The ‘hydrogen economy’ represents an energy system in which hydrogen and electricity are the dominant energy carriers for use in transportation applications. The ‘hydrogen economy’ minimizes the use of fossil fuels in order to lower the environmental impact of energy use associated with urban air pollution and climate change. An integrated energy system is required to deal with diverse and distributed energy generation technologies such a wind and solar which require energy storage to level energy availability and demand. A distributed ‘energy hub’ is considered a viable concept in envisioning the structure of an integrated energy system. An energy hub is a system which consists of energy input/output, conversion and storage technologies for multiple energy carriers, and would provide an interface between energy producers, consumers, and the transportation infrastructure. Considered in a decentralized network, these hubs would form the nodes of an integrated energy system or network. In this work, a model of a clean energy hub comprising of wind turbines, electrolyzers, hydrogen storage, a commercial building, and a fleet of plug-in fuel cell vehicles (PFCVs) was developed in MATLAB, with electricity and hydrogen used as the energy carriers. This model represents a hypothetical commercial facility which is powered by a renewable energy source and utilizes a zero-emissions fleet of light duty vehicles. The models developed herein capture the energy and cost interactions between the various energy components, and also calculate the CO2 emissions avoided through the implementation of hydrogen economy principles. Wherever possible, similar models were used to inform the development of the clean energy hub model. The purpose of the modelling was to investigate the interactions between a single energy hub and novel components such as a plug-in fuel cell vehicle fleet (PFCV). The final model reports four key results: price of hub electricity, price of hub hydrogen, total annual costs and CO2 emissions avoided. Three scenarios were analysed: minimizing price of hub electricity, minimizing total annual costs, and maximizing the CO2 emissions avoided. Since the clean energy hub could feasibly represent both a facility located within an urban area as well as a remote facility, two separate analyses were also conducted: an on-grid analysis (if the energy hub is close to transmission lines), and an off-grid analysis (representing the remote scenarios). The connection of the energy hub to the broader electricity grid was the most significant factor affecting the results collected. Grid electricity was found to be generally cheaper than electricity produced by wind turbines, and scenarios for minimizing costs heavily favoured the use grid electricity. However, wind turbines were found to avoid CO2 emissions over the use of grid electricity, and scenarios for maximizing emissions avoided heavily favoured wind turbine electricity. In one case, removing the grid connection resulted in the price of electricity from the energy hub increasing from $82/MWh to $300/MWh. The mean travel distance of the fleet was another important factor affecting the cost modelling of the energy hub. The hub’s performance was simulated over a range of mean travel distances (20km to 100km), and the results varied greatly within the range. This is because the mean travel distance directly affects the quantities of electricity and hydrogen consumed by the fleet, a large consumer of energy within the hub. Other factors, such as the output of the wind turbines, or the consumption of the commercial building, are largely fixed. A key sensitivity was discovered within this range; the results were ‘better’ (lower costs and higher emissions avoided) when the mean travel distance exceeded the electric travel range of the fleet. This effect was more noticeable in the on-grid analysis. This sensitivity is due to the underutilization of the hydrogen systems within the hub at lower mean travel distances. It was found that the greater the mean travel distance, the greater the utilization of the electrolyzers and storage tanks lowering the associated per km capital cost of these components. At lower mean travel distances the utilization of the electrolyzers ranged from 25% to 30%, whereas at higher mean travel distances it ranged from 97% to 99%. At higher utilization factors the price of hydrogen is reduced, since the cost recovery is spread over a larger quantity of hydrogen.

Submitted by Johnny Rodrigues (johnnyrodrigues@ufcg.edu.br) on 2018-03-14T21:37:10Z No. of bitstreams: 1 NATÁLIA DE OLIVEIRA SANTIAGO - DISSERTAÇÃO PPGEQ 2015..pdf: 2885726 bytes, checksum: 42752aa08c69c959e3a3f1367b0e8e7a (MD5) / Made available in DSpace on 2018-03-14T21:37:10Z (GMT). No. of bitstreams: 1 NATÁLIA DE OLIVEIRA SANTIAGO - DISSERTAÇÃO PPGEQ 2015..pdf: 2885726 bytes, checksum: 42752aa08c69c959e3a3f1367b0e8e7a (MD5) Previous issue date: 2015 / Capes / O uso desenfreado de combustíveis fósseis tem causado problemas climáticos graves em todo o planeta, tais como o aquecimento global e a poluição do ar. Além de seus efeitos negativos perante a natureza, estes acarretam custos cada vez maiores de energia, devido à disponibilidade cada vez menor de reservas de petróleo, de produção e de fornecimento. Nesse contexto o hidrogênio vem a ser um vetor energético, devido a principalmente à sua alta eficiência de conversão, reciclagem e natureza não-poluente. É um combustível que não se encontra na natureza, mas ele pode ser facilmente produzido. Este trabalho apresenta a produção do hidrogênio através da eletrólise da água em meio alcalino (hidróxido de potássio, KOH) num reator de tipo bipolar usando eletrodos de espuma de níquel. A avaliação do reator eletrolítico, constituído de uma célula unitária, foi realizada pelo método estatístico de superfície de resposta visando a otimização dos experimentos através de dois planejamentos com duas variáveis dependentes: a tensão aplicada e a concentração em porcentagem de massa do KOH. A resposta é dada na forma de fluxo de hidrogênio (L/h) com o intuito de analisar o comportamento do reator em diferentes situações. A partir dos parâmetros analisados, foi encontrado o ponto ótimo de funcionamento do reator, obtido com uma concentração de 16,6% em massa de KOH e uma tensão aplicada de 2,6 V, produzindo 0,841 L/h de H2, valor máximo obtido para ambos planejamentos. / The society development is associated to the increasing use of fossil fuels, creating serious climatic problems such as global warning and air pollution. The ecological disasters, like floods and droughts, are a consequence of the increasing release of CO2 and other greenhouse gases. Besides these environmental problems, the costs relied to the extraction, production and supply of oil, are increasing due to its availability. Changes are necessary to control this situation and a way out is the use of another fuel in order to guarantee sustainability. This fuel of the future can be hydrogen, mainly due to its high conversion efficiency, recycling and non-polluting nature. It is particularly attractive as a promising substitute of the fossil fuels. This work presents the production of hydrogen by alkaline water electrolysis (potassium hydroxide, KOH) using nickel foam based electrodes. The evaluation of the electrolytic reactor, consisting of a unit cell, was performed by the statistical method of response surface experiments through two plans with two dependent variables: applied tension and KOH concentration. The response is the hydrogen flow (L/h) in order to analyze the reactor behavior in different situations. The optimum point of the reactor operation for both schedules was obtained with a concentration of 16,6% KOH and an applied voltage of 2.6 V, producing 0,841 L/h of H2.

In this thesis different materials have been developed to use them in electrochemical cells. The electrochemical cells studied can be divided into two material big groups: solids oxides and acid salts materials. In the first group, materials to use them in electrodes for fuel cells an electrolyzer based on oxygen ion conductor electrolytes were optimized. Pertaining to this group, the influence of doping the Ba0.5Sr0.5Co0.8Fe0.2O3-d perovskite with 3% of Y, Zr and Sc in B position (ABO3-d) was checked. That optimization could reduce the polarization resistance of electrodes and improve the stability with time. Additionally, the limiting mechanisms in the oxygen reduction reaction were determined, and the influence of CO2 containing atmospheres was checked. La2NiO4+d;, pertaining to the Ruddlesden-Popper serie, is a mixed conductor of electron and oxygen ions. This compound was doped in La position (with Nd and Pr) and in Ni position (with Co). The dopants introduced were able to produce structural change and improve the cell performance, reducing in more than one order of magnitude the La1.5Pr0.5Ni0.8Co0.2O4+d; polarization resistance respect to the reference material (La2NiO4+d). In addition, the properties of an electrode based on the pure electronic conductor, La0.8Sr0.2MnO3-d; (LSM), were optimized. The triple phase boundary was enlarged by the addition of a second phase with ionic conductivity. That strategy made possible to reduce the electrode polarization resistance. In order to improve the oxygen reduction reaction, the addition of different catalysts by infiltration was studied. The different infiltrated oxides changed the electrochemistry properties, being the praseodymium oxide the catalyst which made possible a reduction in two orders of magnitude the electrode polarization resistance respects to the composite without infiltration. Furthermore, the efficiency of the cell working in fuel cell and electrolyzer mode was improved. Concerning the materials selected to use as electrodes on proton conductor electrolytes, the efficiency of electrodes based on LSM was optimized by using a second phase with protonic conductivity (La5.5WO12-d) and varying the sintering temperature of the electrode. Finally, the catalytic activity of the cell was boosted by infiltrating samaria doped ceria nanoparticles, achieving higher power densities for the fuel cell. The materials pertaining to the Ruddlesden-Popper series and studied for ionic conductor electrolytes were also used for cathodes in proton conductor fuel cells. After checking the compatibility with the electrolyte material, the influence of different electrode sintering temperatures and air containing atmospheres (dry, H2O y D2O) on the cathode performance was studied. Finally, the electrochemical cells based on acid salts (CsH2PO4) were designed and optimized. In that way, different cell configurations were studied, enabling to obtain thin and dense electrolytes and active electrodes for the hydrogen reduction/oxidation reactions. The thickness of the electrolyte was reduced by using steel and nickel porous supports. Furthermore, an epoxy resin type was added to the electrolyte material to enhance the mechanical properties. The electrodes configuration was modified from pure electronic conductors to composite electrodes. Moreover, copper was selected as an alternative of the expensive platinum working at high operation pressures. The cells developed were able to work with high pressures and with high content of water steam in fuel cell and electrolyzer modes. / En la presente tesis doctoral se han desarrollado materiales para su uso en celdas electroquímicas. Las celdas electroquímicas estudiadas, se podrían separar en dos grandes grupos: materiales de óxido sólido y sales ácidas. En el primer grupo, se optimizaron materiales para su uso como electrodos en pilas de combustible y electrolizadores, basados en electrolitos con conducción puramente iónica. Dentro de este grupo, se comprobó la influencia de dopar la perovskita Ba0.5Sr0.5Co0.8Fe0.2O3-d, con un 3% de Y, Zr y Sc en la posición B (ABO3-d). Esta optimización llevó a la reducción de la resistencia de polarización así como a una mejora de la estabilidad con el tiempo. Así mismo, se determinaron los mecanismos limitantes en la reacción de reducción de oxígeno, y se comprobó la influencia de la presencia de CO2 en condiciones de operación. El La2NiO4+d perteneciente a la serie de Ruddlesden-Popper, es un conductor mixto de iones oxígeno y electrones. Éste, fue dopado tanto en la posición del La (con Nd y Pr) como en la posición del Ni (con Co). Los dopantes introducidos además de producir cambios estructurales, provocaron mejoras en el rendimiento de la celda, reduciendo para alguno de ellos, como el La1.5Pr0.5Ni0.8Co0.2O4+d, en casi un orden de magnitud la resistencia de polarización del electrodo de referencia (La2NiO4+d). De la misma manera, se optimizaron las propiedades del electrodo basado en el conductor electrónico puro La0.8Sr0.2MnO3-d (LSM). La adición de una segunda fase, con conductividad iónica, permitió aumentar los puntos triples (TPB) en los que la reacción de reducción de oxígeno tiene lugar y reducir la resistencia de polarización. Con el fin de mejorar la reacción de reducción de oxígeno, se estudió la adición de nanocatalizadores mediante la técnica de infiltración. Los diferentes óxidos infiltrados produjeron el cambio de las propiedades electroquímicas del electrodo, siendo el óxido de praseodimio el catalizador que consiguió disminuir en dos órdenes de magnitud la resistencia de polarización del composite no infiltrado. De la misma manera, la mejora de la eficiencia del electrodo infiltrado con Pr, mejoró los resultados de la celda electroquímica trabajando como pila (mayores densidades de potencia) y como electrolizador (menores voltajes). En lo que respecta a los materiales seleccionados para su uso como electrodos en electrolitos con conductividad protónica, se optimizó la eficiencia del cátodo basado en LSM, mediante el uso de una segunda fase conductora protónica (La5.5WO12-d) y variando la temperatura de sinterización del electrodo. Finalmente, se mejoró la actividad catalítica mediante la infiltración de nanopartículas de ceria dopada con samario, produciendo mayores densidades de corriente de la pila de combustible. Los materiales pertenecientes a la serie de Ruddlesden-Popper y usados para cátodos en pilas iónicas, fueron empleados también para cátodos en pilas protónicas. Después de comprobar que el material electrolítico (LWO) era compatible con los compuestos de la serie de Ruddlesden-Popper, se estudió la influencia de la temperatura de sinterización de los electrodos en el rendimiento, así como de la composición de la atmosfera de aire (seca, H2O y D2O). Finalmente, se diseñó y optimizó las celdas electroquímicas basadas en sales ácidas (CsH2PO4). En este sentido, se estudiaron diferentes configuraciones de celda, que permitieran obtener un electrolito denso con el menor espesor posible y unos electrodos activos a la reacción de reducción/oxidación de hidrógeno. Se consiguió reducir el espesor del electrolito soportando la celda en discos de acero y níquel porosos. Se añadió una resina tipo epoxi al material electrolítico para aumentar sus propiedades mecánicas. De la misma manera, se cambió la configuración de los electrodos pasando por conductores electrónicos puros a electrodos compuestos por conductores / En la present tesis doctoral es van desenvolupar materials per al seu ús en cel·les electroquímiques. Les cel·les electroquímiques estudiades poden ser dividides en dos grans grups: materials d'òxid sòlid i sals àcides. En el primer grup, es van optimitzar materials per al seu ús com a elèctrodes en piles de combustible i electrolitzadors, basats en electròlits amb conducció purament iònica. Dins d'este grup, es va comprovar la influència de dopar la perovskita Ba0.5Sr0.5Co0.8Fe0.2O3-d amb un 3% de Y, Zr i Sc en la posició B (ABO3-d;). Esta optimització va portar a la reducció de la resistència de polarització així com a una millora de l'estabilitat amb el temps. Així mateix, es van determinar els mecanismes limitants en la reacció de reducció d'oxigen, i es va comprovar la influència de la presència de CO2 en condicions d'operació. El La2NiO4+d pertanyent a la sèrie de Ruddlesden-Popper, és un conductor mixt d'ions oxigen i electrons. Este, va ser dopat tant en la posició del La (amb Nd i Pr) com en la posició del Ni (amb Co). Els dopants introduïts a més de produir canvis estructurals, van provocar millores en el rendiment de la cel·la, reduint per a algun d'ells, com el La1.5Pr0.5Ni0.8Co0.2O4+d, en quasi un ordre de magnitud la resistència de polarització de l'elèctrode de referència (La2NiO4+d). De la mateixa manera, es van optimitzar les propietats de l'elèctrode basat en el conductor electrònic pur La0.8Sr0.2MnO3-d (LSM). L'addició d'una segona fase, amb conductivitat iònica, va permetre augmentar els punts triples (TPB), en els que la reacció de reducció d'oxigen té lloc, i reduir la resistència de polarització. A fi de millorar la reacció de reducció d'oxigen, es va estudiar l'adició de nanocatalitzadors per mitjà de la tècnica d'infiltració. Els diferents òxids infiltrats van produir el canvi de les propietats electroquímiques de l'elèctrode, sent l'òxid de praseodimi el catalitzador que va aconseguir disminuir en dos ordres de magnitud la resistència de polarització del composite no infiltrat. De la mateixa manera, la millora de l'eficiència de l'elèctrode infiltrat amb Pr, va millorar els resultats de la cel·la electroquímica treballant com a pila (majors densitats de potència) i com a electrolitzador (menors voltatges). Pel que fa als materials seleccionats per al seu ús com a elèctrodes en electròlits amb conductivitat protònica, es va optimitzar l'eficiència del càtode basat en LSM, per mitjà de l'ús d'una segona fase conductora protònica (La5.5WO12-d;) i variant la temperatura de sinterització de l'elèctrode. Finalment, es va millorar l'activitat catalítica mitjançant la infiltració de nanopartícules de ceria dopada amb samari, produint majors densitats de corrent de la pila de combustible. Els materials pertanyents a la sèrie de Ruddlesden-Popper i usats per a càtodes en piles iòniques, van ser empleats també per a càtodes en piles protòniques. Després de comprovar que el material electrolític (LWO) era compatible amb els compostos de la sèrie de Ruddlesden-Popper, es va estudiar la influència de la temperatura de sinterització dels elèctrodes en el rendiment, així com de la composició de l'atmosfera d'aire (seca, H2O i D2O). Finalment, es van dissenyar i optimitzar les cel·les electroquímiques basades en sals àcides (CsH2PO4). En este sentit, es van estudiar diferents configuracions de cel·la, que permeteren obtindre un electròlit dens amb el menor espessor possible i uns elèctrodes actius a la reacció de reducció/oxidació d'hidrogen. Es va aconseguir reduir l'espessor de l'electròlit suportant la cel·la en discos d'acer i níquel porosos. Es va afegir una resina tipus epoxi al material electrolític per a augmentar les seues propietats mecàniques. De la mateixa manera, es va canviar la configuració dels elèctrodes passant per conductors electrònics purs a elèctrodes compostos per conductors protònics / Navarrete Algaba, L. (2017). New electrochemical cells for energy conversion and storage [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/78458 / TESIS

Hydrogen gas (H2), that is not produced from fossil oil or natural gas, is expected to become a cornerstone in the energy transition strategy in Europe. The recent years, technological and economic advances in the electrolyzer area, along with political and corporate support, have put H2 at the forefront of many countries’ climate change agenda. Consequently, green H2 is poised to play a large role in the coming energy transition to combat climate change. The possible advantages of integrating H2 production with a combined heat and power plant, or CHP, is investigated in this study. More precisely, the water electrolysis is carried out based on the purified flue gas condensate water and excess heat is recovered as district heating. A comparison of today’s three most common electrolyzer technologies was made, where Proton Exchange Membrane, or PEM, technology was chosen for this project, mainly for its high purity of H2 gas, robust construction, and the ability to run it as a fuel cell. Based on a mass and energy balance, a model including the integration of a PEM with a generic CHP plant was developed. The model was made modifiable, making it possible to change governing parameters, to be able to investigate different possible scenarios. Production flows, losses and other relevant data was calculated from the model. Operational data for the PEM electrolyzer were collected from several manufacturers where a mean value of the data was used as a base-case for the calculations. Based on literature and consulting experts, several assumptions were made, for example the selling price of H2 and the price for electricity. From the base-case were two cases made: a linear and non-linear case. The linear case uses the same input data each year for 20 years, while the non-linear case uses a changing input data each year for 20 years. Calculations were based on an electrolyzer size of 1,4 MW, where auxiliary equipment consumed additional 0,04 MW, resulting in a total energy consumption of 1,44 MW. An operational temperature of 80°C was assumed along with an operational pressure of 5 and 30 bar for the anode and cathode respectively. This resulted in an H2 production flow of 26 kg/h, a process water requirement of 0,2 m3/h, and a possible heat recovery amount of 0,34 MWh with a relevant temperature for the use in district heating. The study shows that the condensate-water at E.ON could provide for ~4000 hours of operation in the wintertime. To enable full operation all year around, a purchase of tap water would be necessary. The economical calculations resulted in an H2 production cost of 53 SEK/kg for the linear case and 58 SEK/kg for the non-linear case. The linear case showed a positive internal rate of return, or IRR, of 1,7%, while the non-linear case resulted in IRR < -25%. A sensitive analysis was made to examine governing parameters. The results of the sensitivity analysis showed that the largest driving variables, that significantly affect the IRR, are the price for electricity and the selling price for H2. The largest OPEX cost was found to be the price of electricity. The results showed that it is feasible to produce H2 at E.ON Örebro in a resource efficient way under certain circumstances, correlated to the electricity and H2 market. With a low electricity price and a selling price of ~50 SEK/kg for H2, good profitability is expected.  It is also clear that future work should focus the areas of O2 usage, infrastructure, and market investigation for a more definitive conclusion.

The need for energy and fuels is predicted to grow within the next decades, in parallel to the need of decreasing the emissions to air and water to operate within the planetary boundaries. The alternatives to consider as energy or fuel options need to be environmentally friendly, evaluated over the whole life cycle. Hydrogen is one of the considered alternatives because it contains no carbon and has a good environmental performance when produced from renewable sources. It can be produced by a variety of methods, where electrolyzers have a good potential environmental impact if powered by renewable energy. Electrolyzers cleave water into hydrogen and oxygen, by using electricity and water. There are currently four technologies on the market or under development but there is a lack of LCA-studies that compare these. This study is an attributional LCA-study, evaluating the potential environmental performance of two electrolyzers: PEMEC and SOEC. The result from this study is thereafter compared to a parallel study of one other electrolyzer: Alkaline. The LCA study considers six impact categories: Abiotic Depletion (element), Abiotic Depletion (fossil), Acidification Potential, Eutrophication Potential, Global Warming Potential and Photochemical Ozone Creation Potential. The system boundary is set as cradle to gate. The electricity source for hydrogen production is evaluated in a sensitivity analysis, together with a scenario of future estimated developments. The electricity during hydrogen production has the highest impact of the life cycle for PEMEC and SOEC, where the energy source has a great impact on the result. PEMEC has the lowest potential environmental impact, in comparison to Alkaline and SOEC, which comes from low energy consumption and low weight of materials with high environmental impact. / Energi- och bränslebehovet förväntas öka inom de närmsta decennierna, samtidigt som utsläpp till luft och vatten måste minska för att nå uppsatta klimatmål. De alternativ som tas fram behöver vara miljövänliga, med bra klimatresultat sett över hela livscykeln. Vätgas är ett alternativ som övervägs, på grund av högt energiinnehåll och låga utsläpp till följd av att den är fri från kol. Vätgas kan produceras med en mängd metoder, där genom elektrolys anses vara en av de bästa teknikerna ur miljösynpunkt. En elektrolysör producerar vät- och syrgas genom att sönderdela vatten med hjälp av elektricitet. Det finns fyra elektrolys-varianter på marknaden och under utveckling, men det saknas LCA-studier där dessa jämförs mot varandra. Denna studie är en bokförings LCA av två elektrolyser: PEMEC och SOEC, som jämförs med resultatet från en parallell studie av en annan elektrolys-typ: Alkalisk. Potentiell miljöpåverkan mättes i sex stycken kategorier: resursutarmning (fossila resurser och ämnen), försurning, övergödning, global uppvärmning och fotokemiskt marknära ozon. Systemgränsen är satt från råmaterialutvinning till vätgasproduktion. Valet av elektricitetskälla för vätgasproduktion utvärderas i en känslighetsanalys, tillsammans med påverkan av framtida teknikers konstruktion. Livscykelfasen ”produktion av vätgas” har övervägande högst påverkan över livscykeln för SOEC och PEMEC, där elektriciteten är den bidragande faktorn. Elektrolysmodellen PEMEC har uppskattningsvis lägst miljömässig påverkan över livscykeln. Den låga påverkan för PEMEC kan härledas till låg elektricitetsförbrukning under vätgasproduktionen samt låga vikter av material med hög miljömässig påverkan.

No description available.

Un outil de diagnostic in situ pour l'étude des électrolyseurs à oxyde solide, fondé sur la spectroscopie d'impédance électrochimique, a été mis en place à travers une analyse systématique de l'influence de plusieurs paramètres (densité de courant, température, composition et débit des gaz) sur les performances et le comportement d'une monocellule commerciale dans une configuration à 2 électrodes. Les principaux phénomènes régissant le fonctionnement de la cellule ont été identifiés. Une analyse de son comportement après apparition et évolution dans le temps d'une dégradation prématurée, suite à une modification sur le banc d'essai, a été réalisée. Un mécanisme expliquant l'origine et les conséquences de cette dégradation prématurée a été proposé. Une étude sur l'influence de l'épaisseur d'une des deux électrodes de la cellule a par ailleurs permis de distinguer deux des phénomènes principaux liés à la diffusion de H2O à l'électrode Ni-YSZ. Enfin, l'étude du comportement de la cellule après dégradation par conduction électronique de l'électrolyte YSZ a mis en évidence la formation de porosités entrainant notamment des délaminations à l'interface YSZ/YDC. Un état de dégradation plus avancé que pour les tests précédents a été observé pour les couches YDC et Ni-YSZ. Ce phénomène se manifeste par un déplacement en fréquence de l'ensemble du diagramme d'impédance mesuré vers les plus basses fréquences, formant une boucle négative. Rp finit par disparaitre, le courant circulant alors majoritairement via la conduction électronique de l'électrolyte YSZ. / An in situ diagnosis tool, based on electrochemical impedance spectroscopy, for the study of solid oxide electrolyzer cells was established through the analysis of the influence of several parameters (current density, temperature, gas composition and gas flow rate) on the performances and the behavior of a commercial single cell studied in a two-electrode configuration. The main phenomena governing the cell were identified. An analysis of its behavior after appearance and evolution with time of a premature degradation was carried out. A mechanism explaining the origin and the consequences of such degradation was suggested. Furthermore, studying the influence of the cathode thickness allowed distinguishing two of the main phenomena associated to H2O diffusion at the Ni-YSZ electrode. In addition, a study of the cell behavior after degradation by electronic conduction of the YSZ electrolyte showed formation of numerous porosities leading to delaminations at the YSZ/YDC interface. This phenomenon was characterized by a shift of the overall impedance diagram to the lowest frequencies, with appearance of a negative loop which finally leads to the disappearance of Rp as the current circulates mostly via electronic conduction of the YSZ electrolyte.

<p>In this study novel composite electrodes were developed, in which the catalytic components were deposited in nanoparticulate form. The efficiency of the nanophase catalysts and membrane electrodes were tested in an important electrocatalytic process, namely hydrogen production by water electrolysis, for renewable energy systems. The activity of electrocatalytic nanostructured electrodes for hydrogen production by water electrolysis were compared with that of more conventional electrodes. Development of the methodology of preparing nanophase materials in a rapid, efficient and simple manner was investigated for potential application at industrial scale. Comparisons with industry standards were performed and electrodes with incorporated nanophases were characterized and evaluated for activity and durability.</p>

Transportation is one of the sectors that directly touches the major challenges that energy utilities are faced with, namely, the significant increase in energy demand and environmental issues. In view of these concerns and the problems with the supply of oil, the pursuit of alternative fuels for meeting the future energy demand of the transport sector has gained much attention. The future of transportation is believed to be based on electric drives in fuel cell vehicles (FCVs) or plug-in electric vehicles (PEVs). There are compelling reasons for this to happen: the efficiency of electric drive is at least three times greater than that of combustion processes and these vehicles produce almost zero emissions, which can help relieve many environmental concerns. The future of PEVs is even more promising because of the availability of electricity infrastructure. Furthermore, governments around the world are showing interest in this technology by investing billions of dollars in battery technology and supportive incentive programs for the customers to buy these vehicles. In view of all these considerations, power systems specialists must be prepared for the possible impacts of these new types of loads on the system and plan for the optimal transition to these new types of vehicles by considering the electricity grid constraints. Electricity infrastructure is designed to meet the highest expected demand, which only occurs a few hundred hours per year. For the remaining time, in particular during off-peak hours, the system is underutilized and could generate and deliver a substantial amount of energy to other sectors such as transport by generating hydrogen for FCVs or charging the batteries in PEVs. This thesis investigates the technical and economic feasibility of improving the utilization of electricity system during off-peak hours through alternative-fuel vehicles (AFVs) and develops optimization planning models for the transition to these types of vehicles. These planning models are based on decomposing the region under study into different zones, where the main power generation and electricity load centers are located, and considering the major transmission corridors among them. An emission cost model of generation is first developed to account for the environmental impacts of the extra load on the electricity grid due to the introduction of AFVs. This is followed by developing a hydrogen transportation model and, consequently, a comprehensive optimization model for transition to FCVs in the context of an integrated electricity and hydrogen system. This model can determine the optimal size of the hydrogen production plants to be developed in different zones in each year, optimal hydrogen transportation routes and ultimately bring about hydrogen economy penetration. This model is also extended to account for optimal transition to plug-in hybrid electric vehicles (PHEVs). Different aspects of the proposed transition models are discussed on a developed 3-zone test system. The practical application of the proposed models is demonstrated by applying them to Ontario, Canada, with the purpose of finding the maximum potential penetrations of AFVs into Ontario’s transport sector by 2025, without jeopardizing the reliability of the grid or developing new infrastructure. Applying the models to this real-case problem requires the development of models for Ontario’s transmission network, generation capacity and base-load demand during the planning study. Thus, a zone-based model for Ontario’s transmission network is developed relying on major 500 and 230 kV transmission corridors. Also, based on Ontario’s Integrated Power System Plan (IPSP) and a variety of information provided by the Ontario Power Authority (OPA) and Ontario’s Independent Electricity System Operator (IESO), a zonal pattern of base-load generation capacity is proposed. The optimization models developed in this study involve many parameters that must be estimated; however, estimation errors may substantially influence the optimal solution. In order to resolve this problem, this thesis proposes the application of robust optimization for planning the transition to AFVs. Thus, a comprehensive sensitivity analysis using Monte Carlo simulation is performed to find the impact of estimation errors in the parameters of the planning models; the results of this study reveals the most influential parameters on the optimal solution. Having a knowledge of the most affecting parameters, a new robust optimization approach is applied to develop robust counterpart problems for planning models. These models address the shortcoming of the classical robust optimization approach where robustness is ensured at the cost of significantly losing optimality. The results of the robust models demonstrate that with a reasonable trade-off between optimality and conservatism, at least 170,000 FCVs and 900,000 PHEVs with 30 km all-electric range (AER) can be supported by Ontario’s grid by 2025 without any additional grid investments.

Transportation is one of the sectors that directly touches the major challenges that energy utilities are faced with, namely, the significant increase in energy demand and environmental issues. In view of these concerns and the problems with the supply of oil, the pursuit of alternative fuels for meeting the future energy demand of the transport sector has gained much attention. The future of transportation is believed to be based on electric drives in fuel cell vehicles (FCVs) or plug-in electric vehicles (PEVs). There are compelling reasons for this to happen: the efficiency of electric drive is at least three times greater than that of combustion processes and these vehicles produce almost zero emissions, which can help relieve many environmental concerns. The future of PEVs is even more promising because of the availability of electricity infrastructure. Furthermore, governments around the world are showing interest in this technology by investing billions of dollars in battery technology and supportive incentive programs for the customers to buy these vehicles. In view of all these considerations, power systems specialists must be prepared for the possible impacts of these new types of loads on the system and plan for the optimal transition to these new types of vehicles by considering the electricity grid constraints. Electricity infrastructure is designed to meet the highest expected demand, which only occurs a few hundred hours per year. For the remaining time, in particular during off-peak hours, the system is underutilized and could generate and deliver a substantial amount of energy to other sectors such as transport by generating hydrogen for FCVs or charging the batteries in PEVs. This thesis investigates the technical and economic feasibility of improving the utilization of electricity system during off-peak hours through alternative-fuel vehicles (AFVs) and develops optimization planning models for the transition to these types of vehicles. These planning models are based on decomposing the region under study into different zones, where the main power generation and electricity load centers are located, and considering the major transmission corridors among them. An emission cost model of generation is first developed to account for the environmental impacts of the extra load on the electricity grid due to the introduction of AFVs. This is followed by developing a hydrogen transportation model and, consequently, a comprehensive optimization model for transition to FCVs in the context of an integrated electricity and hydrogen system. This model can determine the optimal size of the hydrogen production plants to be developed in different zones in each year, optimal hydrogen transportation routes and ultimately bring about hydrogen economy penetration. This model is also extended to account for optimal transition to plug-in hybrid electric vehicles (PHEVs). Different aspects of the proposed transition models are discussed on a developed 3-zone test system. The practical application of the proposed models is demonstrated by applying them to Ontario, Canada, with the purpose of finding the maximum potential penetrations of AFVs into Ontario’s transport sector by 2025, without jeopardizing the reliability of the grid or developing new infrastructure. Applying the models to this real-case problem requires the development of models for Ontario’s transmission network, generation capacity and base-load demand during the planning study. Thus, a zone-based model for Ontario’s transmission network is developed relying on major 500 and 230 kV transmission corridors. Also, based on Ontario’s Integrated Power System Plan (IPSP) and a variety of information provided by the Ontario Power Authority (OPA) and Ontario’s Independent Electricity System Operator (IESO), a zonal pattern of base-load generation capacity is proposed. The optimization models developed in this study involve many parameters that must be estimated; however, estimation errors may substantially influence the optimal solution. In order to resolve this problem, this thesis proposes the application of robust optimization for planning the transition to AFVs. Thus, a comprehensive sensitivity analysis using Monte Carlo simulation is performed to find the impact of estimation errors in the parameters of the planning models; the results of this study reveals the most influential parameters on the optimal solution. Having a knowledge of the most affecting parameters, a new robust optimization approach is applied to develop robust counterpart problems for planning models. These models address the shortcoming of the classical robust optimization approach where robustness is ensured at the cost of significantly losing optimality. The results of the robust models demonstrate that with a reasonable trade-off between optimality and conservatism, at least 170,000 FCVs and 900,000 PHEVs with 30 km all-electric range (AER) can be supported by Ontario’s grid by 2025 without any additional grid investments.