Thermoeconomic and environmental optimization of polygeneration systems for small-scale residential buildingsintegrating thermal and electric energy storage, renewable energy and legal restrictions.

El sector residencial, responsable del 27% del consumo energético mundial y 17% de emisiones de gases de efecto invernadero aproximadamente, desempeña un papel clave para combatir el cambio climático. Por esto, el uso de sistemas de poligeneración resulta una alternativa apropiada para cubrir las demandas energéticas de los edificios, ya que permiten un uso eficiente de los recursos naturales con un bajo impacto ambiental. En este sentido, esta tesis ha desarrollado un modelo de programación lineal entera mixta (MILP) para investigar estos sistemas de forma sistemática, integrando tecnologías renovables, como la solar y eólica, con almacenamiento de energía térmica y eléctrica, considerando equipos comerciales, teniendo en cuenta aspectos económicos y ambientales en el diseño. La investigación comienza por la forma de abordar el proceso de optimización, partiendo por la elección del método para seleccionar días representativos. Comparando diferentes métodos, se demuestra que su idoneidad depende en gran medida de la variabilidad de las series temporales involucradas en el sistema analizado. Además, se ha desarrollado un nuevo método que mejora los resultados del proceso de optimización. Por otro lado, se ha estudiado la viabilidad del uso de edificios residenciales como microrred. El estudio muestra que resultan rentables con respecto a los sistemas energéticos convencionales actuales, pero es necesario la aplicación de incentivos o permitir la venta de electricidad a un precio razonable para que sean competitivos. Adicionalmente, se han estudiado e identificado sinergias entre los componentes del sistema energético gracias al desarrollo de un modelo termoeconómico, que muestran la importancia de abordar el diseño de los sistemas energéticos considerando conjuntamente tecnologías térmicas y eléctricas, destacando la bomba de calor y los acumuladores de energía como tecnologías claves para lograr soluciones más económicas y sostenibles. Finalmente, se han aplicado las últimas regulaciones españolas de autoconsumo para evaluar su impacto económico y ambiental en el diseño de sistemas energéticos. Además, a través de la aplicación de la optimización multiobjetivo, se analizó si la reciente regulación de autoconsumo se ajusta a las metas europeas e internacionales para combatir el cambio climático. Asimismo, se estudia cómo podría abordarse la regulación para promover el desarrollo de sistemas energéticos sostenibles para el sector residencial. Los resultados sugieren actuar sobre la regulación de autoconsumo para reducir el impacto ambiental de forma efectiva. En general, esta tesis proporciona metodologías e ideas útiles para el diseño de sistemas energéticos sostenibles capaces de cubrir las demandas de energía de los edificios residenciales.The residential sector, responsible of about 27% of the global energy consumption and 17% of the greenhouse gas emissions, plays a key role in the action to combat climate change. In this sense, polygeneration systems could be considered a suitable alternative to attend the energy demands of residential buildings since they enable an efficient use of natural resources with a low environmental impact. This thesis developed a Mixed Integer Linear Programming (MILP) model to research these kind of systems in a systematic way to integrate renewable energy such as solar and wind energy with thermal and electric energy storage, considering commercial equipment for small-medium scale residential buildings, taking into account both economic and environmental aspects for the optimal design of such systems. The research starts from the suitable way to address the optimization process focused on the selection of the method to select representative days. Through the comparison of different methods, it was demonstrated that its right selection strongly depends on the variability of the time series involved in the analysed system. Besides, a new method was developed in order to improve the results of the optimization process. The developed MILP model was applied to study the feasibility of residential buildings as a microgrid. This innovative approach was found profitable with respect to the current conventional energy systems but it is necessary the application of feed-in tariff schemes or allowing the sale of electricity at reasonable price in order to make them competitive. Further, a thermoeconomic analysis was carried out to evaluate synergies between the components of the energy system. It was shown the importance of considering both thermal and electrical parts in the design of energy systems, highlighting the role of heat pumps and energy storage as key technologies, to achieve more cost-effective and sustainable solutions. Finally, the recent Spanish self-consumption regulations were applied to evaluate its impact on the design of energy systems. Moreover, through the application of multiobjective optimization and the analysis of different trade-off solutions was evaluated if this regulation aligned with European and international goals to combat climate change, and how it could be addressed in order to promote the design of affordable sustainable energy supply systems for the residential buildings. The obtained results suggest to act on the self-consumption regulation in order to achieve more significant reduction of greenhouse gas emissions. Overall, this thesis provided methodologies and useful insights for the design of sustainable energy systems for residential buildings.<br /

Evaluation of methods to select representative days for the optimization of polygeneration systems

The optimization of polygeneration systems considering hourly periods throughout one year is a computationally demanding task, and, therefore, methods for the selection of representative days are employed to reproduce reasonably the entire year. However, the suitability of a method strongly depends on the variability of the time series involved in the system. This work compares the methods Averaging, k-Medoids and OPT for the selection of representative days by carrying out the optimization of grid-connected and standalone polygeneration systems for a building in two different locations. The suitability of the representative days obtained with each method were assessed regarding the optimization of the polygeneration systems. Sizing errors under 5% were achieved by using 14 representative days, and the computational time, with respect to the entire year data, was reduced from hours to a few seconds. The results demonstrated that the Averaging method is suitable when there is low variability in the time series data; but, when the time series presents high stochastic variability (e.g., consideration of wind energy), the OPT method presented better performance. Also, a new method has been developed for the selection of representative days by combining the k-Medoids and OPT methods, although its implementation requires additional computational effort

Diagnóstico de la productividad sectorial en Antioquia

RESUMEN: El trabajo presenta las principales características de productividad y competitividad de seis sectores estratégicos de Medellín y Antioquia. Utilizando el “diamante de Porter”, se hace un diagnóstico global de los sectores y un análisis individual que conduce a plantear una serie de recomendaciones generales dirigidas al gobierno, empresarios e instituciones interesadas en impulsar proyectos o acciones para la mejora de la competitividad

Reducing the environmental impact of surgery on a global scale: systematic review and co-prioritization with healthcare workers in 132 countries

Abstract Background Healthcare cannot achieve net-zero carbon without addressing operating theatres. The aim of this study was to prioritize feasible interventions to reduce the environmental impact of operating theatres. Methods This study adopted a four-phase Delphi consensus co-prioritization methodology. In phase 1, a systematic review of published interventions and global consultation of perioperative healthcare professionals were used to longlist interventions. In phase 2, iterative thematic analysis consolidated comparable interventions into a shortlist. In phase 3, the shortlist was co-prioritized based on patient and clinician views on acceptability, feasibility, and safety. In phase 4, ranked lists of interventions were presented by their relevance to high-income countries and low–middle-income countries. Results In phase 1, 43 interventions were identified, which had low uptake in practice according to 3042 professionals globally. In phase 2, a shortlist of 15 intervention domains was generated. In phase 3, interventions were deemed acceptable for more than 90 per cent of patients except for reducing general anaesthesia (84 per cent) and re-sterilization of ‘single-use’ consumables (86 per cent). In phase 4, the top three shortlisted interventions for high-income countries were: introducing recycling; reducing use of anaesthetic gases; and appropriate clinical waste processing. In phase 4, the top three shortlisted interventions for low–middle-income countries were: introducing reusable surgical devices; reducing use of consumables; and reducing the use of general anaesthesia. Conclusion This is a step toward environmentally sustainable operating environments with actionable interventions applicable to both high– and low–middle–income countries