Rafael López-Luque

• Professor
• University of Córdoba

Increasing daylighting levels contributes to improving the energy efficiency of buildings and consequently to the fight against climate change. This work presents a new illuminator based on a previous single-axis polar heliostat. This heliostat allows redirecting sunlight to a specific space to be illuminated at any time of the day. The system pres...

Renewable energies play an important role as a solution to the challenge of satisfying the growing global energy demand without jeopardizing the achievements in the fight against climate change. Given this panorama, different countries, including Spain, have developed policies to promote renewable energies. One of the technologies that benefit from...

Agrivoltaics is currently presented as a possible effective solution to one of society’s greatest challenges: responding to the increasing demand for energy and food in an efficient and sustainable manner. To this end, agrivoltaics proposes to combine agricultural and renewable energy production on the same land using photovoltaic technology. The p...

The fight against climate change makes it necessary, among other measures, to improve the energy efficiency of buildings. One way of doing this is to improve the levels of natural lighting inside buildings. In this sense, this paper analyses the possible use of heliostats as natural illuminators in an educational space. For this purpose, a classroo...

The continuous growth of the world population is causing an increase in the demands for food and energy of the population. Given these circumstances and the negative consequences derived from climate change, it is necessary to evolve towards a more efficient and sustainable agricultural system. In this sense, the agrivoltaic proposes to combine agr...

The growing need to increase environmental and energy sustainability in buildings (housing, offices, warehouses, etc.) requires the use of solar radiation as a renewable source of energy that can help to lower carbon footprint, making buildings more efficient and thereby contributing to a more sustainable planet, while enhancing the health and well...

World population growth is leading to an increased demand for energy and food. This is creating a conflict over land use as terrain for large renewable energy facilities is not available for agricultural. As a solution, agrivoltaics combines the use of the land for agricultural and photovoltaic exploitation. In this work, the conversion of photovol...

In this study, an algorithm has been developed that manages photovoltaic solar energy in such a manner that all generated power is delivered to the system formed by a pump and irrigation network with compensated emitters. The algorithm is based on the daily work matrix that is updated daily by considering water and energy balances. The algorithm de...

A significant percentage of energy consumption in buildings is to produce hot water. Photovoltaic solar heating can be considered a clean and renewable energy option—easy to install, silent, and without maintenance—to replace the consumption of fossil fuels used in this process. This paper presents a study that simulates the heating process using t...

PV self-consumption can contribute positively to the spread of PV and, therefore, to the progress of renewable energies as a key element in a decarbonized energy model. However, the policies of each country regarding the promotion of this type of renewable technology is fundamental for their growth. Despite the high number of sunshine hours registe...

This paper investigates how to optimally orient the photovoltaic solar trackers of an axis parallel to the terrain, applying the sky model of Hay–Davies. This problem has been widely studied. However, the number of studies that consider the orientation (inclination and azimuth of the terrain) is very limited. This paper provides an examination of i...

Photovoltaics is experiencing significant growth because it is a renewable energy resource capable of contributing positively to the global energy system. However, the high variability in solar resources and the inter-collectors shadows negatively influence the energy conversion of a photovoltaic plant, making it necessary to develop technologies t...

The control of refrigeration in the food chain is fundamental at all stages, with special emphasis on the retail stage. The implementation of information and communication technologies (IoT, open-source hardware and software, cloud computing, etc.) is representing a revolution in the operational paradigm of food control. This paper presents a low-c...

Standalone direct pumping PV irrigation systems are a special type of PV system in which water is not lifted to a tank but, instead, is pumped to the irrigation system to satisfy the crop water needs. The operation of these PV irrigation systems requires efficient new operation rules in order to maximize the energy use efficiency as the PV energy m...

Small off-grid photovoltaic (PV) pumping irrigation systems with storage tanks are an environmentally friendly, cost effective and efficient way of taking advantage of solar energy to irrigate crops, and they are increasingly being used today. However, finding the optimal design of this type of system is cumbersome since there are many possible des...

The growing need to improve the environmental and energy sustainability of buildings involves the use of solar radiation incident on their surfaces. However, in cities, this task is complicated due to the constructive geometry that leads to shading between buildings. In this context, this work presents a study of solar access to the façades of buil...

Solar tracking is a technique required to increase energy production in multiple photovoltaic (PV) facilities. In these plants, during low-elevation solar angle hours, shadows appear between the collectors causing a dramatic decrease in production. This paper presents a novel optimal tracking strategy to prevent the creation of these shadows. The p...

In recent decades, considerable efforts have been devoted to process automation in agriculture. Regarding irrigation systems, this demand has found several difficulties, including the lack of communication networks and the large distances to electricity supply points. With the recent implementation of LPWAN wireless communication networks (SIGFOX,...

Presentation of the Solar Energy Assessment and Planning Tool (SEAP) service

This chapter describes the main components of a photovoltaic (PV) irrigation system. These elements are the PV modules, the maximum power point tracker, the inverter, the pumping system, and the irrigation system. Two main types of PV irrigation systems can be distinguished, and a comprehensive discussion on their advantages and disadvantages is do...

This work presents a new approach to increase the efficiency of the heuristics methods applied to the optimal design of water distribution systems. The approach is based on reducing the search space by bounding the diameters that can be used for every network pipe. To reduce the search space, two opposite extreme flow distribution scenarios are ana...

This paper presents the analytical deduction of generic and unified equations of the movement of solar tracking systems. These equations reproduce published equations, which only consider the sun position, or the equations of the astronomical movement. As a novelty, these equations are more generic, thus allowing the optimization of the positioning...

RESUMEN Este trabajo se realizó como una evaluación de la viabilidad técnico-económica de la utilización de la energía solar fotovoltaica para el riego de cultivos de invernaderos existentes en la cuenca mediterránea al sur de España, con dos diferentes modelos de gestión de la energía solar: el del autoconsumo y el del balance neto. Se desarrolló...

Electric lighting is the most important source of power consumption in buildings. For that reason, one of the most common measures adopted when constructing sustainable buildings is the use of elements of daylighting to reduce the use of artificial lighting. However, high density of buildings in cities complicates the introduction of natural lighti...

The increasing improvement of energy sustainability entails a raise in the use of heliostats in small applications. These devices aim to use direct radiation as a source of natural lighting, and they are also used as components for concentration systems in thermal and photovoltaic applications. Most technological developments published about helios...

Stochastic simulation methods are normally extended as the only available to assess the reliability of the PV system implies the generation, for an extended period of time, of the main state variables of the physical equations describing the energy balance of the system, that is, the energy delivered to the load and the energy stored in the batteri...

The profitability of photovoltaic (PV) systems for irrigating Mediterranean greenhouse crops is analyzed. A standalone direct pumping PV system is proposed. A simulation model of the system was developed in order to obtain the economically optimal design of this system and evaluate its feasibility. The model is composed of several submodels: the ph...

The increasing improvement of energy sustainability entails an increase in the use of heliostats in small applications for urban environments. For these applications, smaller heliostats and lower distances traveled by reflected rays are proposed, and, consequently, higher tolerances in error are allowed. This paper describes a new simple heliostati...

The solar radiation balance in buildings has a significant impact on their energy needs, as well as on their potential BIPV energy production. It also influences the potentials of daylight, its healthiness and sustainability. Solar radiation models for urban environments require the characterization of the obstruction degree to which each point is...

The solar radiation balance in buildings has a significant impact on their energy needs, as well as on their potential BIPV energy production. It also influences the potentials of daylight, its healthiness and sustainability. Solar radiation models for urban environments require the characterization of the obstruction degree to which each point is...

In soilless culture, water and nutrients must be frequently and precisely applied due to the reduced volume and low water holding capacity of the substrate. For this reason, irrigation scheduling is an important and difficult task. The use of an irrigation control tray with two electrodes (level sensor) is a simple way for controlling irrigation. I...

Sizing SAPV techniques try to assess the reliability of the system from the stochastic simulation of the energy balance. This stochastic simulation implies the generation, for an extended period of time, of the main state variables of the physical equations describing the energy balance of the system, that is, the energy delivered to the load and t...

The quality of cork is one of the most important issues for the cork industry. It is a complex process that requires evaluating many factors and simultaneously handles continuous and discrete variables, sometimes with a high degree of subjectivity. There are two objectives, in first place to establish the relationship between the commercial quality...

The level of comfort inside buildings is highly related to daylight availability, which is associated with solar access, irradiation on windows as well as solar rights. These mentioned variables are frequently calculated using similar methods. For the graphic study of these variables, mathematical projections are used which provide a geometric view...

In this report, solar radiation and daylight functions for the analysis of shadows, irradiance and radiant exposure on building facades in urban environments are presented. The functions are fully developed in MS Excel using Visual Basic for Applications.

The sun is the more plentiful source of natural power that we have in the Earth. However, the amount of radiation reaching the Earth's surface depends on astronomical and climatic factors. One of the factors exerting a greater influence is cloudiness. For that reason, it is important to quantify its influence on solar radiation. According to that,...

El objetivo de este trabajo es evaluar el potencial de la espectroscopía en el infrarrojo cercano combinada con análisis multivariante para identificar el origen geográfico de planchas y tapones de corcho natural. Se utilizaron tres colectivos, el primero formado por 479 planchas de Marruecos, Portugal y España (escala internacional), el segundo po...

The objective of this viability study is to assess the potential of near infrared spectroscopy (VIS +NIRS) technology combined with multivariate analysis for characterising cork plank and stoppers according to the following variables: Visual quality, porosity, physical properties, mechanical properties and geographical origin. The study was carried...

Nowadays irrigation district managers require several tools to assess irrigation networks' performance such as hydraulic models, geographic information systems (GIS) or decision support systems (DSS) which are available but as independent elements. Thus, simplifying the use of these tools by means of applications that integrate all these components...

This paper presents a new solar irradiance model for the estimation of the solar radiation on façades of buildings in urban environments. A model and a computer tool, using Visual Basic Application of Excel, have been developed to analyse in detail the radiation on façades. It can be used to determine, in a very intuitive, easy and fast way, using...

Energy audits of existing buildings require efficient devices and procedures to assess the solar potential through windows and building openings. The use of insolation is related to solar rights, solar gain, daylight potential and solar control. The methods described in the literature to assess insolation on windows require the geometric characteri...

The procedures used today to characterize cork plank for the manufacture of cork bottle stoppers continue to be based on a traditional, manual method that is highly subjective. Furthermore, there is no specific legislation regarding cork classification. The objective of this viability study is to assess the potential of near-infrared spectroscopy (...

An analysis of models for the estimation of hourly diffuse irradiation based on the interrelations between the hourly diffuse fraction kd and the hourly clearness index kt, has concluded that kt is not a sufficient variable for parametrizing the effect of clouds on diffuse irradiation. A detailed study of the dispersion recorded by this diffuse com...

Pressurized irrigation networks and organized on-demand are usually constrained by the high amounts of energy required for their operation. In this line, sectoring, where farmers are organized in turns, is one of the most efficient measures to reduce their energy consumption. In this work, a methodology for optimal sectoring is developed. Initially...

Se aborda el desarrollo de un modelo de producción de piña considerando diferentes parámetros dasonómicos, dasométricos y fisiográficos medidos en campo en los montes públicos de Cabeza Aguda, Las Parrillas y Cañadas del Névalo, en la comarca de Villaviciosa de Córdoba. Resultan ser el diámetro normal y la superficie de proyección de copa, las vari...

On-demand pressurised irrigation networks are analysed from the point of view of energy requirements. The Fuente Palmera Irrigation District, Southern Spain, was analysed and simulated using four alternative management scenarios for several levels of water demand using a model based on the hydraulic simulator EPANET. Results showed that substantial...

The performance of three diffuse hourly irradiation models on tilted surfaces was evaluated by making a database of hourly global and diffuse solar irradiation on a horizontal surface, as well as global solar irradiation on a tilted surface, recorded in a solar radiation station located at Córdoba University (Spain).The method for a comparison of t...

Hourly global irradiations on tilted planes are required for dimensioning PV systems. However, for most sites, only global irradiations on a horizontal plane are available, and, given that to calculate the global irradiation on inclined planes the first step is to determine the diffuse component and this is not collected, we have studied the behavi...

A methodology based on indicators was developed to study the quality of service provided in irrigation distribution networks. The indicators were divided into network descriptors and operational indicators, some calculated periodically and others in real time. The methodology has been applied to the Palos de la Frontera irrigation district ͑Spain͒...

Accurate sizing is one of the most important aspects to take into consideration when designing a stand-alone photovoltaic system (SAPV). Various methods, which differ in terms of their simplicity or reliability, have been developed for this purpose. Analytical methods, which seek functional relationships between variables of interest to the sizing...

The practical applicability of the considerations made in a previous paper to characterize energy balances in stand-alone photovoltaic systems (SAPV) is presented. Given that energy balances were characterized based on monthly estimations, the method is appropriate for sizing installations with variable monthly demands and variable monthly panel ti...

Performance indicators are a powerful tool for identifying deficiencies in irrigation district management and determining which measures should be taken to improve them. This process is known as Benchmarking. Until now, analysis has been based on direct comparisons of performance indicators from different irrigation districts. However, this procedu...

A model is developed using data from an on-demand pressurized water distribution network located in sector VIII of the Genil-Cabra irrigation district of Santaella, Córdoba (Southern Spain), to simulate an irrigation season and calculate the flows that circulate in the system at any given time during the irrigation day. Using the results obtained b...

La presencia de un depósito de regulación en un sistema de impulsión permite independizar los caudales bombeados de la variabilidad del uso del agua en la red de distribución. De este modo el depósito se podrá utilizar, además de como acumulación del recurso agua, en la reducción de los costes energéticos al poder adaptar el esquema de operación de...

The design, development and testing of a prototype interactive expert system (SEDPA) capable of diagnosing eel pathologies is described. The system incorporates a multiple subprogram modular design, although only the inference engine is largely described. Its user interface incorporates a natural language module. Starting from this kind of informat...

Water is an essential and yet scarce good whose rational use has come to be of key concern in today's world. Irrigation is one of the activities involving highest water consumption, hence the importance that it be performed correctly. Irrigation performance indicators are useful tools for improving irrigation management and making its optimisation...

Benchmarking es una técnica para lograr mejoras en organizaciones, realizando comparaciones y adaptando las prácticas que han llevado a otras a ser consideradas como las mejores. En este trabajo se realiza una aplicación de dichas técnicas al análisis y la mejora de nueve Comunidades de Regantes de Andalucía, cubriéndose una superficie total de más...

El control y la predicción de parámetros físico-químicos del agua en tanques de cultivo de plantas de producción en medio acuático es un aspecto fundamental del buen funcionamiento de este tipo de instalaciones. En este trabajo se propone la estimación de la temperatura del agua en las próximas 24 horas en una planta de producción de anguilas europ...

The semiarid climate of the majority of agricultural districts in the Mediterranean means that water is a key factor limiting production. It is therefore necessary to distribute water in the most efficient way possible and foment the sustainable use of this valuable resource. It is a difficult task to ascertain whether the use of water in an irriga...

One of the main problems in the management of fishfarms with water recirculating system is the forecasting and control of ammonia concentration in order to minimise the fish stress status. This paper examines methodologies of prediction in a real-time environment for an eel intensive rearing system. Approaches based on linear multiple regression, u...

In this research, the application of data envelopment analysis (DEA) is proposed as a methodology to overcome the problems related to the lack of methodology to assign the correct weightings for the calculation of indexes and to the subjectivity of the interpretations of results. DEA is a linear programming technique to determine the relative effic...

The semiarid climate of the majority of agricultural districts in the Mediterranean means that water is a key factor limiting production. It is therefore necessary to distribute water in the most efficient way possible and foment the sustainable use of this valuable resource. It is a difficult task to ascertain whether the use of water in an irriga...

The semiarid climate of the majority of agricultural districts in the Mediterranean means that water is a key factor limiting production. It is therefore necessary to distribute water in the most efficient way possible and foment the sustainable use of this valuable resource. It is a difficult task to ascertain whether the use of water in an irriga...

Water is an essential yet scarce resource and its rational use has become a top priority throughout the world. Irrigation is one of the activities involving highest water consumption, hence the importance that it be performed correctly. Irrigation performance indicators are useful tools for improving irrigation management and making optimisation po...

One of the main problems in the management of large water supply and distribution systems is the forecasting of daily demand in order to schedule pumping effort and minimize costs. This paper examines methodologies for consumer demand modeling and prediction in a real-time environment for an on-demand irrigation water distribution system. Approache...

Time should be considered in carrying out the design and management of demand irrigation distribution systems. In this paper, a method to characterize the pumping flow in demand pressurized systems throughout the day and irrigation season is presented. This method considers the temporal evolution of water requirements during the irrigation season a...

La demanda de agua es la magnitud de referencia en la gestión óptima de los sistemas de distribución. En este trabajo se propone la estimación de la demanda en las próximas 24 horas en un sistema de distribución de agua para riego, y se utilizan, junto con los métodos tradicionales de predicción de regresión múltiple y de modelos univariantes de se...

In this paper, the proposed optimisation model is applied to optimise water management in the Bembézar system, a small hydrological basin belonging to the Guadalquivir River basin in southern Spain that supplies water to the Bembézar River Irrigation District.In order to apply the model, the irrigation methods and performance in the irrigation dist...

In this paper, an economic optimisation model for hydrologic planning in deficit irrigation systems is proposed. Irrigation water allocation between agricultural demands is carried out following an economic efficiency criterion with the aim of maximising the overall economic benefits obtained, allocating available water to each user as a function o...

La estimación de la evapotranspiración es esencial en los sistemas de riego, en el cálculo de pérdidas de agua en embalses, en la estimación de balances hídricos, en las predicciones de escorrentía, así como en estudios climatológicos y meteorológicos. Las nuevas técnicas denominadas teledetección y sistemas de información geográfica (SIG) permiten...

Evapotranspiration estimations are essential in irrigation schemes, reservoir water losses, water balance computations, runoff predictions, and meteorology and climatology studies.The new techniques called remote sensing and geographical information systems (GIS), allow a spatially distributed calculation of this parameter. A new rational model, SE...

Tradicionalmente, el olivo ha sido un cultivo de secano en Andalucía, al Sur de España. Sin embargo, la respuesta del olivo a aplicaciones adicionales de agua es espectacular. Han sido calculados mapas anuales de ET para la provincia de Jaén, el área en la que el riego de esta cosecha crece con mayor velocidad. Se ha utilizado la ecuación de Hargre...

En este trabajo se presenta una metodología para la valoración energética de estaciones de bombeo que abastecen caudales variables. El caudal impulsado se caracteriza como variable estocástica mediante su función de densidad. Dada la dificultad de conocer dicha función en la realidad cuando no existen aforadores, se deberá estimar mediante la adopc...