Metodología para el diseño de sistemas de electrificación autónomos para comunidades rurales

Los sistemas de electrificación autónomos basados en el uso de energías renovables son adecuados para electrificar comunidades rurales aisladas. Para su diseño existen herramientas de apoyo a la toma de decisiones, pero no abarcan algunas consideraciones técnicas y sociales, y/o no entran en el detalle específico del proyecto. En este contexto, el objetivo de esta tesis doctoral es desarrollar una metodología para ayudar en el diseño de sistemas de electrificación autónomos basados en las energías eólica y solar, que sea adecuada a las características económicas, técnicas y sociales de comunidades rurales de países en desarrollo, y que considere la opinión de todos los actores involucrados en el proyecto. La metodología de diseño propuesta se divide en 3 etapas principales: - La primera etapa consiste en realizar evaluaciones iniciales (socioeconómica, energética y técnica) para recopilar la información característica de la comunidad a electrificar. - La segunda etapa es el propio proceso de diseño en sí y se divide en 3 niveles de decisión, ordenados en función de la importancia de las decisiones a tomar. En concreto se estudia la influencia sobre el coste de modificaciones en la demanda (nivel 1), la gestión del sistema (nivel 2) y la seguridad del suministro (nivel 3). Cada nivel de decisión se estructura en 2 pasos: primero se generan diversas alternativas de electrificación con un modelo de programación lineal, incluyendo consideraciones técnicas y sociales; y segundo se selecciona la alternativa más adecuada en función de criterios económicos, técnicos y sociales, mediante la técnica multicriterio de la programación compromiso. - La tercera etapa, opcional, permite intentar mejorar el coste de la solución obtenida, manteniendo las decisiones previamente tomadas. Para la validación de este trabajo de investigación, dos expertos en el campo de la electrificación rural han actuado como hipotéticos usuarios de la metodología de diseño, y han realizado todo el proceso para las comunidades reales de El Alumbre y Alto Perú, ambas en Cajamarca (Perú). Se valida, de esta forma, que la metodología propuesta es adecuada para diseñar sistemas de electrificación autónomos. En concreto, permite personalizar la toma de decisiones de forma clara y estructurada, evaluando una gran cantidad de alternativas de electrificación y obteniendo unos resultados que concuerdan con las preferencias del usuario.Autonomous electrification systems based on the use of renewable energies are suitable to electrify isolated rural communities. For its design there are decision-making support tools, but they do not cover some technical and social constraints and do not consider the specific detail of the project. In this context, the aim of this PhD is to develop a methodology for helping to the design of autonomous electrification systems based on wind and solar energies, which is appropriate to the economic, technical and social aspects of rural communities in developing countries, and which considers the views of all stakeholders involved in the project. The proposed design methodology is divided into 3 principal stages: - In the first stage characteristics from the community to electrify are gathered through some initial assessments (socio-economic, resource and technical). - The second stage is the design process itself and is divided into 3 decision levels, ordered according to the importance of the decisions to take. Specifically the influence on the cost of modifications on the demand (level 1), the system management (level 2) and the security of supply (level 3) are studied. Each decision level is divided into 2 steps: first several electrification alternatives are generated through a linear programming model, including technical and social considerations; second the most appropriate alternative is selected based on economic, technical and social criteria, through compromise programming multicriteria technique. - The third stage, optional, allows trying to improve the cost of the obtained solutions, maintaining previously taken decisions. To validate this research work, two experts in the field of rural electrification have acted as hypothetical users of the design methodology, and have carried out all the process for the real communities of El Alumbre and Alto Peru, both in Cajamarca (Peru). Thus, it is validated that the proposed methodology is suitable to design autonomous electrification systems. Specifically, it allows personalizing decision-making in a clear and structured way, evaluating many electrification alternatives and obtaining results that match user’s preferences up

A MILP model for the teacher assignment problem considering teachers’ preferences

The Teacher Assignment Problem is part of the University Timetabling Problem and involves assigning teachers to courses, taking their preferences into consideration. This is a complex problem, usually solved by means of heuristic algorithms. In this paper a Mixed Integer Linear Programing model is developed to balance teachers’ teaching load (first optimization criterion), while maximizing teachers’ preferences for courses according to their category (second optimization criterion). The model is used to solve the teachers-courses assignment in the Department of Management at the School of Industrial Engineering of Barcelona, in the Universitat Politècnica de Catalunya. Results are discussed regarding the importance given to the optimization criteria. Moreover, to test the model's performance a computational experiment is carried out using randomly generated instances based on real patterns. Results show that the model is proven to be suitable for many situations (number of teachers-courses and weight of the criteria), being useful for departments with similar requests.Peer ReviewedPostprint (author's final draft

Modelo para el diseño de proyectos de electrificación rural con consideraciones técnicas y sociales

En la casi totalidad de los países del mundo, la estrategia más utilizada para dar acceso a la electricidad es la extensión de la red eléctrica. Sin embargo, esta estrategia es poco factible cuando se trata de llegar a zonas alejadas, de difícil acceso y con baja densidad de población. Una buena alternativa, son los sistemas autónomos y descentralizados, basados en energías renovables. Los sistemas eólicos y fotovoltaicos son una de las opciones técnicas posibles. Para diseñar estos sistemas, existen modelos matemáticos que consideran criterios técnicos y económicos pero se ha visto que es necesario incorporar criterios sociales para facilitar la integración de los sistemas de electrificación en el día a día de los beneficiarios. Este trabajo tiene como objetivo analizar las características sociales a incluir, incorporar éstas en los modelos matemáticos y estudiar la influencia de cada una sobre las soluciones de electrificación. Con este trabajo se obtiene un modelo matemático de programación lineal entera y mixta que minimiza costes a la vez que cumple con las exigencias técnicas de los equipos e incorpora consideraciones sociales para mejorar la calidad y la seguridad del suministro energético así como facilitar la gestión de los sistemas de electrificación. Para ello, en primer lugar se analizan problemas sociales hallados en diferentes experiencias de electrificación y se determinan posibles soluciones o mejoras. En segundo lugar, se proponen y validan distintas modelizaciones para cada mejora, con el objetivo determinar la modelización más eficiente e incorporarla a los modelos. Finalmente, en tercer lugar, se estudia la influencia de cada mejora sobre las soluciones de electrificación, para comprobar el aporte de cada una al bienestar social de las comunidades. La experimentación se valida en 5 comunidades de la sierra andina peruana (Cajamarca, Perú); 3 de ellas ya electrificadas (El Alumbre, Alto Perú parte carretera y Campo Alegre) y 2 por electrificar (Alto Perú parte Norte y Alto Perú parte Sur). Como resultado de la experimentación, las mejoras sociales aportadas en este trabajo logran generar sistemas de electrificación que mejoran la seguridad del suministro energético y facilitan la gestión de los sistemas de electrificación, con unos incrementos de coste muy pequeños

Evaluating urban freight transport policies within complex urban environments

Urban Freight Transport (UFT) entails significant advantages for the economic growth of cities, but can also hamper population quality of life, obstructing vehicles and people movements while exacerbating environmental problems. Many initiatives have been engaged by many city administrators in order to efficiently manage UFT, evaluating different policies at a global scale. From the perspective of operators, most works analyze a limited set of policies or only focus on the benefits of companies. In this work, a decisionmaking process is used to evaluate a large set of UFT policies, through different attributes representing the advantages and limitations of each policy over promoter companies and the society. To do so, an ex-ante procedure in five steps is proposed to classify the policies: (1) attributes definition, (2) attributes weighting, (3) policy-attribute assessment, (4) policy ranking, and (5) feasibility threshold satisfaction. The whole process is supported on consultations to 26 experts regarding shop supply and restocking activities within complex urban environments. Results show a classification of the analyzed policies, according to their suitability for implementation ; which could be extended (directly or with small adjustments) to other contexts, given the flexibility of the decision-making procedure developed.Peer ReviewedPostprint (author's final draft

A step-by-step guide to assist logistics managers in defining efficient re-shelving solutions for retail store deliveries

Purpose City logistics is a challenge in many cities. Literature works focus on the analysis of large or local-scale solutions to increase the efficiency of freight transport. However, store deliveries from the perspective of practitioners, particularly retail stores, are still an issue. In this context, the purpose of this paper is to propose a decision framework to assist logistics managers in defining efficient re-shelving solutions for store deliveries, according to the emplacement characteristics, city administration constraints and social issues. Design/methodology/approach An iterative step-by-step decision framework is developed, which allows taking decisions in a clear and structured way, including the preferences of key stakeholders. Moreover, a “what if” procedure is proposed, aiming to modify some initial conditions of the target store to achieve more efficient solutions. Findings The proposed decision framework is applicable in practice and helps users (mainly logistics managers) to identify solutions for efficient re-shelving in urban settings. Research limitations/implications The decision framework is applied by the logistics manager of two Spanish food retail stores, but it could be used in different logistics sectors and cities/regions, although adapting the decisions taken at each phase. Practical implications Logistics managers have a support tool when addressing re-shelving solutions for store deliveries. Social implications A balance can be found between company interests (minimise costs) and citizens quality of life (less contamination, noise, traffic, etc.). Originality/value This study simultaneously deals with large- and local-scale decisions faced by logistics managers in their day-to-day activity, considering details about the store location, its surroundings and the company it belongs.Peer ReviewedPostprint (author's final draft

Potential of implementation of residential photovoltaics at city level: the case of London

In recent years, reductions in the price of photovoltaic panels and batteries have made them profitable. However, the achievement of grid parity, i.e. whether these systems are cheaper than the national grid for residential users, is still being debated. This paper quantifies the proportion of demand that could be covered assuming that solar-battery adoption is decided based on the maximum profit, the maximum autarky with no extra cost or the maximum autarky with limited extra-cost. A simulation model is developed which performs a half-hourly analysis for one year, considering the solar radiation, the consumption pattern and characteristics of equipment. London is examined using a database gathering consumption from 5567 households. In particular, the techno-economic performance of the systems is studied according to different reward schemes (from a non-subsidized to a high compensation one). Results are discussed according to the optimisation strategy: maximising profit, for users seeking economic performance; and maximum autarky, for users willing independence from the grid. Complementarily, the correlation between characteristics of consumption profiles and autarky is analysed. Results show that installations are profitable for a reward of 0.03 £/kWh, under profit maximisation, and can attain 90% autarky. The injection reward is still essential to make batteries profitable.Peer ReviewedPostprint (published version

A community electrification project: combination of microgrids and household systems fed by wind, PV or micro-hydro energies according to micro-scale resource evaluation and social constraints

When electrifying isolated rural communities, usually standardized solutions have been implemented using the same technology at all the points. However these solutions are not always appropriate to the community and its population. This article aims to describe the technical design of the electrification system of the community of Alto Peru (in the region of Cajamarca, Peru), where the adequate technology was used at each area according to micro-scale resource evaluation and the socioeconomic requirements of the population. Specifically four technologies were implemented: wind microgrids in highlands, a micro-hydro power plant in the presence of a waterfall, a PV microgrid in a group of points sheltered from the wind and individual PV systems in scattered points with low wind potential. This project brought electricity to 58 households, a health center, a school, a church, two restaurants and two shops.Peer ReviewedPostprint (author’s final draft

Including management and security of supply constraints for designing stand-alone electrification systems in developing countries

Hybrid wind-photovoltaic stand-alone systems have proven to be suitable to electrify isolated communities autonomously. Moreover, the use of a combination of microgrids and individual systems has been demonstrated to be very adequate. There are a few tools to assist their design but they only consider economical and technical characteristics. However, the management of the system and the security of supply, both at a community level, are key aspects to design appropriate electrification systems for end-users, thus ensuring projects' long-term sustainability, especially in rural areas of developing countries. In this context, this paper develops a mathematical model to optimise the design of wind-photovoltaic projects combining microgrids and individual systems, and including the aforesaid key issues as constraints. Thus, the aim is to minimise the cost while meeting the technical but also the management and the security of supply constraints. Finally a validation is carried out in the real community of Alto Peru (Peru), proving that the two studied aspects allow obtaining electrification solutions with some benefits that strongly compensate the obtained slight cost increases.Peer ReviewedPostprint (author’s final draft

Hierarchical methodology to optimize the design of stand-alone electrification systems for rural communities considering technical and social criteria

Stand-alone electrification systems based on the use of renewable energies are suitable to electrify isolated rural communities in developing countries. For their design several support tools exist, but they do not cover some of the technical and social existing constraints and they do not consider the project detail. In this context, this research aims to develop a methodology to optimize the design of such systems, combining the wind and solar generation technologies as well as microgrids and individual systems as distribution scheme, and including economical, technical and social considerations. The design methodology is divided in three stages. First, the characteristics of the target community are gathered. Secondly, the design process is realized in three decision levels, ordered according to the importance of the decisions taken. At each level several electrification alternatives are generated and then the most appropriate is selected. Third, the final solution cost can be optionally tried to be improved, maintaining the decisions previously taken. The design methodology has been applied to a community to show its suitability to assist rural electrification promoters to design socially adapted and sustainable projects.Postprint (author's final draft

Multicriteria analysis of renewable-based electrification projects in developing countries

The design of wind-photovoltaic stand-alone electrification projects that combine individual systems and microgrids is complex and requires from support tools. In this paper, a multicriteria procedure is presented in detail, which aims to assist project developers in such a design. More specifically, the procedure has been developed under a four-part structure, using support tools and expert consultations to enhance practicality into the rural context of developing countries. First, from a large amount of criteria, a reduced and easy to handle set is chosen, representing the main characteristics to be assessed in rural electrification projects. Second, two iterative processes, one based on the Analytical Hierarchy Process and one based on a typical 1–10 assessment, are tested to assign weights to the criteria, reflecting end-user preferences. Third, some indicators are proposed to evaluate the accomplishment of each solution regarding each criterion, in an objective manner. Fourth, considering the weights and evaluations, the solutions are ranked, using the compromise programming technique, thus selecting the best one/s. The whole procedure is illustrated by designing the electrification project of a real community in the Andean highlands. In short, this paper provides insights about the suitable decision-making process for the design of wind-PV electrification systems and, in addition, shows how different multicriteria techniques are applied to a very local context in rural, remote and very poor areas of developing countries.Peer ReviewedPostprint (author's final draft