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In recent years, the severe environmental degradation and high levels of fossil fuel consumption linked to conventional ship energy systems have drawn attention to the advancement of alternative ship energy systems. Consequently, ship energy systems based on the use of an electrical microgrid are coming to the fore as an increasingly popular alternative solution. However, managing the energy flows within a shipboard microgrid can be highly challenging due to the multiple energy sources (including renewable energy sources) and types of loads involved. Additionally, the integration of an energy storage system has been identified as an effective solution for improving the reliability of shipboard power systems, pointing out the important role of energy storage systems in maritime microgrids and their potential to enhance the energy management process. As such, effective energy management strategies are necessary to optimize performance and ensure that the vessel's energy demands are met while minimizing fuel consumption and reducing cost and environmental impacts. This paper presents a comprehensive review of such strategies and methods recently presented in the literature associated with energy management in shipboard microgrids integrating energy storage systems and examine the different techniques that can be utilized to achieve optimal system performance. Moreover, the paper also sheds light on the future challenges and perspectives imposed by the modern shipboard microgrids operation on the energy/power management of these systems. The aim of this paper is to provide a helpful guideline for researchers and engineers conducting research in the field of electrically powered ships. [Display omitted] • A comprehensive review of EMS for electrical and hybrid ship is presented. • A comprehensive review of ESS which can be used in such ships is presented. • Technologies of ESS and their suitability to ships are discussed and commented. • Future challenges and perspectives imposed by modern SMG operation are presented. [ABSTRACT FROM AUTHOR]

Zero energy buildings (ZEBs) are targeted by several developed countries around the world which consequently promotes the progress toward achieving ZEBs. The concept of ZEBs is, however, uncommon in developing economies such as Oman. In 2011, The Research Council of Oman has announced a competition to design, construct and operate buildings that embrace sustainability principles. The first five eco-friendly buildings were designed and constructed by academic institutions in different climatic conditions of Oman. This project has significantly contributed toward raising awareness of energy efficiency and renewable energy systems in buildings. This paper outlines the design of sustainable energy systems of one of these five buildings. The ZEB prototype is located at the Sultan Qaboos University campus in Muscat, which is an extremely hot climate as classified by the ASHRAE Standard 169-2013. The ZEB building was designed with full manipulation of natural energy. This paper also reports the experimental results of its one year of operation. The results showed that energy use intensity (EUI) of 103 kWh/m2 was achieved by this building. The building was less than 3% from achieving its net-zero energy source/site/emissions status. Nonetheless, it was able to achieve a positive energy cost status because of the financial credits received from the exported energy, which is subjected to high cost feed-in tariffs. When grid interaction was considered, 40% of the building load was met by site generation. For 33% of the time, this building was independent of the electrical grid, which is comparable to other net-zero energy buildings located in other climates. While several experimental studies for ZEB performance have been described in literature for heating dominated climates, very few experimental studies have been published for cooling dominated climates. Hence, this study aims to fill the gap in the knowledge of energy performance of ZEBs located in this region. • The design of sustainable energy systems for ZEB in a hot climate is described. • ZEB is feasible in cooling dominated climate. • Experimental result for one year of operation for a prototype ZEB is described. • For 33% of the time, the building was independent of the electrical grid. 40% of the building load was met by the site generation. [ABSTRACT FROM AUTHOR]

Abstract African countries are in a unique position to reap the socio-economic and environmental benefits of renewable resources as a means for meeting increasing energy demand in a sustainable way. A critical obstacle for the deployment of renewable energy technologies in Africa is the difficulty of attracting sufficient and affordable finance. This paper compares the impact of financial conditions on the cost of electricity generation across six renewable and three fossil-based technologies in 46 African countries. The results show large cost variations and highlight the extent to which renewables are disadvantaged by current financial practices. The energy-economy-environment model TIAM-ECN is used to show how lowering financing costs results in a much higher deployment of renewables. For example, solar PV could account for 10–15% of total electricity generation by 2050, even without explicit climate policy, thanks to financial de-risking programmes. The results demonstrate that changes in financing schemes could outweigh the impact of technology learning. This paper also demonstrates that, once ambitious climate policies are in place, reducing financing costs for renewables could be an efficient way to lower greenhouse gas emissions. Financial de-risking is thus a key ingredient for unlocking the renewable energy potential in Africa. Highlights • We show how renewables are disadvantaged by today's financial practices in Africa. • We show how lower financing costs result in a higher deployment of renewables. • PV can account for 10–15% of electricity generation by 2050 without climate policy. • Changes in financing schemes could outweigh the impact of technology learning. • Financial de-risking is key for unlocking the renewable energy potential in Africa. [ABSTRACT FROM AUTHOR]

Abstract In recent years, China's wind power industry has developed rapidly, and become the global wind power leader. At the same time, China's wind power industry is also facing many problems and challenges. In this paper, a comprehensive assessment is presented to reveal the development history of China's wind power industry, power demand and cost, regional distribution of wind power, wind turbine manufacturers, and government incentives to wind power industry. Subsequently, future development and challenges are proposed, focusing on the challenge of wind power integration and consumption, the challenge of management and market competition mechanism, and the challenge of large-scale and rapid development. Finally, the corresponding measures are put forward. The fundamental goal of this paper is to understand the history, current situation and future challenges of China's wind power industry. Highlights • A comprehensive assessment on the development of China's wind power industry is presented. • The development history of China's wind power and energy demand are introduced. • Multi factors related to China's wind power industry are investigated. • Future challenges and corresponding measures of China's wind power industry are proposed. [ABSTRACT FROM AUTHOR]

Abstract As a result of the increased awareness of the dangers posed by global climate changes (mainly caused by growing global energy consumption needs), the quest for clean and sustainable energy future is becoming of paramount importance. This can be largely realized via a large-scale integration of variable renewable energy sources (RESs) such as wind and solar, which have relatively low carbon footprints. In many power systems, the level of integration of such resources is dramatically increasing. However, their intermittent nature poses significant challenges in the predominantly conventional power systems that currently exist. Among others, frequency and voltage regulation issues can, for example, arise because of improperly balanced and largely uncoordinated RES supply and demand. Generally, the higher the integration level of intermittent power sources is, the higher the flexibility needs are in the system under consideration. Flexibility, in a power systems context, refers to the ability of such a system to effectively cope with unforeseen changes in operational situations, which are mainly induced by the inherent uncertainty and variability arising from the supply side, demand side or any other external factors. In the absence of appropriate flexibility mechanisms, it is increasingly difficult to manage the imbalances between generation and demand as a result of their natural variations in real-time. This paper presents an extensive and critical review of the main existing and emerging flexibility options that can be deployed in power systems to support the integration of "carbon-free" and variable power production technologies. Starting from a broader definition of flexibility, we highlight the growing importance of such flexibility in renewable-rich energy systems, and provide insights into the challenges and opportunities associated with various flexibility options provided by different technologies. Highlights • This paper presents an extensive and critical review of the main existing and emerging flexibility options. • Starting from a broader definition of flexibility, we highlight the growing importance of such flexibility. • Insights into the challenges and opportunities associated with various flexibility options are provided. • Certain barriers that may hinder their developments in the short to medium terms are also provided. [ABSTRACT FROM AUTHOR]

The small island developing states of the Pacific suffer from both the high cost of fossil fuel imports and from numerous climate-related disasters. These vulnerabilities will worsen unless there is a substantial global shift away from fossil fuels towards renewable energy (RE) sources, coupled with significant improvements in energy efficiency. Apart from traditional biomass-fuelled cooking, the most substantial uses of RE in the Pacific in 2016 were hydropower in some of the hillier island countries and the thousands of household photovoltaic (PV) systems in the remoter parts of island countries. This paper considers also the prospects for grid PV, geothermal, and biofuels – all of which have good technical potential in at least some islands. Barriers to wider use of RE in the region are mostly institutional and financial, but also include opportunity costs, environmental factors, and the limited skills base in small island states. The paper examines the mixed progress since the 1990s towards overcoming these barriers. The Fiji Electricity Authority has a reasonably realistic plan to have 81% of its supply from RE by 2020, drawing on hydropower (~ 50% in 2015), biomass (including bagasse), and some solar and wind. Tonga has its Renewable Energy Roadmap with clear milestones. Several other Pacific Island countries have ambitious RE targets but some are rather vague about how they are to be achieved. [ABSTRACT FROM AUTHOR]

The energy sector is undergoing substantial changes in order to promote better efficiency, increase the use of renewable energy, reduce emissions and effectively deploy technologies to trade off costs and benefits One emerging solution is the application of the Power-to-Gas technology, which can be used for different purposes. In recent years, Power-to-Gas has been studied to understand the role it could play in the electrical system. This paper has the aims of analysing the existing literature about the Power-to-Gas technology in detail, by considering some solutions that have a direct impact on the electrical system (in particular electrolyser and CO 2 production) and applications in the different sectors of the electricity value chain (i.e., generation, transmission, distribution and utilisation). This paper sets out the conceptual aspects that are necessary to include Power-to-Gas facilities in a more comprehensive analysis framework of the operation of the electrical system in various sectors. Some perspectives concerning new Power-to-Gas applications are also presented for each sector, and some promising aspects that are expected to play a relevant role in the future technical and economic evolution of electrical systems are discussed. [ABSTRACT FROM AUTHOR]

In recent decades, freshwater reserves have been under high threats, generated mainly by anthropogenic causes such as rapid population growth and climate change. Currently, one of the technologies that has been used to meet the freshwater global demand is seawater desalination. However, this solution has two major drawbacks. First, the discharge of reject brines with a high concentration of pollutants and nitrates, causing environmental problems such as eutrophication processes. Second, desalination systems, both membrane and thermal technologies, have a high energy consumption that is supplied with fossil fuels, contributing to the emission of greenhouse gas. Recently, to solve both problems, the zero —or minimal— liquid discharge strategy has emerged. This alternative for brine management is based on recovery of more than 90% of the freshwater fraction and salts, which can be revalued. Currently, there are some zero liquid discharge desalination plants that incorporate renewables to supply the necessary energy, making desalination a totally sustainable and environmentally-friendly process. Zero liquid discharge desalination plants powered by renewables already exist, although in an immature stage. This paper analyzes and discusses the potential of combining different renewables with the most developed and efficient desalination technologies. In addition, the most important plants and solutions currently installed on a real scale, mostly the result of different research projects, are described and compared. [Display omitted] • Water scarcity is a global problem that has promoted policies included in SDG 6. • Over 21,123 desalination plants produce 142 million m3/day of freshwater. • Reject brine and GHG emission reductions are crucial for sustainable desalination. • MLD and ZLD combined with RES are a strategy to solve desalination's negative impact. • The newest ZLD-desalination plants powered by RES are discussed. [ABSTRACT FROM AUTHOR]

Integration of renewable energy including solar energy is growing faster than ever before. Solar energy supplies more than 1.3% of global power, and it is predicted to become the largest electricity source by 2050 with about 11% of global power consumption. However, the improper installation, non-frequently scheduled maintenance, and aging effect can accelerate the deterioration of PV system components, which directly increase the possibility of arc fault occurrence. The undetected arc faults pose a severe fire hazard to residential, commercial, and utility-scaled PV systems. To deliver electricity in a safe and reliable manner, such a dangerous event must be detected at early stage. This paper presents a comprehensive review of the-state-of-art techniques for DC arc faults detection in photovoltaic systems (PV). Different methods and the features used for detection are discussed and compared in detail. This paper also emphasizes the importance of DC arc fault simulation for characteristics study and fault diagnosis purpose. Several DC arc fault models have been reviewed and compared. [ABSTRACT FROM AUTHOR]

Carbon dioxide emissions from burning fossil fuels are believed to be the main factor for alarming rise in global temperatures. Conference of Parties 21 held at Paris in the year 2015 strictly warned and asked the nations to reduce their greenhouse gas emission level. This makes the nations to adopt renewable energy technology to substitute burning fossil fuels. Solar energy due to its accessibility and affordability leads the renewable energy application race. Even though Photovoltaic (PV) technology is mature but the effect of temperature on its efficiency is considerable, which opens up new front of research where combination of PV and thermal absorber is focussed to harness thermal energy which otherwise negatively affect the PV electrical efficiency. In the proposed study starting from the effect temperature on PV electrical efficiency, construction of Photovoltaic-Thermal (PV/T) module, historical development of PV/T, about different types of PV/T's developed around the globe along with performance of developed PV/T's, effect of operating parameters and methods of thermodynamic management are reviewed and presented. The study emphasised on the use of nano fluid and phase change material to harness maximum thermal energy from the system, also includes an insight into commercially available PV/T modules across the globe. This paper presents enviro-economic evaluation of PV/T systems developed by various researchers and also enumerated thermodynamic methods for evaluating system efficiency, which includes both energy and exergy analysis. This paper also provides the necessary information about the requirement of future research in PV/T. [ABSTRACT FROM AUTHOR]

With increasing energy demands worldwide, the consumption of fossil fuels has increased unprecedently which are scarce in nature. This has led to environmental degradation and global warming which is a matter of concern. These factors lead to the rise in renewable energy sector in last decade. Among various renewable energy sources, solar energy is most exclusively used because of its ease of availability and least impact on the environment. Flat plate solar collector is most widely used solar collector but is less efficient (low capability to convert solar energy to thermal energy). The use of nanofluid (fluid obtained by mixing nanoparticle in base fluid) in place of base fluid has improved effect on thermophysical properties such as thermal conductivity. The use of nanofluid on flat plate solar collector (FPSC) & direct absorption solar collector (DASC) can be identified as an effective way to enhance the performance of solar collector. With the advancement in nanotechnology and growing thrust over increasing the performance of solar devices a lot of work has been done in this regard. The purpose of this literature review is to summarize the various research work done on the application of nanofluid in solar thermal devices. This review paper identifies the effect of various parameters and the optimum working condition. This paper also identifies the probable challenges we ought to face while developing thermal collector using nanofluids thus identifying the opportunities for future research. [ABSTRACT FROM AUTHOR]

Solar energy has been one of the environmental friendly sources of energy. The low cost solution with minimal maintenance motivates towards photovoltaic (PV) cells based energy harnessing methods to meet energy demands. However, majority of conventional PV systems suffer from low energy conversion ratio (ECR) due to improper selection of the PV parameters and maximum power point tracking (MPPT) algorithm. Even ECR is adversely affected under varying environmental conditions. Therefore, accurate estimation of PV parameter can be of paramount significance for efficient PV model design. In addition, the development of a robust MPPT algorithm in conjunction with the effective PV design parameter can enable optimal ECR achievement. In this review paper, a number of literatures pertaining to PV parameter estimation and MPPT algorithms are discussed. Different methods including analytical, iterative and evolutionary computing algorithms are assessed for their efficacy towards PV parameter estimation. This review paper revealed that the analytical approaches suffer from singularity problem as well as limited mathematical calculation that confine its efficacy for optimal PV parameter estimation under dynamic irradiation pattern. The iterative approaches too are limited due to dynamic environment conditions. Our study has revealed that the evolutionary computing approaches, such as genetic algorithm (GA), particle swarm optimization (PSO), differential evolution (DE), etc. have played vital role in PV design parameter estimation and classical approaches suffer from local minima and convergence issues. This manuscript reveals that to enable an optimal PV design parameter estimation there is an inevitable need to incorporate either evolutionary computation schemes or apply an efficient multi-objective optimization measures. This as a result can not only alleviate local minima and convergence issues but can also enable swift and precise parameter estimation to assist optimal PV design and augmented ECR performance. [ABSTRACT FROM AUTHOR]

This paper presents a multi-objective model for expansion with a high share of renewable energy. The model considers three objective functions (minimizing the total cost, maximizing generation at the peak load, and maximizing the contribution of non-hydro renewable sources). The model was then applied to the Brazilian case, using the new government targets for renewable energy. The introduction of the objectives regarding peak load and non-hydro renewable generation lead to an increase of solar power generation. In many studies about Brazil, solar power was not considered, or its participation was negligible, but in this paper the results show solar energy as the main non-hydro renewable source in 2030, due to its capacity to meet the peak demand, since its daily curve coincides with the peak load period. In this study, it was possible to meet 90% of the annual load with renewable sources (with 23% being ensured by non-hydro) and the solar power increased from 21 MW to 40000 MW by 2030. [ABSTRACT FROM AUTHOR]

Countries worldwide have set national targets for energy production from renewable sources. Yet, while many governments are committed to more renewable energy, obtaining permission to site installations is becoming increasingly difficult. With large tracts of land for renewables becoming intensely contested, countries seeking to meet their renewables targets are directing attention also towards tapping the potential in the urban environment through smaller-scale facilities. These entail other challenges, and countries are seeking ways to overcome them. The focus of this paper is on one, still evolving, type of renewable energy technology: small-scale wind turbines (SSWT). The paper presents a review of current but limited international academic knowledge on the land-regulation aspects of siting SSWT in countries that already have experience with such installations, including the USA, UK and New Zealand. The paper also reports on a comparative analysis of the land-related regulations and practices in two selected Mediterranean jurisdictions – Spain (Catalonia) and Israel. The approach of this study is exploratory, relying on analysis of legal and policy documents complemented by field work through in-depth interviews with key-stakeholders in both jurisdictions. The overall aim of this study is to examine different approaches of planning systems to new technologies. The findings show that despite their shared objective factors, the two jurisdictions have adopted almost opposite approach to regulating SSWTs. The findings, therefore, suggest that the incorporation of an unknown technology within the city requires a change of mindset both among the officials and among the city residents. A more effective regulatory framework might therefore entails a combination of strategic thinking, an experimental approach and the capacity to learn from cross-national comparative experiences. [ABSTRACT FROM AUTHOR]

This paper analyses the media image of solar power in order to understand the recent technology development trends. The increase in both solar PV panels as well as concentrated solar power plants has been influenced by decrease in solar power price, as well as subsidies and general public acceptance. This paper focuses to the latter, through quantitative media analysis. This paper utilises a modern method for media sentiment analysis from both editorial and social media, learning machine based analysis including over 50 000 data points. The results indicate that sentiment toward solar power, especially in social media, has been mostly neutral or positive thus with expected positive effect on technology market deployment. [ABSTRACT FROM AUTHOR]

The purpose of this paper is to review the literature focused on the energy/electricity-growth nexus, highlighting how the focus has shifted from aggregated energy/electricity consumption towards specific energy sources. Moreover, it aims to shed light on the relationships between different energy/electricity sources and economic growth. Empirically, the paper focuses on the analysis of interactions between electricity generation in Spain under both the Special Regime ( SR ) and the Ordinary Regime ( OR ), and their relationship with economic activity. Data for Spain is studied for a time span from January 2003 to January 2016. The Toda-Yamamoto causality test is carried out to check for causality relationships. Additionally, both short- and long-run effects are assessed by using the ARDL bounds test approach. Overall, the results reveal high internal consistency when comparing the ARDL results with the causality analysis. The substitution effect was detected between OR and SR. However, the negative effect of the SR on economic activity deserves special attention by energy policymakers. This paper argues that the main challenge of renewable sources for policymakers is their cost-effectiveness. [ABSTRACT FROM AUTHOR]

As an important energy base of China, Xinjiang is the key part of the “Silk Road” economic belt development strategy and is in an superior position. This paper analyzes the problems exist in the sustainable energy industry based on the distribution status of sustainable resources of Xinjiang. The evaluation index system of the application level of Renewable Energy Systems (RESs) is discussed using the wind farm as an example. Besides it investigates the advantages and disadvantages of the development process of each node in the “Silk Road” economic belt areas according to the current situation of the resources, economic and social development. Suggestions for the development of each area are proposed in the end. This paper will contribute to the sustainable development of renewable energy industry and economy in Xinjiang. [ABSTRACT FROM AUTHOR]

Increasing in oil consumption and ridiculous prices has caused the urgency for the main global oil industry players to search new alternative fuels which is biofuels. Biodiesel is better option to replace the crude oil due to its similar characteristics and sustainable. This paper will review the biodiesel produced and implementation from palm oil in Malaysia and current engine research that related to palm oil. Precedency given to the palm oil as it is main raw stock for biodiesel produced in Malaysia. Among scopes of this paper are to discuss current issues related to the palm biodiesel production and specific use in diesel engines. Another issue that arisen for Malaysia is to promote the palm oil as the alternative fuel that meets the stringent regulations and standards in Europe and North America. This paper also briefly covers the continuous global biodiesel consumption trend including the constraints that faced by Malaysia for leading the global biodiesel market with the benefits and drawbacks of palm oil biodiesel as an alternate fuel compared to the other common biodiesel sources. [ABSTRACT FROM AUTHOR]

Energy demand in China has risen rapidly and reached an unprecedented level due to the high-speed economic growth and modern development. As a result, the Chinese government faces a growing pressure to address the energy shortage and environmental deterioration, mainly resulting from an over-dependence on fossil energy. China has become both the largest energy consumer and CO 2 emitting country in the world in 2015. Utilization of potential for renewable energy is necessary for changing inappropriate energy consumption structure, protecting environment and achieving sustainable economic and social development. In view of such mentioned situation, this paper firstly introduces the energy structure as well as the development status of renewable energy in China, which includes hydropower, wind power, solar power, biomass power and other renewable energy. Besides, based on the current situation in China, the paper makes a preliminary prediction of the development of renewable energy in the country for the future decades, and proposes targeted countermeasures and suggestions. [ABSTRACT FROM AUTHOR]

Global energy demand is lowering its growth, but it is still expected to increase by 30% between now and 2040. To decrease greenhouse gas emissions a shift to more sustainable renewable energy sources is fundamental. Among the renewable energy sources, biomasses already have the largest share in Europe and their future demand for biorefinery plants will increase at global level. This study provides a comprehensive and exportable categorization of the residual biomasses (RB) from different supply sectors. Thanks to the individual descriptive and quantitative parameters introduced in the paper, an estimate of the theoretical and techno-economic potential is presented for a well-industrialized, agricultural-oriented and environmentally advanced European Region. Results are presented as recoverable biogas or biomethane, considering also the seasonal availability. In a relatively small region like Emilia Romagna (Italy), 106 different types of residual biomasses belonging to 6 main groups have been characterized. Over half of the total residues come from the agro-industrial and food businesses (58) followed by the agricultural sector (33). The estimate reveals a theoretical potential of 3544 ± 291 Gg/year of total solids for thermochemical valorisation and 3460 ± 639 Gg/year of total solids suitable for biological treatment. In terms of unused potential, the quantities decrease respectively to 2120 ± 298 and 915 ± 167 Gg/year. The estimates indicate stable results over the years from 2014 to 2016. The seasonal availability shows two evident peaks from August to October, while a significant shortage is present from April to June for the residues suitable for thermochemical valorisation. The theoretical potential that can be obtained from the Region's residues corresponds to about 1.8–2.3 million TOE/year, corresponding to 13–17% of the total regional consumption. Unused residues contribute to 0.9–1.2 million TOE/year. Image 1 • A fully comprehensive and exportable categorization of the RBs is developed. • 106 residual biomasses have been identified and estimated in Emilia Romagna Region. • About 1.5 Mg/year/capita of total solids is produced in the Region. • The theoretical RB potential covers the 13–17% of the regional energy consumption. • The unused RB potential decrease to 7–9% of the annual regional energy consumption. [ABSTRACT FROM AUTHOR]

Demand-side management (DSM) can transfer the dynamic fluctuations of load to match the renewable energy sources and realize the interaction of source-load. In most existing combined cooling heating and power (CCHP) system scheduling, user-side and system-side resources are independently optimized to achieve optimum economic performances without efficiently combining resources. In this paper, the devices with adjusted loads on the system-side and the user-side are integrated to construct generalized energy storage (GES) model, including traditional flexible resources, batteries, electric vehicles, cooling and heating load response, and electro-to-thermal conversion devices. Then, the GES model is integrated into the system for optimization including economy, load fluctuation, energy efficiency, and exergy efficiency. A case study demonstrates the application of the proposed method. The scheduling results of four DSM cases under different objectives are comprehensively obtained and compared. The optimized schemes are assessed in multi-dimension decision-making method and the effects of objective weights on decision results are analyzed. The simulation results illustrate that the load variation is decreased by 54% to obtain a smooth electrical load, resulting in the stable operation of equipment and improving the security and stability of the CCHP system. The exergy efficiency, energy efficiency, and economy performances through the DSM optimization are improved by up to 8.7%, 2.5%, and 2.4%, respectively. The system optimized with the objective of load fluctuation achieves the highest score in the TOPSIS decision-making scenarios and has the best comprehensive performance. [Display omitted] • A multi-dimension day-ahead scheduling optimization model is proposed. • The transformation model between rigid and flexible electric load is built. • The multi-dimensional performance indicators are applied to demand response. • The load variance index has the most prominent performance improvement, 54%. • The exergy efficiency, energy efficiency and cost boosted by 8.7%, 2.5% and 2.4%, respectively. [ABSTRACT FROM AUTHOR]

Due to increasing amounts of energy being supplied by intermittent renewable energy sources, future energy systems need to be able to react flexibly to sudden changes. To address this challenge, a large body of research is devoted to improving the utilization of energy flexibility of various types of energy resources on the supply and demand side. This is commonly done by applying mathematical models. The objective of this paper is to review such models and identify common modeling approaches used to quantify and optimize the use of flexible energy resources. The literature review is conducted systematically, encompassing 215 publications that feature 694 models of different energy resources. The main distinction of this work, in comparison to other reviews on the topic of energy flexibility lies in its focus on the mathematical formulation of models of energy resources and the quantification of the models' level of detail. The aim is to identify common modeling approaches and the corresponding research problems they address. The review shows that the majority of research efforts are directed towards the management and optimization of distributed energy resources. The most commonly employed modeling approach involves abstract black-box models with limited levels of detail. Linear programming and meta-heuristics are frequently used to optimize energy flexibility. A critical reflection of the current common practice is conducted and recommendations for future research are formulated. [Display omitted] • Literature review of 215 reports presenting model approaches for energy flexibility. • Categories of research problems identified and deduction of two main research focuses. • Presenting models of common energy resources classified into different model types. • Mostly low level of detail seen in modeling energy flexibility. • Optimization models are used to represent and quantify flexibility. [ABSTRACT FROM AUTHOR]

Under the rising pressure for low carbon energy transitions in Northeast Asia (NEA), interconnecting local power grids for interstate power trade allows to share reserve capacity and to redistribute intermittent renewable energy across time zones, contributing to regional sustainability. Using a linear programming model that minimizes total energy system costs to meet hourly power demand, we build a hypothetical electricity transmission model for three urban demand centers interconnecting China, South Korea, and Japan to test economic and environmental competitiveness of the trilateral power trade with carbon pricing. In the economic perspective our results indicate that interstate electricity trade enables cost savings at all levels of CO2 prices tested (0–180USD/ton of CO2 emitted) through more efficient fuel consumptions on an hourly basis at the NEA regional level. However, ambitious carbon pricing (above 90 USD/ton CO2 emitted) is still essential for trade to ensure equitable trade impacts for all participating nodes. While trade utilizes gaps in resource availabilities and technology costs across nodes in cost minimization, results show inadequate carbon pricing leads to extra thermal combustions at the local level although regional total emissions reduce. • This paper proposes a phased approach to Asia Supergrid by interconnecting the three demand centers of Northeast Asia, China North, South Korea, and Japan West, without remote renewable sources as a regional energy cooperation model to accelerate carbon phaseout. • The trilateral power trade is effective in reducing the total cost of energy system at all levels of CO2 prices tested (0–180USD/ton of CO2 emitted) compared to autarkic generation, but ambitious carbon pricing (above 90) is essential for ensuring low carbon transitions at all participating nodes. • Trade enables cost savings by increasing renewable power output in export nodesfor transmission and avoiding fuel/emission cost at import nodes. New investment cost for line construction and renewable expansion is offset. [ABSTRACT FROM AUTHOR]

Fossil fuels such as coal, petroleum, and natural gas have been used as the major sources of energy in the recent past. However, the negative environmental impacts associated with the emission of the greenhouse gases from these conventional energy sources forced to realize the importance of renewable energy resources. At the same time, the average annual exponential rate of population growth in India needs increasing amounts of fresh-water for the basic necessities. This might result in water scarcity as the overall population in India is expected to increase to 1.60 billion by 2050. It has been forecasted that, by the year 2040, India will rank 40th in the world in terms of water scarcity. To meet the rising fresh-water demand, desalination is an intelligent and sustainable option for India, which has a very long coastline measuring 7517 km. In this paper, an attempt has been made to provide a comprehensive review of water scarcity in India and suggest a possible solution, which is implementing desalination technologies coupled with renewable resources. The paper reviews the ground water scenario in India and the global desalination market. We summarize the energy consumption in various desalination processes and provide a brief outlook of the desalination techniques in India. Apart from this, desalination using non-conventional sources such as solar, wind, and geothermal energy is discussed. In addition, factors affecting the environment due to desalination and the potential counter measures are presented. This review aims to provide an awareness of the projected water crisis in India, in the coming decades, and is also aimed to help the policy makers for selecting an appropriate desalination technology. [ABSTRACT FROM AUTHOR]

India with a fast growing demand for electricity and increasing consideration to emissions reduction is investing strongly in renewable electricity generation. Among renewables, the Central and State Governments have set aspirational targets for on-grid solar electricity and legislated several supporting policies to realise these targets. As a result of the favourable political environment, the development of on-grid solar, in terms of the rate of growth in installed capacity, has been increasing in the recent years, and it is expected to continue in the future. This paper aims to investigate the impact of historical transitions of India's electricity sector on the ongoing development of on-grid solar electricity and to explore the prospect of solar sector development in the future. First of all, we investigate how the historical transformation of governmental intervention's approach intertwined with the gradual shift of the source of generation has paved the way for the current achievements in on-grid solar electricity. Second, we envision the future challenges and opportunities for the development of solar sector by looking ahead and discussing the continuity of government's support and the prospective competitions between different sources. We conclude the paper with some required steps to be taken in order to secure the achievement of the targets in solar electricity in the future. [ABSTRACT FROM AUTHOR]

Turkey’s rapid economic growth followed by increasing gap between domestic energy production and consumption signifies the large-scale integration of low-carbon and renewable resources into energy system. Turkey’s energy demand is increasing and supplying fossil energies such as oil and gas is becoming more challenging due to the lack of domestic hydrocarbon resources. The country is facing two main issues; first, maintaining energy balance and second, handling environmental issues. Nevertheless, Turkey has substantial renewable and low-carbon energy resources with co-benefits for the country’s fast growing economy and environmental sustainability. This paper aims to present a comprehensive update on Turkey’s renewable and low-carbon energy sector. It reviews not only the current status of the technology, policy and economy, but also provides an insight into the social aspects as well. From a policy point of view, the paper critically discusses Turkey’s energy strategy and perspectives and from the social point of view, the paper argues that there is a research gap in recent literature regarding public awareness and social acceptance of low-carbon energy technologies. Also, the future challenges for promoting low-carbon society in Turkey are discussed in terms of sustainable development and socio-environmental conditions. [ABSTRACT FROM AUTHOR]

This paper proposes a thermally compensated electrolyser model coupled with a Pressurised Hydrogen Storage model for modelling Renewable Hydrogen Energy Storage Systems needed to support the uptake of renewable energy sources (RES) integration into the grid. The model accurately simulates the output of real world electrolyser and hydrogen storage installations and can be used as a tool for assessing their integrity with intermittent RES. The model, which has been developed using Matlab/Simulink, incorporates a set of thermally compensated simulation equations to emulate the real world operating installations and define their hydrogen production under different energy configurations (grid connected or directly connected to the RES). It can also be used to determine the efficiency of an electrolyser under cold start or during full temperature operation. The proposed model has proved its ability to emulate real world hydrogen energy systems, and this has been validated by comparing its output to the real-world data logged from an existing field installation. The developed model has also been used as a tool to assess the performance of an operating real world system, installed in Africa, and which has not been performing as anticipated. Simulation results revealed the presence of a hydrogen leak within this infield installation, and this has been confirmed by an onsite inspection. The developed model has therefore also proved to be able to examine the performance of operating real-world hydrogen energy systems and detect irregularities and operation performance issues. In summary, this paper proposes a Hydrogen Energy Storage system (HES) model as an enabler simulation tool to support the projected increase of renewable integration into the grid. The model also allows the detection of performance issues within operating HES systems and allows the identification of leaks without the need for conducting intrusive inspections of the installations, hence saving money and time. [ABSTRACT FROM AUTHOR]

This paper investigates whether there is a unit root in renewable energy consumption in three large developing economies: Brazil, China, and India over the period 1971–2014. To do so, it uses four unit root tests assuming one structural break, two structural breaks, and more than two structural breaks. It observes that renewable energy consumption is a unit root process in Brazil, but it is found as stationary in China and India. The paper also tackles issues and challenges in the unit root test methodology in energy economics literature and provides implications for renewable energy consumption in three economies. [ABSTRACT FROM AUTHOR]

The scarcity of natural resources and the growing need for electricity requires the development of new technologies that can provide alternatives to traditional energy sources in a sustainable fashion. One of the promising opportunities currently under development is Microbial Fuel Cell (MFC) technology. The aim of our study was to analyze the relevant literature related to MFCs through a scientometric approach in order to produce a comprehensive synthesis, something that is lacking. We identified 19671 relevant studies in the field and examined 3427 papers in detail in a systematic review performed in the ISI database Web of Science. Our primary goals were to: (i) determine the temporal evolution of publications, (ii) reveal which journals publish on the subject, (iii) show the global distribution of MFC research and funding perspectives, (iv) uncover the scales of application of the technology, (v) account for the most commonly used substrates, (vi) find out whether pure or mixed cultures of microorganisms are involved and (vii) determine the major species used. We detected a substantial increase in publications after 2006. We found that the US and East Asia are the most promising locations for the development of MFCs, given both the number of publications and the amount of financial investment in research and development. The main technological barrier to the wide-spread use of MFCs is the scale of application, restricted to small prototypes insufficient to generate electricity for practical purposes. The most cited substrate was wastewater, both domestic and industrial, demonstrating the great potential of MFCs in wastewater treatment. Finally, our results demonstrated that there is a wide variety of microorganisms capable of generating electricity, although the great majority of papers focus on a few well-established species. Taken together, our results can help research and application in this field on a global level perspective. [ABSTRACT FROM AUTHOR]

Iran's energy system is extremely dependent on fossil fuels which, in turn, have led to problems such as fossil fuels depletion, social, economic and environmental damage and territorial imbalance. The country should therefore design a sustainable energy system based on clean energy a s well as renewable energy. Accordingly, and given that Iran's rural areas suffer from the unsustainable energy system, it is necessary to integrate renewable energy into comprehensive development programs in general, and into rural development programs, specifically. This review paper answers the following questions: Why is renewable energy important for Iran at national and rural levels? How is renewable energy related to sustainable rural development? and What are the challenges in the promotion of renewable energy technologies in Iran? The paper concludes that although renewable energy has potential for development in Iran's rural areas due to environmental, social and economic advantages, it could face some infrastructural, managerial, socio-cultural and economic challenges. Accordingly, aggressive and innovative policy making is required to meet these challenges. [ABSTRACT FROM AUTHOR]

This paper provides a comprehensive review on the status of renewable energy developments and hydrogen economy in the Middle East and North Africa region. This region is heavily reliant on fossil fuels for its domestic energy supply and is also considered a global energy exporter. In this regard, an overview of the current state of energy sector in the region is provided. Moreover, the region possesses great potential for renewable energy exploitation due to its climatic advantages. Therefore, the current status of renewable energy utilization within the region's various countries is reviewed by presenting several operational renewable energy-based plants and future projects for deployment of renewable power in the region. Green hydrogen is an important sustainable clean fuel, and its utilization is essential for both environmental preservation and energy security. Thus, the status of hydrogen production and utilization in the region is discussed considering the various operational systems and future hydrogen generation projects. The concept of source, system and service is also incorporated which considers the utilization of clean energy sources for sustainable hydrogen production through environmentally benign pathways. The potential deployment opportunities for the renewable hydrogen production are also discussed based on available renewable sources in the region. Moreover, this paper discusses the challenges of increasing renewable energy utilization in the region. Furthermore, this paper provides a road map for achieving renewable hydrogen economy including a reduction in domestic utilization of oil and gas sources, subsidization of renewable production sector, and financial support to hydrogen production and transportation infrastructure. • Providing an overview of the status of energy sector in the region. • Providing an overview of the status of renewable energy utilization in the region. • Discussing the challenges and opportunities of renewable and hydrogen energy development in the region. • Providing a road map for renewable hydrogen development in the region. [ABSTRACT FROM AUTHOR]

Abstract Islands' energy systems present a challenge in energy planning due to a limited amount of resources which could be used to make islands self-sufficient and sustainable. This paper presents a novel approach for defining energy system of a carbon neutral island which utilizes only intermittent renewable energy sources in combination with vehicle-to-grid concept as a demand response technology, where marine transportation has also been taken into account. Integration of power, heating, cooling and transport sectors has been modelled by using EnergyPLAN tool, i.e. its updated November 2017 version which is capable of simulating vehicle-to-grid operation in mentioned conditions. Power supply capacities have been selected not by using scenario analysis but by implementing an optimization procedure based on series of simulations in EnergyPLAN tool. In order to choose the most suitable power supply system configuration, two boundary conditions have been defined. Firstly, only solar and wind capacities must be utilized. Secondly, total electricity import and export must be balanced, i.e. the island has to be CO 2 neutral. In order to validate the approach, Croatian Island of Korčula has been used as the case study. 2011 has been selected as the base year for which final energy consumption has been calculated. The final simulation year was set to 2030 in which optimal capacities are installed. It has been shown that configuration with 40 MW of wind and 6 MW of installed solar capacities presents the least cost solution, while 22 MW of wind in combination with 30 MW of installed solar capacities provides the lowest amount of total electricity import and export. Analysis of the vehicle-to-grid share reduction has shown increase in total import and export in both cases, while transmission peak loads have not been influenced. Highlights • Optimization of supply capacities in order to achieve carbon neutrality. • Vehicle-to-grid with 100% share, including the ferry line. • Case study of Island of Korčula in Croatia. [ABSTRACT FROM AUTHOR]

Abstract This paper presents the steps taken by the Korea Electric Power Corporation (KEPCO), the nation's only utility, to overcome limitations involved in increasing renewable energy penetration in an effort to support the government's movement for renewable energy expansion. While the government proposes reducing carbon dioxide emissions by 37% of the Business As Usual (BAU) value by 2030, which is about 315 million tonnes, it has improved energy policies for developing and deploying renewable energy technologies. To facilitate the integration of renewable energy into the future Korean power system, the government has announced a guaranteed interconnection policy for renewable energy sources under 1 MW. Based on this movement, the following measures have been enacted. First, examination of the hosting capacity of the current power system has been initiated to streamline the interconnection process for the distributed renewable energy sources and to reinforce the transmission and distribution network in a proactive manner. Second, to comply with reliability performance standards, an efficient planning procedure has been established for determining the optimal location and size of a renewable complex. To proceed with interconnection requests without delay, a prototype of a Renewable Energy Map (REM) based on PSS/e and Python has been developed. This tool facilitates more practical impact studies by incorporating capacity factors of renewable sources. In addition, it automates the screening process for determining suitable interconnection buses and feasible options for grid reinforcement. This tool is a step toward realizing the twin visions of "G-Platform" and "Carbon Zero" projects in Jeju Island." These efforts, which have been initiated in response to the Paris Climate Change Accord of 2015 and the 23rd Conference of the Parties 2017, aim to increase renewable energy from 7% to 20% of the total generated energy in Korea by 2030. Highlights • The movement of the Korea government in improving support policy, interconnection procedure, and investments for renewable energy expansion. • The movement of Korea Electric Power Corporation (KEPCO) in fully understanding current hosting capacity of the power system for enabling 'Guaranteed interconnection of renewable energy sources under 1 MW'. • The movement of KEPCO and associated universities for developing renewable energy map (REM) for establishing foundation of predicting efficient installation of renewable energy aggregation without violating reliability standard. • Current projects regarding renewable energy expansion. [ABSTRACT FROM AUTHOR]

Abstract Life cycle assessment (LCA) is a comprehensive method used to investigate the environmental impacts and energy use of a product throughout its entire life cycle. For solar photovoltaic (PV) technologies, LCA studies need to be conducted to address environmental and energy issues and foster the development of PV technologies in a sustainable manner. This paper reviews and analyzes LCA studies on solar PV technologies, such as silicon, thin film, dye-sensitized solar cell, perovskite solar cell, and quantum dot-sensitized solar cell. The PV life cycle assumes a cradle-to-grave mechanism, starting from the extraction of raw materials until the disposal or recycling of the solar PV. Three impact assessment methods in LCA were reviewed and summarized, namely, cumulative energy demand (CED), energy payback time (EPBT), and GHG emission rate, based on data and information published in the literature. LCA results show that mono-crystalline silicon PV technology has the highest energy consumption, longest EPBT, and highest greenhouse gas emissions rate compared with other solar PV technologies. Highlights • Mono-Si indicated the highest energy, longer EPBT and excessive GHG emissions contribution. • DSSC shows the lowest energy requirement and shorter EPBT among other PV technologies. • EPBT depends on solar irradiation, module efficiency and lifetime, and type of technology. • Differences in GHG emissions rates were caused by energy mix for each countries, solar irradiations and lifetime of PV technologies. [ABSTRACT FROM AUTHOR]

The Sun is the primary energy source for all life on Earth. Solar energy is clean and is available all over the world. The total energy produced, in 2016, was 7236 MWh, while the total consumed was 6660 MWh. The average photovoltaic energy generated was 255 MWh, which accounts for 3.5% of the total production and 8.2% of the RES (3096 MWh). Investments in renewable energy in Romania began in late 2008, when Green Certificates were granted by Law no. 220. In this paper, we review the photovoltaic system development in Romania, from 2011, when the market began to develop, to the present day. The climate change and air pollution have to be slowed down and reduced by implementing renewable and sustainable solutions in order to generate electricity. The photovoltaic industry has an important role in Romania's development, both economically and environmentally and by having the “unlimited resource” advantage, it is a good alternative to fossil fuels. Now, the largest solar park in Romania, with 332,000 operational PV units, located in Ucea de Sus, Brasov County and commissioned in 2013, has an installed capacity of 82 MW, and covers a land surface of 200 ha. 178 years ago, French physicist Edmond Becquerel discovered the photoelectric effect, in 1839. At the moment, the typical power of solar PV modules is less than 500 W, depending on efficiency and temperature sensitivity. Currently, long-term research on photovoltaic cells focus on increasing the power output, increasing the efficiency and reducing the temperature sensitivity. [ABSTRACT FROM AUTHOR]

Malaysia's framework for energy development was established in the early 1970s. Henceforth, many successive policies were introduced as potential resources for electricity generation and utilization. Currently, as a signatory to the United Nations Framework Convention on Climate Change, Malaysia is sparing a number of effort to comply with the policy to meet the challenges of mitigating over-dependence on fossil fuels, reducing carbon levels, and achieving sustainable national development. This paper reviews the baseline studies on electrical energy policies and the measurement indicators used in Malaysia's electric power system. This research involves a comprehensive survey of electrical energy policies in Malaysia that focus on issues pertaining to energy supply, utilization, its environmental impact and considerations, renewable energy (RE) policies, production and consumption, energy efficiency, and feed-in tariffs. Fourteen energy indicators for sustainable development in Malaysia were investigated through the identification of energy policies in significant areas, such as reliability, safety, adequacy and cost-effectiveness of energy supply; increasing energy efficiency; minimizing environmental impact; and enhancing quality of life in terms of social well-being. The policies and the indicators are classified into different sustainable dimensions and summarized in tables along with the corresponding key references. In this study, future energy planning and options, especially in nuclear and RE programs, as well as the conflict between them, are illustrated through the overall performance relative to targets and benchmarks for past and future projections up to the year 2030. This review seeks to examine the past, present, and future policies and indicators to provide a sufficient overview of Malaysian energy policies for optimizing sustainable development. The goal is for this review to lead to increased efforts to accommodate the increasing demand for the management and utilization of RE, promote energy efficiency, and improve performance in achieving sustainable national development. [ABSTRACT FROM AUTHOR]

Water shortage can constrain energy development and use, and climate change partially caused by energy consumption can profoundly affect the quantity and distribution of water resources worldwide. The chronic water shortage in the Beijing–Tianjin–Hebei region of China is likely to worsen under the impact of global climate change. The coal-dominated electricity sector will continuously have a high water demand. This reality will intensify the dilemma between water supply and power generation. This paper presents an adaptability analysis of the Beijing–Tianjin–Hebei region in 2013–2030 based on the current situation. Water evaluation and planning and long-range energy alternative planning systems are used to simulate changes in water and energy systems, respectively, and the impacts on the electricity sector under two climate scenarios and three development scenarios. On this basis, this study explores the potential of power structure adjustment and technological advancement in easing baseline water stress and promoting sustainable development in the region. Findings show that the Beijing–Tianjin–Hebei region is under high water stress, which will be aggravated under global climate change. In representative concentration pathway (RCP) 4.5 and RCP 8.5 scenarios, the baseline water stress of the region in 2017–2030 averages 259% and 494%, and the annual unmet water demand reaches 15.3 and 21.1 billion m 3 , respectively. In the renewable energy and advanced technology scenarios, the regional water savings are expected to reach 200–250 million m 3 by 2030. The unmet water demand of power generation can be alleviated to some extent, but the water shortage trend cannot be reversed. Therefore, the Beijing–Tianjin–Hebei region should develop an overall plan and layout of energy and water resources and adopt a combination of policy instruments to support the expansion of renewable energy or promote advanced power generation technologies. [ABSTRACT FROM AUTHOR]

With ever-increasing demands for energy and gradual climate changes, development and advancements of renewable energy have become a major priority of every country. The applications of renewable energy increase many folds when coupled with wireless power transfer (WPT) technology. About a century ago the advents of Tesla provided us with the principles of WPT. Since then a lot of research has been done in this field. Many efforts have been put to transmit power of renewable energy wirelessly. In this paper, the basic principles and various methods of WPT are reviewed and also discuss the recent developments in wireless transmission of renewable energy. An update for application and limitations of WPT has been presented. The possible systems produced with the coupling of WPT are also presented. [ABSTRACT FROM AUTHOR]

The deployment of energy storage systems (ESSs) is a significant avenue for maximising the energy efficiency of a distribution network, and overall network performance can be enhanced by their optimal placement, sizing, and operation. An optimally sized and placed ESS can facilitate peak energy demand fulfilment, enhance the benefits from the integration of renewables and distributed energy sources, aid power quality management, and reduce distribution network expansion costs. This paper provides an overview of optimal ESS placement, sizing, and operation. It considers a range of grid scenarios, targeted performance objectives, applied strategies, ESS types, and advantages and limitations of the proposed systems and approaches. While batteries are widely used as ESSs in various applications, the detailed comparative analysis of ESS technical characteristics suggests that flywheel energy storage (FES) also warrants consideration in some distribution network scenarios. This research provides recommendations for related requirements or procedures, appropriate ESS selection, smart ESS charging and discharging, ESS sizing, placement and operation, and power quality issues. Furthermore, this study identifies future research opportunities in relation to challenges for optimal ESS placement planning, development and implementation issues, optimisation techniques, social impacts, and energy security. [ABSTRACT FROM AUTHOR]

This paper investigates the determinants of carbon emissions based on energy consumption, analyzing the data of 30 countries using nuclear energy for the period 1990–2014. Renewable energy and nuclear energy consumption are adopted as determinants, and real coal price and real GDP are used as additive variables. The panel cointegration analysis and Granger causality tests are conducted to investigating the relationship among the variables. First, the panel cointegration test results suggest that long-run equilibrium relationship exists among carbon emissions, renewable energy consumption, and nuclear energy consumption. The results of the long-run cointegrating vector and Granger causality tests indicate that nuclear energy does not contribute to carbon reduction unlike renewable energy. Thus, the development and expansion of renewable, not nuclear, energy are essential to prevent global warming. Though there is a concern that rising energy prices caused by the expansion of renewable energy may impact the economy negatively, our empirical results also imply that renewable energy consumption will promote economic growth. In other words, our evidence shows that using and expanding renewable energy is both economically and ecologically beneficial. [ABSTRACT FROM AUTHOR]

The population of Pakistan is increasing rapidly and hence the energy demand. Since ninety׳s, people of Pakistan has been experiencing load shedding because of the intense shortfall throughout the country. Pakistan, being an agricultural country, has a lot of potential of renewable energy sources especially biomass. The thing is to utilize the potential in a right direction. This paper presents the policy direction to get rid of the current energy crisis in the country through utilization of different types of biomass. The animal manure, municipal solid wastes and the crop residues are the main biomass sources in the country. This study also focuses the potential of main biomass sources present in the country and its technical routes for the production of bioenergy. The design parameters for standard bioreactor of gasifier and anaerobic digestion and their economic comparison are highlighted with respect to Pakistan environmental conditions. The development of anaerobic digestion technology is reviewed critically. This paper also discusses the different scenarios for the use of biomass sources in urban and rural environment. This verifies the use of biogas energy as the cheapest and the safest way to remove the crisis from the country. The stand-alone biogas plants should be constructed throughout the country where there is not electrification infrastructure exists. [ABSTRACT FROM AUTHOR]

Life on Earth originated and survived millions of years as a result of the favorable climatic conditions. The climate can be considered as a renewable resource whose energy component is comprised from the solar energy, while the material component represents oceans as water tanks. Renewable energy sources (RES) can be divided into two main categories: traditional renewable energy sources such as biomass and large hydropower plants and the so called “new renewable energy sources” such as the solar energy, wind energy, geothermal energy, etc. This paper refers to the potential and utilization of RES in the southeastern planning region in the Republic of Macedonia. The main goal of the paper is to analyze possibilities of using the RES which naturally belong to the areas of the ten municipalities located in this part of the Republic of Macedonia. This is achieved by defining the existing potentials of RES in the region, the state of their current usage, balance and categorization based on quality, energy value, energy resources, etc. Methodology used in the research is also presented in the paper. [ABSTRACT FROM AUTHOR]

This paper looks into the possible methods of harvesting energy for applications involving wireless sensors from renewable or sustainable sources. An overview of the fundamentals of energy harvesting models using renewable sources and the advancements in the components used for this purpose is given. It also provides an analysis of the issues that are restricting the current harvesting models and indicates possible advances in technologies that may soon solve those problems. There are two main issues that plague these harvesting models. Firstly, the technology involved in the actual harvesting of renewable energy sources is not well developed and offer poor efficiency. In addition to that, most of the models need a permanent storage device, such as a battery or capacitor in order to operate. This is a serious drawback in applications involving wireless sensors as these devices have limited capacity, lifetime, and require a large area to work efficiently. This is most often not favorable as the attractions of using wireless sensors are in its portability and form. This paper looks into the studies dedicated to solving these problems. The latter part of the paper contains a discussion regarding the technologies that are best suited for applications in wireless sensors. The two most readily available and feasible options of a sustainable energy for these applications are found out to be RF (Radio Frequency) signal and solar radiation. Therefore, the final part of the paper concentrates on reviewing a model that may potentially be able to serve as a basis for a singular model for any kind of energy harvesting from renewable sources. [ABSTRACT FROM AUTHOR]

Improvement of thermal performance of a solar air heater can be obtained by enhancing the rate of heat transfer. Thermal efficiency of matrix solar air heater is higher in comparison to conventional type. Number of studies has been reported in the literature on the performance of matrix air heater with different material packing and elaborated various parameters such as design; heat transfer enhancement, flow phenomenon and pressure drop in the duct. Majority of the studies revealed an increase in the thermal efficiency for matrix collector as compared to conventional plane solar air heater. This review paper presents an extensive study of the research carried out on matrix solar air heater. Based on literature review, it is concluded that the solar air heaters performed well when packed with porous medium and this is due to the geometrical parameters of porous material. In addition double pass porous bed solar air heaters performed better than single pass. Various types of matrix materials used in the literature and correlations developed for heat transfer and friction factor by different researchers have been presented. Much attention has been devoted in this paper to portrait the development of various types of solar air heaters over the years. The merits and demerits of different models evolved by many researchers have been critically analyzed. Finding in a nut shell is that the drawbacks associated with conventional nonporous solar air heaters such as high heat loss to the ambient, decreased convective heat flow from plate to air, etc. can be overcome by the use of an effective design of porous bed solar air heater. [ABSTRACT FROM AUTHOR]

Given that the first industrial revolution was based on Steam Engine (coal as energy source), and the second on oil and electricity, where both these revolutions are actually "high carbon" revolutions, it is logical to expect that the third industrial revolution should be based on systems of renewable energy sources (RES), in order to minimize the problems arising from climate changes and to achieve sustainable development. However, the usage of the RES technologies and daily/weekly storage of energy and their connection to smart grids is not enough for the expected third industrial revolution. The start of this revolution would require technologies that have a great potential for further development and ability to supply, at any time, the necessary energy and power to a settlement/city, as well as drinking water, meeting the peak load requirements, continuously throughout the year, and independently of external sources of energy and drinking water. This would be provided from intermittent RES energy (solar, wind, etc.) and sea or other unclean source of water as natural resources. In that context, this paper presents a radically new technological solution: Key Engine which uses only natural resources: the sun, sea and gravity, in order to continuously and simultaneously supply a consumer with energy, power and drinking water. This solution has all the essential features required to start a third industrial revolution. The basic unit of Key Engine consists of the solar thermal (ST) generator with parabolic trough collectors through which sea water flows directly, absorbing thermal energy of solar radiation. After the separation of steam from seawater, the steam drives turbines and generators and produces electricity that is delivered to Pump Storage Hydroelectric (PSH) facility with seawater, which balances the daily and seasonal surpluses and shortages of energy, thus ensuring a continuous supply of electric power and energy to a consumer. At the same time, the water that comes out of the turbine, passes through the water treatment unit and is stored in drinking water reservoir, enabling continuous supply of the same consumer with drinking water. The paper presents theoretical aspects of Key Engine, model for optimal sizing and practical formulas for the calculation of characteristic values of the system, which could be the basis for further scientific research, development and innovative solutions that would help engineers in practice for numerous and diverse applications of Key Engine. In order to verify the derived mathematical relationships and models for optimizing the Key Engine in real conditions, the case study of the island of Vis in the Adriatic Sea, Croatia, has been considered, along with total annual irradiance of 1575 kW h/m 2 a, total annual electric energy consumption of 20 GW h and drinking water consumption of 453,382 m 3 . The obtained results: power of ST generator of 52 MW, working volume of the upper reservoir of 7 hm 3 , total annual electric energy production of 62 GW h/a, and drinking water production of 480,754 m 3 /a, clearly show that the new technology can fully meet the needs of the considered consumer for energy and drinking water. As the basic idea of Key Engine relies on the use of natural resources, i.e. RES energy and sea, the paper presents only the starting solution, whereby, apart from the sun, RES can be wind, or other renewable sources, that can perform separation of vapor from seawater and thus produce drinking water, as well as energy simultanously. Also, energy storage may not be performed solely by the PSH technology, but also by any other technology that can provide seasonal balancing of energy. All this suggests that the Key Engine can be understood as an open-source for RES technology development and thus bring changes in all three aspects of sustainable development: economy, society and environment. [ABSTRACT FROM AUTHOR]

The rapid growth of China׳s installed wind power capacity in recent years is closely related to the wind energy policies issued by the Chinese government. Using content analysis and quantitative analysis methods, this paper studies the historical evolution of Chinese wind energy policies. Based on 72 wind energy policies issued in the past two decades (1995–2014), this paper analyzes the issuing organization, form, number and stringency of wind energy policies and compares different policy instruments in two periods. The results show that the number and stringency of wind energy policies fluctuated greatly from 1995 to 2014 and that more than twenty organizations had independently or jointly issued the policies. The main organization issuing wind energy policies, however, is the department that controls key economic and administrative resources and not the one that is in charge of wind energy. Of the 72 policies issued, twenty-three took the form of notices, and eleven were measures. As to the policy instrument, environmental policies are most widely applied by the Chinese government, and “regulation control” and “goal-planning” instruments are the ones most frequently adopted. Furthermore, the application of supply- and demand-type policies is inadequate, and few effective instruments have been adopted. [ABSTRACT FROM AUTHOR]

Power grids have faced major challenges such as increasing consumption, peak demand and CO 2 emission. Distributed Generation (DG) as a solution to these issues is affected by source intermittency, grid-side limited storage capabilities and supply/demand mismatch. In order to achieve more benefits and profits for both customers and the utility, integrated demand management techniques can be used. This paper reviews the issues caused by high penetration of renewables in power production, depending on utility characteristics. In addition, several methods in the literature were reviewed and their both single and combined use was investigated with a comparison study in Turkey. In field data based simulations, consumption of refrigerators were scheduled according to the output of a small scale PV system and changes in consumption in a year were calculated. The results were analyzed and compared with each other from the standpoint of change in amount of power taken from grid, number of active operation hours shifted to solar periods, change in annual consumption and achievable savings in electricity bills. In addition to the analysis and comparison of several management methods, the paper also proposes a number of terms that widens applicability and can be used in decision-making processes. [ABSTRACT FROM AUTHOR]

This paper considers a revisited Environmental Kuznets Curve (EKC) hypothesis with potential impact of renewable energy consumption on environmental quality. To this end, paper aims at investigating the validity of the EKC hypothesis employing the dependent variable of CO 2 emissions and regressors of GDP, quadratic GDP and renewable energy consumption. This paper, hence, analyzes this revisited EKC hypothesis to observe if (i) there exists an inverted-U shaped relationship between environmental quality (in terms of CO 2 emissions), per capita income and per capita income squared and (ii) there exists a negative causality from renewables to CO 2 emissions within EKC model. Paper employs a panel data set of 17 OECD countries over the period 1977–2010 and launches panel FMOLS and panel DOLS estimations. The findings support the EKC hypothesis for the panel and indicate that GDP per capita and GDP per capita squared have the impacts on CO 2 emissions positively and negatively, respectively, and that renewable energy consumption yields negative impact on CO 2 emissions. Another remark of this paper is that the validity of EKC does not depend on income level of individual countries of panel in which EKC hypothesis holds. Eventually, paper argues that if countries carry out (i) policies, i.e., for fair and easy access to the electricity from renewable sources and (ii) policies to increase renewables supply through i.e. improved renewable energy technologies, they will be able to contribute to combating global warming problem as they increase their GDP’s. [ABSTRACT FROM AUTHOR]

A sustainable energy system can be treated as a development of the distributed generation concept. It meets energy demands locally from renewable energy or/and high-efficiency polygeneration production technologies, and is characterized by energy and cost efficiency, reliability, and environmental-friendliness. Distributed energy systems typically use renewable energy resources to supply all energy demands, such as heat, cooling, and electric power in an integrated way. However, it seems that too much emphasis is placed on power and associated renewable energy-based power technologies for dealing with sustainability issues in public discussion and the research community. Often, equally important thermal energy (heat and cooling) and polygeneration are ignored. Polygeneration is an energy-efficient technology for generating simultaneously heat and power as well as other energy products in a single integrated process. Energy efficiency contributes significantly to CO 2 emission reduction. This paper discusses the role of polygeneration in a distributed energy system and the contributions of polygeneration to the development of sustainable energy systems. The paper also stresses that efficient decision support tools for sustainable polygeneration systems are important to achieve sustainability. First, the joint characteristic of a polygeneration plant that defines the dependency between different energy products is reviewed. Then, typical methods for dealing with polygeneration systems are reviewed. The review attempts to highlight the complexity of polygeneration systems and potential of polygeneration systems to adjust output of different energy products. Next, the challenges of sustainable polygeneration energy systems are discussed. Then some practices for operating polygeneration plants are discussed. [ABSTRACT FROM AUTHOR]

Introduction of renewable energy sources (RES) in insular areas is growing on different islands of various regions in the world and the large-scale deployment of renewables in island power systems is appealing to local attention of grid operators as a method to decrease fossil fuel consumption. Planning a grid based on renewable power plants (RPP) presents serious challenges to the normal operation of a power system, precisely on voltage and frequency stability. Despite of its inherent problems, there is a consensus that in near future the RES could supply most of local needs without depending exclusively on fossil fuels. In previous grid code compliance, wind turbines did not required services to support grid operation. Thus, in order to shift to large-scale integration of renewables, the insular grid code ought to incorporate a new set of requirements with the intention of regulating the inclusion of these services. Hence, this paper discusses grid code requirements for large-scale integration of renewables in an island context, as a new contribution to earlier studies. The current trends on grid code formulation, towards an improved integration of distributed renewable resources in island power systems, are addressed. The paper also discusses advanced grid code requirement concepts such as virtual wind inertia and synthetic inertia for improving regulation capability of wind farms and the application of energy storage systems (EES) for enhancing renewable generation integration. Finally, a comparative analysis of insular grid code compliance to these requirements is presented in the European context. [ABSTRACT FROM AUTHOR]