Análisis comparativo entre una planta de ciclo combinado convencional y una incorporando una pila de combustible de óxidos sólidos

Cada año, el consumo de energía se ve incrementado ya que aumenta la población y con ello las necesidades de cada individuo: el trabajo, ocio y bienestar, en general, dependen del abastecimiento de energía. Este abastecimiento debe ser suficiente e ininterrumpido. La población en general, actúa como si el abastecimiento fuera ilimitado, pero no es así. Aunque no se está concienciado de ello, las fuentes de energía tradicionales basadas en combustibles fósiles son limitadas y altamente contaminantes. Hay que tratar de esforzarse en buscar medidas más sostenibles ya que hay un alto desfase entre la demanda creciente y la oferta que disminuye considerablemente debido a la reducción de los recursos. En la búsqueda de fuentes alternativas se ha descubierto que el hidrógeno podría ser uno de los combustibles con el futuro más prometedor aunque, a día de hoy, es muy caro producirlo. La forma actual más barata de producirlo es a partir de gas natural. La transición del uso de combustibles fósiles al uso de hidrógeno no es nada fácil y necesita de una planificación, se debe de hacer de manera progresiva. Europa se ha propuesto: a corto plazo una intensa investigación; a medio plazo se deberá incentivar el uso de combustibles líquidos derivados de la biomasa y desarrollar procesos de producción de hidrógeno a partir de fuentes renovables y, finalmente a largo plazo el hidrógeno deberá complementar la demanda de electricidad. Pese a que un rendimiento en torno al 60% en un principio puede parecer bajo, las pilas de combustibles son más eficientes que otras formas de generación de energía y, como se va a demostrar, si se utilizan de manera conjunta con otros sistemas de producción, estos rendimientos pueden alcanzar casi el 80%. Pese a ello, las celdas de combustible no se utilizan demasiado debido a su alto coste y a los problemas que presenta el hidrógeno, tanto de transporte como de almacenamiento y debido a la tendencia de fuga del mismo. Estos inconvenientes podrían ser resueltos con la investigación. Si se emplean nuevos materiales y técnicas de diseño, los costes de reducirían y podrían ser más rentables que los sistemas convencionales. El uso del hidrógeno podría eliminar con el tiempo las emisiones de gases que causan el efecto invernadero ya que las pilas de combustible generan electricidad de manera eficiente y limpia. Otra cualidad de las pilas de combustible es que se pueden ubicar cerca de los puntos de uso final pudiéndose aprovechar el calor generado durante el proceso. En este proyecto, se ha hecho un análisis paramétrico comparativo entre la generación de electricidad mediante una central de ciclo combinado convencional y una central a la que se le ha incorporado una pila de combustible de óxidos sólidos. Para realizar este análisis se ha tenido en cuenta la tendencia que tiene el sistema de generación mediante SOFC a disminuir el precio en los próximos años.Each year, energy consumption increases, because the population increases and with it the needs of each person: work, leisure and well-being, in general, depend on the energy supply. This supply must be sufficient and uninterrupted. The general population acts as if the supply were unlimited, but that is not the case. Although there is no awareness of this, traditional energy sources based on fossil fuels are limited and highly polluting. Efforts must be made to seek more sustainable measures as there is a high gap between growing demand and supply that is greatly reduced due to reduced resources. In the search for alternative sources it has been discovered that hydrogen could be one of the fuels with the most promising future, although it is currently very expensive to produce it. The cheapest way to produce it today is from natural gas. The transition from the use of fossil fuels to the use of hydrogen is not easy and needs to be planned, it must be done progressively. Europe has set itself the following goals: in the short term, intensive research; in the medium term, the use of liquid fuels derived from biomass should be encouraged and hydrogen production processes developed from renewable sources; and, finally, in the long term, hydrogen should complement electricity demand. Although a yield of around 60% may initially seem low, fuel cells are more efficient than other forms of power generation and, as will be shown, if used in conjunction with other production systems , these yields can reach almost 80%. In spite of this, the fuel cells are not used too much due to their high cost and the problems that hydrogen presents, both in transport and storage and due to the tendency of its leakage. These problems could be solved with the investigation. If new materials and design techniques are used, the costs would be reduced and could be more cost-effective than conventional systems. The use of hydrogen could eventually eliminate greenhouse gas emissions as fuel cells generate electricity efficiently and cleanly. Another quality of fuel cells is that they can be located close to end-use points and the heat generated during the process can be harnessed. In the present work, a parametric comparative analysis has been made between the generation of electricity by means of a conventional combined cycle plant and a plant to which a solid oxide fuel cell has been incorporated. In order to carry out this analysis, the tendency of the SOFC generation system to reduce the price in the coming years has been taken into account.Universidad de Sevilla. Master en Ingeniería Industria

Contemporary use of cefazolin for MSSA infective endocarditis: analysis of a national prospective cohort

Objectives: This study aimed to assess the real use of cefazolin for methicillin-susceptible Staphylococcus aureus (MSSA) infective endocarditis (IE) in the Spanish National Endocarditis Database (GAMES) and to compare it with antistaphylococcal penicillin (ASP). Methods: Prospective cohort study with retrospective analysis of a cohort of MSSA IE treated with cloxacillin and/or cefazolin. Outcomes assessed were relapse; intra-hospital, overall, and endocarditis-related mortality; and adverse events. Risk of renal toxicity with each treatment was evaluated separately. Results: We included 631 IE episodes caused by MSSA treated with cloxacillin and/or cefazolin. Antibiotic treatment was cloxacillin, cefazolin, or both in 537 (85%), 57 (9%), and 37 (6%) episodes, respectively. Patients treated with cefazolin had significantly higher rates of comorbidities (median Charlson Index 7, P <0.01) and previous renal failure (57.9%, P <0.01). Patients treated with cloxacillin presented higher rates of septic shock (25%, P = 0.033) and new-onset or worsening renal failure (47.3%, P = 0.024) with significantly higher rates of in-hospital mortality (38.5%, P = 0.017). One-year IE-related mortality and rate of relapses were similar between treatment groups. None of the treatments were identified as risk or protective factors. Conclusion: Our results suggest that cefazolin is a valuable option for the treatment of MSSA IE, without differences in 1-year mortality or relapses compared with cloxacillin, and might be considered equally effective