384 research outputs found

    La Igualdad de oportunidades en la negociación colectiva. Un antes y un después tras la reforma laboral de 2012

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    La reforma laboral aprovada pel govern del Partit Popular en 2012 ha suposat un important descens en l'adopció de plans d'igualtat en les empreses. L'article passa revista als continguts d'igualtat en la negociació col·lectiva que es van engegar com a conseqüència de l'impuls donat per l'aprovació de la Llei Orgànica 3/2007 per a la igualtat efectiva entre dones i homes, i explica quins són les diferents mesures adoptades per avançar en el camí de la igualtat (accions positives, eliminació de discriminacions indirectes, protocols contra l'assetjament, mesures de conciliació de la vida familiar i laboral, etc.). Conclou amb la necessitat de plantejar un canvi de rumb en la política laboral que permeti avançar cap a la senda de la igualtat efectiva entre dones i homes.La reforma laboral aprobada por el gobierno del Partido Popular en 2012 ha supuesto un importante descenso en la adopción de planes de igualdad en las empresas. El artículo pasa revista a los contenidos de igualdad en la negociación colectiva que se pusieron en marcha como consecuencia del impulso dado por la aprobación de la Ley Orgánica 3/2007 para la igualdad efectiva entre mujeres y hombres, y explica cuáles son las diferentes medidas adoptadas para avanzar en el camino de la igualdad (acciones positivas, eliminación de discriminaciones indirectas, protocolos contra el acoso, medidas de conciliación de la vida familiar y laboral, etc.). Concluye con la necesidad de plantear un cambio de rumbo en la política laboral que permite avanzar hacia la senda de la igualdad efectiva entre mujeres y hombres.The labor reform approved by the Popular Party government in 2012 resulted in a major decline in the adoption of equal opportunity plans in companies.This article reviews the contents of equality in collective bargaining, which were launched as a result of the impetus given by the adoption of the Organic Law 3/2007 on effective equality between women and men. This article also explains the different measures taken to advance the road to equality: positive actions, eliminating indirect discrimination, harassment protocols, measures to improve work-life balance, etc. This article concludes putting forward the need to propose a shift in labor policy that advances towards the path of equality between women and men

    The Ammonia Looping System for Mid-Temperature Thermochemical Energy Storage

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    Thermochemical reactions have a great potential for energy storage and transport. Their application to solar energy is of utmost interest because the possibility of reaching high energy densities and seasonal storage capacity. In this work, thermochemical energy storage of Concentrated Solar Power (CSP) based on an ammonia looping (AL) system is analysed. The AL process for energy storage is based on the reversible reaction of ammonia to produce hydrogen and nitrogen. Concentrating solar energy is used to carry out the decomposition endothermic reaction at temperatures around 650 ºC, which fits in the range of currently commercial CSP plants with tower technology. The stored energy is released through the reverse exothermic reaction. Our work is focused on energy integration in the system modelled by pinch analysis to optimize the process performance and competitiveness. As result a novel configuration is derived which is able to recover high-temperature heat for electricity production with a thermal-to-electric efficiency up to 27 %. The current study shows a clear interest of the system from an energy integration perspective. Further research should be conducted to access the potential for commercial applications

    Transcritical Carbon Dioxide Charge-Discharge Energy Storage with Integration of Solar Energy

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    New and improved energy storage technologies are required to overcome non-dispatchability, which is the main challenge for the successful integration of large shares of renewable energy within energy supply systems. Energy storage is proposed to tackle daily variations on the demand side, i.e., storing low-price energy during off-peak or valley periods for utilization during peak periods. Regarding electrical energy storage, several technologies are available with different potentials for scalability, density, and cost. A recent approach for grid-scale applications is based on transcritical carbon dioxide charge and discharge cycles in combination with thermal energy storage systems. This alternative to pumped-hydro and compressed air energy storage has been discussed in scientific literature, where different configurations have been proposed and their efficiency and costs calculated. The potential of the concept has been demonstrated to be an economical alternative, including hybrid concepts with solar thermal storage. Even at low temperatures, the addition of solar energy has proved to be cost effective. This paper explores the effect of introducing solar-based high temperature heat on the performance of different configurations of “Transcritical carbon dioxide ‒ thermal energy storage system” cycles. A base-cycle with 8-hour discharge time is compared with different layouts. Discussions include details on the models, parametric analyses -including solar technology alternatives-, and simulation results. Round trip efficiency of the base case, without solar support and at pressure ratio of 9.4, is 52%. When solar input is considered, the efficiency is above 60%, increasing the turbine inlet temperature to 950 K. Estimated levelized cost of electricity values are in the range of pumped hydro and compressed air energy storage, 90-140 USD/MWh in agreement with other works on this thermal storage technology. The global analysis shows clear advantages for advancing in the study and definition of this technology for exploitation of synergies at different power ranges, integrated with mid/high temperature solar power plants and with smaller-scale renewable installations.Unión Europea. Fondo Europeo de Desarrollo Regional SOE1 / P3 / P0429E

    Techno-Economic Analysis of Rural 4th Generation Biomass District Heating

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    Biomass heating networks provide renewable heat using low carbon energy sources. They can be powerful tools for economy decarbonization. Heating networks can increase heating efficiency in districts and small size municipalities, using more efficient thermal generation technologies, with higher efficiencies and with more efficient emissions abatement technologies. This paper analyzes the application of a biomass fourth generation district heating, 4GDH (4th Generation Biomass District Heating), in a rural municipality. The heating network is designed to supply 77 residential buildings and eight public buildings, to replace the current individual diesel boilers and electrical heating systems. The development of the new fourth district heating generation implies the challenge of combining using low or very low temperatures in the distribution network pipes and delivery temperatures in existing facilities buildings. In this work biomass district heating designs based on third and fourth generation district heating network criteria are evaluated in terms of design conditions, operating ranges, effect of variable temperature operation, energy efficiency and investment and operating costs. The Internal Rate of Return of the different options ranges from 6.55% for a design based on the third generation network to 7.46% for a design based on the fourth generation network, with a 25 years investment horizon. The results and analyses of this work show the interest and challenges for the next low temperature DH generation for the rural area under analysis

    Modeling, Simulation and Optimal Operation of Multi-Extraction Packed-Bed Thermal Storage Systems

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    Solar thermal power technologies require storage systems to mitigate the natural variability of solar irradiation. Packed bed thermal storage systems (PBTES) offer a cost-effective solution using air as heat transfer fluid and rocks as a storage medium. Compared to its alternatives, however, PBTES presents a limited flexibility of operation due to the conventional unidirectional flow, which involves the progressive reduction of the outlet temperature during discharge and thus lowers the thermodynamic efficiency of the power cycle. The present study summarizes the progress on the design and optimal operation of a novel multi-extraction PBTES, a project that aims at mitigating its typically poor operational flexibility for solar power applications. To this end, a one-dimensional model with a high spatial resolution of a PBTES was developed, which includes four intermediate outlet points along the axial direction to investigate the benefits of optimal extraction operation. In order to reduce the computational burden, a coarser model of the storage system is used in combination with non-linear model predictive control (NLMPC). Through the optimal manipulation of the extraction valves, the output temperature is maintained close to a prescribed temperature throughout the discharge. The control admits not only constant temperature targets, but also time-varying scheduled profiles. This work describes the limitation of such a design and control approach and sets the direction for the future, more detailed analyses needed to demonstrate its applicability.Fondo Nacional de Investigación Científica F.4526.1

    The Calcium-Looping (CaCO3/CaO) Process for Thermochemical Energy Storage in Concentrating Solar Power Plants

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    Articulo aceptado por la revista. * No publicado aún [28-06-2019]Energy storage based on thermochemical systems is gaining momentum as potential alternative to molten salts in Concentrating Solar Power (CSP) plants. This work is a detailed review about the promising integration of a CaCO3/CaO based system, the so-called Calcium-Looping (CaL) process, in CSP plants with tower technology. The CaL process relies on low cost, widely available and non-toxic natural materials (such as limestone or dolomite), which are necessary conditions for the commercial expansion of any energy storage technology at large scale. A comprehensive analysis of the advantages and challenges to be faced for the process to reach a commercial scale is carried out. The review includes a deep overview of reaction mechanisms and process integration schemes proposed in the recent literature. Enhancing the multicycle CaO conversion is a major challenge of the CaL process. Many lab-scale analyses carried out show that residual effective CaO conversion is highly dependent on the process conditions and CaO precursors used, reaching values as different as 0.07-0.82. The selection of the optimal operating conditions must be based on materials, process integration, technology and economics aspects. Global plant efficiencies over 45% (without considering solar-side losses) show the interest of the technology. Furthermore, the technological maturity and potential of the process is assessed. The direction towards which future works should be headed is discussed.Ministerio de Economia y Competitividad CTQ2014-52763-C2, CTQ2017- 83602-C2 (-1-R and -2-R)Unión Europea Horizon 2020 Grant agreement No 727348, project SOCRATCES

    The mOxy-CaL Process: Integration of Membrane Separation, Partial Oxy-combustion and Calcium Looping for CO2 Capture

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    CO2 capture and storage (CCS) is considered as a key strategy in the short to medium term to mitigate global warming. The Calcium-Looping process, based on the reversible carbonation/calcination of CaO particles, is a promising technology for post-combustion CO2 capture because of the low cost and non-toxicity of natural CaO precursors and the minor energy penalty on the power plant in comparison with amines capture based technologies (4-9 % compared to 8-12 %). Another interesting process to reduce CO2 emissions in power plants is oxy-combustion, which is based on replacing the air used for combustion by a highly concentrated (~95 % v/v) O2 stream. This work proposes a novel process (mOxy-CaL) for post-combustion CO2 capture based on the integration of membrane separation, partial oxy-combustion and the Calcium-Looping process. An oxygenenriched air stream, which is obtained from air separation by using highly permeable polymeric membranes, is used to carry out partial oxy-combustion. The flue gas exiting partial oxy-combustion shows a CO2 concentration of ~30 % v/v (higher than 15 % v/v typical in coal power plants). After that, the flue gas is passed to the CaL process where the CO2 reacts with CaO solids according to the carbonation reaction. Thermogravimetric analysis show that the multicycle CaO conversion is enhanced as the CO2 concentration in the flue gas stream is increased. Process simulations show that the mOxy-CaL process has a high CO2 capture efficiency (~95%) with lower energy consumption per kg of CO2 avoided than previously proposed post-combustion CO2 capture technologies. Moreover, the overall system size is significantly lower that state-of-the-art CaL systems, which allows for an important reduction in the capital cost of the technology

    Identification of best available thermal energy storage compounds for low-to-moderate temperature storage applications in buildings

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    Award-winning paper at III International Congress and V National on Sustainable Construction and Eco-Efficient Solutions (CICSE) March 2017Over the last 40 years different thermal energy storage materials have been investigated with the aim of enhancing energy efficiency in buildings, improving systems performance, and increasing the share of renewable energies. However, the main requirements for their efficient implementation are not fully met by most of them. This paper develops a comparative review of thermophysical properties of materials reported in the literature. The results show that the highest volumetric storage capacities for the best available sensible, latent and thermochemical storage materials are 250 MJ/m3, 514 MJ/m3 and 2000 MJ/m3, respectively, corresponding to water, barium hydroxide octahydrate, and magnesium chloride hexahydrate. A group of salt hydrates and inorganic eutectics have been identified as the most promising for the development of competitive thermal storage materials for cooling, heating and comfort applications in the short-term. In the long-term, thermochemical storage materials seem promising. However, additional research efforts are required.Identificación de los mejores compuestos disponibles de almacenamiento de energía térmica para aplicaciones de baja a moderada temperatura en edificación. En los últimos 40 años se han investigado diferentes materiales de almacenamiento térmico con el objetivo de mejorar la eficiencia energética en los edificios, mejorar el rendimiento de sistemas y aumentar el uso de renovables. Sin embargo, la mayoría no cumple los principales requisitos para su eficiente implementación. Este artículo desarrolla una revisión de las propiedades termofísicas de los materiales existentes en la literatura. Los resultados muestran que las mayores capacidades de almacenamiento volumétrico para los mejores materiales de almacenamiento sensible, latente y termoquímico son 250 MJ/m3, 514 MJ/m3 y 2000 MJ/m3, respectivamente, correspondientes a agua, hidróxido de bario octahidratado y cloruro de magnesio hexahidratado. Un conjunto de sales hidratadas y eutécticos han sido identificados como los más prometedores para el desarrollo de materiales competitivos para aplicaciones de enfriamiento, calefacción y confort a corto plazo. A largo plazo, el almacenamiento termoquímico parece prometedor. Sin embargo, investigación adicional es requerida.Fondo Europeo de Desarrollo Regional SOE1/P3/P0429EUMinisterio de Educación, Cultura y Deportes FPU14/06583Ministerio de Economía y Competitividad BES-2015-0703149Ministerio de Economía y Competitividad CTQ2014-52763-C2-2-RMinisterio de Economía y Competitividad CTQ2017- 83602-C2-2
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