Comparison of CO2 from coal captureprocesses and valorisation technologies

Coal is the most plentiful and evenly distributed fossil fuel worldwide. Based on current production, it is estimated that the reserves will last approximately 130 years. Its use worldwide has been increasing, mainly due to consumption by emerging countries. CO2 emissions generated by combustion and the repercussions of such on climate change support the view that it could no longer be used. CO2 capture may be the solution to continue using it, which would cater for the growing energy demand worldwide. The aim of this study is to compare different processes concerning CO2 capture that may be economically viable, ultimately showing that coal, a fossil energy source widely distributed around the world, can, as a result of using different CO2 capture processes, be used as a clean source of electricity. Hence, in places where geological hurdles may render the costs of CO2 storage considerably higher, since it might have to travel far, coal may be used for other purposes, thus valorizing CO2 within the industrial sector. This research is focused on the technical and economic comparison of the most relevant CO2 capture projects designed in Spain using different existing technologies. The oxyfuel project in Ciuden (Leon, Spain), the IGCC Elcogas, precombustion CO2-capture project (Puertollano, Spain) and the postcombustion project in Carboneras (Almeria, Spain) will be analyzed in order to assess the options available to valorizecaptured CO2. Valorizing captured CO2 may be an adequate solution in areas where, although CO2 capture is still possible, storage is not equally so, thus generating a further benefit. The possible uses of CO2 will be assessed in vegetable growing greenhouses, harnessing CO2 in vegetable life cycles. This will also be used in growing algae for subsequent biodiesel production. Both CO2capture and valorizing will eventually lead to the clean use of coal, which will thus enhance the level of self-supply, aiding the development of electric vehicles, which require large amounts of electricity, as well as improve the level of energy autonomy in countries around the world. Another type of fuel, biodiesel, will also be obtained, without this affecting international food prices.

Desarrollo de un modelo para la caracterización termoeconómica de ciclos combinados de turbinas de gas y de vapor en condiciones de carga variable

En la actualidad, el interés por las plantas de potencia de ciclo combinado de gas y vapor ha experimentado un notable aumento debido a su alto rendimiento, bajo coste de generación y rápida construcción. El objetivo fundamental de la tesis es profundizar en el conocimiento de esta tecnología, insuficientemente conocida hasta el momento debido al gran número de grados de libertad que existen en el diseño de este tipo de instalaciones. El estudio se realizó en varias fases. La primera consistió en analizar y estudiar las distintas tecnologías que se pueden emplear en este tipo de centrales, algunas muy recientes o en fase de investigación, como las turbinas de gas de geometría variable, las turbinas de gas refrigeradas con agua o vapor del ciclo de vapor o las calderas de paso único que trabajan con agua en condiciones supercríticas. Posteriormente se elaboraron los modelos matemáticos que permiten la simulación termodinámica de cada uno de los componentes que integran las plantas, tanto en el punto de diseño como a cargas parciales. Al mismo tiempo, se desarrolló una metodología novedosa que permite resolver el sistema de ecuaciones que resulta de la simulación de cualquier configuración posible de ciclo combinado. De esa forma se puede conocer el comportamiento de cualquier planta en cualquier punto de funcionamiento. Por último se desarrolló un modelo de atribución de costes para este tipo de centrales. Con dicho modelo, los estudios se pueden realizar no sólo desde un punto de vista termodinámico sino también termoeconómico, con lo que se pueden encontrar soluciones de compromiso entre rendimiento y coste, asignar costes de producción, determinar curvas de oferta, beneficios económicos de la planta y delimitar el rango de potencias donde la planta es rentable. El programa informático, desarrollado en paralelo con los modelos de simulación, se ha empleado para obtener resultados de forma intensiva. El estudio de los resultados permite profundizar ampliamente en el conocimiento de la tecnología y, así, desarrollar una metodología de diseño de este tipo de plantas bajo un criterio termoeconómico. ABSTRACT The growing energy demand and the need of shrinking costs have led to the design of high efficiency and quick installation power plants. The success of combined cycle gas turbine power plants lies on their high efficiency, low cost and short construction lead time. The main objective of the work is to study in detail this technology, which is not thoroughly known owing to the great number of degrees of freedom that exist in the design of this kind of power plants. The study is divided into three parts. Firstly, the different technologies and components that could be used in any configuration of a combined cycle gas turbine power plant are studied. Some of them could be of recent technology, such as the variable inlet guide vane compressors, the H-technology for gas turbine cooling or the once-through heat recovery steam generators, used with water at supercritical conditions. Secondly, a mathematical model has been developed to simulate at full and part load the components of the power plant. At the same time, a new methodology is proposed in order to solve the equation system resulting for any possible power plant configuration. Therefore, any combined cycle gas turbine could be simulated at any part load condition. Finally a themoeconomic model is proposed. This model allows studying the power plant not only from a thermodynamic point of view but also from a thermoeconomic one. Likewise, it allows determining the generating costs or the cash flow, thus achieving a trade off between efficiency and cost. Likewise, the model calculates the part load range where the power plant is profitable. Once the thermodynamic and thermoeconomic models are developed, they are intensively used in order to gain knowledge in the combined cycle gas turbine technology and, in this way, to propose a methodology aimed at the design of this kind of power plants from a thermoeconomic point of view.

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.

Problemática del ruido neutrónico

El objetivo del presente proyecto es identificar y definir la problemática del ruido neutrónico en el tratamiento y procesamiento de los canales de medida y tratamiento del flujo neutrónico interno y externo en los sistemas de control y protección de los reactores nucleares tipo PWR (que trabajan con agua a presión) que dan lugar a actuaciones indeseadas de los sistemas de vigilancia y control no relacionadas con situaciones reales del proceso como cambios significativos en los parámetros de temperatura y por lo tanto de potencia del reactor que reducen la disponibilidad de operación de la central y provocan transitorios no justificados por dichas actuaciones. Finalmente, se proponen algunas soluciones. Abstract The aim of this project is to identify and define the problem of neutron noise in PWR nuclear power plants, its influence on the treatment and processing of the measurement channels and external neutron flux treatment, its contributions to the control and protection systems that result in undesired actions of monitoring and control systems that are not related to the actual process conditions. These actions reduce the availability of plant operation and unjustified transient causes. Finally, some possible solutions are proposed

EU-CargoXpress: wind propulsion concept

The EU-CargoXpress project suggests the usage of sustainable energies to reduce the fuel consumption. The updated concept consists of hoisting the superstructure and using it as a sail together with the conventional propulsion. This paper presents the study of the sail performance by means of a computational analysis and wind tunnel tests. Moreover, a research of the energy saving in different operational areas has been conducted. It is concluded that there is a significant energy saving by using the superstructure as a sail which leads to a reduction of fossil fuel consumption and consequently, a reduction of greenhouse gas emissions.

AFBC of coal with tyre rubber. Influence of the co-combustion variables on the mineral matter of solid by-products and on Zn lixiviation

The study focuses on the generation and distribution of mineral species in fly and bottom ashes. These were formed during a fluidised co-combustion of a fossil fuel (coal) and a non-fossil fuel (tyre rubber) in a small fluidised bed combustor (7cm x 70cm). The pilot plant had continuous fuel feed using varying ratios of coal and rubber. The study also focuses on the lixiviation behaviour of metallic elements with the assessement of zinc recovering.

The NACIR Project: New Applications for CPV'S: A fast way to improve reliability and Technology progress

The main goal of this proposal is to join together the owners of the most advanced CPV technology, with respect to the state of the art, in order to research from its leading position new applications for CPV systems. In addition to opening up new markets, it will unveil possible sources of failure in new environments outside Europe, in order to assure component reliability. The proposed project will also try to improve the current technology of the industrial partners (ISOFOTON and CONCENTRIX) by accelerating the learning curve that CPV must follow in order to reach the competitive market, and lowering the cost under the current flat panel PV significantly within 3-4 years. The use of CPV systems in remote areas, together with harsher radiation, ambient and infrastructure conditions will help to increase the rate of progress of this technology. In addition, the ISFOC s contribution, which brings together seven power plants from seven CPV technologies up to 3 MWpeak, will allow creating the most complete database of components and systems performance to be generated as well as the effects of radiation and meteorology on systems operations. Finally, regarding the new applications for CPV subject, the project will use a CPV system sized 25 kWp in a stand-alone station in Egypt (NWRC) for the first time for water pumping and irrigation purposes. In a similar way ISOFOTON will connect up to 25 kWp CPV to the Moroccan ONE utility grid. From the research content point of view of this project, which is directly addressed by the scope of the call, the cooperative research between UPM, FhG-ISE and the two companies will be favoured by the fact that all are progressing in similar directions: developing two-stage optics CPV systems. In addition to these technology improvements the UPM is very interested in developing a new concept of module, recently patented, which will fulfil all required characteristics of a good CPV with less components and reducing cost.

Vigilancia por análisis de ruido de los sensores de temperatura

En este proyecto se van a aplicar las técnicas de análisis de ruido para caracterizar la respuesta dinámica de varios sensores de temperatura, tanto termorresistencias de platino como de termopares. Estos sensores son imprescindibles para él correcto funcionamiento de las centrales nucleares y requieren vigilancia para garantizar la exactitud de las medidas. Las técnicas de análisis de ruido son técnicas pasivas, es decir, no afectan a la operación de la planta y permiten realizar una vigilancia in situ de los sensores. Para el caso de los sensores de temperatura, dado que se pueden asimilar a sistemas de primer orden, el parámetro fundamental a vigilar es el tiempo de respuesta. Éste puede obtenerse para cada una de las sondas por medio de técnicas en el dominio de la frecuencia (análisis espectral) o por medio de técnicas en el dominio del tiempo (modelos autorregresivos). Además de la estimación del tiempo de respuesta, se realizará una caracterización estadística de las sondas. El objetivo es conocer el comportamiento de los sensores y vigilarlos de manera que se puedan diagnosticar las averías aunque éstas estén en una etapa incipiente. ABSTRACT In this project we use noise analysis technique to study the dynamic response of RTDs (Resistant temperature detectors) and thermocouples. These sensors are essential for the proper functioning of nuclear power plants and therefore need to be monitored to guarantee accurate measurements. The noise analysis techniques do not affect plant operation and allow in situ monitoring of the sensors. Temperature sensors are equivalent to first order systems. In these systems the main parameter to monitor is the response time which can be obtained by means of techniques in the frequency domain (spectral analysis) as well as time domain (autoregressive models). Besides response time estimation the project will also include a statistical study of the probes. The goal is to understand the behavior of the sensors and monitor them in order to detect any anomalies or malfunctions even if they occur in an early stage.

Comportamiento estructural de tuberías forzadas y blindajes en saltos hidroeléctricos : propuestas de diseño y cálculo

En los últimos años ha aumentado el interés en el desarrollo de proyectos en el ámbito de las centrales hidroeléctricas y en concreto en las centrales reversibles. Estas centrales están diseñadas para grandes caudales y saltos, lo cual conlleva túneles de gran diámetro y alta presión y a menudo son esquemas subterráneos. Por ello, los estudios relativos a revestimientos de túneles en presión y los referentes a los blindajes de acero han cobrado una mayor relevancia. En las décadas de los 60 y 70 se realizó una importante labor de investigación coincidiendo con el desarrollo hidroeléctrico en Europa y Norteamérica, que sin embargo ha quedado sin continuidad hasta esta década, en la que se ha experimentado un impulso debido al desarrollo de nuevos proyectos hidroeléctricos de gran magnitud. La adecuación de los métodos de cálculo de blindajes supone una herramienta imprescindible en el correcto desarrollo técnico de los nuevos proyectos hidroeléctricos, así como para la evaluación de la seguridad de los saltos hidroeléctricos existentes en operación. En la presente Tesis se realiza un análisis del comportamiento estructural de las galerías en presión de saltos hidroeléctricos, así como una discusión y revisión de los métodos de cálculo existentes. En concreto se analizan los siguientes aspectos: •Descripción y comparación de las formulaciones existentes para el cálculo de blindajes tanto a presión exterior como interior. •Aplicación del Método de Elementos Finitos para la modelización y cálculo resistente y frente a inestabilidad de blindajes sometidos a presión exterior. •Análisis de un caso real, en el que se ha producido un fallo estructural en un blindaje sometido a presión exterior. Discusión sobre el comportamiento de blindajes con rigidizadores. Estudio paramétrico de la capacidad resistente y de la estabilidad de los blindajes con rigidizadores. •Estudio del comportamiento diferenciado entre un rigidizador y un conector. •Detalles constructivos y de durabilidad de las galerías en presión. •Desarrollo de una metodología para el cálculo de blindajes y tuberías forzadas a fatiga derivada de las variaciones de presión de la conducción. •Análisis de un caso real de una tubería forzada sometida a procesos de variación de carga, evaluando su seguridad frente a la fatiga. El cálculo de blindajes en galerías forzadas presenta una serie de aspectos complejos, y que no permiten la definición del problema con exactitud, tales como las características del macizo rocoso y su permeabilidad, la determinación del nivel freático, la holgura existente entre el blindaje y el revestimiento del trasdós y sus posibles defectos geométricos. Por estas incertidumbres, el cálculo de blindajes supone una materia compleja y que debe ser abordada desde la cautela y el análisis de otros trabajos y/o análisis realizados con anterioridad. En cualquier caso, debe realizarse un análisis de sensibilidad de los diversos parámetros que intervienen en el cálculo. En esta tesis se han descrito las principales formulaciones de cálculo de blindajes de galerías forzadas sometidas a presión interior y exterior; se ha constatado que existe una gran diversidad y que de su aplicación no se llega a resultados concluyentes. Las formulaciones clásicas utilizadas en el cálculo de blindajes lisos y con rigidizadores sometidos a presión exterior (Amstutz y Jacobsen) no resultan del todo adecuadas ni son de aplicación general. Además, pueden arrojar resultados no conservadores o conducir a un sobredimensionamiento del blindaje en otros casos. En las formulaciones tradicionales de diseño se han tenido en cuenta como imperfecciones la holgura del blindaje y la ovalidad del mismo. En la presente tesis, se han analizado imperfecciones de tipo ondulatorio derivadas de los procesos de soldadura y la existencia de espesores reducidos en zonas de corrosión. En el caso práctico analizado sometido a presión exterior, se ha comprobado el funcionamiento real del blindaje mediante los modelos realizados con elementos finitos. Se desprende que los rigidizadores no han funcionado como tales, puesto que para blindajes lisos se obtienen presiones más bajas de pandeo y para el caso de funcionamiento correcto de los rigidizadores se habría obtenido un coeficiente de seguridad suficiente. Por este motivo, se ha analizado el posible funcionamiento de los rigidizadores, que en determinados casos pueden actuar como conectores. En estos casos deben dimensionarse de forma adecuada las soldaduras para soportar las tensiones entre chapa y conector. Por otra parte, tradicionalmente no se han tenido en cuenta los efectos de fatiga que pueden ocasionar los golpes de ariete y las pulsaciones de presión debidas a la regulación secundaria de la red. En esta tesis se ha establecido un procedimiento de comprobación de tuberías forzadas y blindajes sometidos a procesos de fatiga. Adicionalmente, se ha estudiado el caso real de las tuberías forzadas de una central reversible real (Bolarque II) en funcionamiento de regulación secundaria. Se ha concluido, como en otros casos analizados en la bibliografía, que las pulsaciones derivadas de la regulación secundaria no son significativas como para tener en cuenta la fatiga del acero. Por otra parte, las maniobras de arranque y parada (golpe de ariete) suponen una variación importante de la presión en la conducción. Sin embargo, el moderado número de ciclos permite asegurar la integridad de la tubería frente a fenómenos de fatiga. Nowadays, there is a significant concern in the development of projects in the field of hydroelectric power plants, particularly in the pump-storage projects. These plants are designed for high flow rates and heads, which entails large-diameter tunnels and high pressure ratios), and often as underground schemes. Therefore, this concern has reactivated studies about penstocks and in particular those related to steel liners. During the 1960s and 1970s due to hydropower-engineering development in Europe and North America, a major research effort was done. However, the increasing development of new large-scale hydropower projects has involved a renewed research effort during this decade. The adequacy of steel liner calculation methods is a very important issue in the proper technical development of new hydroelectric projects, and for the safety assessment of existing hydroelectric power plants in operation. In this work, an analysis of the structural behavior of pressure galleries in hydroelectric schemes was carried out. Also, a discussion and a review of existing calculation methods are included. In particular, the following issues have been considered: •Description and comparison of existing formulations for calculating the liner response to both external and internal pressure. •Analysis of an actual case study of a steel liner which failed due to external pressure. •Application of the Finite Element Method to liner modeling and analysis subjected to external pressure. •A parametric study of the shielding with stiffeners and discussion about the behavior of liner with stiffeners. •Constructive aspects and durability of pressure galleries. •Development of a methodology for estimating fatigue effects on penstocks and liners sue to pressure changes. •Analysis of an actual case study of a penstock under varying load and assessment of its safety against fatigue. The project of a hydropower penstock is a complex issue, due to the uncertainties in the definition of the problem data, such as the characteristics of the rock mass and its permeability, the determination of the water table, the existing gap between the steel liner and the concrete of the backfill, the geometric imperfections... Hence, the design and analysis of a steel liner must be addressed cautiously and take into account a review of previous studies performed. Ever, a sensitivity analysis of the various parameters involved in the calculation should be performed. In this work, some of the most relevant formulations for liner design subjected to inside and outside pressure have been studied. As a whole, there is a wide variety and its application does not lead to conclusive results. The classical formulations used in the steel liner calculation either with or without stiffeners under external pressure (Amstutz and Jacobsen) are not entirely adequate Also, those can yield both conservative and non-conservative results in large ranges of application. Traditionally design approaches only considered initial gap and ovality as the most relevant geometric imperfections. Thus, little attention was paid to those caused either by welding or by thickness loss in corroded areas. In the case study analyzed in this thesis, the actual working of the liner under external pressure has been simulated by the Finite Element Method. Results show that the stiffeners have not performed as such, since for unstiffened liner lower buckling pressures are obtained and for proper performance of the stiffeners would give a sufficient safety factor. Hence, it must be pointed out that stiffeners may perform either as such or as connectors. For the latter, welding must be designed to properly withstand stresses between the shell and the stiffener. Likewise, the potential fatigue effects due to both water hammer and pressure pulsations due to secondary regulation of the network have not been considered in many studies. It has been included in this work a procedure for checking penstocks and liners under fatigue processes. Additionally, the penstock fatigue response of an actual pump storage project (Bolarque II, Spain) subjected to secondary control operation has been assessed. As in other cases discussed in the literature, pulsations derived from the secondary control are not significant to account for fatigue of steel. Moreover, the start and stop manoeuvres (water hammer) cause a significant change in penstock pressure. However, the moderate number of cycles ensures the integrity of the penstock against fatigue phenomena.

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.

D-depth profiling in as-implanted and annealed Li-based breeder blanket ceramics

In future power plants (i.e. DEMO), the nuclear fusion of hydrogen isotopes will be used for energy production. The behaviour of hydrogen isotopes in lithium-enriched ceramics for breeder blankets (BBs) is one of the most important items to be understood. In this paper we present the chemical, microstructural and morphological features of Li4SiO4, Li2TiO3 and a third ceramic candidate with a higher Li:Si proportion (3:1), implanted with D at an energy of 100 keV and at room temperature at a fluence of 1 × 1017 cm−2. The D depth-profile in as-implanted and annealed ceramics (at T ⩽ 200 °C) was characterised by Resonance Nuclear Reaction Analysis (RNRA). The RNRA data indicate that the total amount of D is retained at room temperature, while annealing at 100 °C promotes D release and annealing at T ⩾ 150 °C drives D to completely desorb from all the studied ceramics. D release will be discussed as a function of the microstructurural and morphological features of each material.

El papel de la hidroelectricidad en el contexto de las energías renovables en España

En el artículo se discute el papel de la energía hidroeléctrica en el marco del sistema eléctrico español, donde existe una elevada penetración de energías no gestionables con una tendencia clara a aumentar en los próximos años. El desarrollo de nuevas centrales hidroeléctricas se basará probablemente en centrales reversibles. La energía hidroeléctrica es una tecnología madura y eficiente para el almacenamiento de energía a gran escala y contribuye por tanto de manera decisiva a la integración de fuentes renovables no gestionables. Los beneficios obtenidos con la operación punta-valle pueden ser insuficientes para compensar el coste de una nueva central. Sin embargo, los ingresos obtenidos pueden incrementarse sustancialmente mediante su participación en los servicios de ajuste del sistema. Ello requeriría un diseño apropiado del mercado eléctrico. La contribución de las centrales hidráulicas reversibles al balance producción-consumo puede extenderse a las horas valle utilizando, bien bombeo en velocidad variable o bien una configuración de cortocircuito hidráulico. La necesidad de mitigar los efectos hidrológicos aguas abajo de las centrales hidroeléctricas puede introducir algunas restricciones en la operación que limitaría de algún modo los servicios descritos más arriba. Sin embargo, cabe esperar que los efectos ambientales provocados por las centrales hidráulicas reversibles sean significativamente menores. In this paper the role of hydropower in electric power systems is discussed, in the framework of the Spanish system, where a high penetration of intermittent power sources exists, showing a clear trend to increase in next years. The development of new hydro power facilities will be likely based on pumped storage hydro power plants. Hydropower is a mature and efficient technology for large-scale energy storage and therefore represents a key contribution for the integration of intermittent power sources, such as wind or photovoltaic. The benefits obtained from load shifting may be insufficient to compensate the costs of a new plant. However, the obtained revenues can significantly increase through its contribution to providing ancillary services. This would require an appropriate design of the electricity market. The contribution of pumped storage hydro power plants to balancing services can be extended to off-peak hours, using either variable speed pumping or the hydraulic shortcircuit configuration. The need to mitigate hydrological effects downstream of hydro plants may introduce some operational constraints which could limit to some extent the services described above. However environmental effects caused by pumped storage hydro power plants are expected to be significantly smaller.

AVR adjustment of Synchronous Generators in Weak Grids under Faulty Conditions.

In weak grids, an important problem with voltage stability and protections coordination of power plants exists. This problem appears because all the generation groups are connected to the same bus bar. As a result, if a fault occurs in any of the generation groups, or in the bus bar that connect them, the system voltage will have large oscillations. Hence, in weak grids the correct adjustment of AVR (Automatic Voltage Regulator) is critical. In this work an experimental study of differents AVR adjustments against fault in weak grids is described.

Fabrication and properties of the SITE-SiCf/SiC composite

Continuous SiC-fiber-reinforced SiC composite (SiCf/SiC) is an attractive candidate structural material for advanced concepts of future fusion power plants, mainly due to the favourable intrinsic properties of the SiC ceramics, i.e. high temperature- and chemical stability, low neutron activation and afterheat levels as well as due to the fact that it is the only nonmagnetic material proposed. Fabrication of such composites is a very challenging task due to limitations and requirements set for fusion-relevant structural materials.