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).

Orientadores: Newton Pimenta Neves Jr., Ennio Peres da Silva / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-08-12T18:18:22Z (GMT). No. of bitstreams: 1 GaleanoEspinola_MichelOsvaldo_M.pdf: 4191812 bytes, checksum: e89fbfa6a03129b67376a8ea9d7227e6 (MD5) Previous issue date: 2008 / Resumo: Em muitas usinas hidrelétricas, quando as afluências são maiores que a demanda de energia, uma parcela de água que ainda poderia ser utilizada para gerar eletricidade é desviada para o vertedouro e literalmente desperdiçada. Essa energia, cuja denominação é Energia Vertida Turbinável, poderia ser aproveitada para gerar algum outro produto ou vetor energético que possibilitasse seu armazenamento e posterior utilização, já que nessas ocasiões os reservatórios de água estão cheios. Este trabalho estuda a viabilidade técnica e econômica do aproveitamento da energia vertida turbinável da Usina Hidrelétrica de Itaipu para produção de hidrogênio eletrolítico que, juntamente com o nitrogênio do ar, é matéria-prima essencial para a síntese da amônia, utilizada na produção de fertilizantes nitrogenados. O custo mínimo de produção do hidrogênio eletrolítico foi estimado em US$ 0,246/m3 ou US$ 2,750/kg para uma planta com capacidade de produção de 55.000 m3/h, correspondendo a 247,5 MW de potência, proveniente de 82% de energia vertida turbinável e 18% de energia garantida. Junto a uma planta de hidrogênio eletrolítico com essa capacidade, é possível acoplar uma planta de amônia com produção de aproximadamente 500 t/dia, operando 350 dias/ano, com um custo de produção de aproximadamente US$ 562,81/t. Com esta capacidade é possível atender a 38,5% da demanda de amônia estimada para a região abrangida pelo projeto, de 1.300 t/dia. Atualmente a amônia está cotada no mercado brasileiro em torno de US$ 525,60/t. Portanto, conclui-se que a produção de amônia via associação de energia garantida e vertida turbinável junto à Usina Hidrelétrica de Itaipu não é viável economicamente no momento, o que pode ser acreditado principalmente ao elevado custo dos eletrolisadores importados. No entanto, com a instalação de uma planta de amônia via eletrólise da água junto à Usina Hidrelétrica de Itaipu seriam evitadas as emissões relacionadas ao uso do gás natural e, mesmo considerando as emissões de metano e dióxido de carbono do reservatório da usina haveria um decréscimo nas emissões anuais da ordem de 234 mil toneladas de carbono. Caso o projeto seja aprovado pelo Mecanismo de Desenvolvimento Limpo, essa diminuição do impacto ambiental representaria um montante anual de ¿ 3,8 milhões1, valor próximo a US$ 5,5 milhões ou R$ 9,9 milhões. Embora essa receita melhore o fluxo de caixa do projeto, ainda não seria suficiente para torná-lo viável economicamente em comparação com os processos de produção de amônia que utilizam gás natural a preços vigentes. / Abstract: In many hydroelectric power plants, when the inflows are greater than the demand for energy, a portion of the water that could be used to generate energy is diverted to the spillway and literally wasted. This energy, designated as "Spilled Turbinable Energy", could be used advantageously to generate other products or an energy vector that could be stored for later use, since in these occasions the dam is full. The present work studies the feasibility of using the spilled turbinable energy of the Itaipu Hydroelectric Power Plant to produce electrolytic hydrogen that, together with the nitrogen from air, is an important feedstock for the ammonia synthesis, used to produce nitrogen fertilizers. The minimum production cost of electrolytic hydrogen was estimated in US$ 0,246/m3 or US$ 2,750/kg, for a plant with capacity of 55 mil m3/h, which correspond to 247,5 MW of electrical power deriving from 82% of spilled turbinable energy and 18% of guaranteed energy. Next to that hydrogen plant it is possible to install an ammonia plant of approximately 500 t/day, operating 350 days/year, with a production cost of approximately US$ 562,81/t. This capacity is enough to supply 38,5% of the ammonia demand estimated for the region focused in the project, 1.300 t/day. Nowadays, ammonia is commercialized in the Brazilian market by approximately US$ 525,60/t. For that reason, it can be concluded that ammonia production through the association of spilled turbinable and guaranteed energy next to Itaipu Hydroelectric Power Plant is not economically feasible by the moment, mainly due to the high cost of imported electrolysers. Nevertheless, with the installation of an ammonia plant based on water electrolysis next to Itaipu Hydroelectric Power Plant, it could be avoided an annual carbon emission of 234 thousand tons, even considering methane and carbon dioxide emissions of the Itaipu's reservoir. If such project were approved by the Clean Development Mechanism, that environmental impact decrease would represent an amount of ¿ 3.8 million2, approximately US$ 5.5 million or R$ 9.9 million. Even with that revenue, the project would not be economically feasible yet, mainly because of the low prices of natural gas used as feedstock to produce ammonia nowadays. / Mestrado / Mestre em Planejamento de Sistemas Energéticos

Orientadores: Ennio Peres da Silva, João Carlos Camargo / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecânica / Made available in DSpace on 2018-08-23T20:36:02Z (GMT). No. of bitstreams: 1 GaleanoEspinola_MichelOsvaldo_D.pdf: 2380684 bytes, checksum: 237fb5f4242c156304a4744f7de92a00 (MD5) Previous issue date: 2013 / Resumo: Este trabalho faz, a partir da determinação do mercado paraguaio atual de hidrogênio usado como insumo químico, uma análise técnico-econômica da viabilidade de atender este mercado a partir do hidrogênio eletrolítico produzido com o uso da disponibilidade existente de eletricidade. Para isso, dois modos de operação da planta de produção industrial de hidrogênio eletrolítico, para os quais foi desenvolvido um modelo matemático para o dimensionamento deles, no qual foram consideradas as principais características e eficiências dos equipamentos que compõem as plantas industriais. Segundo os resultados do levantamento do mercado paraguaio atual de hidrogênio, os principais setores consumidores são os de síntese de ureia para uso agrícola e de metanol. A seguir foi realizada uma análise econômica da produção industrial desses produtos a partir de hidrogênio eletrolítico tendo sido verificado que a instalação de uma planta industrial de ureia para uso agrícola de 600 mil t?ano de capacidade visando atender o MERCOSUL oferece viabilidade econômica com TIR = 14%, VPL = US$ 28.691.471 e IL = 1,10 e TIR = 16%, VPL = US$ 31.560.620 e IL = 1,76 para os dois modos de operação da planta de amônia eletrolítica, respectivamente. Porém, a instalação de uma planta industrial de metanol sintético de 66 mil t?ano a partir de hidrogênio eletrolítico para atender os mercados paraguaio e brasileiro não oferece potencial econômico no Paraguai no momento para os dois modos de operação da planta de hidrogênio eletrolítico tendo sido verificado que o projeto tornar-se-á viável se o custo de produção do hidrogênio eletrolítico for US$ 1,50?kg ou a capacidade de produção da planta industrial de metanol for o dobro, ou seja, superior a 132 mil t?ano de metanol verificando-se que acima desse valor o custo de produção do hidrogênio eletrolítico cai consideravelmente correspondendo a um ganho de escala significativo / Abstract: From the evaluation of the current Paraguayan hydrogen market, this work aims to present a technical-economic feasibility analysis to satisfy this market with electrolytic hydrogen produced from available hydroelectricity. First of all, two operation modes of electrolytic hydrogen facility were proposed and a mathematical model was established considering the main features and efficiencies of the equipment that compose the industrial facilities. According to results of current Paraguayan hydrogen market evaluation, the main industrial sectors that consume hydrogen were urea and methanol synthesis. Secondly, an economic analysis of industrial production of those products from electrolytic hydrogen was carried out. The installation of a 600 thousands ton?year urea production facility using electrolytic hydrogen to supply the MERCOSUR market is economically feasible with IROR = 14%, NPV = US$ 28,691,471, PI = 1.10 and IROR = 16%, NPV = US$ 31.560.620, PI = 1.76 for both operation modes of electrolytic ammonia facilities, respectively. Nevertheless, the installation of a 66 thousands ton?year methanol production facility using electrolytic hydrogen to supply Paraguayan and Brazilian markets did not offer economic potential at the moment. To turn that project feasible, electrolytic hydrogen production cost should to be US$ 1.50?kg or methanol production capacity should to be higher than 132 thousands ton?year to decrease electrolytic hydrogen production cost due to economy of scale / Doutorado / Planejamento de Sistemas Energeticos / Doutor em Planejamento de Sistemas Energéticos

Hydrogen energy sector has gained significant attention worldwide but one of the key enabling components for its success would be cheaper and sustainable hydrogen production. Hydrogen could be produced directly from natural gas or coal etc; alternatively it could be produced by electrolysis of water powered by renewable energy sources, nuclear energy or fossil fuel. Wind energy is growing rapidly, which can produce cheap hydrogen. Electrolysers can be employed to control the frequency of the electricity grid while also making fuel as a by-product. This thesis concerns the intricacies of hydrogen production by electrolysers from renewable energy sources. A generalised, input-based mathematical model of the electrolyser has been developed for various subsystems, such as current-voltage, Faraday efficiency, gas production, gas purity, differential pressure, temperature subsystem, parasitic losses, gas losses and efficiencies at various stages of operation. Some empirical equations have been developed and some adjusted parameters have been used in the model. The model has been tested and verified against the experimental measurements. A generic method has been developed for modelling the Faraday efficiency. Model simulations have been carried out to investigate the sensitivity of the results to the value of the capacitance and how this affects the dynamic response of the electrolyser. A new sizing method of the electrolyser has been developed for a stand-alone energy system such as the HARI project. The electrolyser model has also been simulated for maximum and efficient hydrogen production in a directly coupled mode of electrolysers with solar PV arrays without the maximum power point (MPP) tracker, which leads to an interesting finding that "electrolysers should not be operated at MPP". It has also been found that the dynamic and intermittent power supply from renewables can damage the stability of electrolysers and reduce the energy capture. This is especially true for pressurised electrolysers, which are favoured by the industry at present. The in-depth theoretical and practical analysis of several aspects confirms - contrary to industry trends - that "Pressurised electrolysers are less energy efficient, less durable, more costly and not adequately compatible for renewable energy powered operation, especially in the stand-alone energy systems, compared to atmospheric electrolysers".

Submitted by Johnny Rodrigues (johnnyrodrigues@ufcg.edu.br) on 2018-10-18T14:27:42Z No. of bitstreams: 1 FRANCINALDO DE FREITAS PEREIRA - TESE PPGEP 2005..pdf: 5181579 bytes, checksum: 4b0502fc646549fa86f1d070395e206c (MD5) / Made available in DSpace on 2018-10-18T14:27:42Z (GMT). No. of bitstreams: 1 FRANCINALDO DE FREITAS PEREIRA - TESE PPGEP 2005..pdf: 5181579 bytes, checksum: 4b0502fc646549fa86f1d070395e206c (MD5) Previous issue date: 2005-08-26 / Capes / O objetivo deste trabalho é estudar o desempenho de um forno tipo mufla adaptado para utilizar hidrogénio eletrolítico como combustível. O sistema de aquecimento poderá ser aplicado em fornos de produção de tijolos, telhas, materiais cerâmicos, e produtos derivados do trigo. Neste sentido o hidrogénio eletrolítico substituiria os combustíveis de origem orgânica, que são os grandes vetores da poluição atmosférica, o hidrogénio poderá ser produzido usando-se energias renováveis como painéis fotovoltaicos e/ou turbinas eólicas. O hidrogénio foi produzido a partir da eletrolise da água em um reator bipolar usando hidróxido de potássio como eletrólito. O consumo de energia e a produção de hidrogénio foram estimados para diferentes níveis temperaturas de 300°C, 900°C e, 1100°C. / The objective of this work is the study of an oven adapted to use electrolytic hydrogen as fuel. The possible applications are the cooking of clay used in the production of ceramic materiais, bricks and tiles; as well as the production of derived products of the wheat. The electrolytic hydrogen, used as a fuel in replacement of carbonaceous fuels which contribute to the atmospheric pollution, can be produced using renewable energies like photovoltaic solar paneis and/or aeolian turbine power generators. The hydrogen production is done by electrolysis of water which occurs in a bipolar reactor using potassium hydroxide as electrolyte. The energy consumption and the hydrogen production are calculated for different temperatures of 300°C, 900°C and 1100°C range. They are respectively, 0,9 kWh and 0,131 m3, 2,1 kWh and 0,311 m3 and 3,2 kWh and 0,498 m3.

Research on new, environment-friendly, clean and efficient energy sources have contributed immensely to the development of new technologies for the generation and storage of electrical energy. Heterogeneous ‘electrocatalysis’ involves catalysis of redox reactions where the electrode material, termed as ‘electrocatalyst’ reduces the overpotential and maximizes the current for the processes occurring at the electrode/electrolyte interface. Efficient catalysts for hydrogen evolution reaction (HER), oxygen evolution reaction (OER), and oxygen reduction reaction (ORR) are of paramount importance for electrochemical energy generation and storage applications in water splitting, fuel cells and batteries. However, high cost of Pt catalysts that are commonly used for such applications restricts their commercial viability. In addition, there are issues related to poisoning of the surface under certain conditions. One particular case of direct methanol fuel cells involves problems of methanol tolerance as well. Hence, the on-going search in this direction, is to search for alternate catalysts that can match the performance of Pt. There is a quest for the development of stable and durable electrocatalysts/ supports for various electrochemical redox reactions particularly based on energy storage and conversion. The present thesis is structured in exploring the multi-functional aspects of ternary palladium phosphochalcogenides (PdPS and PdPSe) that possess layer-type structure with high crystallinity. They are semiconducting in nature and possess favorable electrochemical, electrical and optical properties. The chalcogenide compounds crystallize in orthorhombic symmetry with an indirect band gap close to 1.5 eV. The current study shows the versatility of ternary phosphochalcogenides in the bulk phase as well as in small sizes. The electrocatalytic activities of the chalcoenides are found to be dramatically improved by increasing the electrical conductivity by way of forming composites with reduced graphene oxide (rGO). The average crystallite size of the PdPS and PdPSe are 30 μm ±10 μm (figure 1). The composites are prepared by simple hydrothermal methods without use of any reducing agent and are characterized using various physico-chemical techniques. Figure 1. FESEM images of (a) PdPSe and (b) PdPS. In the present investigations, PdPS and its reduced graphene oxide composite (rGO-PdPS) are shown to be very efficient hydrogen evolution electrocatalysts (figure 2a). The bulk form of PdPS is found to be very active and the composite of PdPS with reduced graphene oxide improves the hydrogen evolution performance dramatically, even superior to state of the art, MoS2-based catalysts. Figure 2. (a) Linear sweep voltammograms of rGO, bulk PdPS, rGO-PdPS composite and 40 % Pt-C in 0.5 M H2SO4 solution (pH 0.8). Scan rate used is 1 mV s-1. (b) Tafel plots for PdPS, rGO, rGO-PdPS and 40 wt% Pt-C in 0.5 M H2SO4 at 1 mVs-1 scan rate. The Tafel slope and the exchange current density values associated with hydrogen evolution reaction are 46 mV dec-1 and 1.4 x 10-4 A cm-2 respectively (figure 2b). The stability of the PdPS-based catalyst is found to be excellent retaining same current densities even after thousand cycles. Moreover, post-HER characterization reveals the durability of the material even after cycling for a long time. Preliminary spectroelectrochemical investigations are attempted to gain further insight in to the HER. Subsequently, the PdPS and its composite are explored as ORR catalysts in alkaline medium. The composite of PdPS with rGO is formed to enhance the catalytic activity of pure PdPS and the electron transfer kinetics is found to be very favorable. The kinetics of the oxygen reduction reactions are followed by RDE/RRDE measurements. It is experimentally verified that the composite eletrocatalyst is very stable, efficient and methanol tolerant in alkaline medium. The characteristics of the composite catalyst are comparable with widely used standard Pt-C for ORR (figure 3a). Moreover, ternary phophochalcogenide, PdPS, combined with rGO shows good catalytic activity towards OER and it affords a current density of 10 mA cm-2 at an overpotential of η = 570 mV (figure 3b). Figure 3. (a) Comparative voltammograms for rGO, bulk PdPS, rGO-PdPS and 40 % Pt-C in 1M KOH at 1600 rpm. The potential is swept at a rate of 5 mVs-1. (b) Linear sweep voltammograms of oxygen evolution reaction on rGO-PdPS, PdPS and 40 % Pt-C in 1 M KOH electrolyte. Scan rate 5 mV s-1. Apart from its tri-functional electrocatalytic behavior, PdPS and its rGO composite act as an anode material for Li-ion batteries showing high storage capacity of lithium (figure 4). The capacity fading of bulk PdPS is analyzed using XRD and SEM. The introduction of rGO, a well-known conducting matrix, improves the performance. Palladium phosphorous selenide (PdPSe) and its composite with rGO (rGO-PdPSe) are also explored as electrocatalysts for HER, ORR and OER. They show the tri¬functional electrocatalytic behavior as well. Figure 4. Discharge capacity as a function of number of cycles for PdPS, rGO rGO-PdPS electrode at current density of 35 mAg-1 in rechargeable lithium ion battery. The next chapter deals with single or few layer PdPS where layer-type PdPS is exfoliated by several methods such as ultra-sonication and solvent exfoliation. Various microscopic and spectroscopic techniques have been used to characterize the material. These sheets show significantly improved electrocatalytic activity towards ORR and HER with notably low onset potential and low Tafel slopes. The charge storage capacity also increases by an order from its bulk counterpart. The catalyst shows excellent stability for HER and good methanol tolerance behavior towards ORR is also observed. This opens up possibilities for applications of few-layer ternary phosphosulphides in energy conversion and storage. However, one should be cautious since the exfoliation results in a slightly different composition of the material. Different aspects of electrodeposition of gallium nanoparticles on exfoliated graphite surfaces from aqueous acidic solution forms part of the next study. The electrodeposited surface is characterized by various microscopic and spectroscopic techniques. The presence of surface plasmon peak in the visible region has led us to explore the use of Ga on EG for SERS studies. This preliminary work shows that the Raman signal of R6G is enhanced in the presence of Ga deposited on EG surface. The research work presented in the next part of the thesis deals with the preparation, physicochemical, spectroscopic characterization of room temperature molten electrolytes based on amides. Room temperature ternary molten electrolyte involving a combination of acetamide, urea and gallium nitrate salt is prepared and the molten eutectic is characterized. An electrochemical process is developed for depositing gallium nitride from the ternary molten electrolyte on Au electrode. Gallium ion is reduced at low potentials while nitrate ion is reduced to produce atomic nitrogen, forming gallium nitride under certain conditions. Au coated TEM grid is used for patterning gallium nitride (figure 5). The deposited gallium nitride is further annealed at high temperature to increase the crystalinity and improve the stoichiometry of gallium nitride. Figure 5. The FESEM image of patterned gallium nitride deposited on Au coated TEM grid. Elemental mapping of Ga and N from the same region is given. The last chapter explores the prepration and uses of textured GaN tubes synthesized from GaOOH rod-like morphology. The precursor material is prepared by simple hydrothermal technique, maintaining certain value for the pH of the solution. The thermal treatment under ammonia atmosphere leads to highly crystalline, single phase textured tube- like morphology. The as-prepared material is explored as photoanodes in photoelectrochemical water splitting, dye sensitized solar cells and active substrate for SERS. The appendix-I discusses the Na-ion storage capacity by rGO-PdPS composite whereas appendix-II deals with the synthesis of InN and FeN from ternary molten electrolyte. (For figures pl refer the abstract pdf file)