ALBERT

Description: Regardless of the rapid development of national gas centers around the world, oil price indexation remains the prevailing pricing process in Continental Europe and the Far East. The instance of Spain is a genuine case where gas supply conditions may, to some extent, clarify the slower pace of execution of a traded gas hub in the nation. This article seeks to explain the persistence of oil-indexed pricing mechanisms, a price model that differs oddly from that of other major commodities, the price of which is normally discovered on the market. In order to do that, we examine time-varying volatility to find that since 2013 until 2016, just about 33% of gradual volatility clustering rooted within oil Brent prices is reflected in Spanish gas prices. In this sense, our research provides quantitative tools to better understand that market-based approaches such as spot and medium-term supply alternatives seem to be a key driver for success in transforming gas markets. Regular updates on the size of the effects observed should facilitate an exact appraisal of the level of progression of national gas liberalization processes and enhance gas markets transparency, these issues of extraordinary importance for both policymakers and gas market agents.

Description: This article contains the results and analysis of the dynamic behavior of a poppet valve through CFD simulation. A computational model based on the finite volume method was developed to characterize the flow at the interior of the valve while it is moving. The model was validated using published data from the valve manufacturer. This data was in accordance with the experimental model. The model was used to predict the behavior of the device as it is operated at high frequencies. Non-dimensional parameters for generalizing and analyzing the effects of the properties of the fluid were used. It was found that it is possible to enhance the dynamic behavior of the valve by altering the viscosity of the working fluid. Finally, using the generated model, the influence of the angle of the poppet was analyzed. It was found that angle has a minimal effect on pressure. However, flow forces increase as angle decreases. Therefore, reducing poppet angle is undesirable because it increases power requirements for valve actuation.

Description: The European Union Establishes that for the next few years, a cleaner and more efficient energy system should be used. In order to achieve this, this work proposes an energy optimization method that facilitates the achievement of these objectives. Existing technologies allow us to create a system that optimizes the use of energy in homes and offers some type of benefit to its residents. Specifically, this study has developed a recommendation system based on a multiagent system that allows to obtain consumption data from electronic devices in a home, obtain information on electricity prices from the Internet, and provide recommendations based on consumption patterns of users and electricity prices. In this way, the system recommends new hours in which to use the appliances, offering the economic benefit that it would propose recommendations for the user. In this way, it is possible to distribute and optimize the use of energy in homes and reduce the peaks in electricity consumption. The system provides encouraging results in order to resolve the problem proposed by the European Union by optimizing the use of energy among different hours of the day and saving money for the customer.

Description: In recent years, municipal solid waste (MSW) management has become a complex problem worldwide. Similarly, Mexico City is facing such a situation for the management and treatment of organic fraction of municipal solid waste (OFMSW). Therefore, in this work, we investigated whether leachate from the composting plant, Bordo Poniente, located in Mexico City can be used as an inoculum for the treatment of OFMSW using thermophilic anaerobic digestion (AD) with a hydraulic retention time of 30 days. We analyzed the physicochemical properties of the leachate and performed a biochemical methane potential test. Archaeal and bacterial diversity was also identified using high throughput DNA sequencing of 16S rDNA libraries. Methane yield was 0.29 m3 CH4/kg VSadded in the positive control and 0.16 m3 CH4/kg VSadded in the treatment group. The phylum, Bacteroidetes, and genus, Methanosarcina, prevailed in the leachate. However, in thermophilic conditions, the microbial communities changed, and the phylum, Firmicutes, genera, Methanoculleus, and candidate genus, vadinCA11, were dominant in the treatment group. We concluded that the leachate contains a suitable initial charge of many active bacteria and methanogenic archaea which contribute to the AD process, hence it can be used as an inoculum for the treatment of OFMSW.

Description: With the continuous increase in the number and relevance of electric transmission lines and distribution networks, there is a higher exposure to the magnetic fields generated by them, leading to more cases of human electrosensitivity, which greatly necessitates the design and development of magnetic field mitigation procedures and, at the same time, the need to minimize both performance degradation and deterioration in the efficiency as well. During the last four decades, fruitful results have been reported about extremely low frequency magnetic field mitigation, giving a wide variety of solutions. This survey paper aims to give a comprehensive overview of cost-effective optimization techniques destined to magnetic field mitigation in power systems, with particular attention to the results reported in the last decade.

Description: This document presents a revised translation to the English language work developed more than 40 years ago by the first author. It further summarizes a common misinterpretation of the method and succinctly describes a graphical procedure to correctly determine the derived displacement volume of a pump or a motor. The original work contains a directive for the determination of the derived displacement volume of hydrostatic positive displacement pumps and motors, from volumetric (flow and speed) measurements. The procedure is based on the definition of the derived displaced volume, defined as: The volumetric flow pushed or admitted by hydrostatic positive displacement pumps and motors per (shaft) revolution, at zero internal and external leakage flow conditions.

Description: This paper analyses the possible applications of medium temperature solar concentration technologies, Compound Parabolic Collector, Linear Fresnel Collector and Parabolic Trough Collector in the Spanish industrial sector. Results of this study allow evaluating whether or not solar technologies are an alternative to conventional sources. This possibility is analyzed energetically, economically and environmentally. Results show that the percentage of solar use is decisive in determining the true thermal energy generation cost. The other essential parameter is the solar field area due to produce economy of scale that reduces investment costs. Fluid temperature has significant influence mainly in Compound Parabolic Collector technology. Results obtained in this paper collect multiple alternatives and allow comparing for different scenarios the suitability to replace conventional energy sources by thermal energy obtained from medium temperature solar concentration technologies from an economic perspective. For instance, for percentage of solar use equal to 100%, the lowest thermal energy generation costs for each technology are 1.3 c€/kWh for Compound Parabolic Collector technology, fluid temperature of 100 °C and industrial process located in Seville, 2.4 c€/kWh for Linear Fresnel Collector technology, fluid temperature of 170 °C and industrial process located in Jaen, 3.3 c€/kWh for technology, fluid temperature of 350 °C and industrial process located in Jaen. These costs are lower than conventional energy sources costs.

Description: Energies, Vol. 11, Pages 1788: Customer Segmentation Based on the Electricity Demand Signature: The Andalusian Case Energies doi: 10.3390/en11071788 Authors: Andrés Camero Gabriel Luque Yesnier Bravo Enrique Alba A smart meter enables electric utilities to get detailed insights into their customer needs, allowing them to offer tailored products and services, and to succeed in an increasingly competitive market. While in an ideal world companies would treat every customer as an individual, in practice this is rather difficult. For this reason, companies usually have to target smaller groups of customers that are similar. There are several ways of tackling this matter and finding the right approach is a key to success. Therefore, in this study we introduce the electricity demand signature, a novel approach to characterize and cluster electricity customers based on their demand habits. We test our proposal using the electricity demand of 64 buildings in Andalusia, Spain, and compare our results to the state-of-the-art. The results show that our proposal is useful for clustering customers in a meaningful way, and that it is an easy and friendly representation of the behavior of a customer that can be used for further analysis.

Description: Energies, Vol. 11, Pages 2019: Understanding Continuance Usage of Natural Gas: A Theoretical Model and Empirical Evaluation Energies doi: 10.3390/en11082019 Authors: Victor Fernández-Guzmán Edgardo R. Bravo The adoption of natural gas increased notably last years, and there is some recognition that it improves the quality of life of inhabitants. While initial acceptance is an essential first step, the continued use is relevant to the long-term success of any technology. However, the literature on energy has focused on adoption and has devoted less attention to models that explain continuance usage. Accordingly, this study developed a model to explain continuance usage, grounded in Expectation-Confirmation Model (ECM). Unlike adoption models, confirmation of previous expectations and satisfaction with the experience of use have a relevant role in this phenomenon. Data was gathered through a questionnaire to 435 users of the service in a Latin American metropolis, and structural equations model was used for analysis. The results show that constructs of the ECM (perceived usefulness, disconfirmation, and satisfaction) influences on continuance intention. While the price impacts as expected, it is surprising that environmental consciousness strongly impacts the intention. These results may be useful for public agents to foster more comprehensive policies (beyond traditional: price and access), which include environmental and safety issues to consolidate the use of this energy source. Energy companies should develop strategies to manage consumer expectations and loyalty programs based on a high level of satisfaction.

Description: Energies, Vol. 11, Pages 363: Impact of Energy Losses Due to Failures on Photovoltaic Plant Energy Balance Energies doi: 10.3390/en11020363 Authors: Isidoro Lillo-Bravo Pablo González-Martínez Miguel Larrañeta José Guasumba-Codena Photovoltaic (PV) plant failures have a significant influence on PV plant security, reliability, and energy balance. Energy losses produced by a PV plant are due to two large causes: failures and inefficiencies. Knowing the relative influence of energy losses due to failures and energy losses due to inefficiencies on the PV plant energy balance contribute to the optimization of its design, commissioning, and maintenance tasks. This paper estimates the failure rates, grouped by components, and the relative impact of the failures on the PV plant energy balance through real operation and maintenance follow-up data of 15 PV plants in Spain and Italy for 15 months. Results show that the influence of failures in energy losses of all analysed PV plants is low, reaching a maximum value of 0.96% of the net energy yield. Solar field energy losses only represent 4.26% of all failure energy losses. On the other hand, energy losses due to inefficiencies have represented between 22.34% and 27.58% of the net energy yield.