improve the kinetics of the process even further. Further improvement needs to be made on the membrane/electrode assembly to improve current density distribution. Every improvement of the process in terms of the reactor design and catalyst will impact on the economics of the process, thus making the process more competitive with current treatment technologies. / AFRIKAANSE OPSOMMING: In die afgelope paar dekades, is daar ’n wye verskeidenheid metodes ontwikkel wat gebruik kan word om industri¨ele afvoer strome te behandel. Hierdie ontwikkeling het plaasgevind as gevolg van die verhoogde eis aan skoner afvoerstrome. Wateragtige afvoerstrome wat organiese verbindings bevat, is van besonderse belang omdat hierdie tipe strome soms besonders moeilik kan wees om te behandel. Gebruiklike metodes is in die meeste gevalle ongeskik vir behandelings-doeleindes. Katalitiese oksidasie is sedert die 1960’s gebruik, maar hierdie prosesse benodig dikwels ho¨e drukke en temperature om suksesvol te wees. Elektrochemiese oksidasie het intussen ’n populˆere behandelingsmetode geword, aangesien die aktiveringsenergie vir die oksidasieproses hoofsaaklik afhanklik is van die aangewende potensiaal en dus kan die proses by atmosferiese toestande gebruik word. In hierdie tesis word die geskiktheid van ’n unieke reaktorstelsel vir water-suiwering ondersoek. Die reaktor gebruik ’n proton-uitruilings-membraan om die behoefte vir konduktiwiteit in die water uit te skakel. Die membraan dien dus as ’n tipe soliede elektroliet en as gevolg hiervan word na die reaktorstelsel verwys as ’n soliede-polimeer-elektroliet reaktor. Nuwe metaal-oksied anodes word in die reaktor gebruik aangesien hulle belowende resultate toon in die oksidasie van organiese verbindings. In die navorsing, is ’n SnO2 katalis wat klein hoeveelhede ZrO2 bevat gebruik. Oksiede soos ZrO2 word dikwels gebruik om die aktiwiteit en konduktiwiteit van hierdie kataliste te bevorder. Kinetiese data is oor ’n wye bereik van parameter waardes ingesamel. Die hoof parameters in die eksperimentele werk was stroom digtheid en vloeitempo. Fenol, ‘n komponent wat volgens die literatuur in hierdie tipe van werk gebruik word, isas die besoedelende komponent gekies. Die doeltreffendheid van die reaktor in die ontsmetting van water, wat met ’n verskeidenheid skadelike mikro-organismes besmet is, is ook getoets. ‘n Eenvoudinge model is opgestel m.b.v. die kinetiese data, waarna ’n volledige analise met betrekking tot grootskaalse bedryf en ekonomiese uitvoerbaarheid gedoen is. ‘n Vereiste van die studie was om die konsentrasie van die afbreek-produkte van die oksidasie akkuraat vas te stel. As gevolg hiervan is ‘n ho¨e-druk-vloeistofchromatografie analitiese metode verfyn. Die analise het getoon dat die reaktorstelsel nie ekonomies sou wees nie. Een van die hoofredes hiervoor is die onrealistiese reaktorlengtes wat benodig sou word. Resultate het getoon dat die reaksie deur beide massa-oordrag en lading-oordrag be¨ınvloed word. Ho¨e drukvalle in die reaktor wat gelei het tot lae vloeitempo’s was hiervoor verantwoordelik. Die deaktivering van die katalis be¨ınvloed waarskynlik die reaksie, maar die deaktiveringsverskynsel is nie ten volle ondersoek nie. Die reaktorstelsel kan verder verbeter word deur verskeie elemente van die reaktor te ondersoek. Die ontwerp van die vloeikanale in die reaktor is nie ondersoek nie en kan die werksverrigting van die reaktor verhoog. Uit die literatuur is gevind dat die tipe metaaloksied wat as katalis gebruik word, die reaksie direk be¨ınvloed. Dus kan navorsing wat tans op die kataliste gedoen word nuwe kataliste na vore bring wat meer doeltreffend sal wees. Laastens, is die huidige membraan/elektrode samestelling nog oneffektief en kan die reaktor-opstelling dus nog verbeter word. Elke verbetering wat op die bogenoemde faktore van die reaktor ontwerp verkry word, sal die ekomoniese uitvoerbaarheid van die proses be¨ınvloed. So, sal die proses al meer kompeterend met huidige behandelingsmetodes word.

The interest of gaining on-line information related to non-metallic inclusions during the steelmaking process has recently increased due to the development as well as the promising results of the Pulse Distribution Analysis with Optical Emission Spectroscopy method (PDA/OES). Even though, the time from sampling to presented results on inclusions is only about 5-10 minutes, the method has also shown limitations with respect to the determination of some inclusion characteristics. Therefore, a first step was to perform a study on other methods such as the cross-section method (CS) on a polished sample surface, the cross-section after etching method (CSE), the bromine-methanol extraction method (BME), and the electrolytic extraction method (EE). This study focused on the evaluation of these methods with respect to the time consumption for preparation and analysis of a sample, the analyzed volume and the determination of inclusion and cluster characteristics such as size, number, particle size distribution (PSD) and composition. The CS and CSE methods were found to be suitable in the determination of the largest cluster in a sample which can be recommended in order to select proper extraction parameters for further studies. The BME method was considered to be fast with the possibility of analyzing a large volume. However, the used solution is chemically stronger compared to electrolytic extraction solutions, which can affect the results. In most aspects, the EE method was found to be the most stable, reliable and accurate method with some limitations regarding the time aspect. Based on this conclusion, the EE method was selected for a comparative study with the PDA/OES method. Reliably detected size ranges by using the PDA/OES method were defined for two low-alloyed steel grades. These are 2.0-5.7 μm and 1.4-5.7 μm for steel samples taken before and after a Ca-addition during the secondary steelmaking, respectively. Moreover, agreements between the EE and PDA/OES methods were observed in the average size and number of detected inclusions when only inclusions with the size &gt; 2 μm were considered. Also, a theoretical minimum size and a maximum number ofinclusions present in the steel sample, which can be detected by using the PDA/OES method, were estimated. The work continued by successfully applying the EE method to study correlations between inclusions observed in the liquid steel samples and in a clogged nozzle (clogging material). It was found that the average sizes of spherical and non-spherical inclusions observed in the steel corresponded well with those observed in the clogging material. However, there were some differences in the frequencies of these inclusions. This was explained by a possible transformation of the present inclusions due to a reoxidation and a reaction with the nozzle refractory of the steel melt. The results of this study may contribute in the selection of proper process parameters or inclusion characteristics for future studies on the improvement and application of on-line methods. Finally, suggestions on how to present and interpret data obtained by the PDA/OES method during production of stainless steels were given in the present thesis. More specifically, the possibilities of defining operating windows with respect to inclusion composition and the use of a B-factor for Al (the total content of Al in inclusions detected by using the PDA/OES method) during the secondary steelmaking were discussed. In addition, a correlation study between B-factors for Al and numbers of inclusions (dV &gt; 4 μm) obtained by using the PDA/OES method on process samples, and corresponding slivers indices from plate products was performed. The results showed a moderate correlation between these parameters as well as an increase of the slivers index with increased values of the chosen PDA/OES data. This indicates that it could be possible to predict when there is an increased risk of having slivers on the final rolled product at an early stage of the steelmaking process. / <p>QC 20150525</p>

This study has been mainly focused on high temperature solid oxide electrolysis cells (HT-SOECs) for steam electrolysis. The compositions, microstructures and metal catalysts for SOEC cathodes based on (La₀.₇₅Sr₀.₂₅)₀.₉₅Mn₀.₅Cr₀.₅O₃ (LSCM) have been investigated. Hydrogen production amounts from SOECs with LSCM cathodes have been detected and current-to-hydrogen efficiencies have been calculated. The effect of humidity on electrochemical performances from SOECs with cathodes based on LSCM has also been studied. LSCM has been applied as the main composite in HT-SOEC cathodes in this study. Cells were measured at temperatures up to 920°C with 3%steam/Ar/4%H₂ or 3%steam/Ar supplied to the steam/hydrogen electrode. SOECs with LSCM cathodes presented better stability and electrochemical performances in both atmospheres compared to cells with traditional Ni cermet cathodes. By mixing materials with higher ionic conductivity such as YSZ(Y₂O₃-stabilized ZrO₂ ) and CGO(Ce₀.₉Gd₀.₁O₁.₉₅ ) into LSCM cathodes, the cell performances have been improved due to the enlarged triple phase boundary (TPB). Metal catalysts such as Pd, Fe, Rh, Ni have been impregnated to LSCM/CGO cathodes in order to improve cell performances. Cells were measured at 900°C using 3%steam/Ar/4%H₂ or 3%steam/Ar and AC impedance data and I-V curves were collected. The addition of metal catalysts has successfully improved electrochemical performances from cells with LSCM/CGO cathodes. Improving SOEC microstructures is an alternative to improve cell performances. Cells with thinner electrolytes and/or better electrode microstructures were fabricated using techniques such as cutting, polishing, tape casting, impregnation, co-pressing and screen printing. Thinner electrolytes gave reduced ohmic resistances, while better electrode microstructures were observed to facilitate electrode processes. Hydrogen production amounts under external potentials from SOECs with LSCM/CGO cathodes were detected by gas chromatograph and current-to-hydrogen efficiencies were calculated according to the law of conservation of charge. Current-to-hydrogen efficiencies from these cells at 900°C were up to 80% in 3%steam/Ar and were close to 100% in 3%steam/Ar/4%H₂. The effect of humidity on SOEC performances with LSCM/CGO cathodes has been studied by testing the cell in cathode atmospheres with different steam contents (3%, 10%, 20% and 50% steam). There was no large influence on cell performances when steam content was increased, indicating that steam diffusion to cathode was not the main limiting process.

The technical and scientific challenges to provide reliable sources energy for US and global economy are enormous tasks, and especially so when combined with strategic and recent economic concerns of the last five years. It is clear that as part of the mix of energy sources necessary to deal with these challenges, fuel cells technology will play critical or even a central role. The US Department of Energy, as well as a number of the national laboratories and academic institutions have been aware of the importance such technology for some time. Recently, car manufacturers, transportation experts, and even utilities are paying attention to this vital source of energy for the future. In this thesis, a review of the main fuel cell technologies is presented with the focus on the modeling, and control of one particular and promising fuel cell technology, aluminum air fuel cells. The basic principles of this fuel cell technology are presented. A major part of the study consists of a description of the electrochemistry of the process, modeling, and simulations of aluminum air FC using Matlab Simulink™. The controller design of the proposed model is also presented. In sequel, a power management unit is designed and analyzed as an alternative source of power. Thus, the system commutes between the fuel cell output and the alternative power source in order to fulfill a changing power load demand. Finally, a cost analysis and assessment of this technology for portable devices, conclusions and future recommendations are presented. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2013.

Solar energy has the potential to meet all of society’s energy demands, but challenges remain in storing it for times when the sun is not shining. Electrolysis is a promising means of energy storage which applies solar-derived electricity to drive the production of chemical fuels. These so-called solar fuels, such as hydrogen gas produced from water electrolysis, can be fed back to the grid for electricity generation or used directly as a fuel in the transportation sector. Solar fuels can be generated by coupling a photovoltaic (PV) cell to an electrolyzer, or by directly converting light to chemical energy using a photoelectrochemical cell (PEC). Presently, both PV-electrolyzers and PECs have prohibitively high capital costs which prevent them from generating hydrogen at competitive prices. This dissertation explores the design of membraneless electrolyzers and PECs in order to simplify their design and decrease their overall capital costs. A membraneless water electrolyzer can operate with as few as three components: A cathode for the hydrogen evolution reaction, an anode for the oxygen evolution reaction, and a chassis for managing the flows of a liquid electrolyte and the product gas streams. Absent from this device is an ionically conducting membrane, a key component in a conventional polymer electrolyte membrane (PEM) electrolyzer that typically serves as a physical barrier for separating product gases generated at the anode and cathode. These membranes can allow for compact and efficient electrolyzer designs, but are prone to degradation and failure if exposed to impurities in the electrolyte. A membraneless electrolyzer has the opportunity to reduce capital costs and operate in non-pristine environments, but little is known about the performance limitations and design rules that govern operation of membraneless electrolyzers. These design rules require a thorough understanding of the thermodynamics, kinetics, and transport processes in electrochemical systems. In Chapter 2, these concepts are reviewed and a framework is provided to guide the continuum scale modeling of the performance of membraneless electrochemical cells. Afterwards, three different studies are presented which combine experiment and theory to demonstrate the mechanisms of product transport and efficiency loss. Chapter 3 investigates the dynamics of hydrogen bubbles during operation of a membraneless electrolyzer, which can strongly affect the product purity of the collected hydrogen. High-speed video imaging was implemented to quantify the size and position of hydrogen gas bubbles as they detach from porous mesh electrodes. The total hydrogen detected was compared to the theoretical value predicted by Faraday’s law. This analysis confirmed that not all electrochemically generated hydrogen enters the gas phase at the cathode surface. In fact, significant quantities of hydrogen remain dissolved in solution, and can result in lower product collection efficiencies. Differences in bubble volume fraction evolved along the length of the cathode reflect differences in the local current densities, and were found to be in agreement with the primary current distribution. Overall, this study demonstrates the ability to use in-situ HSV to quantitatively evaluate key performance metrics of membraneless electrolyzers in a non-invasive manner. This technique can be of great value for future experiments, where statistical analysis of bubble sizes and positions can provide information on how to collect hydrogen at maximum purity. Chapter 4 presents an electrode design where selective placement of the electrocatalyst is shown to enhance the purity of hydrogen collected. These “asymmetric electrodes” were prepared by coating only one planar face of a porous titanium mesh electrode with platinum electrocatalyst. For an opposing pair of electrodes, the platinum coated surface faces outwards such that the electrochemically generated bubbles nucleate and grow on the outside while ions conduct through the void spacing in the mesh and across the inter-electrode gap. A key metric used in evaluating the performance of membraneless electrolyzers is the hydrogen cross-over percentage, which is defined as the fraction of electrochemically generated hydrogen that is collected in the headspace over the oxygen-evolving anode. When compared to the performance of symmetric electrodes – electrodes coated on both faces with platinum – the asymmetric electrodes demonstrated significantly lower rates of cross-over. With optimization, asymmetric electrodes were able to achieve hydrogen cross-over values as low as 1%. These electrodes were then incorporated into a floating photovoltaic electrolysis device for a direct demonstration of solar driven electrolysis. The assembled “solar fuels rig” was allowed to float in a reservoir of 0.5 M sulfuric acid under a light source calibrated to simulate sunlight, and a solar to hydrogen efficiency of 5.3% was observed. In Chapter 5, the design principles for membraneless electrolyzers were applied to a photoelectrochemical (PEC) cell. Whereas an electrolyzer is externally powered by electricity, a PEC cell can directly harvest light to drive an electrochemical reaction. The PEC reactor was based on a parallel plate design, where the current was demonstrated to be limited by the intensity of light and the concentration of the electrolyte. By increasing the average flow rate of the electrolyte, mass transport limitations could be alleviated. The limiting current density was compared to theoretical values based off of the solution to a convection-diffusion problem. This modeled solution was used to predict the limitations to PEC performance in scaled up designs, where solar concentration mirrors could increase the total current density. The mass transport limitations of a PEC flow cell are also highly relevant to the study of CO2 reduction, where the solubility limit of CO2 in aqueous electrolyte can also limit performance.

Made available in DSpace on 2017-07-24T19:37:59Z (GMT). No. of bitstreams: 1 Cristiane_de_Abreu_Dias.pdf: 17390080 bytes, checksum: 6e0128183854fb8cc356100b574dac1a (MD5) Previous issue date: 2009-02-17 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Throughout the times, new pigment systems have been gradually developed. In the nowadays, the development of ceramic pigments represents a part of the Materials Science, where there is a lack of concepts, roles and strategies, which in goal allows the developing of new rotes of preparing or pigments, in both scientific and technological areas. This work deals with the development of an innovative processing route and characterization of ceramic pigments based on the formation of solid solution of zircon silicate via doping with manganese cations being the source of manganese cations a waste of alkaline battery. In fact, an electrolytic paste of zinc-carbon batteries was used as a starting precursor of the manganese oxide, major component of the electrolytic paste, as a precursor of the chromophore agent. As a standard, Mn doped ZrSiO4 pigments were prepared via mechanical mixture of oxides process using analytical MnO2 (P.A.) oxide as a starting precursor of manganese cations. Powder mixtures exhibiting different percentages in weight of electrolytic paste were homogenized in the isopropyl alcohol via ball milling during 6 h. In the sequence, precursors were dried in furnace type oven at 110°C until the weight stabilizing giving the precursor of the pigment. Then, the precursor was calcined, desagglomerated and sieved (350 mesh).The precursor calcination was carried out in an oven furnace at 1150°C with a soaking time of 4h, in air atmosphere, heating rate of 10°C/min, cooling rate stemming from high temperature to the room temperature was carried out via natural rate of the furnace. After the calcination of precursor, powders were characterized by scanning electron microscopy, X-ray diffraction, UV-Vis spectroscopy and laser granulometry, so the crystalline phases, microstructure, the colorimetric parameters and the some spectroscopic properties of pigments were determined. Pigment exhibiting the highest color intensity was obtained using higher fraction of electrolytic paste. As a whole, pigments proved to be chemically and thermally resistant at 800°C, when applied in vitreous enamels with industrial composition directed to ceramic plating. Pigments showed excellent dispersion degree in a low-density polyethylene and a homogeneous color. / Embora se tenha descoberto novos sistemas pigmentares, os pigmentos cerâmicos constituem um dos campos da Ciência dos Materiais onde existe um maior desconhecimento, tanto em nível de centros de pesquisa como industrial. A presente pesquisa pretende desenvolver e caracterizar pigmentos cerâmicos, à base de zirconita, com incorporação de pasta eletrolítica de pilhas Zinco-carbono, descarregadas energeticamente, explorando como agente cromóforo o manganês presente na pasta eletrolítica. Paralelamente, foram obtidas e caracterizadas amostras utilizando como dopante MnO2 P.A. Amostras com diferentes proporções em peso de pasta eletrolítica de pilhas foram homogeneizadas a úmido com álcool isopropílico em moinho de bolas por um período de 6 h, e posteriormente secas em estufa à 110oC até peso constante, levadas à calcinação, desagregadas e peneiradas. O tratamento térmico foi realizado em forno à 1150oC com um tempo de patamar de 4h, ao ar, aplicando uma velocidade de aquecimento de 10ºC/min, sendo o resfriamento das amostras a temperatura ambiente. Após o tratamento térmico as amostras foram caracterizadas por microscopia eletrônica de varredura, difração de raios X, UV-Vis e granulometria à laser e as microestruturas, as fases presentes, os parâmetros colorimétricos e as propriedades físicas dos pigmentos foram determinados. Cores mais intensas foram obtidas nas amostras com maior concentração de pasta eletrolítica adicionado. Os pigmentos mostraram ser resistentes química e termicamente à 8000C, quando aplicados em esmalte vítreo em placas cerâmicas. Em polietileno de baixa densidade os pigmentos apresentaram excelente dispersão e homogeneidade de cor.

This work presents information obtained from high-speed video and electrical monitoring of electrical breakdown (discharge) events during plasma electrolytic oxidation (PEO) of aluminium alloy substrates. Discharges were found to occur in extended sequences termed "cascades" at particular locations. This was a feature common to all the substrates and processing frequencies investigated. As the coating thickness increases, the characteristics remained broadly similar, although discharges become more energetic and longer-lived. Short PEO treatments were applied to existing PEO coatings in order to investigate the microstructural effects of discharge cascades. It was found that cascades persist at particular locations due to the residual deep pore channel left by previous discharges in the cascade. Observations were made of the way the coating was restructured around a cascade location. Samples were illuminated with very high intensity flashes during PEO processing, revealing that relatively large (1 mm diameter) bubbles form where a discharge emerges from the surface of a coating. Analysis of the overall energy consumption, as well as the energetic processes occurring within an individual discharge, indicate that the bubble growth occurs due to rapid volatilisation of water originating from the electrolyte. It is postulated that the growth of this bubble causes the electrical resistance to rise and is responsible for the termination of the discharge current. Investigations of high frequency (2,500 Hz) processing lead to the discovery of discharges occurring during the cathodic half-cycle, after a certain coating thickness had been achieved. Cathodic discharges were more energetic than anodic discharges, and created large craters in the coatings. Gas evolution was found to exceed the electrochemical Faraday yield, and was similar at low and high frequency initially. Once cathodic discharges began, the gas evolution rate increased and the coating mass gain levelled off.

Concerns over both environmental issues and about the depletion of fossil fuels have acted as twin driving forces to the development of renewable energy and its integration into existing electricity grids. The variable nature of RE generators assessment affects the ability to balance supply and demand across electricity networks; however, the use of energy storage and demand-side response techniques is expected to help relieve this situation. One possibility in this regard might be the use of water electrolysis to produce hydrogen while producing industrial-scale DSR services. This would be facilitated by the use of tariff structures that incentive the operation of electrolysers as dispatchable loads. This research has been carried out to answer the following question: What is the feasibility of using electrolysers to provide industrial-scale of Demand-side Response for grid balancing while producing hydrogen at a competitive price? The hydrogen thus produced can then be used, and indeed sold, as a clean automotive fuel. To these ends, two common types of electrolyser, alkaline and PEM, are examined in considerable detail. In particular, two cost scenarios for system components are considered, namely those for 2015 and 2030. The coastal city of Darnah in Libya was chosen as the basis for this case study, where renewable energy can be produced via wind turbines and photovoltaics (PVs), and where there are currently six petrol stations serving the city that can be converted to hydrogen refuelling stations (HRSs). In 2015 all scenarios for both PEM and alkaline electrolysers were considered and were found to be able to partly meet the project aims but with high cost of hydrogen due to the high cost of system capital costs, low price of social carbon cost and less government support. However, by 2030 the price of hydrogen price will make it a good option as energy storage and clean fuel for many reasons such as the expected drop in capital cost, improvement in the efficiency of the equipment, and the expectation of high price of social carbon cost. Penetration of hydrogen into the energy sector requires strong governmental support by either establishing or modifying policies and energy laws to increasingly support renewable energy usage. Government support could effectively bring forward the date at which hydrogen becomes techno-economically viable (i.e. sooner than 2030).

Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 1980. / MICROFICHE COPY AVAILABLE IN ARCHIVES AND SCIENCE. / Bibliography: leaves 190-192. / by James Edwin Garmirian. / Ph.D.