Sistema de comunicaciones para una planta fotovoltaica

Las plantas solares fotovoltaicas, que son cada vez más habituales en nuestra sociedad, necesitan contar con un sistema de comunicaciones que permita la monitorización continua del funcionamiento de los diferentes equipos así como el control remoto de los mismos y la regulación de la producción. En este Proyecto se ha estudiado la estructura eléctrica y constructiva de una planta fotovoltaica genérica, prestando especial atención a los requerimientos que debe reunir el sistema de comunicaciones. El diseño del sistema de comunicaciones se ha realizado sobre una planta solar ficticia aún sin construir analizando su estructura sobre plano y aproximando la topología de red que se necesita implementar. Partiendo de esta estructura y de las cualidades de este tipo de instalaciones se ha realizado un análisis de las tecnologías disponibles, optando por una solución inalámbrica mixta, utilizando enlaces WiMAX y WiFi, manteniendo tecnología cableada únicamente para interconexión cercana de equipos. Esta elección se ha realizado con la intención de dotar a la planta de un sistema fiable, robusto y flexible sin descuidar el factor económico; para eso se ha cuidado la selección de equipamiento, su disposición en la planta y su configuración básica de funcionamiento. A partir de la solución definitiva se ha obtenido un presupuesto económico de la instalación. Se ha completado el diseño mediante simulaciones radioeléctricas, para asegurar un correcto funcionamiento de los diferentes enlaces. The photovoltaic solar power plants, which are becoming more common in our society, need a communications system that allowing continuous monitoring of the operation of the different devices as well as their remote control and regulation of the production. In this Project, electrical structure and construction of a generic photovoltaic solar plant have been studied, paying special attention to the essential requirements which must be fulfilled by the communication system. The communication system design is was carried out assuming that photovoltaic solar plant is fictitious and before its construction, analysing its structure over site plan and approximating the net topology in order to implement it. The analysis of the available technologies was performed basing on this structure as well as the qualities of this kind of facilities. As a result, a wireless mix option with WIMAX and WiFi links was chosen, using cable technology only to the close interconnection between equipments. This choice was made with the intention of giving the plant with a reliable, robust and flexible system without neglecting the economic factor, so that, the selection of equipment, the layout at the plant and operating basic configuration have been paid great attention. From the final solution is obtained a financial budget of the facility. Design is completed by radioelectric simulations to ensure the operation of the several links properly.

Magnetic self-field effects on current collection by an ionospheric bare tether

It was recently suggested that the magnetic field created by the current of a bare tether strongly reduces its own electron-collection capability when a magnetic separatrix disconnecting ambient magnetized plasma from tether extends beyond its electric sheath. It is here shown that current reduction by the self-field depends on the ratio meterizing bias and current profiles along the tether (Lt tether length, characteristic length gauging ohmic effects) and on a new dimensionless number Ks involving ambient and tether parameters. Current reduction is weaker the lower Ks and L*/ Lt, which depend critically on the type of cross section: Ks varies as R5/3, h2/3R, and h2/3 1/4 width for wires, round tethers conductive only in a thin layer, and thin tapes, respectively; L* varies as R2/3 for wires and as h2/3 for tapes and round tethers conductive in a layer (R radius, h thickness). Self-field effects are fully negligible for the last two types of cross sections whatever the mode of operation. In practical efficient tether systems having L*/Lt low, maximum current reduction in case of wires is again negligible for power generation; for deorbiting, reduction is <1% for a 10 km tether and 15% for a 20 km tether. In the reboost mode there are no effects for Ks below some threshold; moderate effects may occur in practical but heavy reboost-wire systems that need no dedicated solar power.

Steady-state thermal analysis of an innovative receiver for linear Fresnel reflectors

The study of the performance of an innovative receiver for linear Fresnel reflectors is carried out in this paper, and the results are analyzed with a physics perspective of the process. The receiver consists of a bundle of tubes parallel to the mirror arrays, resulting on a smaller cross section for the same receiver width as the number of tubes increases, due to the diminution of their diameter. This implies higher heat carrier fluid speeds, and thus, a more effective heat transfer process, although it conveys higher pumping power as well. Mass flow is optimized for different tubes diameters, different impinging radiation intensities and different fluid inlet temperatures. It is found that the best receiver design, namely the tubes diameter that maximizes the exergetic efficiency for given working conditions, is similar for the cases studied. There is a range of tubes diameters that imply similar efficiencies, which can drive to capital cost reduction thanks to the flexibility of design. In addition, the length of the receiver is also optimized, and it is observed that the optimal length is similar for the working conditions considered. As a result of this study, it is found that this innovative receiver provides an optimum design for the whole day, even though impinging radiation intensity varies notably. Thermal features of this type of receiver could be the base of a new generation of concentrated solar power plants with a great potential for cost reduction, because of the simplicity of the system and the lower weigh of the components, plus the flexibility of using the receiver tubes for different streams of the heat carrier fluid.

SolarPaces 2013: Innovations on direct steam generation in linear fresnel collectors

Direct Steam Generation (DSG) in Linear Fresnel (LF) solar collectors is being consolidated as a feasible technology for Concentrating Solar Power (CSP) plants. The competitiveness of this technology relies on the following main features: water as heat transfer fluid (HTF) in Solar Field (SF), obtaining high superheated steam temperatures and pressures at turbine inlet (500ºC and 90 bar), no heat tracing required to avoid HTF freezing, no HTF degradation, no environmental impacts, any heat exchanger between SF and Balance Of Plant (BOP), and low cost installation and maintenance. Regarding to LF solar collectors, were recently developed as an alternative to Parabolic Trough Collector (PTC) technology. The main advantages of LF are: the reduced collector manufacturing cost and maintenance, linear mirrors shapes versus parabolic mirror, fixed receiver pipes (no ball joints reducing leaking for high pressures), lower susceptibility to wind damages, and light supporting structures allowing reduced driving devices. Companies as Novatec, Areva, Solar Euromed, etc., are investing in LF DSG technology and constructing different pilot plants to demonstrate the benefits and feasibility of this solution for defined locations and conditions (Puerto Errado 1 and 2 in Murcia Spain, Lidellin Newcastle Australia, Kogran Creek in South West Queensland Australia, Kimberlina in Bakersfield California USA, Llo Solar in Pyrénées France,Dhursar in India,etc). There are several critical decisions that must be taken in order to obtain a compromise and optimization between plant performance, cost, and durability. Some of these decisions go through the SF design: proper thermodynamic operational parameters, receiver material selection for high pressures, phase separators and recirculation pumps number and location, pipes distribution to reduce the amount of tubes (reducing possible leaks points and transient time, etc.), etc. Attending to these aspects, the correct design parameters selection and its correct assessment are the main target for designing DSG LF power plants. For this purpose in the recent few years some commercial software tools were developed to simulatesolar thermal power plants, the most focused on LF DSG design are Thermoflex and System Advisor Model (SAM). Once the simulation tool is selected,it is made the study of the proposed SFconfiguration that constitutes the main innovation of this work, and also a comparison with one of the most typical state-of-the-art configuration. The transient analysis must be simulated with high detail level, mainly in the BOP during start up, shut down, stand by, and partial loads are crucial, to obtain the annual plant performance. An innovative SF configurationwas proposed and analyzed to improve plant performance. Finally it was demonstrated thermal inertia and BOP regulation mode are critical points in low sun irradiation day plant behavior, impacting in annual performance depending on power plant location.

Pre-diseño de una instalación mixta fotovoltaica-térmica para una vivienda

El objetivo del presente proyecto es realizar el pre-diseño de una instalación solar mixta fotovoltaica-térmica para satisfacer la demanda eléctrica para iluminación y para parte de las necesidades de energía térmica para agua caliente de una vivienda. El proyecto define las condiciones técnicas de la instalación a partir de la radiación solar registrada en la localización elegida. Además de incluir el estudio económico y los planos correspondientes que indican la viabilidad del mismo. Como puntos a destacar en el proyecto, se puede tomar los datos obtenidos de generación eléctrica y térmica, la viabilidad técnica y económica y el análisis de la incipiente tecnología de paneles híbridos fotovoltaicos-térmicos. La incorporación de las energías renovables es ya una realidad para las viviendas de nueva construcción, en cambio son pocas las nuevas instalaciones en edificios o viviendas ya construidas. Es importante promover este tipo de tecnologías con objetivo de reducir la dependencia actual de los combustibles fósiles y evitar así sus efectos nocivos al medio ambiente. ABSTRACT The purpose of this project is to carry out the draft design of a solar mixed photovoltaic-thermal installation to satisfy the electrical and thermal demand in a building, for lighting as well as for some of the energy required for water heating. The project defines the technical conditions of the system, given the solar radiation registered in the chosen location. It also includes the economic analysis and the respective plans that indicates the viability of the project. The highlights of the project are the following: electricity and thermal energy generation data, the technical and financial viability and the analysis of the new technology of the Photovoltaic-Thermal hybrid solar collectors. The inclusion of renewable energies is already a living reality for newly constructed buildings. By contrast, they are rarely implemented in old buildings. In order to be able to reduce the fossil fuels dependency, and in doing so, avoid its damaging effects on the environment, it is very important to promote the use of these cleaner technologies.

Electrodynamic tethers for spacecraft propulsion

Relatively short electrodynamic tethers can use solar power to "push" against a planetary magnetic field to achieve propul sion without expenditure of propellant. The groundwork has been laid for this type of propulsion. Recent important milestones include retrieval of a tether in space (TSS-1, 1992), successful deployment of a 20-km-long tether in space (SEDS-1, 1993), and operation of an electrodynamic tether with tether current driven in both directions (PMG, 1993). The planned Propulsive Small Expendable Deployer System (ProSEDS) experiment will use the flight-proven Small Expendable Deployer System (SEDS) to deploy a 5-km bare copper tether from a Delta II upper stage to achieve -0,4 N drag thrust, thus deorbiting the stage, The experiment will use a predominantly "bare" tether for current collection in lieu of the endmass collector and insulated tether approach used on previous missions, Theory and ground-based plasma chamber testing indicate that the bare tether is a highly efficient current collector. The flight experiment is a precursor to utilization of the technology on the International Space tation (JSS) for reboost and the electrodynamic tether pper stage demonstration misión which will be capable of orbit raising, lowering, and inclination changes—all using electrodynamic thrust. In addition, the use of this type of propulsion may be attractive for future missions to Jupiter.

Diseño de receptor de torre central para generación directa de vapor con perfil de potencia variable longitudinal y transversalmente

En este estudio se ha realizado el diseño de un receptor de una central de Torre Central de energía solar para generación directa de vapor, mediante el uso de métodos numéricos, con un perfil de potencia incidente variable longitudinal y transversalmente. Para ello se ha dividido la geometría del receptor según el método de diferencias finitas, y se ha procedido a resolver las ecuaciones del balance de energía. Una vez resuelto el sistema de ecuaciones se dispone de la distribución de temperaturas en el receptor y se puede proceder a analizar los resultados así como a calcular otros datos de interés. ABSTRACT In this study it has been made a Central Receiver Solar Thermal Power Plant’s Receiver design for direct steam production, by using numerical methods, with a variable longitudinally and transversely income solar power profile. With this propose, the receiver’s geometry has been divided using the finite difference method, and the energy balance equations have been solved. Once the equations system has been solved, the receiver´s temperature distribution is known, and you can analyze the results as well as calculate other interesting data.

Stoichiometry in Context: Inquiry-Guided Problems of Chemistry for Encouraging Critical Thinking in Engineering Students

This paper focuses on examples of educational tools concerning the learning of chemistry for engineering students through different daily life cases. These tools were developed during the past few years for enhancing the active role of students. They refer to cases about mineral water, medicaments, dentifrices and informative panels about solar power, where an adequate quantitative treatment through stoichiometry calculations allows the interpretation of data and values announced by manufacturers. These cases were developed in the context of an inquiry-guided instruction model. By bringing tangible chemistry examples into the classroom we provide an opportunity for engineering students to apply this science to familiar products in hopes that they will appreciate chemistry more, will be motivated to study concepts in greater detail, and will connect the relevance of chemistry to everyday life.

Adaptación de una central térmica de carbón a la Directiva de Emisiones Industriales

El proyecto que se presenta a continuación recoge la adaptación de una Central Térmica de carbón al cumplimiento de la DIRECTIVA 2010/75/UE DEL PARLAMENTO EUROPEO Y DEL CONSEJO de 24 de noviembre de 2010 sobre las emisiones industriales. La Central sobre la que se realiza el proyecto tiene un grupo térmico de carbón suscritico refrigerado por agua, con una potencia a plena carga de 350 MWe y de 190 MWe a mínimo técnico. Genera 1 090 t/h de vapor a 540 °C y 168 kg/cm2 funcionando a plena carga. Actualmente las emisiones de NOx son de 650 mg/m3, (condiciones normales, seco, 6 % O2). El objeto del proyecto es reducir estas emisiones a un valor máximo de 200 mg/m3 en las mismas condiciones. El proyecto analiza detalladamente las condiciones actuales de operación de la instalación en cuanto a combustible utilizado, horas de funcionamiento, condiciones climáticas y producción. Se analiza así mismo, todas las técnicas disponibles en mercado para la reducción del NOx, diferenciando entre medidas primarias (actúan sobre los efectos de formación) y secundarias (limpieza de gases). Las medidas primarias ya están implementadas en la central, por tanto, el proyecto plantea la reducción con medidas secundarias. De las medidas secundarias analizadas se ha seleccionado la instalación de un Reactor de Reducción Selectiva Catalítica (Reactor SCR). Tras un análisis de los diferentes reactores y catalizadores disponibles se ha seleccionado un reactor de configuración High-dust, una disposición de catalizador en 3 capas más 1, cuyos componentes están basados en óxidos metálicos (TiO2, V2O5, WO3) y estructura laminar. Se ha buscado la instalación del reactor para operar a una temperatura inferior a 450 °C. Como agente reductor se ha seleccionado NH3 a una dilución del 24,5 %. El proyecto recoge también el diseño de todo el sistema de almacenamiento, evaporación, dilución e inyección de amoniaco. El resultado del proyecto garantiza una concentración en los gases de salida por la chimenea inferior 180 mg/m3(n) de NOx. La reducción del NOx a los límites establecidos, tienen un coste por MWh neto generado para la central, trabajando 60 % a plena carga y 40 % a mínimo técnico y una amortización de 10 años, de 4,10 €/MWh. ABSTRACT The following project shows the compliance adjustment of a coal-fired power station to the 2010/75/EU Directive of the European Parliament and Council 24th November 2010 on industrial emissions. The project is based on a power station with a subcritical thermal coal unit, cooled with water, with a maximum power of 350 MWe and a technical minimum of 190 MWe. It produces 1 090 t/h of steam at 540 ° C and 168 kg/cm2 operating under full load. Currently, NOx emissions are 650 mg / m3 (normal conditions, dry, 6% O2). The project aims to reduce these emissions to a maximum value of 200 mg / m3 under the same conditions. The project analyses in detail the current operating conditions of the system in terms of fuel used, hours of operation, climatic conditions and production. In addition, it also analyses every available technique of NOx reduction on the market, distinguishing between primary (acting on the effects of formation) and secondary measures (gas cleaning). Primary measures are already implemented in the plant, thus proposing reduction with secondary measures. Among the secondary measures analyzed, it has been selected to install a Selective Catalytic Reduction Reactor (SCR Reactor). Having researched the different reactors and catalysts available, for the reactor has been selected High-dust configuration, an arrangement of catalyst in 3 layers plus 1, whose components are based on metal oxides (TiO2, V2O5, WO3) and laminar structure. The reactor has been sought facility to operate at a temperature below 450 ° C. NH3 diluted to 24,5 % has been selected as reducing agent. The project also includes the design of the entire storage system, evaporation, dilution and ammonia injection. The results of the project ensure a gas concentration in the lower chimney exit below 180 mg / m3(n) NOx. The reduction of NOx to the established limits has a cost per net MWh generated in the plant, working at 60% of full load and at 40% of technical minimum, with an amortization of 10 years, 4,10 € / MWh.

Desarrollo de un sistema de almacenamiento térmico para la central termosolar Astexol 2

En este proyecto se elabora la ingeniería básica de un sistema de almacenamiento térmico para la central termosolar Astexol 2 (Badajoz, España). Para ello, primeramente se decidió que el sistema térmico de almacenamiento a diseñar fuera indirecto de dos tanques con sales fundidas. Una vez seleccionado el tipo de almacenamiento adecuado, se seleccionó la capacidad de almacenamiento óptima, en base a unos objetivos establecidos para la instalación del TES en Astexol 2. Finalmente, se procedió con el diseño de los equipos principales y con la realización de los planos de implantación y de los PFD’s (diagramas de flujo) y P&ID’s (diagramas de instrumentación y control) del sistema de almacenamiento. ABSTRACT This project includes the basic engineering of a thermal storage system for the concentrating solar power plant Astexol 2 (Badajoz, Spain). First of all, it was decided that the type of thermal storage system to design had to be an indirect two-tank molten salt thermal storage system. Once the proper type of storage system was chosen, the optimum storage capacity was selected, according to the main aims designated for the thermal storage system installation in Astexol 2.Finally, the design of the main equipment of the thermal storage system was done, together with the elaboration of the associated plot plans, PFD’s (Process Flow Diagrams) and P&ID’s (Process and Instrumentation Diagrams).

Integración técnica y económica de energías renovables, en un sistema eléctrico liberalizado, a partir de vectores energéticos

El objetivo de la tesis es estudiar la bondad del almacenamiento de energía en hidrógeno para minorar los desvíos de energía respecto a su previsión de parques eólicos y huertas solares. Para ello se ha partido de datos de energías horarias previstas con 24 h de antelación y la energía real generada. Se ha procedido a dimensionar la planta de hidrógeno, a partir de una modelización de la operación de la misma, teniendo siempre como objetivo la limitación de los desvíos. Posteriormente, se ha procedido a simular la operación de la planta con dos objetivos en mente, uno limitar los desvíos y por otro lado operar la planta como una central de bombeo, generando hidrógeno en horas valle y generando electricidad en horas punta. Las dos simulaciones se han aplicado a tres parques eólicos de diferentes potencias, y a una huerta solar fotovoltaica. Se ha realizado un estudio económico para determinar la viabilidad de las plantas dimensionadas, obteniendo como resultado que no son viables a día de hoy y con la estimación de precios considerada, necesitando disminuir considerablemente los costes, dependiendo fuertemente de la bondad de los métodos de previsión de viento. Por último se ha estudiado la influencia de la disminución de los desvíos generados sobre una red tipo de 30 nudos, obteniendo como resultado, que si bien no disminuyen sensiblemente los extra costes generados en regulación, sí que mejora la penetración de las energías renovables no despachables en la red. Se observa disminuyen los vertidos eólicos cuando se usa la planta de hidrógeno. ABSTRACT The aim of this thesis is to study the benefit of hydrogen energy storage to minimize energy deviations of Wind Power and Solar Photovoltaic (PV) Power Plants compared to its forecast. To achieve this goal, first of all we have started with hourly energy data provided 24 h in advance (scheduled energy), and real generation (measured energy). Secondly, It has been sized the hydrogen plant, from a modeling of its working mode, always keeping the goal in mind of limiting energy imbalances. Subsequently, It have been simulated the plant working mode following two goals, one, to limit energy imbalances and secondly to operate the plant as a pumping power plant, generating hydrogen-in valley hours and generating electricity at peak hours. The two simulations have been applied to three wind power plants with different installed power capacities, and a photovoltaic solar power plant. It has been done an economic analysis in order to determine the viability of this sized plants, turning out not viable plants today with the estimated prices considered, requiring significantly lower costs, depending heavily on the reliability of the Wind Power forecast methods. Finally, It has been studied the influence of decreasing measured imbalances (of energy) in a 30 grid node, resulting that, while it not reduces significantly the extra costs generated by reserve power, it does improve the penetration of non-manageable renewable energy on the grid, by reducing the curtailments of power of these plants.

Aprovechamiento térmico de residuos estériles de carbón para generación eléctrica mediante tecnologías de combustión y gasificación eficientes y con mínimo impacto ambiental

La presente tesis doctoral, “Aprovechamiento térmico de residuos estériles de carbón para generación eléctrica mediante tecnologías de combustión y gasificación eficientes y con mínimo impacto ambiental”, desarrolla la valorización energética de los residuos del carbón, estériles de carbón, producidos durante las etapas de extracción y lavado del carbón. El sistema energético se encuentra en una encrucijada, estamos asistiendo a un cambio en el paradigma energético y, en concreto, en el sector de la generación eléctrica. Se precipita un cambio en la generación y el consumo eléctricos. Una mayor concienciación por la salud está forzando la contención y eliminación de agentes contaminantes que se generan por la utilización de combustibles fósiles de la forma en la que se viene haciendo. Aumenta la preocupación por el cambio climático y por contener en 2°C el aumento de la temperatura de la Tierra para final de este siglo, circunstancia que está impulsando el desarrollo e implantación definitiva de tecnología de control y reducción de emisiones CO2. Generar electricidad de una manera sostenible se está convirtiendo en una obligación. Esto se materializa en generar electricidad respetando el medioambiente, de una forma eficiente en la utilización de los recursos naturales y a un coste competitivo, pensando en el desarrollo de la sociedad y en el beneficio de las personas. En la actualidad, el carbón es la principal fuente de energía utilizada para generar electricidad, y su empleo presenta la forma de energía más barata para mejorar el nivel de vida de cualquier grupo y sociedad. Además, se espera que el carbón siga presente en el mix de generación eléctrica, manteniendo una significativa presencia y extrayéndose en elevadas cantidades. Pero la producción de carbón lleva asociada la generación de un residuo, estéril, que se produce durante la extracción y el lavado del mineral de carbón. Durante décadas se ha estudiado la posibilidad de utilizar el estéril y actualmente se utiliza, en un limitado porcentaje, en la construcción de carreteras, terraplenes y rellenos, y en la producción de algunos materiales de construcción. Esta tesis doctoral aborda la valorización energética del estéril, y analiza el potencial aprovechamiento del residuo para generar electricidad, en una instalación que integre tecnología disponible para minimizar el impacto medioambiental. Además, persigue aprovechar el significativo contenido en azufre que presenta el estéril para producir ácido sulfúrico (H2SO4) como subproducto de la instalación, un compuesto químico muy demandado por la industria de los fertilizantes y con multitud de aplicaciones en otros mercados. Se ha realizado el análisis de caracterización del estéril, los parámetros significativos y los valores de referencia para su empleo como combustible, encontrándose que su empleo como combustible para generar electricidad es posible. Aunque en España se lleva extrayendo carbón desde principios del siglo XVIII, se ha evaluado para un período más reciente la disponibilidad del recurso en España y la normativa existente que condiciona su aplicación en el territorio nacional. Para el período evaluado, se ha calculado que podrían estar disponibles más de 68 millones de toneladas de estéril susceptibles de ser valorizados energéticamente. Una vez realizado el análisis de la tecnología disponible y que podría considerarse para emplear el estéril como combustible, se proponen cuatro configuraciones posibles de planta, tres de ellas basadas en un proceso de combustión y una de ellas en un proceso de gasificación. Tras evaluar las cuatro configuraciones por su interés tecnológico, innovador y económico, se desarrolla el análisis conceptual de una de ellas, basada en un proceso de combustión. La instalación propuesta tiene una capacidad de 65 MW y emplea como combustible una mezcla de carbón y estéril en relación 20/80 en peso. La instalación integra tecnología para eliminar en un 99,8% el SO2 presente en el gas de combustión y en más de un 99% las partículas generadas. La instalación incorpora una unidad de producción de H2SO4, capaz de producir 18,5 t/h de producto, y otra unidad de captura para retirar un 60% del CO2 presente en la corriente de gases de combustión, produciendo 48 tCO2/h. La potencia neta de la planta es 49,7 MW. Se ha calculado el coste de inversión de la instalación, y su cálculo resulta en un coste de inversión unitario de 3.685 €/kW. ABSTRACT The present doctoral thesis, “Thermal utilisation of waste coal for electricity generation by deployment of efficient combustion and gasification technologies with minimum environmental impact”, develops an innovative waste-to-energy concept of waste coals produced during coal mining and washing. The energy system is at a dilemma, we are witnessing a shift in the energy paradigm and specifically in the field of electricity generation. A change in the generation and electrical consumption is foreseen. An increased health consciousness is forcing the containment and elimination of pollutants that are generated by the use of fossil fuels in the way that is being done. Increasing concern about climate change and to contain the rise of global temperature by 2°C by the end of this century, is promoting the development and final implementation of technology to control and reduce the CO2 emission. Electricity generation in a sustainable manner is becoming an obligation. This concept materialised in generating electricity while protecting the environment and deployment of natural resources at a competitive cost, considering the development of society and people´s benefit. Currently, coal is the main source of energy employ to generate electricity, and its use represents the most cost competitive form of energy to increase the standard of living of any group or society. Moreover, coal will keep playing a key role in the global electricity generation mix, maintaining a significant presence and being extracting in large amounts. However, coal production implies the production of waste, termed waste coal or culm in Pennsylvania anthracite extraction, produced during coal mining and coal washing activities. During the last decades, the potential use of waste coal has been studied, and currently, in a limited amount, waste coal is used in roads construction, embankments and fillings, and to produce some construction materials. This doctoral thesis evaluates the waste to energy of waste coals and assesses its potential use to generate electricity, implementing available technology to minimise the environment impact. Additionally, it pursues the significant advantage that presents sulphur content in waste coal to produce sulphuric acid (H2SO4) as a byproduct of the waste-to-energy process, a chemical compound highly demanded by the fertiliser industry and many applications in other markets. It analyses the characteristics of waste coal, and assesses the significant parameters and reference values for its use as fuel, being its fuel use for electricity generation very possible. While mining coal is taking place in Spain since the 1700s, it has been evaluated for a more recent period the waste coal available in Spain and the existing legislation that affects its application and deploy to generate electricity in the country. For the evaluation period has been calculated that may be available more than 68 million tons of waste coal that can be waste-toenergy. The potential available technology to deploy waste coal as fuel has been evaluated and assessed. After considering this, the doctoral thesis proposes four innovative alternatives of facility configuration, three of them based on a combustion process and one in a gasification process. After evaluating the four configurations for its technological, innovative and economic interest, the conceptual analysis of one of alternatives, based on a combustion process, takes place. The proposed alternative facility developed has a capacity of 65 MW, using as fuel a mixture of coal and waste coal 80/20 by weight. The facility comprises technology to remove 99.8% SO2 present in the flue gas and more than 99% of the particles. The facility includes a unit capable of producing 18.5 t/h of H2SO4, and another capture facility, removing 60% of CO2 present in the flue gas stream, producing 48 tCO2/h. The net capacity of the power station is 49.7 MW. The facility unitary cost of investment is 3,685 €/kW.

Inorganic Photovoltaics - Planar and Nanostructured Devices

Since its invention in the 1950s, semiconductor solar cell technology has evolved in great leaps and bounds. Solar power is now being considered as a serious leading contender for replacing fossil fuel based power generation. This article reviews the evolution and current state, and potential areas of near future research focus, of leading inorganic materials based solar cells, including bulk crystalline, amorphous thin-films, and nanomaterials based solar cells. Bulk crystalline silicon solar cells continue to dominate the solar power market, and continued efforts at device fabrication improvements, and device topology advancements are discussed. III-V compound semiconductor materials on c-Si for solar power generation are also reviewed. Developments in thin-film based solar cells are reviewed, with a focus on amorphous silicon, copper zinc tin sulfide, cadmium telluride, as well as nanostructured Cadmium telluride. Recent developments in the use of nano-materials for solar power generation, including silicon and gallium arsenide nanowires, are also reviewed.

Ultra high temperature latent heat energy storage and thermophotovoltaic energy conversion

A conceptual energy storage system design that utilizes ultra high temperature phase change materials is presented. In this system, the energy is stored in the form of latent heat and converted to electricity upon demand by TPV (thermophotovoltaic) cells. Silicon is considered in this study as PCM (phase change material) due to its extremely high latent heat (1800 J/g or 500 Wh/kg), melting point (1410 C), thermal conductivity (~25 W/mK), low cost (less than $2/kg or $4/kWh) and abundance on earth. The proposed system enables an enormous thermal energy storage density of ~1 MWh/m3, which is 10e20 times higher than that of lead-acid batteries, 2e6 times than that of Li-ion batteries and 5e10 times than that of the current state of the art LHTES systems utilized in CSP (concentrated solar power) applications. The discharge efficiency of the system is ultimately determined by the TPV converter, which theoretically can exceed 50%. However, realistic discharge efficiencies utilizing single junction TPV cells are in the range of 20e45%, depending on the semiconductor bandgap and quality, and the photon recycling efficiency. This concept has the potential to achieve output electric energy densities in the range of 200-450 kWhe/m3, which is comparable to the best performing state of the art Lithium-ion batteries.

Evaluation of the PV cell operation temperature in the process of fast switching to open-circuit mode

A procedure for measuring the overheating temperature (ΔT ) of a p-n junction area in the structure of photovoltaic (PV) cells converting laser or solar radiations relative to the ambient temperature has been proposed for the conditions of connecting to an electric load. The basis of the procedure is the measurement of the open-circuit voltage (VO C ) during the initial time period after the fast disconnection of the external resistive load. The simultaneous temperature control on an external heated part of a PV module gives the means for determining the value of VO C at ambient temperature. Comparing it with that measured after switching OFF the load makes the calculation of ΔT possible. Calibration data on the VO C = f(T ) dependences for single-junction AlGaAs/GaAs and triple-junction InGaP/GaAs/Ge PV cells are presented. The temperature dynamics in the PV cells has been determined under flash illumination and during fast commutation of the load. Temperature measurements were taken in two cases: converting continuous laser power by single-junction cells and converting solar power by triple-junction cells operating in the concentrator modules.