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Abstract Discussions on the appropriate policy design and level of incentive to promote renewable energy adoption and meet the 20/20/20 goals have spurred recently in the European Union. These discussions are also ongoing in Portugal, namely in what concerns the level and duration of feed-in tariffs that should be provided to independent power producers. This, in turn, raises the question of whether the past feed-in tariff levels were well designed to achieve the goals of a larger penetration of renewables in the Portuguese grid. The policies to induce wind adoption have led to a growth in wind installed capacity and share of electricity generated by wind in Portugal, but questions arise on their cost-effectiveness and whether alternative policy designs would have led to the same goal. In this work, we estimate profits made by wind independent power producers for wind parks that were connected in Portugal between 1992 and 2010, and conclude that the feed-in tariffs have overcompensated some wind power producers. We also discuss the recent changes in feed-in tariff legislation published in February 2013 and estimate the expected costs of the introduced changes.

In this paper, multiarea economic dispatch (MAED) problems are solved by a novel straightforward process. The solved MAED problems include transmission losses, tie-line constraints, multiple fuels, valve-point effects, and prohibited operating zones in which small, medium, and large scale test systems are involved. The methodology of tackling the problems consists in a new hybrid combination of JAYA and TLBO algorithms simultaneously to take the advantages of both to solve even nonsmooth and nonconvex MAED problems. In addition, a new and simple process is used to tackle with the interaction between areas. The objective is to economically supply demanded loads in all areas while satisfying all of the constraints. Indeed, by combining JAYA and TLBO algorithms, the convergence speed and the robustness have been improved. The computational results on small, medium, and large-scale test systems indicate the effectiveness of our proposed algorithm in terms of accuracy, robustness, and convergence speed. The obtained results of the proposed JAYA–TLBO algorithm are compared with those obtained from ten well-known algorithms. The results depict the capability of the proposed JAYA–TLBO based approach to provide a better solution.

This paper proposes a method of load shedding in a microgrid system operated in an Island Mode, which is disconnected with the main power grid and balanced loss of the electrical power. This proposed method calculates the minimum value of the shed power with reference to renewable energy sources such as wind power generator, solar energy and the ability to control the frequency of the generator to restore the frequency to the allowable range and reduce the amount of load that needs to be shed. Computing the load importance factor (LIF) using AHP algorithm supports to determine the order of which load to be shed. The damaged outcome of load shedding, thus, will be noticeably reduced. The experimental results of this proposed method is demonstrated by simulating on IEEE 16-Bus microgrid system with six power sources.

Debido al vertiginoso crecimiento económico, demográfico y a las constantes migraciones a la capital, Lima se ha convertido en un conglomerado de focos donde el ruido sobrepasa los niveles recomendados por la OMS. De ahí la importancia de hacer un análisis del ruido en la capital, con el fin de compararlo con otros países y estudiar la normativa que regula la contaminación acústica, para así dar a conocer las razones por las cuales la problemática del ruido debe ser solucionada. De la comparación hecha entre las ciudades elegidas (Lima, Bogotá y Santiago), se determinó que el ruido en Santiago es menor y está mejor controlado que en Lima y Bogotá, mientras que estos dos comparten realidades similares respecto a niveles de ruido. En el marco legal, los tres países tienen un sólido sistema normativo, pero en el caso del Perú, este empezó al menos una década tarde, ya que Chile y Colombia empezaron a preocuparse por ese problema desde los noventa. Es más, Chile sigue llevando la ventaja ya que posee un plan de gestión del ruido ambiental en donde expone medidas para su control. Todos estos factores hacen sentido en que la sociedad chilena está más a la vanguardia en temas de gestión de la contaminación acústica que la peruana, y su realidad se alinea más a los países referentes en acústica en el mundo.Bajo este modelo, es importante que las autoridades reflexionen sobre la problemática ambiental del ruido y puedan tomar como punto de partida el análisis brindado en este estudio para una mejor gestión del ruido ambiental en Lima y el resto del Perú.

A resonant vibration energy harvester typically comprises of a clamped anchor and a vibrating shuttle with a proof mass. Piezoelectric materials are embedded in locations of high strain in order to transduce mechanical deformation into electric charge. Conventional design for piezoelectric vibration energy harvesters (PVEH) usually utilizes piezoelectric material and metal electrode layers covering the entire surface area of the cantilever with no consideration provided to examining the trade-off involved with respect to maximizing output power. This paper reports on the theory and experimental verification underpinning optimization of the active electrode area of a cantilevered PVEH in order to maximize output power. The analytical formulation utilizes Euler-Bernoulli beam theory to model the mechanical response of the cantilever. The expression for output power is reduced to a fifth order polynomial expression as a function of the electrode area. The maximum output power corresponds to the case when 44% area of the cantilever is covered by electrode metal. Experimental results are also provided to verify the theory.

Abstract Global textile consumption has increased significantly in the last decades and, consequently, millions of tons of textile waste have been discarded every year. Landfills and incinerators are their main fates, causing several and significant environmental problems. Cotton, second to polyester, is the most widely used fibre in the textile industry. Therefore, the recovery of this fibre from wastes is an imperative waste management strategy to mitigate the environmental impacts related with their disposable as well as its farming. Various approaches have been employed to reuse these waste cotton textiles. The extraction of cellulose nanomaterials, such as cellulose nanofibrils (CNFs) and cellulose nanocrystals (CNCs) from these solid wastes has shown to be a promising methodology. Owing to its outstanding and natural properties, nanocellulose applications have gained high attraction in different areas. In this review, the potential of using waste cotton textiles to extract nanocellulose instead of other cellulosic resources is highlighted and discussed. The concept of nanocellulose and the differences between types is well clarified. A background on the typically applied extraction methods is presented, giving special relevance to those already employed to extract nanocellulose from textile wastes, in particular those containing cotton. In addition, limitations to these methodologies are also examined, as well as possible applications of the extracted nanocellulose on high value-added products.

An adequate integration of demand response programs requires the definition of distinct models covering a wide diversity of operation scenarios. In this paper, the proposed methodology addresses the definition of demand response programs considering the demand shifting between periods, in scenarios of multi-period demand response events. The optimization problem refers to the minimization of the operation costs for a Virtual Power Player in the energy resources schedule. Differential search algorithm has been used in order to obtain the solutions for the optimization problem in a large set of operation scenarios. The case study illustrates the use of the proposed methodology to support the decisions concerning the duration of each demand response event and considering the consumption shifting modeling as constraints of the optimization problem.