Showing papers in "Renewable & Sustainable Energy Reviews in 2017"

A comparative overview of hydrogen production processes

Abstract: Climate change and fossil fuel depletion are the main reasons leading to hydrogen technology. There are many processes for hydrogen production from both conventional and alternative energy resources such as natural gas, coal, nuclear, biomass, solar and wind. In this work, a comparative overview of the major hydrogen production methods is carried out. The process descriptions along with the technical and economic aspects of 14 different production methods are discussed. An overall comparison is carried out, and the results regarding both the conventional and renewable methods are presented. The thermochemical pyrolysis and gasification are economically viable approaches providing the highest potential to become competitive on a large scale in the near future while conventional methods retain their dominant role in H2 production with costs in the range of 1.34–2.27 $/kg. Biological methods appear to be a promising pathway but further research studies are needed to improve their production rates, while the low conversion efficiencies in combination with the high investment costs are the key restrictions for water-splitting technologies to compete with conventional methods. However, further development of these technologies along with significant innovations concerning H2 storage, transportation and utilization, implies the decrease of the national dependence on fossil fuel imports and green hydrogen will dominate over the traditional energy resources.

A review of lithium-ion battery state of charge estimation and management system in electric vehicle applications: Challenges and recommendations

Abstract: Due to increasing concerns about global warming, greenhouse gas emissions, and the depletion of fossil fuels, the electric vehicles (EVs) receive massive popularity due to their performances and efficiencies in recent decades. EVs have already been widely accepted in the automotive industries considering the most promising replacements in reducing CO2 emissions and global environmental issues. Lithium-ion batteries have attained huge attention in EVs application due to their lucrative features such as lightweight, fast charging, high energy density, low self-discharge and long lifespan. This paper comprehensively reviews the lithium-ion battery state of charge (SOC) estimation and its management system towards the sustainable future EV applications. The significance of battery management system (BMS) employing lithium-ion batteries is presented, which can guarantee a reliable and safe operation and assess the battery SOC. The review identifies that the SOC is a crucial parameter as it signifies the remaining available energy in a battery that provides an idea about charging/discharging strategies and protect the battery from overcharging/over discharging. It is also observed that the SOC of the existing lithium-ion batteries have a good contribution to run the EVs safely and efficiently with their charging/discharging capabilities. However, they still have some challenges due to their complex electro-chemical reactions, performance degradation and lack of accuracy towards the enhancement of battery performance and life. The classification of the estimation methodologies to estimate SOC focusing with the estimation model/algorithm, benefits, drawbacks and estimation error are extensively reviewed. The review highlights many factors and challenges with possible recommendations for the development of BMS and estimation of SOC in next-generation EV applications. All the highlighted insights of this review will widen the increasing efforts towards the development of the advanced SOC estimation method and energy management system of lithium-ion battery for the future high-tech EV applications.

A review of multi criteria decision making (MCDM) towards sustainable renewable energy development

Abstract: In the current era of sustainable development, energy planning has become complex due to the involvement of multiple benchmarks like technical, social, economic and environmental. This in turn puts major constraints for decision makers to optimize energy alternatives independently and discretely especially in case of rural communities. In addition, topographical limitations concerning renewable energy systems which are mostly distributed in nature, the energy planning becomes more complicated. In such cases, decision analysis plays a vital role for designing such systems by considering various criteria and objectives even at disintegrated levels of electrification. Multiple criteria decision making (MCDM) is a branch of operational research dealing with finding optimal results in complex scenarios including various indicators, conflicting objectives and criteria. This tool is becoming popular in the field of energy planning due to the flexibility it provides to the decision makers to take decisions while considering all the criteria and objectives simultaneously. This article develops an insight into various MCDM techniques, progress made by considering renewable energy applications over MCDM methods and future prospects in this area. An extensive review in the sphere of sustainable energy has been performed by utilizing MCDM technique.

Review on dye-sensitized solar cells (DSSCs): Advanced techniques and research trends

Abstract: Dye-sensitized solar cell (DSSC) offers an efficient and easily implemented technology for future energy supply. Compared to conventional silicon solar cells, it provides comparable power conversion efficiency (PCE) at low material and manufacturing costs. DSSC materials such as titanium oxide (TiO 2 ) are inexpensive, abundant and innocuous to the environment. Since DSSC materials are less prone to contamination and processable at ambient temperature, a roll-to-roll process could be utilized to print DSSCs on the mass production line. DSSCs perform better under lower light intensities, which makes them an excellent choice for indoor applications. Due to the advancement of molecular engineering, colored and transparent thin films have been introduced to enhance the aesthetic values. Up to now, such benefits have attracted considerable research interests and commercialization effort. Here, this review examines advanced techniques and research trends of this promising technology from the perspective of device modeling, state-of-art techniques, and novel device structures.

The wood from the trees: The use of timber in construction

Abstract: Trees, and their derivative products, have been used by societies around the world for thousands of years. Contemporary construction of tall buildings from timber, in whole or in part, suggests a growing interest in the potential for building with wood at a scale not previously attainable. As wood is the only significant building material that is grown, we have a natural inclination that building in wood is good for the environment. But under what conditions is this really the case? The environmental benefits of using timber are not straightforward; although it is a natural product, a large amount of energy is used to dry and process it. Much of this can come from the biomass of the tree itself, but that requires investment in plant, which is not always possible in an industry that is widely distributed among many small producers. And what should we build with wood? Are skyscrapers in timber a good use of this natural resource, or are there other aspects of civil and structural engineering, or large-scale infrastructure, that would be a better use of wood? Here, we consider a holistic picture ranging in scale from the science of the cell wall to the engineering and global policies that could maximise forestry and timber construction as a boon to both people and the planet.

A review of thin film solar cell technologies and challenges

Abstract: Thin film solar cells are favorable because of their minimum material usage and rising efficiencies. The three major thin film solar cell technologies include amorphous silicon (α-Si), copper indium gallium selenide (CIGS), and cadmium telluride (CdTe). In this paper, the evolution of each technology is discussed in both laboratory and commercial settings, and market share and reliability are equally explored. The module efficiencies of CIGS and CdTe technologies almost rival that of crystalline solar cells, which currently possess greater than 55% of the market share. α-Si is plagued with low efficiency and light-induced degradation, so it is almost extinct in terrestrial applications. CIGS and CdTe hold the greatest promise for the future of thin film. Longevity, reliability, consumer confidence and greater investments must be established before thin film solar cells are explored on building integrated photovoltaic systems.

A comprehensive review on vibration energy harvesting: Modelling and realization

Abstract: This paper presents a state-of-the-art review on a hot topic in the literature, i.e., vibration based energy harvesting techniques, including theory, modelling methods and the realizations of the piezoelectric, electromagnetic and electrostatic approaches. To minimize the requirement of external power source and maintenance for electric devices such as wireless sensor networks, the energy harvesting technique based on vibrations has been a dynamic field of studying interest over past years. One important limitation of existing energy harvesting techniques is that the power output performance is seriously subject to the resonant frequencies of ambient vibrations, which are often random and broadband. To solve this problem, researchers have concentrated on developing efficient energy harvesters by adopting new materials and optimising the harvesting devices. Particularly, among these approaches, different types of energy harvesters have been designed with consideration of nonlinear characteristics so that the frequency bandwidth for effective energy harvesting of energy harvesters can be broadened. This paper reviews three main and important vibration-to-electricity conversion mechanisms, their design theory or methods and potential applications in the literature. As one of important factors to estimate the power output performance, the energy conversion efficiency of different conversion mechanisms is also summarised. Finally, the challenging issues based on the existing methods and future requirement of energy harvesting are discussed.

Review of energy storage systems for electric vehicle applications: Issues and challenges

Abstract: The electric vehicle (EV) technology addresses the issue of the reduction of carbon and greenhouse gas emissions. The concept of EVs focuses on the utilization of alternative energy resources. However, EV systems currently face challenges in energy storage systems (ESSs) with regard to their safety, size, cost, and overall management issues. In addition, hybridization of ESSs with advanced power electronic technologies has a significant influence on optimal power utilization to lead advanced EV technologies. This paper comprehensively reviews technologies of ESSs, its classifications, characteristics, constructions, electricity conversion, and evaluation processes with advantages and disadvantages for EV applications. Moreover, this paper discusses various classifications of ESS according to their energy formations, composition materials, and techniques on average power delivery over its capacity and overall efficiencies exhibited within their life expectancies. The rigorous review indicates that existing technologies for ESS can be used for EVs, but the optimum use of ESSs for efficient EV energy storage applications has not yet been achieved. This review highlights many factors, challenges, and problems for sustainable development of ESS technologies in next-generation EV applications. Thus, this review will widen the effort toward the development of economic and efficient ESSs with a longer lifetime for future EV uses.

A review on time series forecasting techniques for building energy consumption

Abstract: Energy consumption forecasting for buildings has immense value in energy efficiency and sustainability research. Accurate energy forecasting models have numerous implications in planning and energy optimization of buildings and campuses. For new buildings, where past recorded data is unavailable, computer simulation methods are used for energy analysis and forecasting future scenarios. However, for existing buildings with historically recorded time series energy data, statistical and machine learning techniques have proved to be more accurate and quick. This study presents a comprehensive review of the existing machine learning techniques for forecasting time series energy consumption. Although the emphasis is given to a single time series data analysis, the review is not just limited to it since energy data is often co-analyzed with other time series variables like outdoor weather and indoor environmental conditions. The nine most popular forecasting techniques that are based on the machine learning platform are analyzed. An in-depth review and analysis of the ‘hybrid model’, that combines two or more forecasting techniques is also presented. The various combinations of the hybrid model are found to be the most effective in time series energy forecasting for building.

Thermal energy storage materials and systems for solar energy applications

Abstract: Usage of renewable and clean solar energy is expanding at a rapid pace Applications of thermal energy storage (TES) facility in solar energy field enable dispatchability in generation of electricity and home space heating requirements It helps mitigate the intermittence issue with an energy source like solar energy TES also helps in smoothing out fluctuations in energy demand during different time periods of the day In this paper, a summary of various solar thermal energy storage materials and thermal energy storage systems that are currently in use is presented The properties of solar thermal energy storage materials are discussed and analyzed The dynamic performances of solar thermal energy storage systems in recent investigations are also presented and summarized

Overview of pretreatment strategies for enhancing sewage sludge disintegration and subsequent anaerobic digestion: Current advances, full-scale application and future perspectives

Abstract: Sewage sludge management is now becoming a serious issue all over the world. Anaerobic digestion is a simple and well-studied process capable of biologically converting the chemical energy of sewage sludge into methane-rich biogas, as a carbon-neutral alternative to fossil fuels whilst destroying pathogens and removing odors. Hydrolysis is the rate-limiting step because of the sewage sludge complex floc structure (such as extracellular polymeric substances) and hard cell wall. To accelerate the rate-limiting hydrolysis and improve the efficiency of anaerobic digestion, various pretreatment technologies have been developed. This paper presents an up-to-date review of recent research achievements in the pretreatment technologies used for improving biogas production including mechanical (ultrasonic, microwave, electrokinetic and high-pressure homogenization), thermal, chemical (acidic, alkali, ozonation, Fenton and Fe(II)-activated persulfate oxidation), and biological options (temperature-phased anaerobic digestion and microbial electrolysis cell). The effectiveness and relative worth of each of the studied technologies are summarized and compared in terms of the resulting sludge properties, the digester performance, the environmental benefits and the current state of real-world application. The challenge and technical issues encountered during sludge cotreatment are discussed, and the future research needs in promoting full-scale implementations of those approaches are proposed.

Inertia response and frequency control techniques for renewable energy sources: A review

Abstract: Preservation of the environment has become the main motivation to integrate more renewable energy sources (RESs) in electrical networks. However, several technical issues are prevalent at high level RES penetration. The most important technical issue is the difficulty in achieving the frequency stability of these new systems, as they contain less generation units that provide reserve power. Moreover, new power systems have small inertia constant due to the decoupling of the RESs from the AC grid using power converters. Therefore, the RESs in normal operation cannot participate with other conventional generation sources in frequency regulation. This paper reviews several inertia and frequency control techniques proposed for variable speed wind turbines and solar PV generators. Generally, the inertia and frequency regulation techniques were divided into two main groups. The first group includes the deloading technique, which allow the RESs to keep a certain amount of reserve power, while the second group includes inertia emulation, fast power reserve, and droop techniques, which is used to release the RESs reserve power at under frequency events.

CO2 emissions, renewable energy and the Environmental Kuznets Curve, a panel cointegration approach

Abstract: This study combines a panel cointegration analysis with a set of robustness tests to assess the short and long-run impacts of renewable energy on CO2 emissions, as well as the Kuznets Environmental Curve hypothesis for 25 selected african countries, over the period 1980-2012. The results provide no evidence of a total validation of EKC predictions. However, CO2 emissions are found to increase with income per capita. The overall estimations strongly reveal that renewable energy, with a negative effect on CO2 emissions, coupled with an increasing long-run effect, remains an efficient substitute for the conventional fossil-fuelled energy. Nonetheless, the impact of renewable energy is outweighed by primary energy consumption in both the short and long run, entailing more global synergy for outpacing the environmental challenges.

Anaerobic co-digestion process for biogas production: Progress, challenges and perspectives

Abstract: Globally, there is increasing awareness that renewable energy and energy efficiency are vital for both creating new economic opportunities and controlling the environmental pollution. AD technology is the biochemical process of biogas production which can change the complex organic materials into a clean and renewable source of energy. AcoD process is a reliable alternative option to resolve the disadvantages of single substrate digestion system related to substrate characteristics and system optimization. This paper reviewed the research progress and challenges of AcoD technology, and the contribution of different techniques in biogas production engineering. As the applicability and demand of the AcoD technology increases, the complexity of the system becomes increased, and the characterization of organic materials becomes volatile which requires advanced methods for investigation. Numerous publications have been noted that ADM1 model and its modified version becomes the most powerful tool to optimize the AcoD process of biogas production, and indicating that the disintegration and hydrolysis steps are the limiting factors of co-digestion process. Biochemical methane potential (BMP) test is promising method to determine the biodegradability and decomposition rate of organic materials. The addition of different environmentally friendly nanoparticles can improve the stability and performance of the AcoD system. The process optimization and improvement of biogas production still seek further investigations. Furthermore, using advanced simulation approaches and characterization methods of organic wastes can accelerate the transformation to industrializations, and realize the significant improvement of biogas production as a renewable source and economically feasible energy in developing countries, like China. Finally, the review reveals, designing and developing a framework, including various aspects to improve the biogas production is essential.

The history and current applications of the circular economy concept

Abstract: The challenges of balancing industrial development, environmental and human health, and economic growth in China and elsewhere in the world are drivers for recent resource use and low-carbon development strategies that include the application of the circular economy (CE) concept. A central theme of the CE concept is the valuation of materials within a closed-looped system with the aim to allow for natural resource use while reducing pollution or avoiding resource constraints and sustaining economic growth. The objectives of this study are (1) to review the history of the CE concept to provide a context for (2) a critical examination of how it is applied currently. Thematic categories are used to organize the literature review results including policy instruments and approaches; value chains, material flows, and products; and technology, organizational, and social innovation. The literature review illustrates the variability in CE project success and failure over time and by region. CE successes, key challenges, and research gaps are identified. The literature review results provide useful information for researchers as well as multi-stakeholder groups who seek to define the CE concept in practical terms, and to consider potential challenges and opportunities it presents when implemented.

Recent advances in the development of biomass gasification technology: A comprehensive review

Abstract: Due to fast climate change and foreseen damage through global warming, access to clean and green energy has become very much essential for the sustainable development of the society, globally. Biomass based energy is one of the important renewable energy resources to meet the day to day energy requirements and is as old as the human civilization. Biomass gasification is among few important aspects of bioenergy for producing heat, power and biofuels for useful applications. Despite, the availability of vast literature, technological and material advancements, the dissemination of gasification technology could not overcome the critical barriers for the widespread acceptability over the conventional energy resources. This article presents a comprehensive review on the technical advancements, developments of biomass gasification technology and the barriers being faced by different stakeholders in the wide dissemination of the technology for day to day requirements of the society, followed by recommendations for policy makers to make this technology popular while serving the society.

Bioethanol production from renewable sources: Current perspectives and technological progress

Abstract: Bioethanol is an attractive biofuel having potential for energy security and environmental safety over fossil fuels. To date, numerous biomass resources have been investigated for bioethanol production, which can broadly be classified into sugars, starch and lignocellulosic biomass. However, conversion of biomass into ethanol varies considerably depending on the nature of feedstock, primarily due to the variation in biochemical composition, and so, only a few feedstocks have been exploited commercially. In recent years, the conversion process of biomass has been improved significantly, even though most of these achievements are yet to be implemented in commercial facility. All the major steps in a typical conversion process, particularly fermentation of sugars that is the common step for all biomass, are greatly influenced by microorganisms. A traditional yeast, Saccharomyces cerevisiae, and a bacterial species, Zymomonas mobilis, are widely used in the ethanol fermentation technology. Many factors affect ethanol production process, and the final yield is directly associated with the optimum conditions of these attributes. This review paper presents an overview on the first and second generation bioethanol production with a particular attention to the potential of various biomass sources, technological approaches, role of microorganisms and factors affecting ethanol production process.

Hydrolytic degradation of polylactic acid (PLA) and its composites

Abstract: Biodegradable polymers are seen as a potential solution to the environmental problems generated by plastic waste In particular, the renewable aliphatic polyesters of poly(hydroxyacid)-type homopolymers and copolymers consisting of polylactic acid (PLA), poly(glycolic acid) (PGA), and poly(e-caprolactone) (PCL) constitute the most promising bioresorbable materials for applications in biomedical and consumer applications Among those polymers, PLA has attracted particular attention as a substitute for conventional petroleum-based plastics PLA is synthesized by the fermentation of renewable agricultural sources, including corn, cellulose, and other polysaccharides Although some of its characteristics are disadvantageous (eg, poor melt properties, mechanical brittleness, low heat resistance, and slow crystallization), there exist potential routes to resolve these shortcomings These include copolymerization, blending, plasticization modification, or the addition of reinforcing phases (eg, chitosan (Cs), cellulose, and starch) In this review, we discuss the degradation mechanisms of PLA and its modified form in the environment, current issues that hinder the achievement of good Cs/PLA combination, and ways to overcome some of these problems Furthermore, our discussion is extended to cover the subjects of hydrolytic degradation and weathering effects with different Cs/PLA blends

Thermochemical routes for the valorization of waste polyolefinic plastics to produce fuels and chemicals. A review

Abstract: The continuous increase in the generation of waste plastics together with the need for developing more sustainable waste management policies have promoted a great research effort dealing with their valorization routes. In this review, the main thermochemical routes are analyzed for the valorization of waste polyolefins to produce chemicals and fuels. Amongst the different strategies, pyrolysis has received greater attention, but most studies are of preliminary character. Likewise, the studies pursuing the incorporation of waste plastics into refinery units (mainly fluid catalytic cracking and hydrocracking) have been carried out in batch laboratory-scale units. Other promising alternative to which great attention is being paid is the process based on two steps: pyrolysis and in-line intensification for olefin production by means of catalytic cracking or thermal cracking at high temperatures.

The environmental impact of Li-Ion batteries and the role of key parameters - A review

Abstract: The increasing presence of Li-Ion batteries (LIB) in mobile and stationary energy storage applications has triggered a growing interest in the environmental impacts associated with their production. Numerous studies on the potential environmental impacts of LIB production and LIB-based electric mobility are available, but these are very heterogeneous and the results are therefore difficult to compare. Furthermore, the source of inventory data, which is key to the outcome of any study, is often difficult to trace back. This paper provides a review of LCA studies on Li-Ion batteries, with a focus on the battery production process. All available original studies that explicitly assess LIB production are summarized, the sources of inventory data are traced back and the main assumptions are extracted in order to provide a quick overview of the technical key parameters used in each study. These key parameters are then compared with actual battery data from industry and research institutions. Based on the results from the reviewed studies, average values for the environmental impacts of LIB production are calculated and the relevance of different assumptions for the outcomes of the different studies is pointed out. On average, producing 1 Wh of storage capacity is associated with a cumulative energy demand of 328 Wh and causes greenhouse gas (GHG) emissions of 110 gCO2eq. Although the majority of existing studies focus on GHG emissions or energy demand, it can be shown that impacts in other categories such as toxicity might be even more important. Taking into account the importance of key parameters for the environmental performance of Li-Ion batteries, research efforts should not only focus on energy density but also on maximizing cycle life and charge-discharge efficiency.

Economic growth, energy, and environmental Kuznets curve

Abstract: The aim of this study is to investigate the relationship between income and Carbon Dioxide (CO2) emissions in the context of the Environmental Kuznets Curve (EKC), which posits the existence of an inverted U-shape relationship between environmental degradation and economic development. For this purpose, two empirical models are examined. For both models, the relationship between per capita income and per capita CO2 emissions and the relationship among per capita income, per capita energy use, and per capita CO2 emissions are analyzed respectively between 1980 and 2010, using the panel data estimation techniques with the application of Driscoll-Kraay Standard Errors. Yet, for the first model, data are analyzed for 26 OECD countries with high income levels, while for the second model, data are examined for 52 emerging countries. The results of both models show that N-shape and an inverted N-shape relationship for cubic functional form are observed. Thus, the results do not support the EKC hypothesis, which implies that environmental degradation cannot be solved automatically by economic growth.

Thermal energy storage systems for concentrated solar power plants

Abstract: Solar thermal energy, especially concentrated solar power (CSP), represents an increasingly attractive renewable energy source. However, one of the key factors that determine the development of this technology is the integration of efficient and cost effective thermal energy storage (TES) systems, so as to overcome CSP's intermittent character and to be more economically competitive. This paper presents a review on thermal energy storage systems installed in CSP plants. Various aspects are discussed including the state-of-the-art on CSP plants all over the world and the trend of development, different technologies of TES systems for high temperature applications (200–1000°C) with a focus on thermochemical heat storage, and storage concepts for their integration in CSP plants. TES systems are necessary options for more than 70% of new CSP plants. Sensible heat storage technology is the most used in CSP plants in operation, for their reliability, low cost, easy to implement and large experimental feedback available. Latent and thermochemical storage technologies have much higher energy density thus may have a bright foreground. New concepts for TES integration are also proposed, especially coupled technology for higher operating temperature and cascade TES of modularized storage units for intelligent temperature control. The key contributions of this review paper consist of a comprehensive survey of CSP plants, their TES systems, the ways to enhance the heat and/or mass transfers and different new concepts for the integration of TES systems.

Production, characterization and performance of biodiesel as an alternative fuel in diesel engines – A review

Abstract: Due to the finite stock of fossil fuels and its negative impact on the environment, many countries across the world are now leaning toward renewable sources energies like solar energy, wind energy, biofuel, hydropower, geothermal and ocean energy to ensure energy for the countries development security. Biodiesel is one kind of biofuel that is renewable, biodegradable and has similar properties of fossil diesel fuel. The aim of this paper is to provide the substantial information on biodiesel to the researchers, engineers and policy makers. To achieve the goal, this paper summarizes the information on biofuel development, feedstocks around the world, oil extraction technic, biodiesel production processes. Furthermore, this paper will also discuss the advantages of biodiesel compared to fossil fuel. Finally, the combustion behavior of biodiesel in an internal combustion engine is discussed and it will help the researchers and policy maker and manufacturer. To determine the future and goal of automotive technology the study found that, feedstock selection for biodiesel production is very important as it associates 75% production cost. Moreover, the test of fuel properties is very important before using in the engine which depends on the type of feedstocks, origin country, and production process. Most of the researchers reported that the use of biodiesel in diesel engine reduces engine power slightly but reduces the harmful emission significantly. Finally, the study concludes that biodiesel has the potential to be used as a diesel fuel substitute in diesel engines to solve the energy and environment crisis.

Photovoltaic solar energy: Conceptual framework

Abstract: The purpose of this article is to understand the state of art of photovoltaic solar energy through a systematic literature research, in which the following themes are approached: ways of obtaining the energy, its advantages and disadvantages, applications, current market, costs and technologies according to what has been approached in the scientific researches published until 2016. For this research, we performed a qualitative and quantitative approach with a non-probabilistic sample size, obtaining 142 articles published since 1996–2016 with a slitting cut. The analysis result of this research shows that studies about photovoltaic energy are rising and may perform an important role in reaching a high-energy demand around the world. To increase the participation of photovoltaic energy in the renewable energy market requires, first, to raise awareness regarding its benefits; to increase the research and development of new technologies; to implement public policies a programs that will encourage photovoltaic energy generation. Although crystal silicon solar cells were predominant, other types of cells have been developed, which can compete, both in terms of cost reduction of production, or in terms of greater efficiency. The main applications are dominated by telecommunications, water pumping, public lighting, BIPV, agriculture, water heating, grain drying, water desalination, space vehicles and satellites. The studies found on photovoltaic solar energy are all technical, thus creating the need for future research related to the economic viability, chain supply coordination, analysis of barriers and incentives to photovoltaic solar energy and deeper studies about the factors that influence the position of such technologies in the market.

A review on current status and challenges of inorganic phase change materials for thermal energy storage systems

Abstract: Latent heat energy storage system is one of the promising solutions for efficient way of storing excess thermal energy during low consumption periods. One of the challenges for latent heat storage systems is the proper selection of the phase change materials (PCMs) for the targeted applications. As compared to organic PCMs, inorganic PCMs have some drawbacks, such as corrosion potential and phase separation; however, there are available techniques to overcome or minimize these drawbacks. On the other hand, inorganic PCMs are found to have higher thermal conductivity and storage capacity over organic PCMs. As a result inorganic PCMs have a great potential in thermal energy storage field, especially in medium to high temperature applications where organic PCMs are not a viable option. In this study, a detailed review of research outcomes and recent technological advancements in the field of inorganic phase change materials is presented while focusing on providing solutions to the associated disadvantages of this class of PCMs. Long term stability, thermal cycling performance, and heat transfer enhancements are also discussed in the context of this review.

Classification and assessment of energy storage systems

Abstract: The increasing electricity generation from renewable resources has side effects on power grid systems, because of daily and seasonally intermittent nature of these sources. Additionally, there are fluctuations in the electricity demand during the day, so energy storage system (ESS) can play a vital role to compensate these troubles and seems to be a crucial part of smart grids in the future. This study comparatively presents a widespread and comprehensive description of energy storage systems with detailed classification, features, advantages, environmental impacts, and implementation possibilities with application variations.

Power to Gas projects review: Lab, pilot and demo plants for storing renewable energy and CO2

Abstract: Power to Gas (PtG) processes have appeared in the last years as a long-term solution for renewable electricity surplus storage through methane production. These promising techniques will play a significant role in the future energy storage scenario since it addresses two crucial issues: electrical grid stability in scenarios with high share of renewable sources and decarbonisation of high energy density fuels for transportation. There is a large number of pathways for the transformation of energy from renewable sources into gaseous or liquid fuels through the combination with residual carbon dioxide. The high energy density of these synthetic fuels allows a share of the original renewable energy to be stored in the long-term. The first objective of this review is to thoroughly gather and classify all these energy storage techniques to define in a clear manner the framework which includes the Power to Gas technologies. Once the boundaries of these PtG processes have been evidenced, the second objective of the work is to detail worldwide existing projects which deal with this technology. Basic information such as main objectives, location and launching date is presented together with a qualitative description of the plant, technical data, budget and project partners. A timeline has been built for every project to be able of tracking the evolution of research lines of different companies and institutions.

A critical review of traditional and emerging techniques and fluids for electronics cooling

Abstract: Continued miniaturization and demand for high-end performance of electronic devices and appliances have led to dramatic increase in their heat flux generation. Consequently, conventional coolants and cooling approaches are increasingly falling short in meeting the ever-increasing cooling needs and challenges of those high heat generating electronic devices. This study provides a critical review of traditional and emerging cooling methods as well as coolants for electronics. In addition to summarizing traditional coolants, heat transfer properties and performances of potential new coolants such as nanofluids are also reviewed and analyzed. With superior thermal properties and numerous benefits nanofluids show great promises in fulfilling the cooling demands of high heat generating electronic devices. It is believed that applications of such novel coolants in emerging techniques like micro-channels and micro-heat pipes can revolutionize cooling technologies for electronics in the future.

Biochar as a Catalyst

Abstract: Biochar is pyrogenic carbon rich material generated from carbon neutral sources ( i.e. , biomass). Being an environmentally benign means for soil amendment, it also offers principle strategies for carbon capture and storage (CCS). In addition, recent recognition of biochar as versatile media for catalytic applications has brought forth initial research exploring the catalytic capacity of biochar and mechanistic practices in various routes. Thus, to provide comprehensive information on the catalytic applications of biochar in the field of catalysis, this review focuses on the catalytic challenges and practices of biochar, e.g. , biodiesel production, tar reduction in bio-oil and syngas (synthetic gas: H 2 and CO), enhanced syngas production, conversion of biomass into chemicals and biofuels, deNO x reactions, and microbial fuel cell electrodes. This review also provides an in-depth assessment on the catalytic properties of biochar with respect to production recipes at the fundamental level. Lastly, the performance of various biochar catalysts is also evaluated in this review.

A review of Battery Electric Vehicle technology and readiness levels

Abstract: As concerns of oil depletion and security of supply remain as severe as ever, and faced with the consequences of climate change due to greenhouse gas emissions, Europe is increasingly looking at alternatives to traditional road transport technologies. Battery Electric Vehicles (BEVs) are seen as a promising technology, which could lead to the decarbonisation of the Light Duty Vehicle fleet and to independence from oil. However it still has to overcome some significant barriers to gain social acceptance and obtain appreciable market penetration. This review evaluates the technological readiness of the different elements of BEV technology and highlights those technological areas where important progress is expected. Techno-economic issues linked with the development of BEVs are investigated. Current BEVs in the market need to be more competitive than other low carbon vehicles, a requirement which stimulates the necessity for new business models. Finally, the all-important role of politics in this development is, also, discussed. As the benefit of BEVs can help countries meet their environmental targets, governments have included them in their roadmaps and have developed incentives to help them penetrate the market.