• Energy Research

This paper evaluates the responses of three aggregated models of a wind farm consisting of variable speed permanent magnet synchronous generator wind turbines when wind fluctuations or grid disturbances occur. These responses are compared with those of the detailed wind farm model, in order to verify the effectiveness of the studied aggregation methods for this type of wind farms. The equivalent wind farm models have been developed by adapting different aggregation criteria that already exist in technical literature and had been applied to other technologies. In this work, these methods have been modified to suit them to the permanent magnet synchronous generator technology. The results show that the three aggregated models provide very similar results to the detailed model, both in the evolution of active power when fluctuations in wind speed occur, and in the active power and DC-link voltage during the two simulated voltage dips. Notably, the aggregated model with an approximate mechanical torque offers excellent results.

This research developed a system that can make factories more independent from the grid. The system enhances efficiency since factory operation is powered by the renewable energy generated during the production process. Winemaking is a key sector that can profit from such a system because wineries can recycle much of the waste from the raw materials employed in wine production. Moreover, the solar energy collected at winemaking facilities can also be used to reduce electricity consumption and thus increase energy efficiency. This study investigated the feasibility of using renewable energy sources, such as solar energy, in wineries in Spain, given the quantity of renewable energy produced in the country. For this purpose, cost-effectiveness, power generation, CO2 emissions and the renewable energy fraction were taken into account. The assumption was that the photovoltaic system was grid-connected. Research results showed a reduction in electrical power costs ranging from 4% to 36%. This reduction was accompanied by an increase in the use of renewable energy of up to 57%. The results obtained are based on self-consumption or net metering policy as well as the production capacity of the winery.

Abstract The decentralization of electrical power production is conducive to a more effective and harmonious use of energy resources. For this reason, photovoltaic grid-connected plants (PVGCPs) as well as other renewable energy sources have come into the spotlight in recent years since they improve the supply of electrical power to the grid. The optimization of PVGCP design has been previously addressed in terms of electrical losses with successful results. However, PVGCP performance can be further enhanced if other characteristics, such as power capacity, are taken into consideration. This paper focuses on the optimization of the design of photovoltaic plants with solar tracking. The research described had the following two objectives: (i) the maximization of power capacity; (ii) the minimization of electrical losses. This problem was solved with multi-objective evolutionary algorithms, which have proved to be powerful optimization techniques that are useful for a wide range of objectives. This paper focuses on the NSGA-II and SPEA2, two well-known multi-objective algorithms, and describes how they were used to optimize PVGCPs. The resulting sets of solutions provide the flexibility and adaptability needed to build a PVGCP. These algorithms were thus found to be an effective tool for enhancing PVGCP performance.

This article describes an innovative method for measuring lighting levels and other lighting parameters through the use of aerial imagery of towns and cities. Combined with electricity consumption data from smart electricity meters, it was possible to measure the energy efficiency of public lighting installations. The results of this study also confirmed that lighting measurements, installation material, luminaire position, and electricity consumption data can be easily integrated into geographic information systems (GIS). The main advantage of this new methodology is that it provides information about lighting installations in large areas in less time than more conventional procedures. It is thus a more effective way of obtaining the data required to calculate the energy efficiency of lighting levels and electricity consumption. There is even the possibility of generating street lighting maps that provide local administrations with up-to-date information regarding the status of public lighting installations in their city. In this way, modifications or improvements can be made to achieve greater energy savings and, if necessary, to correct the distribution or configuration of public lighting systems to make them more efficient and sustainable. This research studied levels of street lighting and calculated the energy efficiency in various streets of Deifontes (Granada), through the use of aerial imagery.

Highlights? The problem of uniformity and installation efficiency in public lighting is optimized. ? The most accurate values of height and spacing have been determined with NSGA-II. ? The results have been successfully compared with a well-known and reliable free software. This paper presents a new method for calculating the design of roadway lighting. Apart from its accuracy, this method, which is based on a multi-objective evolutionary algorithm, has the added advantage of enhancing the energy efficiency of lighting installations. This is positive because the economic use of energy resources is evidently a priority in the world today. In our study, an exhaustive calibration process was used to fine-tune the accuracy and precision of the new method presented. The results obtained were then compared with those of DIALUX, a well-known free software program that is frequently used for the design of lighting installations. In the second phase of this research, the lighting installation was made more complex in order to verify the applicability of this new method to a wide range of different contexts.

In this study, new relationships between the energy efficiency of street lighting systems, street width, and luminaire height were derived from the analysis of a large sample of outputs, generated with a software application widely used for lighting design. The result was a quadratic polynomial that perfectly fit the relationships obtained and whose coefficients characterize each type of luminaire. This greatly simplifies the design of lighting facilities because it only uses one equation, but at the same time, takes all necessary variables into account. The procedure maximized the energy efficiency of the street lighting systems, as far as conditions allowed, and greatly facilitated the calculation of the parameters of a basic lighting installation, according to CIE (International Commission on Illumination) recommendations.

In recent years, due to the rise in petroleum prices and greenhouse gas emissions, renewable energy has been recommended as a power source for different types of facilities. For the period 2010 to 2020 the European Commission has established three key objectives related to climatic change and energy sustainability, such as reductions of CO2 emissions, increases in the use of renewable energy, and improvements in energy efficiency. A key industry is olive oil production in olive mills, where there is a great opportunity to reduce electricity consumption, increase additional profits related to the reduction of technologies that are harmful to the environment, and to cut back maintenance costs. For this reason, a feasibility study of grid-connected photovoltaics (PV) systems has been carried out for different types of olive mills in Andalusia (southern Spain). This region is highly energy dependent, but has an abundance of “green” resources to be exploited. The results of this study contemplate a reduction in spending on electrical power of between 2% and 37%, and an increase in the use of renewable energy of between 2% and 26%. These results are according to the self-consumption or net metering policy and the production capacity of olive oil.