López González, A.; Domenech, B.; González, D.; Ferrer-Martí, L. Renewable and sustainable energy reviews Vol. 79, p. 1255-1265 DOI: 10.1016/j.rser.2017.05.203 Data de publicació: 2017-11 Article en revista
Nowadays, 84% of the world population without access to electricity is located in rural areas of developing countries. In particular, in the Andean countries, about 10.4 million people lack of access to electricity, mainly in isolated poor regions. Considering the relevance of electricity in overcoming poverty and promoting socioeconomic development, local-regional-national governments, supported by international organizations, are making efforts to achieve full rural electrification. In this regard, renewable microgrid projects are an effective alternative where the national grid extension has limitations. The literature on the design of such projects is significant. However, when evaluating experiences, most works focus on an analysis of projects’ performance from a technical and/or economical point of view. In contrast, very few literature has been reported on the comparison of such experiences from the perspective of the design process itself and how decisions are taken by project developers. In this article, five rural electrification experiences in Andean Countries (Bolivia, Ecuador, Peru and Venezuela) are reviewed, analyzing the decisions taken across the design process and showing the suitability of these technologies to extend access to electricity. In the target projects, first, a preliminary analysis is carried out to estimate the energy resources and demand. Next, the system is designed and implemented to meet the demand using the available resources. The five projects illustrate different options for the electrical generation (single, hybrid or combination of technologies), storage (battery or diesel backup) and distribution (microgrid or individual systems), as well as different methods for data gathering and systems design. In addition, a comparison of projects’ real behavior is carried out and their technical performance in terms of energy production and suitability of the technologies implemented is analyzed. These projects can be a good reference for the dissemination of such technologies in future projects in the Andean countries and abroad.
Due to the increasing penetration of fluctuating distributed generation electrical grids require reinforcement, in order to secure a grid operation in accordance with given technical specifications. This grid reinforcement often leads to over-dimensioning of the distribution grids. Therefore, traditional and recent advances in distribution grid planning are analysed and possible alternative applications with large scale battery storage systems are reviewed. The review starts with an examination of possible revenue streams along the value chain of the German electricity market. The resulting operation strategies of the two most promising business cases are discussed in detail, and a project overview in which these strategies are applied is presented. Finally, the impact of the operation strategies are assessed with regard to distribution grid planning.
Rouzbehi, K.; Candela, J.; Gharehpetian, G.B.; Harnefors, L.; Luna, A.; Rodriguez, P. Renewable and sustainable energy reviews Vol. 70, p. 886-895 DOI: 10.1016/j.rser.2016.11.270 Data de publicació: 2016-12-06 Article en revista
Nowadays, some Multi-terminal DC (MTDC) systems are in operation around the world. Soon, MTDC grids will be built and overlay the present AC grids. The main driver for the construction of such a grid is to facilitate large-scale integration of remote renewable energy sources to existing AC grids and to develop the energy market. This paper presents a comprehensive analogy between the control and operation aspects of the emerging MTDC grids to those of the traditional AC power grids. Similarities and difference between the two technologies are presented and highlighted. Based on the performed detailed overview, even though a three-layered control system, i.e., primary, secondary, and tertiary control layers is state-of-the-art in large-scale AC power systems, a two-layered control system will satisfy MTDC grids control and operation requirements. This paper also addresses some control and operational issues and limitations of MTDC grids.
The electric generation systems on islands are based generally on fossil fuel. This fact and its supply make the electricity cost higher than in systems used in the continent. In this article, we present a review of the renewable energy generation systems on islands. To do it we analysed 77 islands from 45 different countries. This work will allow us to know how the implementation of renewable energy sources could help these islands in developing a renewable and sustainable energy sector, including a reduction of electricity generation cost. This paper shows the results from a study case of the application of renewable energy technology in Cozumel Island, Mexico. This Island is located in front of the Riviera Maya area. The analysis was made through long- term statistical models. A deterministic methodology was used to perform time-series simulations. The simulations shows that for the year 2050 a feasible integration of a system based on wind/PV can be achieved on the Island, reducing the electricity price from 0.37 US$/kW h to 0.24 US$/kW h (2050 scenario). With this scenario, the government will achieve its targets in renewable energy and in the reduction of the emissions of CO2. This will allow reaching a sustainable electricity sector.
The installation of large scale photovoltaic power plants connected at transmission level has increased during the last years. There are some challenges that these power plants have to overcome regarding the operation and control while dealing with the solar energy variability and uncertainty. Today, few countries are aware of the importance of this source of energy as part of the utility system and how it can affect the operability. Thus, this paper discusses about the trend of large scale photovoltaic power plants around the world and the importance of the development of grid codes for its integration. Then, the paper addresses a comparison of the grid codes of Germany, US, Puerto Rico, Romania, China and South Africa considering: fault ride through capability, frequency and voltage regulation, as well as active and reactive power support. In addition, a broad discussion about the challenges that the large scale photovoltaic power plants have to overcome is presented together with the compliance technology and future trend.
This review aims to provide an overview of household biogas digester implementation in rural areas of Latin America. It considers the history of household-digesters in Latin America, including technical, environmental, social and economic aspects. Several successful experiences have been promoted during the last decade, including the creation of the Network for Biodigesters in Latin America and the Caribbean (RedBioLAC) that provides a forum to coordinate implementation and research programmes throughout the continent. Although the potential of this technology is well demonstrated, some barriers are identified, such as the need for technical improvements, lack of social acceptance and high investment costs. Thus, further efforts should be undertaken to overcome these barriers and improve the technical performance, social acceptance, economic benefits and environmental impact in order to enhance its wide-spread dissemination in energy poor communities. (C) 2016 Elsevier Ltd. All rights reserved.
This review aims to provide an overview of household biogas digester implementation in rural areas of Latin America. It considers the history of household digesters in Latin America, including technical, environmental, social and economic aspects. Several successful experiences have been promoted during the last decade, including the creation of the Network for Biodigesters in Latin America and the Caribbean (RedBioLAC) that provides a forum to coordinate implementation and research programmes throughout the continent. Although the potential of this technology is well demonstrated, some barriers are identified, such as the need for technical improvements, lack of social acceptance and high investment costs. Thus, further efforts should be undertaken to overcome these barriers and improve the technical performance, social acceptance, economic benefits and environmental impact in order to enhance its wide-spread dissemination in energy poor communities.
Several factors including fossil fuels scarcity, prices volatility, greenhouse gas emissions or current pollution levels in metropolitan areas are forcing the development of greener transportation systems based on more efficient electric and hybrid vehicles. Most of the current hybrid electric vehicles use electric motors containing powerful rare-earth permanent magnets. However, both private companies and estates are aware of possible future shortages, price uncertainty and geographical concentration of some critical rare-earth elements needed to manufacture such magnets. Therefore, there is a growing interest in developing electric motors for vehicular propulsion systems without rare-earth permanent magnets. In this paper this problematic is addressed and the state-of-the-art of the electric motor technologies for vehicular propulsion systems is reviewed, where the features required, design considerations and restrictions are addressed.
Gangolells, M.; Casals, M.; Forcada, N.; Macarulla, M.; Giretti, A. Renewable and sustainable energy reviews Vol. 55, p. 662-667 DOI: 10.1016/j.rser.2015.11.006 Data de publicació: 2016-03-01 Article en revista
Although energy management systems are expected to result in decreased energy consumption, it is important not to overlook the energy used until commissioning (including raw materials acquisition, manufacturing and transportation) and during the usage phase (including operation and maintenance). This paper examines the energy performance of an intelligent energy management system for underground metro stations. The results show that the energy management system has high energy performance in terms of energy payback time and energy return factor, due to its low cumulative energy demand and its potential for energy savings. When we assumed that the lifespan of energy management systems may vary between 5 and 10 years, their cumulative energy demand was found to range between 505,316 and 852,493 MJp eq. In all cases, the operating energy was found to far outweigh the embodied energy (68-81%). The energy management system was implemented in a pilot underground station and was found to provide an energy saving of 13.2±1.1% of the total energy consumption of the pilot station. The energy payback time of the energy management system for underground stations was found to range between 40 and 55 days. Consequently, the system pays back between 33 and 91 times the energy invested in it. The results of this research provide valuable information for stakeholders in the energy management systems industry, as they contribute to ascertaining the sustainability of products.
Stand-alone electrification systems based on the use of renewable energies are suitable to electrify isolated rural communities in developing countries. For their design several support tools exist, but they do not cover some of the technical and social existing constraints and they do not consider the project detail. In this context, this research aims to develop a methodology to optimize the design of such systems, combining the wind and solar generation technologies as well as microgrids and individual systems as distribution scheme, and including economical, technical and social considerations. The design methodology is divided in three stages. First, the characteristics of the target community are gathered. Secondly, the design process is realized in three decision levels, ordered according to the importance of the decisions taken. At each level several electrification alternatives are generated and then the most appropriate is selected. Third, the final solution cost can be optionally tried to be improved, maintaining the decisions previously taken. The design methodology has been applied to a community to show its suitability to assist rural electrification promoters to design socially adapted and sustainable projects.
The integration of distributed generation (DG) units into distribution networks has challenged the operating principles of traditional AC distribution systems, and also motivated the development of emerging DC systems. Of particular concern are the challenges associated with the Operation of conventional protection schemes and/or devices. This paper first analyses the fault current characteristics in AC and DC distribution systems; it then presents a comprehensive review of the latest protection methods proposed for distribution systems embedding DGs. In addition, the advantages and disadvantages of each method are outlined and compared. The differences between the protection algorithms employed in/proposed for AC and DC systems are also discussed. Finally, this study identifies the future trends and provides recommendation for researches in the field of protections of DC distribution networks. (C) 2015 Elsevier Ltd. All rights reserved.
Eduardo Prieto-Araujo; Olivella, P.; Cheah-Mane, M.; R. Villafafila-Robles; Gomis-Bellmunt, O. Renewable and sustainable energy reviews Vol. 50, p. 325-345 DOI: 10.1016/j.rser.2015.04.101 Data de publicació: 2015-10-01 Article en revista
This paper reviews the renewable energy systems emulators proposals for microgrid laboratory testing platforms. Four emulation conceptual levels are identified based on the literature analysis performed. Each of these levels is explained through a microgrid example, detailing its features and possibilities. Finally, an experimental microgrid, built based on emulators, is presented to exemplify the system performance. (C) 2015 Elsevier Ltd. All rights reserved.
Martin, M.; De La Hoz, J.; Velasco, G.; Castilla, M.; Garcia de Vicuña, J. Renewable and sustainable energy reviews Vol. 50, p. 1052-1068 DOI: 10.1016/j.rser.2015.05.062 Data de publicació: 2015-10-01 Article en revista
A thorough analysis of the Concentrating Solar Thermal Power (CSP) development in Spain in the period 1998–2013 has been carried out in order to identify the main drivers behind the bubble-like behaviour exhibited by this renewable technology. Tending a parallelism with the basic principles of the control systems theory has facilitated the identification of the main shortcomings in the design of the various control frameworks governing the CSP deployment in the studied period. The CSP disorderly proliferation propitiated by inefficient control mechanisms has resulted in an overrun cost to the electricity system that has tried to be mitigated with the application of retroactive measures seriously harmful for the investors. It is expected that the conclusions drawn from this comprehensive review of the Spanish case have a general relevance for other countries undertaking the development path of renewable technologies.
de Arespacochaga, N.; Valderrama, C.; Raich-Montiu, J.; Crest, M.; Mehta, S.; Cortina, J. Renewable and sustainable energy reviews Vol. 52, p. 366-381 DOI: 10.1016/j.rser.2015.07.106 Data de publicació: 2015-08-14 Article en revista
This paper reviews the effects of the origin, occurrence, monitoring, control, fate and removal of siloxanes on the energetic valorization of sewage biogas, which can be severely compromised by its volatile organic silicon compound (VOSiC) content. Almost 25 years after identifying silicon dioxide in the exhaust gases from engines powered using sewage and landfill gas, a wide range of studies have been conducted addressing the different stages of the siloxane life cycle. The cycle starts with the production and use of polydimethylsiloxane polymers in a wide range of industrial and domestic applications and its further dispersal into environmental compartments. Siloxanes are subsequently introduced into wastewater treatment plants, where as a result of their low biodegradability and high affinity to dissolved and particulate matter, they are first transferred from wastewater into sludge and later volatilized in biogas in anaerobic digesters. Biogas treatment technologies can reduce siloxane concentrations to less than 0.1 mg/m3; adsorbent materials with micro- and mesoporous structures appear to be the most relevant technology in technical and economic terms. The state-of-the-art on siloxanes is vast and extensive, but there are still some knowledge gaps to be addressed in the future, such as the standardization of the methodology for off-line analysis, the development of on-line monitoring equipment, better understanding the fates of siloxanes in wastewater treatment processes to operate at specific conditions to avoid siloxanes-related problems, the development of more selective and regenerative removal technologies from biogas to reduce operating costs and even to recover silicon, and better understand the detrimental effects on energy recovery technologies to determine the inlet concentration limits. This work compiles the most relevant results available in the literature for each stage of the siloxane life cycle
In the current energy conjunction, with an expected growth of energy consumption in a context of fossil fuel depletion, more focus is being placed on renewable energy sources (RES) for electricity generation. One of the most appealing alternatives is biomass, which can be efficiently used to generate electricity as well as heat with the application of cogeneration technologies that enhance the efficiency of the entire energy conversion process. The Mediterranean basin is a region with a recognized potential for electricity and heat production using primary forest biomass and sub-products from sawmills, among which highlight wood chips for their easiness to be obtained, processed and dried as well as for their good and stable burning or gasification behavior. However, in order to efficiently use the available resources, that is, minimizing logistical requirements to reduce the energy necessary for the electricity generation process, the biomass found in Mediterranean forests can only be used at micro- and small-scale levels to be compatible with sustainable forestry practices. This article is aimed to describe the different technological alternatives to convert wood chips into electricity and heat and it also reviews and compares the current performances in terms of efficiency of these technologies at the micro- and small-scale levels.
Large synchronous generators with high temperature superconductors are in constant development due to their advantages such as weight and volume reduction and the increased efficiency compared with conventional technologies. The offshore wind turbine market is growing by the day, increasing the capacity and energy production of the wind farms installed and increasing the electrical power for the electrical generators installed, consequently raising the total volume and weight for the electrical generators installed. The HTS synchronous generators (HTSSG) are an alternative to consider due to their low dimensions and low weight per megawatt. This article presents a detailed review of the geometric configurations of the large HTSSG for offshore wind energy followed by an explanation of the main non-conventional technological parts. Additionally, the experience from the most important projects - both ongoing and completed - by companies and research institutes related to the design and construction of HTSSG for offshore wind energy is reviewed. (C) 2014 Elsevier Ltd. All rights reserved.
Active power reserves are needed for the proper operation of an electrical system. These reserves are continuously regulated in order to match the generation and consumption in the system and thus, to maintain a constant electrical frequency. They are usually provided by synchronized conventional generating units such as hydraulic or thermal power plants. With the progressive displacement of these generating plants by non-synchronized renewable-based power plants (e.g. wind and solar) the net level of synchronous power reserves in the system becomes reduced. Therefore, wind power plants are required, according to some European Grid Codes, to also provide power reserves like conventional generating units do. This paper focuses not only on the review of the requirements set by Grid Codes, but also on control methods of wind turbines for their participation in primary frequency control and synthetic inertia.
This paper is about the benefits of a plug-in based software architecture, but it is not only intended for programmers. It also stands the fact that monitoring is needed in any renewable energy generation plant and describes a way to fulfill this need. The fast evolution of renewable energy sources during the last decades resulted in the installation of many power systems all over the world, showing a sharp trend towards Distributed Resources (DR). There are many people related to them (because they use, own, operate, maintain or receive services from DR) who may be interested in knowing things about them for several reasons like production, maintenance, investigation, profitability, etc.; that is why data-acquisition systems are widely used in renewable energy source applications. These systems allow to collect and analyze data regarding the renewable energy installation performance as well as meteorological data. The basic idea on this paper is to achieve monitoring of different energy generation plants using a plug-in driven design technique, presenting as a result of an extensible software architecture design. The main difference between this paper and the previous work is that we focus specifically on monitoring as a necessity, proposing a generic and extensible software system, which could be employed to monitor any kind of renewable energy plant and extended to connect to new developed devices by changing small pieces of software.
Cabeza, L. F.; Barreneche, C.; Miró, L.; Morera, J.M.; Bartolí, E.; Fernández , A.I. Renewable and sustainable energy reviews Vol. 23, p. 536-542 DOI: 10.1016/j.rser.2013.03.017 Data de publicació: 2013-07 Article en revista
This paper presents a review of the literature on low carbon and low embodied energy materials in buildings. Embodied energy is defined and discussed vs. operating energy of buildings and its growing
importance due to the implementation of the Energy Building Performance Directive(EBPD) in Europeas
example.The difficulty of measuring embodied energy and the difficulty incomparing published data are
highlighted, showing an example of proposed new methodology found in the literature. Relationship
between embodied energy and embodied CO2 or CO2 footprint is defined. Different materials defined in
the literature as low carbon materials are referred, such as cement and concrete, wood, bricks, rammed
earth and sandstone. The review shows the research efforts found in the literature to develop new
materials with less embodied energy. Finally, the effect of material substitution in the embodied energy
of a building is reviewed in the literature
De La Hoz, J.; Martin, M.; Ballart, J.; Corcoles, F.; Graells, M. Renewable and sustainable energy reviews Vol. 19, p. 541-554 DOI: 10.1016/j.rser.2012.11.020 Data de publicació: 2013-03-01 Article en revista
Dominguez, J.; Gomis-Bellmunt, O.; Bianchi, F.; Sumper, A. Renewable and sustainable energy reviews Vol. 16, num. 7, p. 4994-5006 DOI: 10.1016/j.rser.2012.03.063 Data de publicació: 2012-09-03 Article en revista
Díaz, F.; Sumper, A.; Gomis-Bellmunt, O.; R. Villafafila-Robles Renewable and sustainable energy reviews Vol. 16, num. 4, p. 2154-2171 DOI: 10.1016/j.rser.2012.01.029 Data de publicació: 2012-05 Article en revista
Ferrer-Martí, L.; Garwood, A.; Chiroque, J.; Ramirez, B.; Marcelo, O.; Marianna Garfi'; Velo, E. Renewable and sustainable energy reviews Vol. 16, p. 5379-5390 DOI: 10.1016/j.rser.2012.04.015 Data de publicació: 2012 Article en revista
Marianna Garfi'; Ferrer-Martí, L.; Velo, E.; Ferrer, I. Renewable and sustainable energy reviews Vol. 16, num. 10, p. 575-581 DOI: 10.1016/j.rser.2011.08.023 Data de publicació: 2012-01 Article en revista
Low-cost household digesters are a promising appropriate technology which can help reducing the pressure on the environment due to deforestation and greenhouse gases emissions. The biogas and biofertilizer produced can alleviate poverty, by improving health conditions, increasing crops productivity and saving working time and burden for women and children. The aim of this study is to evaluate low-cost digesters technical, environmental and socio-economic impacts in rural communities of the Peruvian Andes, where a pilot project was developed during the last 3 years. Although the benefits are restricted by the performance of anaerobic digestion at high altitude, the results show that the digesters improve household living conditions and economy, while reducing environmental impacts. Biogas production covers around 60% of fuel needs for cooking, leading to 50–60% decrease in firewood consumption (i.e. deforestation) and greenhouse gases emissions; the annual income is increased by 3–5.5% due to fertilizer savings and potato sales. These values could be improved by enhancing digesters performance and the sustainability of the technology.
Sumper, A.; Robledo, M.; R. Villafafila-Robles; Bergas, J.; Andrés-Peiró, J. Renewable and sustainable energy reviews Vol. 15, num. 8, p. 3888-3896 DOI: 10.1016/j.rser.2011.07.023 Data de publicació: 2011-10 Article en revista
Any analysis of the role played by energy in architecture is faced with serious limitations due to the lack of studies in the architectural bibliography, especially studies of popular architecture. An awareness of these limitations will allow us to understand better why architects have paid little attention to the interaction of form and energy, and to the bioclimatic approach in contemporary architecture in general. The first limitation stems from the very essence of bioclimatic analysis; energy is immaterial, difficult to represent in images, changing in time and wrongfully left out of the architectural literature. This is why it is difficult to find a basic knowledge of the functional aesthetic possibilities of bioclimatism in the cultural experience of present-day architects. The second limitation to this knowledge, even more important than the previous one, is the low value given to the more anonymous popular architecture as opposed to representative architecture. The latter is the kind of architecture built by established power, which attempts to impress the observer and clashes with, dominates, and often destroys the natural environment. This style of architecture is crammed with theoretical aesthetic concerns, which would rather create artificial environments than be integrated in the natural milieu. To sum up, it is the architecture undertaken by well-known authors, found in important buildings, which have been commented and widely appreciated by architecture critics throughout history. Nowadays, representative architecture can be said to describe the architecture found in large office buildings, which embody the legacy of such works from the history of culture as the pyramids, classic shrines, medieval castles and large Gothic cathedrals, baroque and Renaissance palaces, etc. These modern buildings, clad in glass as a symbol of their modernity, are incongruously dark and require artificial lighting during the day, while the flimsy casing separating them from the outside makes it necessary to use air conditioning all year round, even when outside conditions are pleasant. We can well affirm that these buildings are so wrong that they work worse than the climate. In comparison with this type of representative architecture, we find popular architecture, performed by the people as a direct response to their needs and values. These buildings show a greater respect for the existing environment, whether natural or artificial. They do not reflect theoretical aesthetic pretensions and use local materials and techniques as far as possible, repeating over and over again the course of history models which take the constraints imposed by the climate fully into account. Our popular architecture—so often forgotten in official circles—may well be the kind which can best teach us today how to assimilate the bioclimatic approach in the practice of architectural design. However, we should not consider these solutions to be models to copy in current architecture. Our technical capacity and our cultural grounding prevent us from returning to these obsolete architecture forms, but what may be of use as a lesson and a source of inspiration is the attitude of the builders of this popular architecture, which recovers a relationship to the environment which has been lost in the more official architecture of the 20th century.