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1.
  • Ackermann, Thomas, et al. (författare)
  • An overview of wind energy-status 2002
  • 2002
  • Ingår i: Renewable & sustainable energy reviews. - 1364-0321 .- 1879-0690. ; 6:1-2, s. 67-128
  • Forskningsöversikt (refereegranskat)
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2.
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3.
  • Abdalla, A. M., et al. (författare)
  • Nanomaterials for solid oxide fuel cells: A review
  • 2018
  • Ingår i: Renewable and Sustainable Energy Reviews. - : Elsevier BV. - 1879-0690 .- 1364-0321. ; 82, s. 353-368
  • Forskningsöversikt (refereegranskat)abstract
    • Nanotechnology is utilized well in the development and improvement of the performance in Solid Oxide Fuel Cells (SOFCs). The high operating temperature of SOFCs (700–900 °C) has resulted in serious demerits regarding their overall performance and durability. Therefore, the operating temperature has been reduced to an intermediate temperature range of approximately 400–700 °C which improved performance and, subsequently, commercialized SOFCs as portable power sources. However, at reduced temperature, challenges such as an increase in internal resistance of the fuel cell components arise. Although, this may not be as serious as problems encountered at high temperature, it still significantly affects the performance of SOFCs. This review paper addresses the work of researchers in the application of nanotechnology in fabricating SOFCs through distinct methods. These methods have successfully omitted or at least reduced the internal resistance and showed considerable improvement in power density of the SOFCs at reduced temperatures.
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4.
  • Abolhosseini, Shahrouz, et al. (författare)
  • The main support mechanisms to finance renewable energy development
  • 2014
  • Ingår i: Renewable & sustainable energy reviews. - : Elsevier BV. - 1364-0321 .- 1879-0690. ; 40, s. 876-885
  • Forskningsöversikt (refereegranskat)abstract
    • Considering that the major part of greenhouse gases is carbon dioxide, there is a global concern aimed at reducing carbon emissions. In addition, major consumer countries are looking for alternative sources of energy to avoid the impact of higher fossil fuel prices and political instability in the major energy supplying countries. In this regard, different policies could be applied to reduce carbon emissions, such as enhancing renewable energy deployment and encouraging technological innovation and the creation of green jobs. This study compares three main support mechanisms employed by governments to finance renewable energy development programs: feed-in-tariffs, tax incentives, and tradable green certificates. Considering that many of the promising technologies to deploy renewable energy require investment in small-scale energy production systems, these mechanisms could be used to enhance renewable energy development at the desired scale. Employing a carbon emission tax or emission trading mechanism could be considered ideal policies to mitigate emissions at the lowest cost. The comparison of feed-in-tariffs and renewable portfolio standard policies showed that the former is good when a policy to develop renewable energy sources with a low level of risk for investors is considered. However, the latter is an appropriate policy when a market view policy is applied by the government. Finally, considering technological progress and the cost reduction for power generation by renewable energy sources, we suggest that support mechanism policies should be reconsidered from the financial point of view. (C) 2014 Elsevier Ltd. All rights reserved.
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5.
  • Adom, Philip Kofi, et al. (författare)
  • What drives the energy saving role of FDI and industrialization in East Africa?
  • 2016
  • Ingår i: Renewable & sustainable energy reviews. - : Elsevier. - 1364-0321 .- 1879-0690. ; 65, s. 925-942
  • Tidskriftsartikel (refereegranskat)abstract
    • Analysis of the unconditional impacts of foreign direct inflows (FDIs) and industrialization on energy intensity does not show the hidden roles of some economic conditions such as income and trade openness. In this study, we focused on the conditional impacts of FDIs and industrialization on energy productivity using a panel data consisting of thirteen (13) East African countries covering 1980–2011. The baseline result shows that higher income and a well-integrated economy are pro-energy productive, but FDIs and intense industrialization are anti-energy productive in the sub-region. This result remains robust even when we exclude the high income group and control for income group effects. Income significantly promotes energy productivity more in low income group than middle income group. Intense industrialization and FDIs significantly decreases energy productivity only in low income countries. Trade openness significantly promotes energy productivity only in middle income group. We have shown that FDIs and income, intense industrialization and FDIs, and intense industrialization and globalization are complementary forces that promote energy productivity in East Africa but this is more evident for the middle income group than the low income group in the sub-region. Based on the result, we recommend a quadruplet programme called the “Growth, Industrial, Foreign investment and Trade programme” (GIFTP). Last, our result suggests that unconditional analysis of energy productivity should not be seen as an end in itself but a basis for further analysis.
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6.
  • Aftab, A., et al. (författare)
  • Nanoparticles based drilling muds a solution to drill elevated temperature wells : a review
  • 2017
  • Ingår i: Renewable & sustainable energy reviews. - : Elsevier. - 1364-0321 .- 1879-0690. ; 76, s. 1301-1313
  • Tidskriftsartikel (refereegranskat)abstract
    • Demand of the oil and gas energy is increasing very drastically. Conventional hydrocarbon reservoirs contain below the sealing cap rock (shale) and easily move towards wellbore are at the depletion stage. Therefore, drilling engineers in collaboration with mud engineers, geologists and geophysicists are looking for innovative materials to drill unconventional hydrocarbons reservoir which are distributed at the basin scale and cannot approach easily. Geo-thermal energy wells and most of unconventional reservoirs are occurred at high pressure high temperature (HPHT) conditions. Conventional micro-macro organic drilling mud additives with heat insulator in nature can minimize efficiency while drilling HPHT wells. Oil-based muds (OBM) are strictly restricted due to high toxic level and poor emulsion stability at HT. However, this review suggests that addition of macro size organic particles and inorganic nanoparticles can enhance rheological performance, reduce filtrate loss volume and improve shale inhibition characteristics of environmental friendly water-based mud (WBM). Despite an impressive amount of experimental work has been done over drilling additives and their effect over rheological and shale inhibition, taking into account their literature review are rare. In addition, there is no review work of the knowledge gained to date. This work will hope fully trigger further development and new research topics in the area of drilling muds system.
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7.
  • Aghaali, Habib, 1981-, et al. (författare)
  • A review of turbocompounding as a waste heat recovery system for internal combustion engines
  • 2015
  • Ingår i: Renewable & sustainable energy reviews. - : Elsevier BV. - 1364-0321 .- 1879-0690. ; 49, s. 813-824
  • Tidskriftsartikel (refereegranskat)abstract
    • Internal combustion engines waste a large amount of fuel energy through their exhausts. Various technologies have been developed for waste heat recovery such as turbocompounds, Rankine bottoming cycles, and thermoelectric generators that reduce fuel consumption and CO2 emissions. Turbocompounding is still not widely applied to vehicular use despite the improved fuel economy, lower cost, volume, and complexity higher exhaust gas recirculation driving capability and improved transient response. This paper comprehensively reviews the latest developments and research on turbocompounding to discover important variables and provide insights into the implementation of a high-efficiency turbocompound engine. Attention should be paid to the optimization of turbocompound engines and their configurations because the major drawback of this technology is additional exhaust back-pressure, which leads to higher pumping loss in the engines. Applying different technologies and concepts on turbocompound engines makes the exhaust energy recovery more efficient and provides more freedom in the design and optimization of the engines. Turbine efficiency plays an important role in the recovery of the wasted heat so turbine design is a crucial issue in turbocompounding. In addition, variability in geometry and rotational speed of power turbines allows for more efficient turbocompound engines in different operating conditions. The conclusion drawn from this review is that turbocompounding is a promising technology for reducing fuel consumption in the coming decades in both light- and heavy-duty engines.
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8.
  • Aguilar Cabezas, Francisco X (författare)
  • Conversion factors for residential wood energy in the European Union: an introduction to harmonizing units of measurement
  • 2021
  • Ingår i: Renewable and Sustainable Energy Reviews. - : Elsevier BV. - 1364-0321. ; 138
  • Tidskriftsartikel (refereegranskat)abstract
    • Wood energy data are reported in forest products and energy statistics but current use of heterogeneous units can result in major inconsistencies. Harmonization of wood energy statistics can benefit data quality and improve measuring sustainable practices, better informing policy-makers and analyzing feedstock competition. Harmonization of wood energy data and subsequent application in the forest product and energy sectors require appropriate conversion factors. We provide conversion factors for forest energy products relative to weight and volume for the residential sectors of EU28 member states. Selected forest products include wood from primary, secondary and tertiary sources considering differences in properties affecting conversion factors. Proposed conversion factors were derived from information on moisture content, heating value, density and changes in wood volumes due to swelling and shrinkage of wood. Heating values relative to weight denote conversion factors to transform weight to energy units that ranged from 13.88 to 17.14 MJ/kg. Computation of heating values relative to volume ranged from 7316 to 11,053 MJ/m³. The use of extreme conversion factors in a sensitivity assessment showed that the ranges between minimum and maximum values accounted for as much as 27% of total wood energy consumption. Application of conversion factors to EU28 residential wood energy consumption revealed inconsistencies between forest products and energy statistics. Closer collaboration between experts and use of universal conversion factors at national levels will likely improve data quality and direct comparability. Conversion factors used in the residential sector can facilitate harmonization in non-residential sectors, but sector-specific product characteristics require further adjustment.
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9.
  • Ahlborg, Helene, 1980, et al. (författare)
  • Thirty-five years of research on energy and power: A landscape analysis
  • 2024
  • Ingår i: Renewable and Sustainable Energy Reviews. - 1879-0690 .- 1364-0321. ; 199
  • Forskningsöversikt (refereegranskat)abstract
    • The urgent need to mitigate climate change and decarbonise the energy sector brings the risk that wider social and environmental concerns about the sustainability of energy systems are neglected. Countries may achieve decarbonization goals while reproducing or worsening the unequal distribution of access, opportunities, costs and burdens that is inherent to current energy systems. This study is motivated by the tension between visions for change towards sustainable energy systems and historic and contemporary inequities on the ground. The study contributes a quantitative, global-scope overview of existing research that places energy users and their lives at the centre of analysis for inclusive and equitable transitions. It further identifies the themes, concepts and perspectives that dominate scholarly debate and analyses the presence and relative influence of work that explicitly considers relations of power. The stepwise review uses the Scopus database and multiple bibliometric tools, covering the period until June 2022. It adopts a novel approach to identify dominant and marginal topics, geographical contexts and theoretical lenses employed including the uptake of critical social science approaches. The results indicate that dominant studies fail to engage critically with relationships of power. Even within the debate on “energy poverty”, work based in critical theory approaches account for less than seven percentages of the total body of work. For work on “energy justice” and users, four percentages of publications account for gender. The dominant language is technical and depoliticized. The study identifies research gaps and promising avenues for further research.
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10.
  • Akhlaghi, Shahin, et al. (författare)
  • Deterioration of automotive rubbers in liquid biofuels : A review
  • 2015
  • Ingår i: Renewable & sustainable energy reviews. - : Elsevier BV. - 1364-0321 .- 1879-0690. ; 43, s. 1238-1248
  • Forskningsöversikt (refereegranskat)abstract
    • Concerns over the fast depletion of fossil fuels, environmental issues and stringent legislation associated with petroleum-based fuels have triggered a shift to bio-based fuels, as an alternative to meet the growing energy demand in the transportation sector. However, since conventional automobile fuel systems are adapted to petroleum-based fuels, switching to biofuels causes a severe deterioration in the performance of currently used rubber components. The degradation of the rubber materials in biofuels is complicated by the presence of different additives in biofuels and rubber compounds, by oxidation of biofuels and by the effects of thermomechanical loadings in the engine. This paper presents a comprehensive review of the effects of different types of biofuels, particularly biodiesel and bioethanol, on the physical, mechanical, morphological and thermal properties of elastomers under different exposure conditions. In addition, the literature data available on the variation of rubbers' resistance to biofuels with the changes in their monomer type and composition, cure system and additives content was also studied. The review essentially focuses on the compatibility of biofuels with acrylonitrile butadiene rubber, fluoroelastomers, polychloroprene rubber and silicon rubber, as the most commonly used automotive rubbers coming into contact with fuels during their service. The knowledge summarized in this study can help to develop a guideline on the selection of rubber for automotive parts designed to withstand biofuels.
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11.
  • Aklilu, Abenezer Zeleke (författare)
  • Gasoline and diesel demand in the EU: Implications for the 2030 emission goal
  • 2020
  • Ingår i: Renewable and Sustainable Energy Reviews. - : Elsevier BV. - 1364-0321. ; 118
  • Tidskriftsartikel (refereegranskat)abstract
    • Methodologically consistent demand estimates are necessary to analyze and forecast the effect of a common fuel policy across the EU-28. This study estimates short-run and long-run price and income elasticities for gasoline and diesel demands using the ARDL Bounds approach that also tests the existence of a long-run relationship using data from 1978 to 2013. The results show that elasticity estimates between the EU-28 countries vary and the estimated long-run elasticities are higher than their short-run counterparts, which is in line with expectations based on the existing literature. The short-run and long-run income elasticities of gasoline and diesel demand are found to be more elastic than their price equivalents implying that if a charge on fuel is designed to decrease emissions by increasing the price, the charge needs to rise at a higher rate than income. An analysis of the EU's 2030 emission and fuel consumption reduction targets using the estimated long-run elasticities shows that, with the current tax scheme, it cannot be guaranteed that emission targets will be achieved and thus a more stringent fuel tax policy is essential.
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12.
  • Allard, Ingrid, et al. (författare)
  • Methods for energy analysis of residential buildings in Nordic countries
  • 2013
  • Ingår i: Renewable & sustainable energy reviews. - : Pergamon-Elsevier Science. - 1364-0321 .- 1879-0690. ; 22, s. 306-318
  • Forskningsöversikt (refereegranskat)abstract
    • To meet the goals of the directive 2010/31/EU on the energy performance of buildings, the building sector in Europe now faces a transition towards more energy efficient buildings. Research and development of new energy solutions and technology will be necessary for the transition and the importance of analyzing building energy performance increases. This paper aims to review and evaluate different methods that are commonly used to analyze energy performance in residential buildings in Nordic countries, primarily in Sweden, Norway and Finland. A short international review of regulations is also included. The goal is to find commonly used methods and possibilities for the future. The introduced methods are summarized, categorized and compared based on their advantages and disadvantages. Although the three Nordic countries have similar climate conditions and building traditions, the review shows relatively large variations in the definitions of energy performance for residential buildings, as well as variations in how measurements and calculations are used in the methods for energy performance analysis. In the conducted review, methods, or parts of methods, are also found to be used. The methods used to analyze energy performance are found to be more similar than the concepts of energy performance itself in the three countries. These aspects may be considered in further work to develop an international policy practice for energy performance of residential buildings in cold climate.
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13.
  • Almssad, Asaad, et al. (författare)
  • Environmental reply to vernacular habitat conformation from a vast areas of Scandinavia
  • 2015
  • Ingår i: Renewable & sustainable energy reviews. - : Elsevier. - 1364-0321 .- 1879-0690. ; 48, s. 825-834
  • Tidskriftsartikel (refereegranskat)abstract
    • There are many original ideas and useful system inputs embedded in the building of human settlements in Scandinavian regions, where the landscape and habitat are strongly interconnected. A cold climate and strong winds are the most prominent risks that affect habitats. The Longhouse is the foremost traditional habitat in the Scandinavian region, dating back to the Iron Age, 2000 BC. This study examines the influence of climate on the conformation of habitats. Climate had a solid impact on the conceptions of habitat form and internal space. Wind and extreme temperatures had firming consequences on the housing arrangements, layouts, orientations, and building materials used in the construction process. Habitats from this region were located in an optimal arrangement, and the south orientation was used effectively. This investigation will provide an evaluative interpretation and analysis of the real facts of vernacular habitats in the context of energy efficiency and ecological concepts, considering human settlement patterns, architectural creation and building material uses. 
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14.
  • Alves, Joao S., et al. (författare)
  • Experimental investigation on performance improvement by mid-plane guide-vanes in a biplane-rotor Wells turbine for wave energy conversion
  • 2021
  • Ingår i: Renewable & sustainable energy reviews. - : Elsevier BV. - 1364-0321 .- 1879-0690. ; 150
  • Tidskriftsartikel (refereegranskat)abstract
    • The Wells turbine is the most frequently used or proposed self-rectifying air turbine for oscillating-water column wave-energy converter application, largely because of its conceptual and mechanical simplicity. Biplane Wells turbines allow a higher total blade solidity to be attained than monoplane turbines do, but this results in larger aerodynamic losses associated with the swirl kinetic energy loss at turbine exit. This may be overcome by the presence of a row of guide vanes between the two rotor planes, a solution that had been proposed and investigated theoretically or by numerical modelling. Results of turbine overall performance and flow details are reported from laboratory tests of a biplane Wells turbine without guide vanes and with specially designed guide vanes. The presence of the guide vanes was found to increase the peak efficiency by seven percentual points, while reducing (for fixed rotational speed) the damping provided by the turbine. Measured losses in the guide vane row were much smaller than in the rotors. Experimental results are compared with previously published numerical results. A stochastic theoretical transform was applied to obtain averaged results for the turbine performance subject to the irregular bidirectional air flow induced by real sea waves.
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15.
  • Amara, Sofiane, et al. (författare)
  • Legionella Disinfection by Solar Concentrator System
  • 2017
  • Ingår i: Renewable & sustainable energy reviews. - : Elsevier. - 1364-0321 .- 1879-0690. ; 70, s. 786-792
  • Tidskriftsartikel (refereegranskat)abstract
    • The current study concerns the fundamental problems of Legionnaires disease. Four decades after Legionnaires' bacteria was first identified there is still a low level of clinical awareness. Humans are infected by inhalation of aerosolized water and/or soil contaminated with the bacteria. Several control methods are available for water disinfection: biocide, ultraviolet light sterilization, copper-silver ionization, ozonation etc. but only thermal treatment can completely eliminate Legionella, which is killed almost instantly at 70 °C. The current paper describes Legionella disinfection by a solar concentrator combined with a heat recovery system that reduces the heat demand. Though this study is made for a small system (160 l of hot water per day) the system can be enlarged (more hot water and more solar collector area) and the results are thus valid also for such larger systems. Here experiments of water treatment by a solar concentrator are summarized and analyzed where the temperature exceeds 80 °C at the outlet of the heat exchanger.
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16.
  • Andersson, Elias, 1989-, et al. (författare)
  • Energy end-use and efficiency potentials among Swedish industrial small and medium-sized enterprises - A dataset analysis from the national energy audit program
  • 2018
  • Ingår i: Renewable & sustainable energy reviews. - : PERGAMON-ELSEVIER SCIENCE LTD. - 1364-0321 .- 1879-0690. ; 93, s. 165-177
  • Forskningsöversikt (refereegranskat)abstract
    • Improving energy efficiency in industry is recognized as one of the most vital activities for the mitigation of climate change. Consequently, policy initiatives from governments addressing both energy-intensive and small and medium-sized industry have been enacted. In this paper, the energy end-use and the energy efficiency potential among industrial small and medium-sized companies participating in the Swedish Energy Audit Program are reviewed. The three manufacturing industries of wood and cork, food products and metal products (excluding machinery and equipment) are studied. A unique categorization of their production processes energy end-use is presented, the results of which show that the amount of energy used in various categories of production processes differ between these industries. This applies to support processes as well, highlighting the problem of generalizing results without available bottom-up energy end-use data. In addition, a calculation of conservation supply curves for measures related to production processes is presented, showing that there still remains energy saving potential among companies participating in the Swedish Energy Audit Program. However, relevant data in the database used from the Swedish Energy Audit Program is lacking which limits the conclusions that can be drawn from the conservation supply curves. This study highlights the need to develop energy policy programs delivering high-quality data. This paper contributes to a further understanding of the intricate matters of industrial energy end-use and energy efficiency measures.
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17.
  • Andersson, Johnn, 1983, et al. (författare)
  • Photovoltaics in Sweden – Success or failure?
  • 2021
  • Ingår i: Renewable and Sustainable Energy Reviews. - : Elsevier BV. - 1879-0690 .- 1364-0321. ; 143
  • Tidskriftsartikel (refereegranskat)abstract
    • Promoting global energy transitions while stimulating domestic industrialization requires national policymaking that shapes technological innovation towards specific outcomes. Although this is inherently difficult, historical case studies may bring a better understanding of innovation dynamics and thereby guide the design of future policy interventions. The purpose of this paper is to review and analyze the emergence of Swedish photovoltaics technology from a policy perspective. Our main aim is to provide a retrospective account of historical developments, but we also derive more general insights about technological innovation and related policy challenges. The paper departs from an adapted analytical framework based on the technological innovation systems approach. Our review identifies four decades of Swedish research that has largely failed to drive domestic commercialization, the rise and fall of an industry that mainly served international markets, and a rapidly growing domestic market based on imported products. This situation is the result of mismatches and fragmentation among key innovation processes, which have not been addressed by strategic policy interventions. We suggest that policymakers should promote a full range of innovation processes and consider making innovation support subject to a payback mechanism that delivers a return on public investments even if industries and markets emerge abroad. Our study also demonstrates how the technological innovation systems approach can be extended to include the function commercialization and emphasizes the importance of paying attention to the directionality of technological innovation processes.
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18.
  • Andrei, Mariana, 1981-, et al. (författare)
  • Exploring a decarbonization framework for a Swedish automotive paint shop
  • 2024
  • Ingår i: Renewable & sustainable energy reviews. - : Elsevier. - 1364-0321 .- 1879-0690. ; 200
  • Tidskriftsartikel (refereegranskat)abstract
    • The automotive industry is the world’s largest manufacturing activity, characterized by complex productionprocesses and some energy-intense processes which use a significant quantity of raw materials. The production processes responsible for the highest energy end-use take place in the paint shop. Depending on the type of paintshop processes, the energy use can account for up to 75 % of the plant’s total energy end-use. This study aims to contribute to an enhanced understanding of the complexity of adopting decarbonization measures and to provide support for planning and decision-making in practice. By adopting a bottom-up perspective, a longitudinal case study was conducted on a state-of-the-art automotive paint-shop between November 2019 and March 2023. To achieve the study’s aim, a bottom-up methodology was developed comprising several steps: i) analysis of decarbonization measures, ii) mapping of process energy use and CO2 emissions, and iii) economic analysis. The data-based methodology is flexible and can be applied in different automotive paint-shops. Main findings show that i) incremental energy efficiency measures have the fastest adoption level, with relatively high savings potential,and most of these are cost effective; ii) radical process innovation measures have a higher savings potential, but long-term adoption levels due to the radical innovations required in the supply chain, and the highly specialized knowledge needed in the pre-treatment process; and iii) the primary drivers for implementing the measures are to achieve the climate targets and establish a leading position in the sector, rather than focusing primarily on the cost-effectiveness of the measures.
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19.
  • Andrei, Mariana, 1981-, et al. (författare)
  • Knowledge demands for energy management in manufacturing industry - A systematic literature review
  • 2022
  • Ingår i: Renewable & sustainable energy reviews. - : Elsevier. - 1364-0321 .- 1879-0690. ; 159
  • Forskningsöversikt (refereegranskat)abstract
    • The social context in relation to energy policies and advances in more energy efficient technologies is changing constantly, thus driving a need for change in the manufacturing sector. This study presents a knowledge-based framework that enables the understanding of the model for knowledge that has taken industrial energy efficiency to current levels and the analysis of the model in the current context of industry transition. The framework consists of three broader forms of knowledge and specific knowledge attributes that can capture the knowledge employed in industrial energy management. The framework is applied in a systematic literature review, analyzing the forms of knowledge and main aspects of energy management in manufacturing industries from 157 articles published between 2010 and 2020 in various academic journals. Besides the framework, the results show that the technical form of knowledge is the primary type of knowledge employed in energy management and that a paradigm-changing towards Industry 4.0. is seen. Another employed form of knowledge is process knowledge, which is concerned with the prerequisite information needed to implement energy management. Finally, lead- ership knowledge is also employed in energy management and a blend in these three forms of knowledge might move us beyond traditional knowledge towards new forms of knowledge that maximize the potential for energy management in manufacturing industries. The knowledge demands brought by Industry 4.0 for all forms of knowledge are identified and discussed.
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20.
  • Anukam, Anthony, et al. (författare)
  • A review of the mechanism of bonding in densified biomass pellets
  • 2021
  • Ingår i: Renewable & sustainable energy reviews. - : Elsevier. - 1364-0321 .- 1879-0690. ; 148
  • Tidskriftsartikel (refereegranskat)abstract
    • The production of durable biomass pellets have always been challenged by several factors including the lack of understanding of the mechanism involved in how particles combine to form pellets under standard conditions of the pellet press. This is because contributing factors span several molecular, microscopic, and even nanoscopic levels as biomass undergoes pelleting. The characteristics of the bonds formed between the combining particles and their relevance to the quality of pellets remains vague, no matter how quality is defined. However, even though few researchers have attempted to explain the mechanism of bonding in densified biomass pellets using different theories, none of their hypotheses supports particle bonding from a structural chemistry perspective. There are still no clear explanations which consider the role of molecular structure and the interactions of substances as milled biomass undergo pelleting. In view of these arguments therefore, this review presents an in-depth analysis of a structural chemistry perspective of the mechanism of bonding and the use of additives in densified biomass pellets and helps identify research areas needed to facilitate better understanding of bonding in densified biomass pellets. The status of current research in biomass pelleting, types of materials suitable as additives and their structural characteristics, as well as the current technical specifications of using additives are also discussed.
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21.
  • Anukam, Anthony, et al. (författare)
  • Pre-processing of sugarcane bagasse for gasification in a downdraft biomass gasifier system : A comprehensive review
  • 2016
  • Ingår i: Renewable & sustainable energy reviews. - : Elsevier. - 1364-0321 .- 1879-0690. ; 66, s. 775-801
  • Forskningsöversikt (refereegranskat)abstract
    • The processing of sugarcane bagasse as a potential feedstock for efficient energy production has attracted a great deal of attention in the sugarcane industry, which has traditionally inefficiently burned bagasse in boilers for steam and electricity generation. Alternative technologies for more efficient utilisation of bagasse for energy production within the industry has also been hindered by the high degree of complexity involved in bagasse handling and pre-processing before it can be utilised as an energy feedstock. This can be attributed to unfavourable characteristics of mill-run bagasse, which includes low bulk and energy densities, a wide range of particle sizes and shapes as well as high moisture content. Gasification is regarded as one of the most promising energy recovery technologies for the widespread use of biomass because of its higher efficiency when compared to the combustion technology commonly used by the sugarcane industry. There has been a strong drive to identify efficient pre-processing methods that can be applied to bagasse to make it a suitable feedstock for energy production in thermochemical conversion systems. This work provides a comprehensive review on the pre-processing of bagasse for gasification, and the gasification technology options for its conversion into energy, with a particular emphasis on the downdraft gasification technology. (C) 2016 The Authors. Published by Elsevier Ltd.
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22.
  • Arens, Marlene, et al. (författare)
  • Which countries are prepared to green their coal-based steel industry with electricity? - Reviewing climate and energy policy as well as the implementation of renewable electricity
  • 2021
  • Ingår i: Renewable and Sustainable Energy Reviews. - : Elsevier BV. - 1364-0321. ; 143
  • Forskningsöversikt (refereegranskat)abstract
    • Global steel production is currently dependent on coal and capital-intensive production facilities with long economic lifetimes. While the Paris Agreement means carbon neutrality must be reached globally by 2050–2070, with negative emissions thereafter, coal-based steel production today accounts for around 8% of global energy-related CO2 emissions. Its production may stabilize or even decline in industrialized countries, but it will increase significantly in the emerging economies. In the past, the focus of CO2 reduction for steel has been on moderate emissions reductions through energy efficiency measures and on exploring carbon capture and storage. However, as (1) the cost of renewable electricity is declining rapidly, (2) carbon capture and storage has not materialized yet, and (3) and more and more countries set deep emission reduction targets, electricity- and hydrogen-based steelmaking has gathered substantial momentum over the past half-decade. Given the short time frame and the sector's deep carbon lock-in, there is an urgent need to understand the national climate and energy policy as well as the current implementation of low-CO2 and renewable electricity that would enable a shift from coal-based to electricity-based steelmaking. In this paper, we first identify the countries that are likely to be major steel producers in the future and thus major CO2-emitters. Then we map medium- and long-term CO2 reduction and renewable targets as well as the current share of low-CO2 and renewable electricity by country. Based on these data, we develop a set of indicators that map the readiness of steel-producing countries for a sustainable transition. Our findings show that although binding long-term CO2 reduction targets are being implemented, medium-term CO2 reduction do not yet affect coal based steel production. Overall, the global steel industry seems not be on track yet, though differences between steel producing countries are large. Common shortcomings across countries are a lack of access to renewable electricity and a lack of demanding medium-term CO2 reduction targets. The paper ends with recommendations on how to enable a low-carbon transition of the global steel industry in line with the Paris Agreement.
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23.
  • Averfalk, Helge, 1988-, et al. (författare)
  • Large heat pumps in Swedish district heating systems
  • 2017
  • Ingår i: Renewable & sustainable energy reviews. - Kidlington : Pergamon Press. - 1364-0321 .- 1879-0690. ; 79, s. 1275-1284
  • Tidskriftsartikel (refereegranskat)abstract
    • Power-to-heat solutions like heat pumps and electric boilers are foreseen to be possible future tools to stabilise international power markets with high proportions of variable power supply. Temporary low cost electricity can be used for heat generation at times with high availability of wind and solar power through substitution of ordinary heat supply, hence contributing to increased energy system sustainability. Power-to-heat installations in district heating systems are competitive due to low specific investment and installation costs for large electric boilers, heat pumps, and heat storages. Several large-scale heat pumps were installed in Swedish district heating systems during the 1980s, since a national electricity surplus from new nuclear power existed for some years. The aim of this paper is to summarise the accumulated operation experiences from these large Swedish heat pumps to support and facilitate planning of future power-to-heat solutions with heat pumps in district heating systems. Gained experiences consider; installed capacities, capacity utilisation, heat sources used, refrigerant replacements, refrigerant leakages, and wear of mechanical components. The major conclusion is that many of the large thirty-year-old heat pumps are still in operation, but with reduced capacity utilisation due to internal competition from waste and biomass cogeneration plants in the district heating systems.
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24.
  • Awais, Fawad, et al. (författare)
  • Logistic characteristics and requirements of Swedish wood biofuel heating plants
  • 2021
  • Ingår i: Renewable & sustainable energy reviews. - : Elsevier Ltd. - 1364-0321 .- 1879-0690. ; 138
  • Tidskriftsartikel (refereegranskat)abstract
    • The demand for wood biofuel for district heating plants and combined heat and power plants (CHPs) has increased, caused by an increase in both the number and size of CHPs. This places large demands on the logistics system supplying these plants with fuel, with a particular interest in the use of alternative modes of transport such as rail and sea. The aim of this paper is to identify the industry actors’ requirements, constraints, and preferences regarding the wood-biofuel supply chain and to identify the logistical challenges this entails, as well as how this impacts the opportunity for an increased use of alternative transport solutions. A survey was sent to all Swedish CHPs, combined with six interviews with transport companies, terminal operators, and forest companies. The study shows that the industry has a local focus that limits potential logistics and sourcing solutions. It is also challenged by urban sprawl, with expanding residential areas close to the CHPs putting further constraints on the operations. Significant variations in fuel demand, depending on unpredictable outside temperature and seasonal variation, is a further challenge. The low density of the fuel has a negative impact on transport costs and introduces a trade-off between chipping close to the forest to increase density versus more efficient chipping at the CHP. Intermodal transport only used by large plants, driven by a shortage of local fuel. © 2020 The Authors
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25.
  • Azuatalam, Donald, et al. (författare)
  • Energy management of small-scale PV-battery systems : A systematic review considering practical implementation, computational requirements, quality of input data and battery degradation
  • 2019
  • Ingår i: Renewable & sustainable energy reviews. - : Elsevier. - 1364-0321 .- 1879-0690. ; 112, s. 555-570
  • Forskningsöversikt (refereegranskat)abstract
    • The home energy management problem has many different facets, including economic viability, data uncertainty and quality of strategy employed. The existing literature in this area focuses on individual aspects of this problem without a detailed, holistic analysis of the results with regards to practicality in implementation. In this paper, we fill this gap by performing a comprehensive comparison of seven different energy management strategies, each with different levels of practicality, sophistication and computational requirements. We analyse the results in the context of these three characteristics, and also critique the modelling assumptions made by each strategy. Our analysis finds that using a more sophisticated energy management strategy may not necessarily improve the performance and economic viability of the PV-battery system due to the effects of modelling assumptions, such as the treatment of uncertainties in the input data and battery degradation effects.
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26.
  • Bahaj, AbuBakr S. (författare)
  • Generating electricity from the oceans
  • 2011
  • Ingår i: Renewable & sustainable energy reviews. - : Elsevier BV. - 1364-0321 .- 1879-0690. ; 15:7, s. 3399-3416
  • Tidskriftsartikel (refereegranskat)abstract
    • Ocean energy has many forms, encompassing tides, surface waves, ocean circulation, salinity and thermal gradients. This paper will considers two of these, namely those found in the kinetic energy resource in tidal streams or marine currents, driven by gravitational effects, and the resources in wind-driven waves, derived ultimately from solar energy. There is growing interest around the world in the utilisation of wave energy and marine currents (tidal stream) for the generation of electrical power. Marine currents are predictable and could be utilised without the need for barrages and the impounding of water, whilst wave energy is inherently less predictable, being a consequence of wind energy. The conversion of these resources into sustainable electrical power offers immense opportunities to nations endowed with such resources and this work is partially aimed at addressing such prospects. The research presented conveys the current status of wave and marine current energy conversion technologies addressing issues related to their infancy (only a handful being at the commercial prototype stage) as compared to others such offshore wind. The work establishes a step-by-step approach that could be used in technology and project development, depicting results based on experimental and field observations on device fundamentals, modelling approaches, project development issues. It includes analysis of the various pathways and approaches needed for technology and device or converter deployment issues. As most technology developments are currently UK based, the paper also discusses the UK's financial mechanisms available to support this area of renewable energy, highlighting the needed economic approaches in technology development phases. Examination of future prospects for wave and marine current ocean energy technologies are also discussed.
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27.
  • Bandara, T M W J, 1968, et al. (författare)
  • High efficiency dye-sensitized solar cell based on a novel gel polymer electrolyte containing RbI and tetrahexylammonium iodide (Hex(4)NI) salts and multi-layered photoelectrodes of TiO2 nanoparticles
  • 2019
  • Ingår i: Renewable & Sustainable Energy Reviews. - : Elsevier BV. - 1364-0321 .- 1879-0690. ; 103, s. 282-290
  • Tidskriftsartikel (refereegranskat)abstract
    • High efficiency dye sensitized solar cells (DSSCs) have been achieved using a novel polymer gel electrolyte containing RbI and tetrahexylammonium iodide (Hex(4)NI) binary salts in combination with multi-layered TiO2 photoelectrodes. Performance enhancers were incorporated to the electrolyte to improve the efficiency in the DSSCs. Varying the salt mass fraction, showed that the conductivity in the electrolyte increases with increasing amount of RbI. The highest ionic conductivity of 4.19 mS cm(-1) is exhibited by the electrolyte sample with RbI: Hex(4)NI weight ratio of 3:1 at 25 degrees C. The temperature dependence of the electrolytes shows Arrhenius behavior. It is found that the electrolyte with RbI: Hex(4)NI weight ratio of 1.06:1 is more suitable for DSSC's applications and it has a conductivity of 3.77 mS cm(-1). A colloidal suspension of P25 TiO2 nanoparticles was used to make the spin coated photo-anodes in the form of stacks of 1-6 layers. The formation of a highly uniform and porous structure is observed with increasing number of layers from scanning electron microscopy and X-ray diffraction studies revealed that the layers are predominantly anatase phase with crystallite size of 19-22 nm. The band gap was estimated to be around 3.22 eV based on UV-Visible spectroscopy and found to be decreasing slightly with increasing layer thickness. The maximum efficiency of 7.5% and an impressively high current density of 20 mA cm(-2) were observed for the 4-layer device with the new gel electrolyte based on RbI and Hex(4)NI. This study not only brings reliability and consistency to the ways of preparing well-ordered TiO2 photoanodes but also offers the possibility of low-cost practical and highly efficient quasi-solid state DSSCs.
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28.
  • Bao, Haiyan, et al. (författare)
  • Condition of setting surge tanks in hydropower plants - A review
  • 2018
  • Ingår i: Renewable & sustainable energy reviews. - : Elsevier BV. - 1364-0321 .- 1879-0690. ; 81, s. 2059-2070
  • Forskningsöversikt (refereegranskat)abstract
    • Hydropower plays an important role in the safe, stable and efficient operation of power systems, especially with current trends toward renewable energy systems. The total global potential of gross, technical, economic, and exploitable hydropower are still enormous in the future, and the developments of new hydropower stations (HPSs) are of great importance. For constructions of new HPSs, the condition of setting surge tanks (CSST) is crucial for various perspectives, e.g. safety, stability and economy of HPSs. In this review, the CSST are summarized and analyzed from the three aspects: regulation assurance, operation stability, and the regulation quality, with an aim of providing a reference and guidance for research and engineering applications regarding surge tanks. Upstream and downstream surge tanks in conventional HPSs and pumped storage power stations are all included. Moreover, a comprehensive comparison of CSST under different conditions is conducted. One of the main focuses of this review is on Chinese studies, for introducing many meaningful results written in Chinese to more readers all over the world.
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29.
  • Bartocci, Pietro, et al. (författare)
  • Bioenergy with Carbon Capture and Storage (BECCS) developed by coupling a Pressurised Chemical Looping combustor with a turbo expander: How to optimize plant efficiency
  • 2022
  • Ingår i: Renewable and Sustainable Energy Reviews. - : Elsevier BV. - 1879-0690 .- 1364-0321. ; 169
  • Forskningsöversikt (refereegranskat)abstract
    • Carbon Capture and Storage is a technology of paramount importance for the fulfillment of the Sustainable Development Goal 7 (Affordable and Clean Energy) and the Sustainable Development Goal 5 (Climate Action). The European Union is moving rapidly towards low carbon technologies, for instance via the Energy Union Strategy. Coupling biofuels and carbon capture and storage to decarbonize the power and the industrial sector can be done through the development of BECCS (Bioenergy with Carbon Capture and Storage). Chemical Looping combustion is one of the cheapest way to capture CO2. A Chemical Looping Combustion (CLC) plant can be coupled with a turbo expander to convert energy to power, but it has to work in pressurised conditions. The effect of pressure on the chemical reactions and on fluidised bed hydrodynamics, at the moment, is not completely clear. The aim of this review is to summarize the most important highlights in this field and also provide an original method to optimize power plant efficiency. The main objective of our research is that to design a pressurised Chemical Looping Combustion plant which can be coupled to a turbo expander. To achieve this we need to start from the characteristics of the turbo expander itself (eg. the Turbine Inlet Temperature and the compression ratio) and then design the chemical looping combustor with a top down approach. Once the air and the fuel reactor have been dimensioned and the oxygen carrier inventory and circulation rate have been identified, the paper proposes a final optimization procedure based on two energy balances applied to the two reactors. The results of this work propose an optimization methodology and guidelines to be used for the design of pressurised chemical looping reactors to be coupled with turbo expanders for the production of power with carbon negative emissions.
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30.
  • Bartoli, A., et al. (författare)
  • Coupling economic and GHG emission accounting models to evaluate the sustainability of biogas policies
  • 2019
  • Ingår i: Renewable & sustainable energy reviews. - : Elsevier. - 1364-0321 .- 1879-0690. ; 106, s. 133-148
  • Tidskriftsartikel (refereegranskat)abstract
    • The aim of this study is to evaluate and quantify the impacts of different biogas and related policies on the agricultural sector as well as their performance in terms of climate change mitigation and associated costs. To do so we coupled the partial equilibrium approach simulating the market clearing process with the perspective of Life Cycle Assessment of GHG applying it to the well-documented Lombardy case. Results show that the recent Italian biogas policy – prompting manure utilization and reducing the average subsidy per kWh – effectively increased the environmental sustainability of the system, which only now seems able to counteract global warming. Synergies are observed when the recent Common Agricultural Policy greening reform is simultaneously considered by the model.
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31.
  • Bartusch, Cajsa, 1965-, et al. (författare)
  • Opening the black box of demand response : Exploring the cognitive processes
  • 2024
  • Ingår i: Renewable & sustainable energy reviews. - : Elsevier. - 1364-0321 .- 1879-0690. ; 189
  • Tidskriftsartikel (refereegranskat)abstract
    • Evaluations of price-based demand response programs tend to focus on users' electricity use patterns and/or their practical experiences. Less is known about the effects that price-based demand response programs have on cognitive drivers and barriers to energy-using behaviors and habits, or how well these predict timing of households' electricity use. This study seeks to address this gap by evaluating the effects of a mandatory demand-based time-of-use distribution tariff, using electricity-meter and questionnaire data in an intervention and a reference area, and a structural equation model following the theory of planned behavior. Although no effect was found of the tariff on the actual proportion of peak-hour use, there were significant effects on users’ intentions and motivations to shift electricity use to off-peak hours. The absence of effect on the proportion of peak-hour use seems explained by the facts that only a minority of consumers were aware of their tariffs, and by the (at least partially correct) beliefs that consumers used very little electricity and most of it was already used in off-peak hours. The relationships between intentions, drivers and the actual proportion of peak-hour use were stronger in the intervention area, compared to the reference area. Interestingly, this was true not only for the motivation targeted by the tariff, economic savings, but also for sustainability concerns and social norms. This suggests that effects of the tariff may partly run via other non-monetary motivators.
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32.
  • Behzadi, Amirmohammad, et al. (författare)
  • Smart design and control of thermal energy storage in low-temperature heating and high-temperature cooling systems : A comprehensive review
  • 2022
  • Ingår i: Renewable & sustainable energy reviews. - : Elsevier BV. - 1364-0321 .- 1879-0690. ; 166, s. 112625-
  • Forskningsöversikt (refereegranskat)abstract
    • Thermal energy storage (TES) is recognized as a well-established technology added to the smart energy systems to support the immediate increase in energy demand, flatten the rapid supply-side changes, and reduce energy costs through an efficient and sustainable integration. On the utilization side, low-temperature heating (LTH) and high-temperature cooling (HTC) systems have grown popular because of their excellent performance in terms of energy efficiency, cost-effectiveness, and ease of integration with renewable resources. This article presents the current state-of-the-art regarding the smart design of TES integrated with LTH and HTC systems. TES is first explained in basic concepts, classification, and design possibilities. Secondly, the literature on well-known existing control approaches, strategies, and optimization methods applied to thermal energy storage is reviewed. Thirdly, the specifications, types, benefits, and drawbacks of the LTH and HTC systems from the viewpoints of supply and demand sides are discussed. Fourthly, the smart design of TES integrated with the LTH and HTC systems based on the control approach/strategy, optimization method, building type, and energy supplier is investigated to find the newest technology, ideas, and features and detect the existing gaps. The present article will provide a realistically feasible solution for having a smart storage configuration with the maximum possible energy efficiency, reliability, and cost-effectiveness for the building owners and the energy suppliers.
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33.
  • Benitez, Almudena, et al. (författare)
  • Recent advances in lithium-sulfur batteries using biomass-derived carbons as sulfur host
  • 2022
  • Ingår i: Renewable & sustainable energy reviews. - : Elsevier. - 1364-0321 .- 1879-0690. ; 154
  • Tidskriftsartikel (refereegranskat)abstract
    • While biomass waste is generated in abundance, these materials and their production processes are generally environmentally friendly, low cost, non-hazardous and easily scalable. These advantages position biomass materials as excellent candidates to solve problems of environmental pollution, primarily by substitution of less sustainable counterparts. This also applies to energy storage systems such as batteries, where several components have large environmental impacts. Lithium-Sulfur batteries have, in this context, been extensively researched to cope with the growing energy needs, and are expected to foresee a growing commercialization. Specifically, advances in the use of renewable cathode materials for Li-S batteries is a field that has been widely addressed in recent years, with carbonaceous materials (C) and/or activated carbons (AC), obtained from biomass, being intensively studied. We here reviewed this field through a classification and discussion of carbonaceous materials from natural waste according to the type of biomass: (1) woody, (2) herbaceous and agricultural, (3) aquatic, (4) animal and human, and (5) contaminated and industrial biomass waste materials. In addition, all porous carbons or activated carbons used as sulfur hosts have been exhaustively evaluated in terms of origin, synthesis parameters, physical properties, and electrochemical performance in Li-S batteries. The purpose is to provide a general description of the progress in the preparation of carbons from biomass resources, examine the textural and electrochemical properties of these materials focusing on the last decade, and also to present an outlook for future research in this developing area.
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34.
  • Betzold, Carola, 1984 (författare)
  • Fuelling the Pacific: Aid for renewable energy across Pacific Island countries
  • 2016
  • Ingår i: Renewable & Sustainable Energy Reviews. - : Elsevier BV. - 1364-0321. ; 58, s. 311-318
  • Tidskriftsartikel (refereegranskat)abstract
    • Pacific island countries have strong economic, political and environmental incentives to switch from imported fossil fuels to indigenous renewable energy technologies, and are well positioned to achieve such a switch, given their ample renewable energy potential as well as their ambitious renewable energy goals. For the Pacific island countries to reach these goals, however, they depend on donor funding. This paper therefore analyses energy-related aid to the South Pacific from 1990 through 2012, and specifically evaluates its development in three areas: energy technology, grid vs. off-grid solutions, and project components. Using data from the Organisation of Economic Cooperation and Development, I find a recent shift in donor thinking: donors have, over the past years, put greater emphasis on renewable energy, especially hydro and increasingly solar power. Donors have also invested more in off-grid solutions - often solar-powered. Finally, donors have begun to focus more on 'software', that is, capacity building, training and policy-making. If Pacific island countries, together with the donors, continue on this path, they are well-positioned to reach their ambitious renewable energy goals - and to serve as an example for other countries, both developing and developed, islands and non-islands. (C) 2015 Elsevier Ltd. All rights reserved.
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35.
  • Bird, Lori, et al. (författare)
  • Wind and solar energy curtailment : A review of international experience
  • 2016
  • Ingår i: Renewable & sustainable energy reviews. - : Elsevier. - 1364-0321 .- 1879-0690. ; 65, s. 577-586
  • Forskningsöversikt (refereegranskat)abstract
    • Greater penetrations of variable renewable generation on some electric grids have resulted in increased levels of curtailment in recent years. Studies of renewable energy grid integration have found that curtailment levels may grow as the penetration of wind and solar energy generation increases. This paper reviews international experience with curtailment of wind and solar energy on bulk power systems in recent years, with a focus on eleven countries in Europe, North America, and Asia. It examines levels of curtailment, the causes of curtailment, curtailment methods and use of market based dispatch, as well as operational, institutional, and other changes that are being made to reduce renewable energy curtailment.
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36.
  • Bolund, Björn, et al. (författare)
  • Flywheel energy and power storage systems
  • 2007
  • Ingår i: Renewable & sustainable energy reviews. - : Elsevier BV. - 1364-0321 .- 1879-0690. ; 11:2, s. 235-258
  • Tidskriftsartikel (refereegranskat)abstract
    • For ages flywheels have been used to achieve smooth operation of machines. The early models where purely mechanical consisting of only a stone wheel attached to an axle. Nowadays flywheels are complex constructions where energy is stored mechanically and transferred to and from the flywheel by an integrated motor/generator. The stone wheel has been replaced by a steel or composite rotor and magnetic bearings have been introduced. Today flywheels are used as supplementary UPS storage at several industries world over. Future applications span a wide range including electric vehicles, intermediate storage for renewable energy generation and direct grid applications from power quality issues to offering an alternative to strengthening transmission. One of the key issues for viable flywheel construction is a high overall efficiency, hence a reduction of the total losses. By increasing the voltage, current losses are decreased and otherwise necessary transformer steps become redundant. So far flywheels over 10 kV have not been constructed, mainly due to isolation problems associated with high voltage, but also because of limitations in the power electronics. Recent progress in semi-conductor technology enables faster switching and lower costs. The predominant part of prior studies have been directed towards optimising mechanical issues whereas the electro technical part now seem to show great potential for improvement. An overview of flywheel technology and previous projects are presented and moreover a 200 kW flywheel using high voltage technology is simulated.
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37.
  • Bourne-Webb, Peter, et al. (författare)
  • Analysis and design methods for energy geostructures
  • 2016
  • Ingår i: Renewable and Sustainable Energy Reviews. - : Elsevier BV. - 1879-0690 .- 1364-0321. ; 65, s. 402-419
  • Forskningsöversikt (refereegranskat)abstract
    • Based on discussions at the international workshop on “Thermoactive geotechnical systems for near-surface geothermal energy”, hosted at École Polytechnique Fédérale de Lausanne (EPFL), Switzerland (http://www.olgun.cee.vt.edu/workshop/), this article attempts to provide a broad overview of the analysis methods used for evaluation of systems that use either boreholes or geo-structures for heat exchange. It identifies commonalities where knowledge transfer from the former to the latter can be made, and highlights where there are significant differences that may limit this cross-fertilisation. The article then focusses on recent developments and current understanding pertaining to the analysis of the thermo-mechanical interaction between a geostructure and the ground, and how this may be incorporated into the geotechnical design of energy geostructures.
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38.
  • Brynolf, Selma, 1984, et al. (författare)
  • Electrofuels for the transport sector: A review of production costs
  • 2018
  • Ingår i: Renewable and Sustainable Energy Reviews. - : Elsevier BV. - 1879-0690 .- 1364-0321. ; 81:2, s. 1887-1905
  • Forskningsöversikt (refereegranskat)abstract
    • Electrofuels (also called power-to-gas/liquids/fuels or synthetic fuels) are potential future carbon-based fuelsproduced from carbon dioxide (CO2) and water using electricity as the primary source of energy. This articleassesses the production cost of electrofuels through: (i) a literature review, focusing on which steps that have thelargest impact as well as the greatest uncertainty; (ii) a more comprehensive review, including the costs andefficiencies for the separate production steps, and (iii) calculations to compare the production costs of thedifferent fuel options in a harmonized way, including a sensitivity analysis of the parameters with the greatestimpact on the total electrofuel production cost. The assessment covers: methane, methanol, dimethyl ether,diesel, and gasoline. The literature review showed large differences among the studies and a broad range ofproduction cost estimates (10–3500 €2015/MWhfuel), which is first and foremost as a result of how authors havehandled technology matureness, installation costs, and external factors. Our calculations result in productionscosts in the range of 200–280 €2015/MWhfuel in 2015 and 160–210 €2015/MWhfuel in 2030 using base costassumptions from the literature review. Compared to biofuels, these estimates are in the upper range or above.Our results also show that the choice of energy carrier is not as critical for the electrofuels production cost astechnological choices and external factors. Instead the two most important factors affecting the production costof all electrofuels are the capital cost of the electrolyser and the electricity price, i.e., the hydrogen productioncost. The capacity factor of the unit and the life span of the electrolyser are also important parameters affectingthat production cost. In order to determine if electrofuels are a cost-effective future transport fuel relative toalternatives other than biofuels, the costs for distribution, propulsion, and storage systems need to beconsidered.
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39.
  • Buberger, Johannes, et al. (författare)
  • Total CO 2 -equivalent life-cycle emissions from commercially available passenger cars
  • 2022
  • Ingår i: Renewable and Sustainable Energy Reviews. - : Elsevier BV. - 1879-0690 .- 1364-0321. ; 159
  • Tidskriftsartikel (refereegranskat)abstract
    • The international passenger car market is undergoing a transition from vehicles with internal combustion engines to hybrid and fully electrified vehicles to reduce the climate impact of the transportation sector. To emphasize the importance of this needed change, this paper provides holistic comparisons of the total life-cycle greenhouse gas (GHG) emissions produced by a wide selection of commercially available passenger cars with different powertrains and energy sources. Simple analytical models are used to quantify the total life-cycle GHG emissions in terms of CO2-equivalent values relative to the vehicle curb weight and the peak motor power. The production, utilization and recycling emissions are separately quantified based on the latest reviewed emission coefficient values. In total 790 different vehicle variants are considered. The results show that Battery Electric Vehicles have the highest production emissions. For example, the additional production emissions of a Tesla Model 3 Standard Plus approximately correspond to the driving emissions of a Volkwagen Passat 2.0 TSI after 18 000km. Nonetheless, it is shown that conventional gasoline and diesel vehicles emit the highest amount of total life-cycle GHGs in comparison to vehicles powered by other available energy resources. When using green electricity, plug-in hybrid electric and fully electric vehicles can reduce the total life-cycle emission in comparison to combustion engine vehicles by 73% and 89%, respectively. A similar emission reduction is achieved by biogas powered vehicles (81%). Fuel cell vehicles approximately reduce the GHG emission to a similar extent as electric vehicles (charged with conventional electricity) when using commercially available gray hydrogen (60%).
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40.
  • Bundschuh, Jochen, et al. (författare)
  • Geothermal arsenic : Occurrence, mobility and environmental implications
  • 2015
  • Ingår i: Renewable & sustainable energy reviews. - : Elsevier BV. - 1364-0321 .- 1879-0690. ; 42, s. 1214-1222
  • Forskningsöversikt (refereegranskat)abstract
    • Arsenic (As) contamination in geothermal systems has been identified in many areas of the world. Arsenic mobilization from rocks and mineral phases into geothermal fluids depends on available As sources, geochemical conditions and microbiological activity. In deep geothermal reservoirs As mobilization is predominantly from As-bearing pyrite at temperatures of 150-250 degrees C, and at higher temperatures also from arsenopyrite. Highest As concentrations, mostly in the range of thousands to tens of thousands of mu g/L and in case of Los Humeros (Mexico) even of up to 162,000 mu g/L are found in volcanic geothermal systems whereas in low- and high-enthalpy sedimentary geothermal systems they reach only about 2000 mu g/L. At many sites, uprising geothermal waters contaminate shallow water resources. From the geothermal springs, those with NaCl water type have the highest As concentrations; these waters correspond to original reservoir waters which were not significantly altered during its ascent. In the geothermal reservoir and deeper parts of hydrothermal system, As is predominantly present as neutral H3As(III)O-3 (arsenius acid) and under sulfidic conditions also as thioarsenites; close to the earth's surface oxidation through atmospheric oxygen to As(V) species may occur; however, this is a slow process. As(III) emerging in geothermal springs is oxidized quickly through microbial catalysis and often most As is present as As(V), at a distance of few meters from the spring outlet. This review highlights the occurrence and distribution of geothermal As worldwide, its sources and its mobilization and the presence of different As species in geothermal fluids considering different geological settings and processes involving geothermal fluids rising from deep geothermal reservoirs to the earth's surface where it may mix with shallow groundwater or surface waters and contaminate these resources. The microbial diversity of hot spring environments which plays an important role to mobilize the As by oxidation and reduction process in the geothermal system is also addressed.
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41.
  • Bundschuh, Jochen, et al. (författare)
  • Low-cost low-enthalpy geothermal heat for freshwater production : Innovative applications using thermal desalination processes
  • 2015
  • Ingår i: Renewable & sustainable energy reviews. - : Elsevier BV. - 1364-0321 .- 1879-0690. ; 43, s. 196-206
  • Forskningsöversikt (refereegranskat)abstract
    • The study is dedicated to exploring different types of low-cost low-enthalpy geothermal and their potential integration with conventional thermal-based water desalination and treatment technologies to deliver energy efficient, environmentally friendly solutions for water desalination and treatment, addressing global water crises. Our in-depth investigation through reviews of various low-enthalpy geothermal and conventional thermal-based technologies suggest that the geothermal option is superior to the solar option if low-cost geothermal heat is available because it provides a constant heat source in contrast to solar. Importantly, the stable heat source further allows up-scaling ( >1000 m(3)/day), which is not currently possible with solar. Solar-geothermal hybrid constellations may also be suitable in areas where both sources are available. The review also discovers that the innovative Membrane distillation (MD) process is very promising as it can be used for many different water compositions, salinity and temperature ranges. Either the geothermal water itself can be desalinated/treated or the geothermal heat can be used to heat feed water from other sources using heat exchangers. However, there are only few economic analyses for large-scale MD units and these are based on theoretical models using often ;uncertain assumptions resulting in a large variety of results.
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42.
  • Busch, Henner, et al. (författare)
  • Policy challenges to community energy in the EU : A systematic review of the scientific literature
  • 2021
  • Ingår i: Renewable and Sustainable Energy Reviews. - : Elsevier BV. - 1364-0321. ; 151
  • Forskningsöversikt (refereegranskat)abstract
    • In response to the ongoing climate crisis, many countries have issued policies to support the uptake of renewable energy. In the same vein, the European Union (EU) has issued a revised renewable energy directive in 2018. One of the pillars of the directive is the support for community energy initiatives, i.e. sustainable energy initiatives run by or with the participation of citizens. The concept of community energy (CE) has been linked to a number of advantages, such as strengthening local democratic processes or economic development for marginalised communities. The aim of this review article is to find out how past policies helped to overcome or aggravated transition challenges towards a higher share of community energy in the EU. To answer this question, we reviewed the scientific literature on community energy from the last decade. We analysed this body through a theoretical lens that highlights four main transition challenges. These occur in relation to 1) directionality, 2) demand articulation, 3) experimentation, 4) policy learning & coordination. Our results show that visions and goals are important policy tools for providing directionality in the energy transition. Feed-in-tariffs (FiT) surface as the most important policy to support community energy projects and spark demand. We found very little indication for a link between community energy and explicit experimentation. Nevertheless, learning does take place amongst peers. Our review underlined the important role intermediaries play in facilitating policy learning and coordination. We conclude by presenting a number of concrete policy recommendations such as strengthening intermediary organisations and providing administrative support to community energy initiatives in case of changes in the policy framework.
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43.
  • Caron, Simon, et al. (författare)
  • A comparative analysis of opto-thermal figures of merit for high temperature solar thermal absorber coatings
  • 2022
  • Ingår i: Renewable & sustainable energy reviews. - : Elsevier BV. - 1364-0321 .- 1879-0690. ; 154
  • Tidskriftsartikel (refereegranskat)abstract
    • Solar thermal absorber coatings play a key role in the thermal efficiency of receivers for applications in the field of Concentrated Solar Power (CSP). The development of stable spectral selective coatings with a high solar absorptance alpha sol and a low thermal emittance epsilon th is often desired to reduce thermal losses. However, quantitative indicators describing selectivity and the trade-off between solar absorptance and thermal emittance is seldom discussed in the literature. In this review, relevant opto-thermal figures of merit are analyzed for the comparison of reference solar thermal absorber coatings, including real and ideal coatings, both black and spectral selective. The comparison is made for a temperature ranging from 25 to 1000 degrees C and for a concentration factor ranging from 20 to 1000, based on spectral data measured at room temperature from 0.25 to 20 mu m. New figures of merit are introduced, i.e. a normalized selectivity ratio Si*, a trade-off factor Ztrade-off, a normalized solar reflectance index SRI* and a peak efficiency temperature Tpeak,opt. These metrics are derived from existing figures of merit and adapted for CSP. The set of figures of merit analyzed in this review offer a complementary perspective for the detailed characterization of any coating opto-thermal performance. For solar thermal absorber coatings, thermal efficiency eta thermal and peak efficiency temperature Tpeak,opt are respectively deemed more insightful than opto-thermal efficiency eta opt-th and maximum steady-state temperature TSST,max, when comparing the relative opto-thermal performance of two coating formulations.
  •  
44.
  • Chawade, Aakash (författare)
  • De-construction of major Indian cereal crop residues through chemical pretreatment for improved biogas production: An overview
  • 2018
  • Ingår i: Renewable and Sustainable Energy Reviews. - : Elsevier BV. - 1364-0321. ; 90, s. 160-170
  • Forskningsöversikt (refereegranskat)abstract
    • The expedition for inexpensive, renewable and environmentally friendly source of energy to replace the conventional sources like coal and petroleum is currently the most focused research area. Biomass resource in the form of crop residues is the abundant and readily accessible renewable resource. Wheat, rice and maize are the major cereal crops around the globe and are found to be the major sources of residual lignocellulosic biomass in the form of straw. In India, this is usually burnt in the field and is thus underutilized. These residues may be harnessed for bioenergy production by thermal and biochemical processes. This review is exclusively focused on chemical pretreatment of these residues to generate biomethane by unmasking lignin. The paper also reviews the essential properties of the residual biomass such as proximate, ultimate and compositional for the quality of derived biofuels (bioethanol and biomethane). Biomass to bioenergy conversion process, biomethane and bioethanol fermentation process and comparison of biomethane and bioethanol in terms of yield and energy value is also discussed. These cereal crop residual biomass contribute in the production of renewable and sustainable energy.
  •  
45.
  • Chen, Jianyong, et al. (författare)
  • A review on versatile ejector applications in refrigeration systems
  • 2015
  • Ingår i: Renewable & sustainable energy reviews. - : Elsevier BV. - 1364-0321 .- 1879-0690. ; 49, s. 67-90
  • Forskningsöversikt (refereegranskat)abstract
    • This paper presents a useful knowledge of ejector working principles and the versatility and diversity of its applications in refrigeration technologies. Various ejector refrigeration systems are described with the associated studies, and categorized as conventional ejector refrigeration system, advanced ejector refrigeration systems, combined refrigeration systems and ejector enhanced vapor compression systems. This paper also presents the important elements that affect the optimum performance of the ejector system, and the results of studies that have generally confirmed their energy saving, great potential for large refrigerating temperature scales and performance enhancement.
  •  
46.
  • Cheng, Chuntian, et al. (författare)
  • Reform and renewables in China : The architecture of Yunnan's hydropower dominated electricity market
  • 2018
  • Ingår i: Renewable & sustainable energy reviews. - : Elsevier BV. - 1364-0321 .- 1879-0690. ; 94, s. 682-693
  • Forskningsöversikt (refereegranskat)abstract
    • Reforms currently under way in China's electricity markets bear important implications for its decarbonization objectives. The southwestern province of Yunnan is among the provinces piloting the current iteration of power market reforms. As such, lessons from Yunnan will inform future market reform and renewable energy policies in China and potentially elsewhere. The dominance of hydropower in Yunnan's energy portfolio and the particular transmission constraints it faces, offer an interesting case study of the challenges of decarbonization. We report on market architecture reforms and aggregate market data collected from the Yunnan Power Exchange. We review four elements in the reformed market architecture. Market pricing rules, transitional quantity controls, the generation rights market, and inter-provincial trade. The specifics of market reform reflect a compromise between decarbonization, inter-provincial competition, grid security and development objectives and contribute to understanding of how the dual transitions of hydropower decarbonization and market liberalization interact. We conclude on six insights regarding the role of the grid operator, security checks on trade, integration of cascade hydropower, the inclusion of renewables in the generation rights market, price controls, and market participant price uncertainty.
  •  
47.
  • Colarullo, Linda, et al. (författare)
  • Second-life EV batteries for stationary storage applications in Local Energy Communities
  • 2022
  • Ingår i: Renewable & sustainable energy reviews. - : Elsevier BV. - 1364-0321 .- 1879-0690. ; 169
  • Tidskriftsartikel (refereegranskat)abstract
    • Alongside the concern for environmental sustainability, the concept of Circular Economy, a term for an economic system designed to regenerate itself, has gained momentum. Circularity finds full expression in Local Energy Communities (LEC), a newly emerging setup wherein the local energy needs of a community are met independently, through the choice of shared solutions for energy production from renewable sources. Erstwhile the use of stationary energy storage systems for self-consumption optimization, load management, peak shaving, backup power and ancillary services, would foster the value of these Local Energy Communities. In this paper, we design a techno-economic analysis to assess the impact of the usage of Second-life Batteries for increasing the energy self-independence of those communities. A cost-minimization approach with technical and economic constraints is used for the analysis and is applied to a use case of Italy. This paper assesses the benefits that a Local Energy Community can entail while considering self-consumption maximization of PV generation, load shifting and grid balancing needs, while addressing the problem of high storage costs through the exploitation of second-life electric vehicles (EV) batteries, adding an extra layer for circularity. Scenarios related to maximizing the selfconsumption of photovoltaic generation and demand side management are designed considering four different LEC technology configurations. The results confirm LEC viability, showing lower energy bills for each scenario and greater benefits coupling a solar generation system with a storage solution.
  •  
48.
  • Cong, Ronggang (författare)
  • An optimization model for renewable energy generation and its application in China: A perspective of maximum utilization
  • 2013
  • Ingår i: Renewable & Sustainable Energy Reviews. - : Elsevier BV. - 1364-0321. ; 17, s. 94-103
  • Tidskriftsartikel (refereegranskat)abstract
    • In response to climate change, China's power industry is undertaking the task of reducing carbon emissions. Renewable energy generation has become an important option. For the government and state grid companies, it is important to know the maximum possible capacities of renewable energy generation from its different sources in order to plan the construction of the power grid in the future. In this paper, several important factors affecting the development of renewable energy generation are identified through a review of the existing literature (such as cost, technical maturity and so on) and analyzed. Combined with the learning curve model, the technology diffusion model and expectations about future economic development in China, a new model, the Renewable Energy Optimization Model (REOM), is developed to analyze the development of three renewable energy sources (wind power, solar power and biomass power) from 2009 to 2020. Results show that (1) the maximum installed capacities of wind power, solar power and biomass power will reach 233321, 26680 and 35506 MW in 2020; (2) from 2009 to 2020, biomass power will develop rapidly at the early stage while wind power is developed massively at the final stage and solar power has relatively stable growth; (3) due to the added capacity in the early periods, the unit investment cost of solar power shows a large decline, which is good for its following scale development; (4) the investment ratio constraint has a large effect on the development of wind power while the constraint of on-grid proportion of renewable energy generation has a significant effect on the development of wind power and solar power. The results have important policy implications for long-term energy planning in developing countries, such as China and India.
  •  
49.
  •  
50.
  • Coronado, Christian Rodriguez, et al. (författare)
  • Development of a thermoeconomic methodology for optimizing biodiesel production. Part II : Manufacture exergetic cost and biodiesel production cost incorporating carbon credits, a Brazilian case study
  • 2014
  • Ingår i: Renewable & sustainable energy reviews. - : Elsevier BV. - 1364-0321 .- 1879-0690. ; 29, s. 565-572
  • Forskningsöversikt (refereegranskat)abstract
    • The purpose of this study is to carry on a thermoeconomic analysis at a biodiesel production plant considering the irreversibilities in each step (part I: biodiesel plant under study and functional thermoeconomic diagram [1]), making it possible to calculate the thermoeconomic cost in US$/kWh and US$/1 of the biodiesel production, and the main byproduct generated, glycerin, incorporating the credits for the CO2 that is not emitted into the atmosphere (carbon credits). Assuming a sale price for both the biodiesel and the byproduct (glycerin), the annual revenue of the total investment in a plant with a capacity of 8000 t/year of biodiesel operating at 8000 h/year was calculated. The variables that directly or indirectly influence the final thermoeconomic cost include total annual biodiesel production, hours of operation, manufacturing exergy cost, molar ratio in the transesterification reaction, reaction temperature and pressure in the process. Depending on the increase or decrease in sale prices for both biodiesel and glycerin, the payback is going to significantly increase or decrease. It is evident that, in exergy terms, the sale of glycerin is of vital importance in order to reduce the biodiesel price, getting a shorter payback period for the plant under study.
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