172 research outputs found
Economic and environmental analysis of central solar heating plants with seasonal storage for the residential sector
Buildings represent 40% of the Union’s final energy consumption; the member states should establish a strategy to improve the energy performance in buildings and reduce the consumption of non-renewable primary energy. In Spain, the implementation of the Technical Building Code (CTE) compels to install solar thermal collectors in new buildings providing a minimum solar contribution of domestic hot water (DHW). In north and center European countries, e.g. Denmark, Germany and Austria, new installations also supply heat for the space heating needs. The approach of central solar heating plants with seasonal storage (CSHPSS) is the storage of solar thermal energy from the period of higher offer (summer) to be consumed in the periods of higher demand (winter). These installations are integrated into district heating systems that supply heat for a large number of dwellings and reach a solar fraction of 50% or higher. In this thesis the experience gained in Europe on centralized solar district heating systems with seasonal storage will be transferred to the Spanish situation, in order to establish the conditions and criteria for installing these systems in Spain in the midterm. The main objective of this thesis is the proposal and design of CSHPSS that could be able to provide a high fraction of thermal energy demand with solar thermal energy for different climatic areas. These systems should be feasible from a technical viewpoint, economically acceptable, and with a low environmental impact. That is, this thesis unveils the requirements for the feasibility of CSHPSS and is intended to foster their development in Spain. In order to reach this objective, it has been performed a revision of the state of the art of district heating systems, with emphasis to: i) solar district heating systems and CSHPSS; ii) design and calculation methods that could be used for new systems in Spain; iii) economic data and results from existing solar district heating systems and CSHPSS in Europe and worldwide; and iv) environmental assessment methodologies and analysis performed for solar thermal components and systems. An original calculation method for the analysis, design and evaluation of these installations from technical, economic and environmental points of view has been developed. The variation of solar radiation along the day and the year and the monthly distribution of the residential sector demand are considered. The main advantage of the method developed, compared to other methods, is the simplification of the calculation process and the utilization of simple climatic and demand data. The method developed has also been used to perform parametric analyses that have served to obtain new design criteria for different locations. The technical viability of these installations is not enough argument to motivate their development. The investment cost of these installations has therefore been analyzed according to the main design parameters (area of solar collectors and seasonal storage volume) and validated with results from real projects in north European countries. Moreover, this thesis analyzes the environmental impact of these installations using the Life Cycle Assessment (LCA) methodology. This impact assessment not only considers the consumption of fuels and electricity for the production of energy but also the consumption of materials for the construction of the plant. Three different environmental assessment methods have been used to determine the impacts generated and avoided by a CSHPSS: i) emission of greenhouse gases and their contribution to the global warming; ii) consumption of primary energy; and iii) environmental indicator IMPACT 2002+, which encompasses a significant range of environmental burdens. Based on the previous thermal, economic and environmental models and analyses developed, appropriate design criteria for CSHPSS in different geographical areas have been established. It has been concluded that design criteria are strongly dependent on the local climatic and demand conditions. Therefore, CSHPSS designs for north European countries cannot be applied in south Europe. Furthermore, it has also been concluded that CSHPSS have a considerable potential in Spain; i.e. it is interesting to build CSHPSS in those regions of Spain with significant heating demand, because they can supply heat to large communities at a competitive cost with a low environmental impact. Finally, from the calculation and analysis tools developed in the thesis, a software application with a friendly user interface has been developed to pre-design CSHPSS. The software is mainly oriented to European locations and provides the thermal performance, economic cost and environmental impact of the evaluated CSHPSS.Los edificios representan el 40% del consumo de energía final de la Unión Europea; los estados miembros deben establecer una estrategia para mejorar la eficiencia energética de los edificios y reducir el consumo de energía primaria no renovable. En España con la entrada en vigor del Código Técnico de la Edificación (CTE) se ha pretendido sustituir energía procedente de combustibles fósiles por energía solar y se obliga a la instalación de sistemas solares térmicos para proporcionar una contribución solar mínima anual a la demanda de agua caliente sanitaria (ACS). Sin embargo en los países del centro y norte de Europa como Dinamarca, Alemania y Austria, que destacan por su aprovechamiento de la energía solar, vemos que parte de sus nuevas instalaciones aportan energía solar térmica para cubrir también las necesidades de calefacción. El interés de las centrales solares térmicas con acumulación estacional consiste en el aprovechamiento del exceso de captación solar en el periodo de mayor oferta (verano) para su consumo en el periodo de mayor demanda (invierno). Estas instalaciones se integran en sistemas de calefacción de distrito que proveen energía térmica a un elevado número de viviendas alcanzando una fracción solar elevada (> 50%). En esta tesis se adapta al caso de España la experiencia obtenida en Europa acerca de los sistemas de calefacción solar de distrito con acumulación estacional y se esclarecen las condiciones y criterios que harían interesante su implantación a medio plazo en nuestro país. El principal objetivo de esta tesis consiste en proponer y prediseñar sistemas de calefacción solar de distrito con acumulación estacional para distintas zonas climáticas y diferentes tamaños de distrito, que sean: i) técnicamente viables, ii) económicamente rentables, y iii) con bajo impacto ambiental. En otras palabras, esta tesis desvela y establece los requisitos para que los sistemas de calefacción solar de distrito con acumulación estacional sean una alternativa interesante, contribuyendo de este modo al desarrollo de estas instalaciones en España. Para poder alcanzar este objetivo se ha llevado a cabo una revisión del estado del arte de los sistemas de calefacción de distrito, haciendo especial énfasis en: i) sistemas de calefacción solar de distrito con acumulación estacional; ii) métodos de cálculo y diseño que puedan ser empleados para la propuesta de sistemas de estas características en distintas zonas geográficas de España; iii) datos y resultados económicos de sistemas de calefacción solar de distrito con acumulación estacional actualmente existentes en Europa y en el mundo; y iv) datos y metodologías para su evaluación ambiental y análisis de ciclo de vida (ACV). Se ha desarrollado un método de cálculo original para el análisis, diseño y evaluación de estas instalaciones desde un punto de vista técnico, económico y ambiental. El método desarrollado considera la variación de la radiación solar a lo largo del día y del año y la distribución mensual de la demanda térmica en el sector residencial. La principal ventaja del método desarrollado frente a otros trabajos es la simplificación del proceso de cálculo y la utilización de datos climáticos y de demanda fáciles de encontrar. Con el método desarrollado se han realizado análisis paramétricos que han servido para definir nuevos criterios de diseño para distintas localizaciones. La comprobación de la viabilidad técnica de estas instalaciones no supondría por si solo un argumento suficiente para impulsar su desarrollo, por tanto se analiza el coste de inversión en función de las principales variables de diseño de la instalación (área de captación solar y volumen del acumulador estacional). Más allá, esta tesis analiza el impacto ambiental de estas instalaciones utilizando la metodología del análisis de ciclo de vida. La evaluación ambiental realizada considera los efectos de los consumos de combustibles y electricidad para la producción de energía térmica, y además el consumo de materiales para la construcción de la planta. Se han utilizado tres métodos diferentes para determinar los impactos ambientales generados y los beneficios ambientales alcanzados: i) emisión de gases de efecto invernadero y su contribución al cambio climático; ii) consumo de energía primaria; y iii) cálculo del indicador ambiental IMPACT 2002+ que abarca una gran variedad de aspectos ambientales. Gracias a los modelos desarrollados y a los análisis llevados a cabo considerando el comportamiento físico, económico y ambiental de los sistemas de calefacción solar de distrito con acumulación estacional, se han definido criterios de diseño adecuados para diferentes zonas geográficas. Una de las principales conclusiones alcanzadas es que el diseño correcto de estos sistemas depende fuertemente de las condiciones climáticas y de la demanda de las viviendas. Por tanto, los diseños aplicados en el norte de Europa no pueden ser trasladados al sur de Europa. Asimismo se concluye que los sistemas de calefacción solar de distrito con acumulación estacional son viables técnica y económicamente en las zonas de España con elevado consumo de calefacción; es decir, estos sistemas cuentan en nuestro país con un potencial elevado para atender las necesidades de calefacción de grandes comunidades a un coste competitivo y además con bajo impacto ambiental. Finalmente indicar que a partir de los modelos y herramientas de análisis elaborados se ha desarrollado una aplicación informática de fácil manejo para el pre-diseño de sistemas de calefacción solar de distrito con acumulación estacional, principalmente orientado a localidades europeas, que proporciona el comportamiento térmico del sistema y estima su coste económico e impacto ambiental
Combining Machine Learning Analysis and Incentive-Based Genetic Algorithms to Optimise Energy District Renewable Self-Consumption in Demand-Response Programs
The recent rise of renewable energy sources connected to the distribution networks and the high peak consumptions requested by electric vehicle-charging bring new challenges for network operators. To operate smart electricity grids, cooperation between grid-owned and third-party assets becomes crucial. In this paper, we propose a methodology that combines machine learning with multi-objective optimization to accurately plan the exploitation of the energy district&rsquo
s flexibility with the objective of reducing peak consumption and avoiding reverse power flow. Using historical data, acquired by the smart meters deployed on the pilot district, the district&rsquo
s power profile can be predicted daily and analyzed to identify potentially critical issues on the network. District&rsquo
s resources, such as electric vehicles, charging stations, photovoltaic panels, buildings energy management systems, and energy storage systems, have been modeled by taking into account their operational constraints and the multi-objective optimization has been adopted to identify the usage pattern that better suits the distribution operator&rsquo
s (DSO) needs. The district is subject to incentives and penalties based on its ability to respond to the DSO request. Analysis of the results shows that this methodology can lead to a substantial reduction of both the reverse power flow and peak consumption.
Document type: Articl
Multi-energy retail market simulation with autonomous intelligent agents
Tese de doutoramento. Engenharia Electrotécnica e de Computadores. 2005. Faculdade de Engenharia. Universidade do Port
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Thermodynamic and thermal comfort optimisation of a coastal social house considering the influence of the thermal breeze
Tropical coastal areas are characterised by high levels of wind and solar resources with large potentials to be utilised for low-energy building design. This paper presents a multi-objective optimisation framework capable of evaluating cost-efficient and low-exergy coastal building designs considering the influence of the thermal breeze. An integrated dynamic simulation tool has been enhanced to consider the impacts of the sea-land breeze effect, aiming at potentiating natural cross-ventilation to improve occupant's thermal comfort and reduce cooling energy demand. Furthermore, the technological database considers a wide range of active and passive energy conservation measures. As a case study, a two-storey/two-flat detached social house located in the North-Pacific coast of Mexico has been investigated. The optimisation problem has considered the minimisation of: i. annual exergy consumption, ii. life cycle cost, and iii. thermal discomfort. Optimisation results have shown that adequate building orientation and window opening control to optimise the effects of the thermal breeze, combined with other passive and active strategies such as solar shading devices, an improved envelope's physical characteristics, and solar assisted air source heat pumps have provided the best performance under a limited budget. Compared to the baseline design, the closest to utopia design has increased thermal comfort by 93.8% and reduced exergy consumption by 10.3% whilst increasing the life cycle cost over the next 50 years by 18.5% (from US47,246). The importance of renewable generation incentives is further discussed as a counter effect measure for capital cost increase as well as unlocking currently high-cost low-exergy technologies
Promoting energy efficiency in the built environment through adapted BIM training and education
The development of new climate change policies has increased the motivation to reduce energy use in buildings, as reflected by a stringent regulatory landscape. The construction industry is expected to adopt new methods and strategies to address such requirements, focusing primarily on reducing energy demand, improving process efficiency and reducing carbon emissions. However, the realisation of these emerging requirements has been constrained by the highly fragmented nature of the industry, which is often portrayed as involving a culture of adversarial relationships and risk avoidance, which is exacerbated by a linear workflow. Recurring problems include low process efficiency, delays and construction waste. Building information modelling (BIM) provides a unique opportunity to enhance building energy efficiency (EE) and to open new pathways towards a more digitalised industry and society. BIM has the potential to reduce (a) waste and carbon emissions, (b) the endemic performance gap, (c) in-use energy and (d) the total lifecycle impact. BIM also targets to improve the whole supply chain related to the design, construction as well as the management and use of the facility. However, the construction workforce is required to upgrade their skills and competencies to satisfy new requirements for delivering BIM for EE. Currently, there is a real gap between the industry expectations for employees and current training and educational programmes. There is also a set of new requirements and expectations that the construction industry needs to identify and address in order to deliver more informed BIM for EE practices. This paper provides an in-depth analysis and gap identification pertaining to the skills and competencies involved in BIM training for EE. Consultations and interviews have been used as a method to collect requirements, and a portfolio of use cases have been created and analysed to better understand existing BIM practices and to determine current limitations and gaps in BIM training. The results show that BIM can contribute to the digitalisation of the construction industry in Europe with adapted BIM training and educational programmes to deliver more informed and adapted energy strategies
Federating cloud systems for collaborative construction and engineering
The construction industry has undergone a transformation in the use of data to drive its processes and outcomes, especially with the use of Building Information Modelling (BIM). In particular, project collaboration in the construction industry can involve multiple stakeholders (architects, engineers, consultants) that exchange data at different project stages. Therefore, the use of Cloud computing in construction projects has continued to increase, primarily due to the ease of access, availability and scalability in data storage and analysis available through such platforms. Federation of cloud systems can provide greater flexibility in choosing a Cloud provider, enabling different members of the construction project to select a provider based on their cost to benefit requirements. When multiple construction disciplines collaborate online, the risk associated with project failure increases as the capability of a provider to deliver on the project cannot be assessed apriori. In such uncontrolled industrial environments, “trust” can be an efficacious mechanism for more informed decision making adaptive to the evolving nature of such multi-organisation dynamic collaborations in construction. This paper presents a trust based Cooperation Value Estimation (CoVE) approach to enable and sustain collaboration among disciplines in construction projects mainly focusing on data privacy, security and performance. The proposed approach is demonstrated with data and processes from a real highway bridge construction project describing the entire selection process of a cloud provider. The selection process uses the audit and assessment process of the Cloud Security Alliance (CSA) and real world performance data from the construction industry workloads. Other application domains can also make use of this proposed approach by adapting it to their respective specifications. Experimental evaluation has shown that the proposed approach ensures on-time completion of projects and enhanced..
Synthesizing multi-layer perceptron network with ant lion biogeography-based dragonfly algorithm evolutionary strategy invasive weed and league champion optimization hybrid algorithms in predicting heating load in residential buildings
The significance of accurate heating load (HL) approximation is the primary motivation of this research to distinguish the most efficient predictive model among several neural-metaheuristic models. The proposed models are formulated through synthesizing a multi-layer perceptron network (MLP) with ant lion optimization (ALO), biogeography-based optimization (BBO), the dragonfly algorithm (DA), evolutionary strategy (ES), invasive weed optimization (IWO), and league champion optimization (LCA) hybrid algorithms. Each ensemble is optimized in terms of the operating population. Accordingly, the ALO-MLP, BBO-MLP, DA-MLP, ES-MLP, IWO-MLP, and LCA-MLP presented their best performance for population sizes of 350, 400, 200, 500, 50, and 300, respectively. The comparison was carried out by implementing a ranking system. Based on the obtained overall scores (OSs), the BBO (OS = 36) featured as the most capable optimization technique, followed by ALO (OS = 27) and ES (OS = 20). Due to the efficient performance of these algorithms, the corresponding MLPs can be promising substitutes for traditional methods used for HL analysis
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