Showing papers in "Renewable & Sustainable Energy Reviews in 2011"
TL;DR: In this paper, a review has been done on scope of CO2 mitigation through solar cooker, water heater, dryer, biofuel, improved cookstove and by hydrogen, which provides an excellent opportunity for mitigation of greenhouse gas emission and reducing global warming through substituting conventional energy sources.
Abstract: Renewable technologies are considered as clean sources of energy and optimal use of these resources minimize environmental impacts, produce minimum secondary wastes and are sustainable based on current and future economic and social societal needs. Sun is the source of all energies. The primary forms of solar energy are heat and light. Sunlight and heat are transformed and absorbed by the environment in a multitude of ways. Some of these transformations result in renewable energy flows such as biomass and wind energy. Renewable energy technologies provide an excellent opportunity for mitigation of greenhouse gas emission and reducing global warming through substituting conventional energy sources. In this article a review has been done on scope of CO2 mitigation through solar cooker, water heater, dryer, biofuel, improved cookstoves and by hydrogen.
2,584 citations
TL;DR: It has been found nan ofluids have a much higher and strongly temperature-dependent thermal conductivity at very low particle concentrations than conventional fluids, which can be considered as one of the key parameters for enhanced performances for many of the applications of nanofluids.
Abstract: Nanofluids are potential heat transfer fluids with enhanced thermophysical properties and heat transfer performance can be applied in many devices for better performances (i.e. energy, heat transfer and other performances). In this paper, a comprehensive literature on the applications and challenges of nanofluids have been compiled and reviewed. Latest up to date literatures on the applications and challenges in terms of PhD and Master thesis, journal articles, conference proceedings, reports and web materials have been reviewed and reported. Recent researches have indicated that substitution of conventional coolants by nanofluids appears promising. Specific application of nanofluids in engine cooling, solar water heating, cooling of electronics, cooling of transformer oil, improving diesel generator efficiency, cooling of heat exchanging devices, improving heat transfer efficiency of chillers, domestic refrigerator-freezers, cooling in machining, in nuclear reactor and defense and space have been reviewed and presented. Authors also critically analyzed some of the applications and identified research gaps for further research. Moreover, challenges and future directions of applications of nanofluids have been reviewed and presented in this paper. Based on results available in the literatures, it has been found nanofluids have a much higher and strongly temperature-dependent thermal conductivity at very low particle concentrations than conventional fluids. This can be considered as one of the key parameters for enhanced performances for many of the applications of nanofluids. Because of its superior thermal performances, latest up to date literatures on this property have been summarized and presented in this paper as well. However, few barriers and challenges that have been identified in this review must be addressed carefully before it can be fully implemented in the industrial applications.
1,558 citations
TL;DR: In this article, the photovoltaic technology, its power generating capability, the different existing light absorbing materials used, its environmental aspect coupled with a variety of its applications have been discussed.
Abstract: Global environmental concerns and the escalating demand for energy, coupled with steady progress in renewable energy technologies, are opening up new opportunities for utilization of renewable energy resources. Solar energy is the most abundant, inexhaustible and clean of all the renewable energy resources till date. The power from sun intercepted by the earth is about 1.8 × 1011 MW, which is many times larger than the present rate of all the energy consumption. Photovoltaic technology is one of the finest ways to harness the solar power. This paper reviews the photovoltaic technology, its power generating capability, the different existing light absorbing materials used, its environmental aspect coupled with a variety of its applications. The different existing performance and reliability evaluation models, sizing and control, grid connection and distribution have also been discussed. © 2011 Published by Elsevier Ltd.
1,524 citations
TL;DR: A review of the current state of the art in computational optimization methods applied to renewable and sustainable energy can be found in this article, which offers a clear vision of the latest research advances in this field.
Abstract: Energy is a vital input for social and economic development. As a result of the generalization of agricultural, industrial and domestic activities the demand for energy has increased remarkably, especially in emergent countries. This has meant rapid grower in the level of greenhouse gas emissions and the increase in fuel prices, which are the main driving forces behind efforts to utilize renewable energy sources more effectively, i.e. energy which comes from natural resources and is also naturally replenished. Despite the obvious advantages of renewable energy, it presents important drawbacks, such as the discontinuity of generation, as most renewable energy resources depend on the climate, which is why their use requires complex design, planning and control optimization methods. Fortunately, the continuous advances in computer hardware and software are allowing researchers to deal with these optimization problems using computational resources, as can be seen in the large number of optimization methods that have been applied to the renewable and sustainable energy field. This paper presents a review of the current state of the art in computational optimization methods applied to renewable and sustainable energy, offering a clear vision of the latest research advances in this field.
1,394 citations
TL;DR: A review of the latest publications on the use of phase change materials (PCM) in buildings is presented in this article, where the authors present a classification of materials, materials available and problems and possible solutions on the application of such materials in buildings.
Abstract: In recent years the use of thermal energy storage with phase change materials has become a topic with a lot of interest within the research community, but also within architects and engineers. Many publications have appeared, and several books, but the information is disseminated and not very much organised. This paper shows a review of the latest publications on the use of phase change materials (PCM) in buildings. The paper compiles information about the requirements of the use of this technology, classification of materials, materials available and problems and possible solutions on the application of such materials in buildings.
1,389 citations
TL;DR: In this paper, several aspects which are associated with burning biomass in boilers have been investigated such as composition of biomass, estimating the higher heating value of biomass and comparison between biomass and other fuels.
Abstract: Currently, fossil fuels such as oil, coal and natural gas represent the prime energy sources in the world. However, it is anticipated that these sources of energy will deplete within the next 40–50 years. Moreover, the expected environmental damages such as the global warming, acid rain and urban smog due to the production of emissions from these sources have tempted the world to try to reduce carbon emissions by 80% and shift towards utilizing a variety of renewable energy resources (RES) which are less environmentally harmful such as solar, wind, biomass etc. in a sustainable way. Biomass is one of the earliest sources of energy with very specific properties. In this review, several aspects which are associated with burning biomass in boilers have been investigated such as composition of biomass, estimating the higher heating value of biomass, comparison between biomass and other fuels, combustion of biomass, co-firing of biomass and coal, impacts of biomass, economic and social analysis of biomass, transportation of biomass, densification of biomass, problems of biomass and future of biomass. It has been found that utilizing biomass in boilers offers many economical, social and environmental benefits such as financial net saving, conservation of fossil fuel resources, job opportunities creation and CO 2 and NO x emissions reduction. However, care should be taken to other environmental impacts of biomass such as land and water resources, soil erosion, loss of biodiversity and deforestation. Fouling, marketing, low heating value, storage and collections and handling are all associated problems when burning biomass in boilers. The future of biomass in boilers depends upon the development of the markets for fossil fuels and on policy decisions regarding the biomass market.
1,293 citations
TL;DR: In this article, the effect of biodiesel on engine power, economy, durability and emissions including regulated and non-regulated emissions, and the corresponding effect factors are surveyed and analyzed in detail.
Abstract: As a renewable, sustainable and alternative fuel for compression ignition engines, biodiesel instead of diesel has been increasingly fueled to study its effects on engine performances and emissions in the recent 10 years. But these studies have been rarely reviewed to favor understanding and popularization for biodiesel so far. In this work, reports about biodiesel engine performances and emissions, published by highly rated journals in scientific indexes, were cited preferentially since 2000 year. From these reports, the effect of biodiesel on engine power, economy, durability and emissions including regulated and non-regulated emissions, and the corresponding effect factors are surveyed and analyzed in detail. The use of biodiesel leads to the substantial reduction in PM, HC and CO emissions accompanying with the imperceptible power loss, the increase in fuel consumption and the increase in NOx emission on conventional diesel engines with no or fewer modification. And it favors to reduce carbon deposit and wear of the key engine parts. Therefore, the blends of biodiesel with small content in place of petroleum diesel can help in controlling air pollution and easing the pressure on scarce resources without significantly sacrificing engine power and economy. However, many further researches about optimization and modification on engine, low temperature performances of engine, new instrumentation and methodology for measurements, etc., should be performed when petroleum diesel is substituted completely by biodiesel.
1,181 citations
TL;DR: An organic Rankine cycle (ORC) machine is similar to a conventional steam cycle energy conversion system, but uses an organic fluid such as refrigerants and hydrocarbons instead of water as discussed by the authors.
Abstract: An organic Rankine cycle (ORC) machine is similar to a conventional steam cycle energy conversion system, but uses an organic fluid such as refrigerants and hydrocarbons instead of water. In recent years, research was intensified on this device as it is being progressively adopted as premier technology to convert low-temperature heat resources into power. Available heat resources are: solar energy, geothermal energy, biomass products, surface seawater, and waste heat from various thermal processes. This paper presents existing applications and analyzes their maturity. Binary geothermal and binary biomass CHP are already mature. Provided the interest to recover waste heat rejected by thermal devices and industrial processes continue to grow, and favorable legislative conditions are adopted, waste heat recovery organic Rankine cycle systems in the near future will experience a rapid growth. Solar modular power plants are being intensely investigated at smaller scale for cogeneration applications in buildings but larger plants are also expected in tropical or Sahel regions with constant and low solar radiation intensity. OTEC power plants operating mainly on offshore installations at very low temperature have been advertised as total resource systems and interest on this technology is growing in large isolated islands.
1,058 citations
TL;DR: In this paper, the levelized cost of electricity (LCOE) of solar photovoltaic (PV) generation is compared to other electricity generation technologies. But there is a lack of clarity of reporting assumptions, justifications and degree of completeness in LCOE calculations, which produces widely varying and contradictory results.
Abstract: As the solar photovoltaic (PV) matures, the economic feasibility of PV projects are increasingly being evaluated using the levelized cost of electricity (LCOE) generation in order to be compared to other electricity generation technologies. Unfortunately, there is lack of clarity of reporting assumptions, justifications and degree of completeness in LCOE calculations, which produces widely varying and contradictory results. This paper reviews the methodology of properly calculating the LCOE for solar PV, correcting the misconceptions made in the assumptions found throughout the literature. Then a template is provided for better reporting of LCOE results for PV needed to influence policy mandates or make invest decisions. A numerical example is provided with variable ranges to test sensitivity, allowing for conclusions to be drawn on the most important variables. Grid parity is considered when the LCOE of solar PV is comparable with grid electrical prices of conventional technologies and is the industry target for cost-effectiveness. Given the state of the art in the technology and favorable financing terms it is clear that PV has already obtained grid parity in specific locations and as installed costs continue to decline, grid electricity prices continue to escalate, and industry experience increases, PV will become an increasingly economically advantageous source of electricity over expanding geographical regions.
1,048 citations
TL;DR: A review of experimental/computational studies to enhance the thermal conductivity of phase change materials (PCM) that were conducted over many decades is presented in this paper, where the authors focus on studies that concern with positioning of fixed, stationary high conductivity inserts/structures.
Abstract: A review of experimental/computational studies to enhance the thermal conductivity of phase change materials (PCM) that were conducted over many decades is presented. Thermal management of electronics for aeronautics and space exploration appears to be the original intended application, with later extension to storage of thermal energy for solar thermal applications. The present review will focus on studies that concern with positioning of fixed, stationary high conductivity inserts/structures. Copper, aluminum, nickel, stainless steel and carbon fiber in various forms (fins, honeycomb, wool, brush, etc.) were generally utilized as the materials of the thermal conductivity promoters. The reviewed research studies covered a variety of PCM, operating conditions, heat exchange and thermal energy storage arrangements. The energy storage vessels included isolated thermal storage units (rectangular boxes, cylindrical and annular tubes and spheres) and containers that transferred heat to a moving fluid medium passing through it. A few studies have focused on the marked role of flow regimes that are formed due to the presence of thermally unstable fluid layers that in turn give rise to greater convective mixing and thus expedited melting of PCM. In general, it can be stated that due to utilization of fixed high conductivity inserts/structures, the conducting pathways linking the hot and cold ends must be minimized.
1,028 citations
TL;DR: In this article, the main advantages of using microalgae for biodiesel production are described in comparison with other available feedstocks, primarily palm oil, in terms of food security and environmental impact compared to palm oil.
Abstract: Of the three generations of biodiesel feedstocks described in this paper, food crops, non-food crops and microalgae-derived biodiesel, it was found that the third generation, microalgae, is the only source that can be sustainably developed in the future. Microalgae can be converted directly into energy, such as biodiesel, and therefore appear to be a promising source of renewable energy. This paper presents a comparison between the use of microalgae and palm oil as biodiesel feedstocks. It was found that microalgae are the more sustainable source of biodiesel in terms of food security and environmental impact compared to palm oil. The inefficiency and unsustainability of the use of food crops as a biodiesel source have increased interest in the development of microalgae species to be used as a renewable energy source. In this paper, the main advantages of using microalgae for biodiesel production are described in comparison with other available feedstocks, primarily palm oil.
TL;DR: In this article, the authors make an exhaustive technical review of the building envelope components and respective improvements from an energy efficiency perspective, including different types of energy efficient walls such as Trombe walls, ventilated walls, and glazed walls.
Abstract: A significant portion of the total primary energy is consumed by today's buildings in developed countries In many of these buildings, the energy consumption can be significantly reduced by adopting energy efficiency strategies Due to environmental concerns and the high cost of energy in recent years there has been a renewed interest in building energy efficiency This article strives to make an exhaustive technical review of the building envelope components and respective improvements from an energy efficiency perspective Different types of energy efficient walls such as Trombe walls, ventilated walls, and glazed walls are discussed Performance of different fenestration technologies including aerogel, vacuum glazing and frames are presented Advances in energy efficient roofs including the contemporary green roofs, photovoltaic roofs, radiant-transmittive barrier and evaporative roof cooling systems are discussed Various types of thermal insulation materials are enumerated along with selection criteria of these materials The effects of thermal mass and phase change material on building cooling/heating loads and peak loads are discussed Application of thermal mass as an energy saving method is more effective in places where the outside ambient air temperature differences between the days and nights are high Air tightness and infiltration of building envelopes are discussed as they play a crucial role in the energy consumption of a building Energy efficiency approaches sometimes might not require additional capital investment For example, a holistic energy efficient building design approach can reduce the size of mechanical systems compensating the additional cost of energy efficiency features
TL;DR: In this article, a review about the different solar energy policies implemented on the different countries of the world is discussed and the status of solar energy policy for Malaysia is investigated and compared with that of the successful countries in the world.
Abstract: To overcome the negative impacts on the environment and other problems associated with fossil fuels have forced many countries to inquire into and change to environmental friendly alternatives that are renewable to sustain the increasing energy demand. Solar energy is one of the best renewable energy sources with least negative impacts on the environment. Different countries have formulated solar energy policies to reducing dependence on fossil fuel and increasing domestic energy production by solar energy. This paper discusses a review about the different solar energy policies implemented on the different countries of the world. According to the 2010 BP Statistical Energy Survey, the world cumulative installed solar energy capacity was 22928.9 MW in 2009, a change of 46.9% compared to 2008. Also this paper discussed the existing successful solar energy policies of few selected countries. Based on literatures, it has been found that FIT, RPS and incentives are the most beneficial energy policies implemented by many countries around the world. These policies provide significant motivation and interest for the development and use of renewable energy technologies. Also the status of solar energy policy for Malaysia is investigated and compared with that of the successful countries in the world.
TL;DR: The principles and applications of the solid-state anaerobic digestion (SS-AD) process are reviewed in this article, and the variation in biogas production yields of different feedstocks is discussed as well as the need for pretreatment of lignocellulosic biomass such as crop residues and energy crops.
Abstract: Solid-state anaerobic digestion (SS-AD) generally occurs at solid concentrations higher than 15%. In contrast, liquid anaerobic digestion (AD) handles feedstocks with solid concentrations between 0.5% and 15%. Animal manure, sewage sludge, and food waste are generally treated by liquid AD, while organic fractions of municipal solid waste (OFMSW) and lignocellulosic biomass such as crop residues and energy crops can be processed through SS-AD. Some advantages of SS-AD include smaller reactor capacity requirements, less energy used for heating, and no processing energy needed for stirring. Due to its lower water content, the digestate of SS-AD is much easier to handle than the effluent of liquid AD. However, SS-AD systems also have disadvantages such as larger amounts of required inocula and much longer retention time. The principles and applications of the SS-AD process are reviewed in this paper. The variation in biogas production yields of different feedstocks is discussed as well as the need for pretreatment of lignocellulosic biomass to enhance biogas production. The effects of major operational parameters, including C/N ratio, solids content, temperature, and inoculation on the performance of SS-AD are summarized. While an increase in operating temperature can improve both the biogas yield and the production efficiency, other practices such as using AD digestate or leachate as an inoculant or decreasing the solid content, may increase the biogas yield but have negative impact on production efficiency. Different reactor configurations used in current commercial scale SS-AD systems and the impact of economics on system selection are also discussed.
TL;DR: In this paper, the authors review the many possible technological pathways for recycling CO2 into fuels using renewable or nuclear energy, considering three stages: CO2 capture, H2O and CO2 dissociation, and fuel synthesis.
Abstract: To improve the sustainability of transportation, a major goal is the replacement of conventional petroleum-based fuels with more sustainable fuels that can be used in the existing infrastructure (fuel distribution and vehicles). While fossil-derived synthetic fuels (e.g. coal derived liquid fuels) and biofuels have received the most attention, similar hydrocarbons can be produced without using fossil fuels or biomass. Using renewable and/or nuclear energy, carbon dioxide and water can be recycled into liquid hydrocarbon fuels in non-biological processes which remove oxygen from CO2 and H2O (the reverse of fuel combustion). Capture of CO2 from the atmosphere would enable a closed-loop carbon-neutral fuel cycle. This article critically reviews the many possible technological pathways for recycling CO2 into fuels using renewable or nuclear energy, considering three stages—CO2 capture, H2O and CO2 dissociation, and fuel synthesis. Dissociation methods include thermolysis, thermochemical cycles, electrolysis, and photoelectrolysis of CO2 and/or H2O. High temperature co-electrolysis of H2O and CO2 makes very efficient use of electricity and heat (near-100% electricity-to-syngas efficiency), provides high reaction rates, and directly produces syngas (CO/H2 mixture) for use in conventional catalytic fuel synthesis reactors. Capturing CO2 from the atmosphere using a solid sorbent, electrolyzing H2O and CO2 in solid oxide electrolysis cells to yield syngas, and converting the syngas to gasoline or diesel by Fischer–Tropsch synthesis is identified as one of the most promising, feasible routes. An analysis of the energy balance and economics of this CO2 recycling process is presented. We estimate that the full system can feasibly operate at 70% electricity-to-liquid fuel efficiency (higher heating value basis) and the price of electricity needed to produce synthetic gasoline at U.S.D$ 2/gal ($ 0.53/L) is 2–3 U.S. cents/kWh. For $ 3/gal ($ 0.78/L) gasoline, electricity at 4–5 cents/kWh is needed. In some regions that have inexpensive renewable electricity, such as Iceland, fuel production may already be economical. The dominant costs of the process are the electricity cost and the capital cost of the electrolyzer, and this capital cost is significantly increased when operating intermittently (on renewable power sources such as solar and wind). The potential of this CO2 recycling process is assessed, in terms of what technological progress is needed to achieve large-scale, economically competitive production of sustainable fuels by this method.
TL;DR: In this article, a comprehensive review of the integration of phase change materials in building walls is presented. But, even if the integrated phase change material have a good potential for reducing energy demand, further investigations are needed to really assess their use.
Abstract: The present paper is the first comprehensive review of the integration of phase change materials in building walls. Many considerations are discussed in this paper including physical considerations about building envelope and phase change material, phase change material integration and thermophysical property measurements and various experimental and numerical studies concerning the integration. Even if the integrated phase change material have a good potential for reducing energy demand, further investigations are needed to really assess their use.
TL;DR: In this article, the properties of butanol are compared with the conventional gasoline, diesel fuel, and some widely used biofuels, i.e. methanol, ethanol, biodiesel.
Abstract: Butanol is a very competitive renewable biofuel for use in internal combustion engines given its many advantages. In this review, the properties of butanol are compared with the conventional gasoline, diesel fuel, and some widely used biofuels, i.e. methanol, ethanol, biodiesel. The comparison of fuel properties indicates that n-butanol has the potential to overcome the drawbacks brought by low-carbon alcohols or biodiesel. Then, the development of butanol production is reviewed and various methods for increasing fermentative butanol production are introduced in detailed, i.e. metabolic engineering of the Clostridia, advanced fermentation technique. The most costive part of the fermentation is the substrate, so methods involved in renewed substrates are also mentioned. Next, the applications of butanol as a biofuel are summarized from three aspects: (1) fundamental combustion experiments in some well-defined burning reactors; (2) a substitute for gasoline in spark ignition engine; (3) a substitute for diesel fuel in compression ignition engine. These studies demonstrate that butanol, as a potential second generation biofuel, is a better alternative for the gasoline or diesel fuel, from the viewpoints of combustion characteristics, engine performance, and exhaust emissions. However, butanol has not been intensively studied when compared to ethanol or biodiesel, for which considerable numbers of reports are available. Finally, some challenges and future research directions are outlined in the last section of this review.
TL;DR: The role of processing conditions including final liquefaction temperature, residence times, rate of biomass heating, size of biomass particles, type of solvent media and hydrogen donor solvents is discussed in this paper.
Abstract: Hydrothermal liquefaction is a technique for obtaining clean biofuel from biomass in the presence of a solvent at moderate to high temperature (250–550 °C) and pressure (5–25 MPa). Hydrothermal decomposition of biomass leads to the formation of various compounds depending upon operating parameters. The role of processing conditions including final liquefaction temperature, residence times, rate of biomass heating, size of biomass particles, type of solvent media and hydrogen donor solvents is important for the bio-oil yield and quality of the product. The effect of these parameters on the yield and composition of the liquid products is reviewed in the paper. A brief description about the decomposition mechanism is also included to highlight the product types during hydrothermal liquefaction.
TL;DR: In this paper, the development of clean vehicles, including pure electric vehicles (EVs), hybrid vehicles (HEVs), and fuel cell electric vehicle (FCEVs) and high energy power batteries, such as nickel metal hydride (Ni-MH), lithium-ion (Li-ion) and proton exchange membrane fuel cells (PEMFCs), are discussed and compared.
Abstract: This paper reviews the development of clean vehicles, including pure electric vehicles (EVs), hybrid electric vehicles (HEVs) and fuel cell electric vehicles (FCEVs), and high energy power batteries, such as nickel metal hydride (Ni-MH), lithium-ion (Li-ion) and proton exchange membrane fuel cells (PEMFCs). The mathematical models and thermal behavior of the batteries are described. Details of various thermal management techniques, especially the PCMs battery thermal management system and the materials thermal conductivity, are discussed and compared. It is concluded that the EVs, HEVs and FCEVs are effective to reduce GHG and pollutants emission and save energy. At stressful and abuse conditions, especially at high discharge rates and at high operating or ambient temperatures, traditional battery thermal energy management systems, such as air and liquid, may be not meeting the requirements. Pulsating heat pipe may be more effective but needs to be well designed. In addition, progress in developing new high temperature material is very difficult. PCM for battery thermal management is a better selection than others. Nevertheless, thermal conductivity of the PCMs such as paraffin is low and some methods are adopted to enhance the heat transfer of the PCMs. The performance and thermo-mechanical behaviors of the improved PCMs in the battery thermal management system need to be investigated experimentally. And the possibility of the heat collection and recycling needs to be discussed in terms of energy saving and efficient.
TL;DR: In this paper, a comparative study on the world energy consumption released by International Energy Agency (IEA) shows that in 2050, solar array installations will supply around 45% of energy demand in the world.
Abstract: Presently, solar energy conversion is widely used to generate heat and produce electricity A comparative study on the world energy consumption released by International Energy Agency (IEA) shows that in 2050, solar array installations will supply around 45% of energy demand in the world It was found that solar thermal is getting remarkable popularity in industrial applications Solar thermal is an alternative to generate electricity, process chemicals or even space heating It can be used in food, non-metallic, textile, building, chemical or even business related industries On the other hand, solar electricity is wildly applied in telecommunication, agricultural, water desalination and building industry to operate lights, pumps, engines, fans, refrigerators and water heaters It is very important to apply solar energy for a wide variety of applications and provide energy solutions by modifying the energy proportion, improving energy stability, increasing energy sustainability, conversion reduction and hence enhance the system efficiency The present work aimed to study the solar energy systems utilization in industrial applications and looked into the industrial applications which are more compatible to be integrated with solar energy systems
TL;DR: In this paper, the main beneficial properties of anaerobic digestion are discussed and the potential, opportunities and challenges of these biomasses are discussed, and the typical biogas yield and points of attention are included.
Abstract: It is clear that renewable resources will play a crucial role in limiting the CO2 emissions. Energy from biomass and waste is regarded as one of the most dominant future renewable energy sources, since it can provide a continuous power generation. In this regard, the application of anaerobic digestion is emerging spectacularly. This manuscript lists and discusses the main beneficial properties of anaerobic digestion. Different types of biomass and waste are suitable for anaerobic digestion: the organic fraction of municipal solid waste, waste oils and animal fat, energy crops and agricultural waste, manure and sewage sludge. The potential, opportunities and challenges of these biomasses are discussed. Typical biogas yield and points of attention are included. The manuscript concludes with an overview and discussion of the major research trends in anaerobic digestion, including the analysis of microbial community development, the extension of anaerobic digestion models, the development of pre-treatment techniques and upgrading of the biogas produced.
TL;DR: A review of existing microgrid test networks around the world (North America, Europe and Asia) and some significantly different microgrid simulation networks present in the literature is presented in this paper.
Abstract: A microgrid is particularly a portion of the power distribution system that comprises distributed generation, energy storage and loads. To be capable of operating in parallel to the grid, as an autonomous power island and in transition modes, microgrids must be robust in controlling the local voltage and frequency, and protecting the network and equipment connected to the microgrid. It also needs to facilitate demand side management and resynchronization. This paper presents a review of existing microgrid test networks around the world (North America, Europe and Asia) and some significantly different microgrid simulation networks present in the literature. Paper is focused on the test systems and available microgrid control options. A summary table comparing and contrasting the existing test systems is presented. The paper is concluded highlighting the worthy findings and possible areas of research that would enhance practical use of microgrid facilities.
TL;DR: A comprehensive literature review about industrial energy saving by management, technologies and policies has been presented in this paper, where the authors have found that in the industrial sectors, a sizeable amount of electric energy, emissions and utility bill can be saved using these technologies.
Abstract: An industrial sector uses more energy than any other end-use sectors and currently this sector is consuming about 37% of the world's total delivered energy. Energy is consumed in the industrial sector by a diverse group of industries including manufacturing, agriculture, mining, and construction and for a wide range of activities, such as processing and assembly, space conditioning, and lighting. This paper presents a comprehensive literature review about industrial energy saving by management, technologies and policies. Latest literatures in terms of thesis (MS and PhD), journal articles, conference proceedings, web materials, reports, books, handbooks on industrial energy management, policies and energy savings strategies have been compiled. Energy saving by management including energy audit, training programs and housekeeping beside some energy management practices in the world has been reviewed. Energy saving technologies, such as use of high efficiency motors (HEMs), variable speed drives (VSDs), economizers, leak prevention and reducing pressure drop has been reviewed. Based on energy saving technologies results, it has been found that in the industrial sectors, a sizeable amount of electric energy, emissions and utility bill can be saved using these technologies. Payback periods for different energy savings measures have been identified and found to be economically viable in most cases. Finally, various energy-saving policies for few selected countries were reviewed.
TL;DR: In this paper, a review of the recent studies in tar treatment from biomass gasification is presented, where the new technologies with their strengths and weaknesses in term of tar reduction are discussed.
Abstract: Biomass gasification presents highly interesting possibilities for expanding the utilization of biomass as power generation using internal combustion engines or turbines. However, the need to reduce the tar in the producer gas is very important. The successful application of producer gas depends not only on the quantity of tar, but also on its properties and compositions, which is associated with the dew-point of tar components. Class 5, 4, and 2 tar become a major cause of condensation which can foul the engines and turbines. Hence, the selectivity of tar treatment method to remove or convert class 5, 4, and 2 tar is a challenge in producer gas utilization. This review was conducted to present the recent studies in tar treatment from biomass gasification. The new technologies with their strengths and the weaknesses in term of tar reduction are discussed.
TL;DR: In this paper, an overview of the previous research work on microencapsulation technology for thermal energy storage incorporating the phase change materials (PCMs) in the building applications, along with few useful conclusive remarks concluded from the available literature.
Abstract: Thermal energy storage (TES) systems using phase change material (PCM) have been recognized as one of the most advanced energy technologies in enhancing the energy efficiency and sustainability of buildings. Now the research is focus on suitable method to incorporate PCMs with building. There are several methods to use phase change materials (PCMs) in thermal energy storage (TES) for different applications. Microencapsulation is one of the well known and advanced technologies for better utilization of PCMs with building parts, such as, wall, roof and floor besides, within the building materials. Phase change materials based microencapsulation for latent heat thermal storage (LHTS) systems for building application offers a challenging option to be employed as effective thermal energy storage and a retrieval device. Since the particular interest in using microencapsulation PCMs for concrete and wall/wallboards, the specific research efforts on both subjects are reviewed separately. This paper presents an overview of the previous research work on microencapsulation technology for thermal energy storage incorporating the phase change materials (PCMs) in the building applications, along with few useful conclusive remarks concluded from the available literature.
TL;DR: The performance of dye-sensitized solar cells is mainly based on the dye as a sensitizer as mentioned in this paper, which has become a viable alternative to expensive and rare organic sensitizers because of its low cost, easy attainability, abundance in supply materials and no environment threat.
Abstract: The performance of dye sensitized solar cells is mainly based on the dye as a sensitizer. Natural dyes have become a viable alternative to expensive and rare organic sensitizers because of its low cost, easy attainability, abundance in supply of raw materials and no environment threat. Various components of a plant such as the flower petals, leaves and bark have been tested as sensitizers. The nature of these pigments together with other parameters has resulted in varying performance. This review briefly discusses the emergence, operation and components of dye sensitized solar cells together with the work done on natural dye based dye sensitized solar cells over the years.
TL;DR: In this article, the impact of plug-in hybrid electric vehicles (PHEVs) on the distribution network can be determined using the following aspects of PHEVs: driving patterns, charging characteristics, charge timing, and vehicle penetration.
Abstract: Plug-in hybrid electric vehicles (PHEVs) are the next big thing in the electric transportation market. While much work has been done to detail what economic costs and benefits PHEVs will have on consumers and producers alike, it seems that it is also important to understand what impact PHEVs will have on distribution networks nationwide. This paper finds that the impact of PHEVs on the distribution network can be determined using the following aspects of PHEVs: driving patterns, charging characteristics, charge timing, and vehicle penetration. The impacts that these aspects of PHEVs will have on distribution networks have been measured and calculated by multiple authors in different locations using many different tools that range from analytical techniques to simulations and beyond. While much work has already been completed in this area, there is still much to do. Areas left for improvement and future work will include adding more stochasticity into models as well as computing and analyzing reliability indices with respect to distribution networks.
TL;DR: In this article, a review of phase-change materials (PCMs) behavior prediction is presented, based on the first law and on the second law of thermodynamics, with selected results for several configurations, from numerous authors.
Abstract: Energy storage components improve the energy efficiency of systems by reducing the mismatch between supply and demand. For this purpose, phase-change materials are particularly attractive since they provide a high-energy storage density at a constant temperature which corresponds to the phase transition temperature of the material. Nevertheless, the incorporation of phase-change materials (PCMs) in a particular application calls for an analysis that will enable the researcher to optimize performances of systems. Due to the non-linear nature of the problem, numerical analysis is generally required to obtain appropriate solutions for the thermal behavior of systems. Therefore, a large amount of research has been carried out on PCMs behavior predictions. The review will present models based on the first law and on the second law of thermodynamics. It shows selected results for several configurations, from numerous authors so as to enable one to start his/her research with an exhaustive overview of the subject. This overview stresses the need to match experimental investigations with recent numerical analyses since in recent years, models mostly rely on other models in their validation stages.
TL;DR: In this paper, a comprehensive literature in terms of Thesis (MS and PhD), peer reviewed journals papers, conference proceedings, books, reports, websites for emission generation and mitigation technique has been presented in this paper.
Abstract: The cement subsector consumes approximately 12–15% of the total industrial energy use. Therefore, this subsector releases CO2 emissions to the atmosphere as a result of burning fossil fuels to produce energy needed for the cement manufacturing process. The cement industry contributes about 7% of the total worldwide CO2 emissions. This study complied a comprehensive literature in terms of Thesis (MS and PhD), peer reviewed journals papers, conference proceedings, books, reports, websites for emission generation and mitigation technique. Emission released associated with the burning of fuels have been presented in this paper. Different sources of emissions in a cement industry has been identified and presented in this study. Different techniques to reduce CO2 emissions from the cement manufacturing industries are reviewed and presented in this paper. The major techniques are: capture and storage CO2 emissions, reducing clinker/cement ratio by replacing clinker with different of additives and using alternative fuels instead of fossil fuels. Apart from these techniques, various energy savings measures in cement industries expected to reduce indirect emissions released to the atmosphere. Based on review results it was found that sizeable amount of emission can be mitigated using different techniques and energy savings measures.
TL;DR: In this paper, the authors discuss various features and technologies that can be integrated with a smart meter and discuss various issues and challenges involved in design, deployment, utilization, and maintenance of the smart meter infrastructure.
Abstract: Smart meter is an advanced energy meter that measures consumption of electrical energy providing additional information compared to a conventional energy meter. Integration of smart meters into electricity grid involves implementation of a variety of techniques and software, depending on the features that the situation demands. Design of a smart meter depends on the requirements of the utility company as well as the customer. This paper discusses various features and technologies that can be integrated with a smart meter. In fact, deployment of smart meters needs proper selection and implementation of a communication network satisfying the security standards of smart grid communication. This paper outlines various issues and challenges involved in design, deployment, utilization, and maintenance of the smart meter infrastructure. In addition, several applications and advantages of smart meter, in the view of future electricity market are discussed in detail. This paper explains the importance of introducing smart meters in developing countries. In addition, the status of smart metering in various countries is also illustrated.