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This paper presents a systematic literature review of urban wind energy harnessing in built environments. In line to foster decarbonisation in urban areas of tropical countries with decentralised renewable energy technologies, such as small wind turbines in buildings, this research has been carried out. To provide a comprehensive foundation on the topic, urban wind assessment research for various purposes was reviewed, where 48 studies for energy harnessing purposes were classified by country, region and methods. The methodologies are divided into six stages, of which environmental assessment and resilience analysis are scarce. Due to tropical countries being exposed to atmospheric events that historically cause human and material losses, potential future research could be made in line with resilience analysis through metrics that are key to the proper mass deployment of building-integrated wind turbine systems. Of 66 methods for wind prospecting, the most used are on-site measurement, computational fluid dynamics simulation and numerical climate prediction, which represent 49 %, 22 % and 17 %, respectively. Other decision-making techniques are presented with the aim of addressing new ways in strategic planning to promote the use of this technology. [Display omitted] • Urban wind energy research does not deem energy resilience analysis. • Few evaluations of urban wind energy have been carried out in the tropics. • Hurricanes represent a hazard for building-integrated wind turbines. • On-site measurement and CFD simulation are the most adopted methods. [ABSTRACT FROM AUTHOR]

Brazil is a case of the achievement of a high share of wind energy integration to an interconnected power system in an emerging market. A series of successful energy supply programmes and a strong renewable-oriented finance framework implemented since 2002, have promoted alternative renewables – wind installed capacity increased over 22-fold from 927 MW in 2011 to 21 GW in 2022, reaching 11.77% of total procured power. From this, about 90% are concentrated in Brazil's least developed region, the Northeast, where wind investment should create jobs and propel socioeconomic development. Despite that, there is no studies specific assessing the regional and economy-wide effects of those programmes, gap that this paper aims to fill by applying the regional Computable General Equilibrium (CGE) model TERM-BR10. We assess that by modelling an alternative scenario for the period 2010-19 based on an official electricity matrix built in 2010, that projected 3.4 additional GW of wind power while not considering all the success of renewable policies, against the observed installed capacity expansion, where wind power was 3.7 times higher than what had been planned. Our results show that in the absence of renewable policies, Brazil would have faced economic losses such as GDP (−0.27%) and investment (−4.76%). The Northeast region would have been the most impacted in terms of GDP (−1.3%), real wage (−2.99%) and employment creation (−0.1%). We propose that such socioeconomic co-benefits are incorporated in energy planning, which could promote regional equality through renewable energy expansion. • Wind power capacity increased over 20-fold from 2011 to 2022. • 90% are in the poorest region where policies propel development and job creation. • Policy absence would entail a GDP loss of 0.27% nationally and of 1.3% in the region. • Negative impacts to labour market are mostly over skilled jobs. [ABSTRACT FROM AUTHOR]

Australia has significant offshore wind resources that can support ever-increasing power demand and hence provide a long-term contribution to the net-zero target by 2050. Although some offshore wind farm projects are proposed in Australia, the industry is not mature enough to justify the benefits and display economic opportunities. More specifically, the techno-economic analysis of offshore wind energy has not been systematically mapped in Australia. Therefore, the investigation of the spatial variation of technical feasibility and economic potential of offshore wind is vital to identify the potential regions and to develop strategies for future offshore wind farm developments in Australia. This paper presents detailed mappings of the techno-economic potential of offshore wind energy in Victoria-Tasmania's exclusive economic zone. Offshore wind energy resources are assessed in the paper in terms of energy availability and variability and the feasibility of various offshore wind technologies is investigated, including turbines, foundation types and transmission topologies. In addition, the high-fidelity life-cycle cost models and two innovative evaluation matrices are developed to assess the economic potential of offshore energy farms in South-eastern Australia. The impact of local power system regulation costs and future carbon prices on the viability of offshore wind is also investigated in this paper. It is concluded that the detailed mapping approach and analysis in the paper can provide a systematic tool for industry partners, investors and policymakers at the pre-planning stage of developing offshore renewable energy systems. • The technical feasibility of offshore wind is mapped under various constraints. • The novel LACE and high-fidelity LCC assessment models are developed. • The techno-economic potential is systemically mapped in South-eastern Australia. • The impacts of electricity market regulation and future carbon prices are studied. [ABSTRACT FROM AUTHOR]

Abstract The demand for reduction of greenhouse gases, the need for a decreased dependence on fossil fuel, and the increasing penetration of the renewable energy sources are changing the world's electrical energy production. The island of Crete in Greece possesses great potential when it comes to wind and solar energy. Currently, a large amount of wind energy is often being curtailed in Crete, due to the technical minima of the existing thermal units, the inherent fluctuating power output of the wind turbines and the electricity demand profile. Electrical energy storage is recognized as an underpinning technology to have great potential in overcoming these challenges. There are many different ways to store the surplus energy and convert it back to electrical energy when it is needed. The aim of the present paper is the investigation of the role that energy storage can play in the further development of renewable energy sources in non-interconnected islands via considering the energy storage technologies of compressed air energy storage, pumped hydroelectric storage and sodium – sulfur batteries. This paper examines the solution of electrical energy storage in curtailment exploitation. A review over the above energy storage technologies is carried out and a comparative analysis is performed for the case study of Crete. Each storage technology is techno-economically evaluated using actual data. Finally, a parallel comparison of the examined storage systems' levelized cost of energy is presented and conclusions are drawn. The compressed air energy storage system appears to be more favorable, having the lowest levelized cost of energy of the examined systems studied at 0.21 €/kWh, while contributing 105.59 GWh of electrical energy to the island's grid per year. For the examined case study, compressed air energy storage system appears to be almost 20% and 50% cheaper in terms of levelized cost of energy in comparison with pumped hydro storage and batteries respectively. Highlights • Review on compressed air energy storage, pumped hydroelectric storage and sodium – sulfur batteries. • Techno-economic comparative analysis of energy storage technologies for the case study of Crete. • Comparative findings on levelized cost of energy of different storage technologies. [ABSTRACT FROM AUTHOR]

Electrical energy becomes necessary for human being. Generation of electrical energy mostly depends on fossils fuel, they are limited in nature and also responsible for environmental pollution. Renewable energy resources provides a better alternative for future,In comparison to conventional energy resources economical aspect is a major issue of renewable energy sources with the feasibility and efficiency. These limitations are tried to overcome by deployment hybrid renewable energy resources. There are certain criteria to analyze and implement the sized, optimized and cost efficient system. This paper focus on hybrid energy systems based on solar photovoltaic (PV) and wind resources. This paper shed lights on various parameters of economic feasibility, sizing strategies with logical advancements to enhance their utilization, future prospects, and their arrangement. Strategies to develop an effective storage system is also presented here.A brief review on developments in optimization techniques, reliability index and cost analyzing techniques for hybrid renewable energy systems are also presented. [ABSTRACT FROM AUTHOR]

The combination of multilevel inverter with renewable energy source power generation is paid more attention among the researchers, because multilevel inverters are widely accepted power converters in for high-power applications. The conventional multilevel inverters are highly implemented in industries, and the success of this has motivated to create newer topologies with the reduced overall power electronics components. In this paper, recent multilevel inverter topologies with reduced number of switches are taken into account and to find a suitable topology for photovoltaic (PV) and wind energy applications. Finally, this paper gives a pathway for the upcoming researchers to consider the design issues and challenges in the development of new multilevel inverter topologies. [ABSTRACT FROM AUTHOR]

Contemporary electrical networks are moving towards distributed electricity production via the implementation of renewable energy sources. One of the most developed renewable technologies comprises the transformation of the wind's kinetic energy to electrical energy by using wind power converters. However, wind power production is highly dependent on the weather conditions and specifically the available wind resource of an area. Intermittent electricity production of wind turbines hinders their further integration in electricity networks suggesting among other solutions, the implementation of energy storage configurations in order to cope with their stochastic operation. Based on an extensive literature review, this study reveals the potential future role of hydrogen as a multifunctional storage application for wind power. The analyses are carried out to identify the focus of recent studies on coupled wind and hydrogen systems in order to define the potential of such systems and predict the future collaboration between the two technologies. Based on the results, it can be derived that research on wind-hydrogen systems is shifting focus from solely applying hydrogen as a storage application to exporting hydrogen as a bi-product to improve wind power investments. Furthermore, the outcome shows that there is an increasing interest in using wind power generation to produce hydrogen as an end product designed specifically for transportation purposes, while contributing simultaneously to a more sustainable energy mix. This paper provides an ultimate overview of wind-hydrogen systems, which reveals the development as well as the state-of-art of such system's applicability in connection to its changing efficiency. • Wind power coupled to water electrolysis systems was reviewed. • Analysis of pilot and simulated grid-connected wind-hydrogen systems was performed. • Wind-hydrogen coupled systems can support autonomous electric networks. • Wind power-based hydrogen systems can mitigate CO 2 emissions significantly. • Levelised cost of wind-based hydrogen production ranges between 0.3 and 26.6 €/kg H2. [ABSTRACT FROM AUTHOR]

In the context of carbon neutrality, renewable energy, especially wind power, solar PV and hydropower, will become the most important power sources in the future low-carbon power system. Since wind power and solar PV are specifically intermittent and space-heterogeneity, an assessment of renewable energy potential considering the variability of wind power and solar PV with high temporal resolution in different regions will facilitate more accurate identification of the decarbonization pathway of power system. In this paper, the complementary output potential of wind-solar-hydro power every 15 min in 31 Chinese provinces is evaluated by developing a multi-objective optimization model based on Nondominated Sorting Genetic Algorithm II. The results show that the total annual complementary power generation potential in China is 17.57 PWh, of which the three components account for 47.8%, 25.3% and 26.9%, respectively. Inner Mongolia and Tibet are the major renewable energy source provinces with annual complementary power generation potential of 5330 TWh and 3907 TWh, accounting for 30.3% and 13.7% of the total power generation potential, respectively. The temporal potential of wind-solar-hydro power varies greatly, with daily potential is more volatile than monthly. Seasonal and spatial heterogeneity of the complemental renewable potential makes some provinces suffer power shortage during long-hours period especially in winter. Our findings will encourage a higher penetration of renewable energy, the promotion of multi-energy complementarity, and the development of inter-provincial power transmission and energy storage infrastructure in China's future power sector. • A multi-objective wind-solar-hydro complementary optimization model is developed. • Electricity supply and demand have gaps at different temporal and spatial scales. • Wind-solar-hydro complementary potential shows great temporal and spatial variation. • Renewable complementarity can improve China's future power system stability. [ABSTRACT FROM AUTHOR]

Renewable energy sources such as wind farms and solar power plants are replacing conventional coal-based synchronous generators (SGs) to achieve net-zero carbon emissions worldwide. SGs play an important role in enhancing system strength in a power system to make it more stable during voltage/frequency disruptions. However, traditional coal-fired SGs are being decommissioned in many parts of the world, owing to stringent environmental regulations and low levelized cost of energy of renewables. Consequently, maintaining system strength in a renewable energy-dominated power system has become a major challenge, and without adequate mitigation techniques, low system strength can potentially cause widespread power outages. This paper provides an overview of system strength and its measurement techniques in a power system with a large number of renewable energy sources (RESs), for example solar and wind farms. The review includes the system strength measurement techniques, mitigation approaches, and future challenges. • A comprehensive review on system strength for Australia. • Integration of power systems with large number of renewable energy sources. • Measurement and mitigation techniques for system strength shortfalls. • Analysis of future challenges and research directions on system strength. [ABSTRACT FROM AUTHOR]

Generation assets applying for grid connection must comply with certain grid code requirements. Grid code compliance verification shall include revision of documentation covering technical data and models, checking of requested capabilities, and validation of model performance. These procedures are singular regarding renewable power generation, due to their technical characteristics, specific topologies and short experience. This paper aims to carry out an updated review of the international regulations and current practices regarding the verification and certification of the electrical performance in renewable generation systems. Grid code compliance can be verified by practical tests or by simulation of validated models. Therefore, this paper also encompasses modelling and validation requirements, highlighting challenges caused by current procedures. [ABSTRACT FROM AUTHOR]

The accurate assessment of the potential wind energy at a define site is very important from economic point of view, measures cost effectiveness of the project and helps estimating future incomes, revenues. Knowledge of wind characteristics also facilitates a proper turbine design selection. There are different techniques for wind energy evaluation. The direct wind speed measurement is the most accurate method to determine wind conditions, but often the different wind speed frequency distributions are proposed. One of the most widely used distribution is Weibull distribution. The two-parameter Weibull distribution is recognized as an appropriate model and the most widely used in the wind industry sector. In some cases, in which the probability of null wind is significant, the Weibull distribution does not reveal good conformity for the low wind speed. In theory, it seems that the three-parameter Weibull distribution, which takes into account the frequency of null winds, may better represent wind ranges with high percentages of null wind speeds and may give better results. In the paper, the review of the literature is carried out on the application of two and three-parameter Weibull distribution in wind energy analyses and also focuses on the comparison of results received from different probability density functions, used in cited papers, with the frequency of 0–2 m/s wind speed range in real data. For higher percentages of null wind speeds or the wind speed below 2 m/s, the three-parameter Weibull model should have the advantage in relation to two-parameter Weibull distribution, gives more appropriate results and can be proposed as an alternative to wind energy estimation technique. [ABSTRACT FROM AUTHOR]

The application of VSC-HVDC (Voltage Source Converter Based High Voltage Direct Current Transmission) is one of the proven solutions to the transmission problems of offshore wind power. As AC and DC networks become more complex, VSC-MTDC (Multi-terminal High Voltage Direct Current Transmission Based on VSC) is developed based on two-terminal HVDC to offer technology support for the accessing among multi-supplier center, multi-loads center and distributed renewable powers. This paper reviews the MTDC and its implementation in China, mainly discusses the topologies of DC network of VSC-MTDC system and the control strategies of VSC-MTDC which includes converter station control and coordinated control. In most cases, double closed-loop space vector control (DCSVC) strategy applied in the Zhoushan project, which includes five-terminals and has been put into operation, is adopted for the converter station control. But the method can not work under the unbalanced voltage situation, thus an improved double closed-loop space vector control strategy, which includes positive and negative sequence components, is proposed in this paper. As for coordinated control, master-slave control, DC voltage droop control and DC voltage margin control are presented. As for the part of implementation of MTDC in China, Zhoushan project is presented in detail. This paper provides good theoretical foundation for the grid integration and the transmission of large offshore wind farms. [ABSTRACT FROM AUTHOR]

Currently, wind energy is one of the most important sources of renewable energy. Offshore locations for wind turbines are increasingly exploited because of their numerous advantages. However, offshore wind farms require high investment in maintenance service. Due to its complexity and special requirements, maintenance service is usually outsourced by wind farm owners. In this paper, we propose a novel approach to determine, quantify, and reduce the possible conflicts of interest between owners and maintenance suppliers. We created a complete techno-economic model to address this problem from an impartial point of view. An iterative process was developed to obtain statistical results that can help stakeholders negotiate the terms of the contract, in which the availability of the wind farm is the reference parameter by which to determine penalisations and incentives. Moreover, a multi-objective programming problem was addressed that maximises the profits of both parties without losing the alignment of their interests. The main scientific contribution of this paper is the maintenance analysis of offshore wind farms from two perspectives: that of the owner and the maintenance supplier. This analysis evaluates the conflicts of interest of both parties. In addition, we demonstrate that proper adjustment of some parameters, such as penalisation, incentives, and resources, and adequate control of availability can help reduce this conflict of interests. • Reliability of OWF analysis for owners and maintenance suppliers. • Consequences of outsourced maintenance for owners and maintenance suppliers. • Costs and profits analysis of OWF owners and maintenance suppliers. • A novel approach to reduce the conflict of interests between both parties. [ABSTRACT FROM AUTHOR]

Offshore wind energy is recognised globally as a viable alternative to finite energy sources. However, large cost reductions are still needed, particularly in the Operations & Maintenance (O&M) phase, which currently accounts for about 30% of the cost of offshore wind. For large component replacements, a jack-up vessel is often leased from the spot market, resulting in high costs and low utilisation. These costs can be lowered when multiple wind farm service providers would share the resources needed to employ jack-up vessels. In this paper, we analyse two types of resource sharing, as an alternative to each service provider leasing its own vessel: (i) vessel purchasing and sharing and (ii) the combined use of vessel and harbour sharing. We design a simulation model and include stochastic processes such as weather patterns and component failures. Results show that cost benefits up to 45% can be achieved compared to a leasing policy, depending on the number of wind farm service providers involved and on the geographical distance between offshore wind farms. Moreover, it is shown that the jack-up vessel should not be fully utilised to minimise costs. The performance benefits of harbour sharing in addition to vessel sharing are generally small, but become more significant if the network faces considerable congestion. Results are illustrated using a case study based on a setting in the Western North Sea. • Three policies are studied for the deployment of jack-up vessels for o_shore wind farm maintenance. • Collaboratively purchasing and sharing a jack-up vessel outperforms individually leasing it. • Adding harbour facility sharing among operators only leads to slightly further cost reductions. • Operators should not focus on high jack-up utilisation as this results in unnecessarily high costs. • Yearly cost and the best coalition size are particularly sensitive to the replacement time and failure rate of the gearbox. [ABSTRACT FROM AUTHOR]

Abstract Offshore wind is a source of clean, renewable energy of great potential value to the power industry in the context of a low carbon society. Rapid development of offshore wind energy depends on a good understanding of technical issues related to offshore wind turbines, which is spurring ongoing research and development programmes. Foundations of offshore wind turbines present one of the main challenges in offshore wind turbine design. This paper reviews the present state of knowledge concerning geotechnical and structural issues affecting foundation types under consideration for the support structures of offshore wind turbines, and provides recommendations for future research and development. Highlights • Reviews the technology development and designs of offshore wind turbine foundations. • Discusses geotechnical and structural issues affecting the foundations. • Provides recommendations for future R&D to improve the effectiveness of different designs. [ABSTRACT FROM AUTHOR]

Abstract Owing to the wind and photovoltaic (PV) potential in Brazil, the country has recently seen increased exploration into the construction of wind-PV hybrid plants. However, as specific criteria for contracting this type of project have not yet been developed, this paper presents a model to assist the government in contracting projects that maximize the socioeconomic well-being of the Brazilian electricity sector. For this, multiobjective programming is used to simultaneously handle two objective functions—maximally reducing emission density and minimizing the levelized cost of electricity (LCOE)—with the aid of the mixture arrangement technique. In this respect, the optimization method called normal boundary intersection (NBI) is applied to solve the multiobjective problem and construct the Pareto frontier. Additionally, a metric based on the ratio between entropy and the global percentage error (GPE) is used to identify the optimal Pareto solution. The model was applied to determine optimal configurations for wind-PV powerplants in twelve Brazilian cities, and the results obtained reveal the capacity of the model to indicate the optimum configuration according to the wind and PV potential of each city. Highlights • The use of renewable energy sources has been encouraged in Brazil. • The construction of PV-wind hybrid plants has been recently explored. • Normal Boundary Intersection is used to simultaneously handle two objective functions. • Reduced emission density and LCOE were optimized in twelve Brazilian cities. • Results reveal the capacity of the model to indicate the plants optimum configuration. [ABSTRACT FROM AUTHOR]

Abstract The focus of this paper is to analyse the determinants of wind energy development in the United States and how procedural and regulatory frameworks influence the deployment of wind power facilities. The empirical analysis uses statistical regression models integrating geospatial, macroeconomic and socio-environmental control variables. Using wind penetration as well as wind capacity additions as dependent variable permits a more differentiated analysis of both absolute and relative growth factors. This enables a precise assessment of state-to-state variations in permitting, zoning and siting procedures that wind developers have to clear before being authorised to start construction. Quantifying the number of state-level financial support measures and various permitting and regulatory process stages allowed for a more comprehensive assessment of administrative barriers to wind energy development than prior research studies. The results indicate a partial reversal of previous findings that showed that a high quantity of state-level regulations negatively affects wind capacity additions. Exogenous factors such as the ratio of in-state federal lands, population density, and especially wind energy potential, as well as federal statutes and incentives remain the main drivers of wind capacity additions and overall wind energy penetration. Contrasting prior literature, the influence of localised financial incentives or regulatory approval procedures appears to be minor; therefore streamlining national policies and incentives at the federal level might prove more effective than promoting wind development at the state level. We point out that future research should also examine the role of quality of state-level regulations in addition to quantity. Highlights • Most up-to-date United States state-level study using recent data sets from 2010 to 2016. • Number of financial incentives & regulatory measures are weak growth indicators. • Overall wind potential is the strongest driver of wind development. • Novel dependent variable for wind penetration enables relative growth analysis. • Quantity of environmental regulations did not influence energy growth. [ABSTRACT FROM AUTHOR]

Solar and wind energy are considered as promising electrical generating sources. These renewable energies are omnipresent, with free access, and a friendly environmental impact. Their integration remains technically and economically advantageous for electrical generation in isolated areas (IS). In several cases, the separate use of solar and wind energy sources may result in considerable over-sizing, which makes the single renewable energy sources in implementation very costly. It is found that the use of one of the optimization sizing techniques could help to guarantee the maximum power reliability and the minimum system cost for the future hybrid implementation. Moreover, a remarkable interest is manifesting for the use of solar and wind renewable energy sources (RES), which provide a realistic form of electrical generation in isolated areas. This paper provides an updated literature review, of the most applied method and techniques used in sizing and optimization of PV-Wind based hybrid system (PWHS) for an isolated area aiming to reach the best compromise between power reliability and hybrid system costs. Furthermore, this work discusses a comparison of the most common topologies used for the implementation of PWHS, then, presents a mathematical model of the hybrid system components with an emphasis on the importance of power reliability and system cost, Finally, provides an extensive analysis of software tools and algorithm approach used in sizing optimization. [ABSTRACT FROM AUTHOR]

Recent increases in the global demand for IT services have increased the power consumption, total ownership costs and environmental footprint of data centers. Recent efforts to reduce these effects have focused on either their cooling systems, or their power systems. In this paper, we have developed an integrated approach to minimize the total power demand of data centers, whilst their reliance on power imported from the grid is minimized. First, the power demand of data center has been reduced utilizing various air-side economizer-based cooling systems. Since the effectiveness of economizers significantly depends on the local weather conditions, 42 stations in major cities across the world have been considered. A more than 80% reduction in total cooling power consumption is achieved by using the most appropriate air-side economizer at each location. Second, the reliance of data centers on power imported from the grid is minimized utilizing on-site hybrid renewable power generation and energy storage. The on-site renewable power generation and capacity factors have been calculated for 1 MW wind and solar renewable power plants to identify the location with the highest renewable power generation capability. The optimal size of a hybrid renewable power plant, and associated battery energy storage system, is also determined for each data center using linear programming to minimize total levelized costs. Finally, the optimal location for constructing and operating the most energy efficient, cost-effective and sustainable data center has been identified by calculating its level of independence from the power grid. It is found that the level of grid independence increases as we move away from the equator, for example more than 50% grid independence can be achieved at Regina station located in Canada. [ABSTRACT FROM AUTHOR]

Multi-criteria decision making (MCDM) methods are becoming increasingly popular in solving energy selection problems because these problems involve multiple and often conflicting criteria. This paper presents comparative analysis of ranking renewable energy sources (RES) for electricity generation in Taiwan using four MCDM methods - WSM, VIKOR, TOPSIS, and ELECTRE. The Shannon entropy weight method is used to assess the importance of each criterion for the ranking of RES. After that, four MCDM methods are utilized for quantitative evaluation to rank all available RE alternatives. From the weights estimation results, efficiency is the first priority in all evaluation criteria, followed by job creation, operation, and maintenance cost. The purpose of this study is to rank the priorities of various RES and propose recommendations for Taiwan's RE development. The ranking results show that hydro is the best alternative in Taiwan, followed by solar, wind, biomass and geothermal. Furthermore, sensitivity analysis of the weights was conducted considering the ranking results heavily depend on the criteria weight. The results of sensitivity analysis indicated that when financial or technical aspects are focused upon, hydropower is the best RES because its technology is the most mature and the cost is the lowest in Taiwan. In addition, from an environmental perspective, wind energy is the best choice, and from the social perspective, solar PV is the best choice. The findings of this study can provide useful information to energy decision makers and serve as a reference for Taiwan's energy policy. [ABSTRACT FROM AUTHOR]

This paper determines a least cost electricity solution for Sub-Saharan Africa (SSA). The power system discussed in this study is hourly resolved and based on 100% Renewable Energy (RE) technologies. Sub-Saharan Africa was subdivided into 16 sub-regions. Four different scenarios were considered involving the setup of a high voltage direct current (HVDC) transmission grid. An integrated scenario that considers water desalination and industrial gas production was also analyzed. This study reveals that RE is sufficient to cover 866.4 TWh estimated electricity demand for 2030 and additional electricity needed to fulfill 319 million m 3 of water desalination and 268 TWh LHV of synthetic natural gas demand. Existing hydro dams can be used as virtual batteries for solar PV and wind electricity storage, diminishing the role of other storage technologies. The results for total levelised cost of electricity (LCOE) decreases from 57.8 €/MWh for a highly decentralized to 54.7 €/MWh for a more centralized grid scenario. For the integrated scenario, including water desalination and synthetic natural gas demand, the levelised cost of gas and the levelised cost of water are 113.7 €/MWh LHV and 1.39 €/m 3 , respectively. A reduction of 6% in total cost and 19% in electricity generation was realized as a result of integrating desalination and power-to-gas sectors into the system. A review of studies on the energy future of Sub-Saharan Africa provides the basis for a detailed discussion of the new results presented. [ABSTRACT FROM AUTHOR]

The most important single event of the last years in wind energy technology is the reduction in the cost of producing wind electricity offshore, a reduction that can reach 75%, depending on the system boundary considered, for installations commissioned by 2024. Surprisingly, there is very little scientific literature showing how this reduction is being achieved. The objective of this paper is to analyse the evidence behind cost reduction in one of the most significant cost elements of offshore wind farms, the installation of foundations and turbines. This cost is directly dependent on the daily rates of the installation vessels and on the days it takes to install those wind farm elements. Therefore, we collected installation data from 87 wind farms installed from 2000 to 2017, to establish the exact time for installation in each. The results show that advances have reached 70% reduction in installation times throughout the period for the whole set, turbine plus foundation. Most of these improvements (and the corresponding impact in reducing costs) relate to the larger size of turbines installed nowadays. There is, therefore, not any leap forward in the installation process, but only incremental improvements applied to turbines that are now four times as large as in 2000. [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]

Pakistan is among the 10 countries that face the worst energy crisis of the world. As the country struggles with a number of financial, political and social issues, the transition from a conventional fuels based economy to a green economy is not an easy one. Pakistan has been blessed with immense potential of clean renewable sources of solar, wind and biomass but they have not been exploited yet. Renewable energy technology sector has not penetrated the energy mix and is currently an emerging market. This paper highlights the steps the country has taken in the past and the steps that are being taken at present to emerge out of the prevailing energy crisis when even the most urban areas suffer from power outages of 12 h per day. Until 2009, no single grid interconnected wind farm existed but now the situation has changed considerably and wind farms contributing to the national grid are a reality now. Three grid interconnected farms have been inaugurated and many others are in pipeline. The national policy regarding wind power systems has recently changed after unexpected setbacks to ongoing projects. This paper reviews the developments in the wind power sector of the country and lists some suggestions that can help improve the wind power penetration in the national energy mix. [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]

Wind power is the most reliable and developed renewable energy source over past decades. With the rapid penetration of the wind generators in the power system grid, it is very essential to utilize the maximum available power from the wind and to operate the wind turbine (WT) at its maximal energy conversion output. For this, the wind energy conversion system (WECS) has to track or operate at the maximum power point (MPP). A decent variety of publication report on various maximum power point tracking (MPPT) algorithms for a WECS. However, making a choice on an exact MPPT algorithm for a particular case require sufficient proficiency because each algorithm has its own merits and demerits. For this reason, an appropriate review of those algorithms is essential. However, only a few attempts have been made in this concern. In this paper, different available MPPT algorithms are described for extracting maximum power which are classified according to the power measurement i.e. direct or indirect power controller. Merits, demerits and comprehensive comparison of the different MPPT algorithms also highlighted in the terms of complexity, wind speed requirement, prior training, speed responses, etc. and also the ability to acquire the maximal energy output. This paper serves as a proper reference for future MPPT users in selecting appropriate MPPT algorithm for their requirement. [ABSTRACT FROM AUTHOR]

More interconnections among countries and synchronous areas are foreseen in order to fulfil the EU 2050 target on the renewable generation share. One proposal to accomplish this challenging objective is the development of the so-called European SuperGrid. Multi-terminal HVDC networks are emerging as the most promising technologies to develop such a concept. Moreover, multi-terminal HVDC grids are based on highly controllable devices, which may allow not only transmitting power, but also supporting the AC grids to ensure a secure and stable operation. This paper aims to present an overview of different control schemes for multi-terminal HVDC grids, including the control of the power converters and the controls for power sharing and the provision of ancillary services. This paper also analyses the proposed modifications of the existing control schemes to manage high participation shares of wind power generation in multi-terminal grids. [ABSTRACT FROM AUTHOR]

Harvesting energy from the wind as an alternative to fossil fuels has many advantages in terms of protecting the environment and promoting sustainability. However, the increasing penetration of wind power in electrical networks presents many challenges such as the intermittency of wind power, its relative high cost as compared to conventional sources, and technical impacts on the distribution systems. Information and Communications Technologies (ICT) are fast becoming integral components of the 21st century electrical grid at all levels including the generation, transmission, distribution and even at the consumer level. The use of ICT in the modern wind power plants has also become the norm and offers numerous benefits in addressing the challenges of wind power integration. ICT can support the efficient scheduling of wind power generation and energy dispatch, and can be used in automation, protection, and even in reactive power control applications. The International Electrotechnical Commission (IEC) has been playing a key role in the transition to a modernized ICT-based electrical grid by developing many communication standards. These standards have opened the path to a unified and interoperable communication platform in different aspects of the power system network. This paper provides an in depth overview of the relevant wind power communication standards and presents a review on their worldwide applications. The key focus is on the application of the two most relevant IEC standards, the IEC 61850 and IEC 61400-25, in wind power systems, the current status of the literature and ongoing research projects. The paper also identifies potential research directions for future development in this field. [ABSTRACT FROM AUTHOR]

Development of alternative energy sources has become a necessity as fossil energy resources are declining. At the same time, energy demand is rapidly increasing, putting the world on the verge of a global energy crisis. Moreover, the extensive use of conventional energy sources is polluting the environment and causing global warming. On the other hand, wind and other renewable energy sources are viable and clean alternatives to fossil fuels. Low operating cost and extensive availability make wind one of the most advantageous and effective renewable energy sources. This paper provides an exposure to the necessity for deployment of renewable energy sources and the worldwide installed capacity of wind power as well as a review of various wind technologies in conjunction with their applications and devices of operation. Furthermore, this paper discusses the cost of electric generation in wind power plants as well as the economic and environmental policies that advocate the installation of wind energy systems. [ABSTRACT FROM AUTHOR]

Wind energy has played an increasingly vital role in renewable power generation, driving the need for more cost-effective wind energy solutions. Health monitoring of turbines could provide a variety of economic and other benefits to aid in wind growth. A number of commercial and research health monitoring systems have been implemented for wind turbines. This paper surveys these systems, providing an analysis of the current state of turbine health monitoring and the challenges associated with monitoring each of the major turbine components. This paper also contextualizes the survey with the various potential benefits of health monitoring for turbines. [ABSTRACT FROM AUTHOR]

Wind energy is an important contributor of modern power systems as a renewable energy source. However, wind energy poses new challenges because of its unique characteristics, such as limited predictability, short-term and long-term variability and close-to-zero marginal cost. This paper puts forward the critical aspects of wind energy systems in respect to the transformation of the power system into a “smart grid”. Issues discussed include the electro-mechanical matters like the selection of wind turbine technology, the structure of wind system, the robustness of mechanical parts (gear box and blades) and fault diagnosis. In addition, the system operational challenges such as complexity, instability, unbalance loading, grid interactive problems and impact of wind energy on power system are discussed in this paper. Moreover, the economical subjects such as investment costs and energy management, communication requirements, and security are involved as important titles. Finally, environmental aspects of wind energy are also highlighted to show that the wind energy is an environmentally friendly energy source since it is sustainable, clean and safe. [ABSTRACT FROM AUTHOR]

Renewable energy becomes an asset to the world׳s energy resource for its eco-friendly and low cost energy production feature. As an important renewable energy source, wind turbine technology has become a significant contributor to the world energy production because of its feasible production cost, reliability and efficiency. Researchers are very active to optimize the effectiveness of wind turbines which may lead to increase the productivity of this source of energy. Vibration in the wind turbine system affects the productivity and thus reduces efficiency. Vibration of a system cannot be destroyed but can be reduced or converted to energy using appropriate strategies. Vibration control system improves structural response of wind turbines and reliability which has impact on lifetime of the components. Lowering the vibration amplitude of a system will provide a lesser amount of noise, assure user and operating comport, maintain the high performance and production efficiency. These will assist the system to prolong the lifetime of an industrial structure or machinery. Also vibration control enhances the performance of wind turbines providing suitable work environment without external disturbance. This paper presents an ample review on performance enhancement of the wind turbines by vibration mitigation. The aim of this review is to provide a concise point for researchers to assess the current trend to control vibration of wind turbines technology. This paper will focus on main vibration control techniques of wind turbine structures. It provides the applications of passive, active and semi-active and vibration control strategies for structures, especially for wind turbines. Besides, this paper reviews on damping devices needed for vibration mitigation of structures. These damping devices have been implemented extensively in wind turbines for increasing their efficiency by mitigating vibration. This paper also reviews and assesses the performance of different control policies to control the system input and power input of damping devices. [ABSTRACT FROM AUTHOR]

Balancing power is used to quickly restore the supply-demand balance in power systems. The need for this tends to be increased by the use of variable renewable energy sources (VRE) such as wind and solar power. This paper reviews three channels through which VRE and balancing systems interact: the impact of VRE forecast errors on balancing reserve requirements; the supply of balancing services by VRE generators; and the incentives to improve forecasting provided by imbalance charges. The paper reviews the literature, provides stylized facts from German market data, and suggests policy options. Surprisingly, while German wind and solar capacity has tripled since 2008, balancing reserves have been reduced by 15%, and costs by 50%. [ABSTRACT FROM AUTHOR]

Rapidly increasing demand for electricity, rising costs of fossil fuels, and growing environmental concerns are driving research into alternative energy sources. Wind energy has experienced significant growth in recent years. Extensive research has been conducted to efficiently generate electricity from wind energy. However, due to limitations such as space and maintenance, it is very difficult and unsafe to install wind turbines for research and educational purposes. A lab-scale wind turbine emulator has many advantages, including independence from prevailing wind conditions, a greater degree of control, and freedom from space constraints. In this article, authors have reviewed and analyzed over 140 technical articles related to wind turbine emulators. It provides comprehensive information on prime movers, generators, and controls used in wind turbine emulator (WTE) research. Additionally, this paper discusses the strengths and weaknesses of various WTE prime movers, generators, and control algorithms used in the literature review. This article will serve as a good reference for the researchers to choose the right technique for WTE according to their needs. [Display omitted] • Overview of the importance of Wind Turbine Emulators (WTE) in wind energy research. • Comparison of different types of wind turbine emulators. • Discussion of recent advances in wind turbine emulation technology. • Analysis of the current state of wind turbine emulation research. [ABSTRACT FROM AUTHOR]

Given the abundant availability of resources, the market potential, and their cost competitiveness, onshore wind farms and photovoltaic units are expected to drive the overall growth of renewable energy sources in the next decade. However, Europe is a small and densely populated continent, which results in many countries experiencing a severe shortage of suitable land sites for installing new wind and photovoltaic facilities. This, combined with the fact that many existing wind turbines and photovoltaic units reach the end of their operational lifetime, has laid the groundwork for 'repowering'. Repowering includes upgrading or retrofitting renewable energy sources' components and exploits existing land sites, in which renewables are operating for years. This paper intends to emphasise the multiple dimensions of repowering, also delving in its surrounding socio-economic context in various European countries, to identify its barriers and allies as well as gather best practices and lessons learnt from its implementation. Considering data availability, extent of spatial use and bulk equipment, and consequent attention in literature and practice, the analysis mainly orbits around repowering of wind projects, rather than solar photovoltaics. Finally, the paper presents key directions toward wider future exploitation of repowering. • Land scarcity problem with high renewable energy potential addressed by repowering. • In-depth socio-economic extensions of repowering are discussed. • Semi-quantified evaluation highlighting main implementation pillars of repowering. • Best practices and lessons learnt from the implementation of repowering. • Legislative barriers against the wider implementation of repowering. [ABSTRACT FROM AUTHOR]

Wind power is one of the main sources of renewable energy. New applications of this technology are currently under development through small vertical axis wind turbines, allowing energy production in small spaces even at low wind speeds. Therefore, creating an effective turbine design methodology tailored to these operating conditions has been the subject of extensive research. The Savonius-type vertical axis wind turbine is one of the most widely used due to its low cost and easy manufacturing. Several works have examined the effect of various geometric parameters on the performance of the Savonius-type wind turbine. However, there are no published overarching conclusions about these works. Thus, this paper aims to review and discuss in a concise way experiments and simulations carried out by several authors evaluating the effect of some geometric parameters on the maximum power and torque coefficient of Savonius vertical axis wind turbines. The paper also discusses additional experiments that should be performed in future work. • The effect of geometrical parameters of Savonius-type vertical axis wind turbine rotor on its efficiency is reviewed. • Power and torque coefficients response to variation of four geometrical parameters are discussed. • Geometrical parameters as aspect ratio, twist angle, overlap ratio, number of blades, and number of stages are explored. • Diverse experimental and numerical researches are explored and maximum power and torque coefficients found are graphically presented as function of each geometrical parameter. [ABSTRACT FROM AUTHOR]

One of the great technological challenges in 21st century is the development of renewable energy technologies due to serious problems related with the production and use of energy. A new promising area of research grows rapidly which is called Nanotechnologies are considered nowadays one of the most recommended choices to solve this problem. This review aims to introduce several significant applications of nanotechnology in renewable energy systems. Papers reviewed including theoretical and experimental works related with nanotechnology applications in solar, hydrogen, wind, biomass, geothermal and tidal energies. A lot of literature are reviewed and summarized carefully in a useful tables to give a panoramic overview about the role of nanotechnology in improving the various sources of renewable energies. We think that this paper can be considered as an important bridge between nanotechnology and all available kinds of renewable energies. From the other side, further researches are required to study the effect of nanotechnology to enhance the renewable energy industry especially in geothermal, wind and tidal energies, since the available papers in these fields are limited. [ABSTRACT FROM AUTHOR]

In recent years, many countries put an emphasis on the development and deployment of renewable energy to cope with the global environmental crisis such as depletion of fossil energy, climate convention to control emissions of greenhouse gases. Among the various new and renewable energy sources, the Korean government selected wind power energy as one of the core areas for R&D investments. In this paper, we evaluate the economic value of the investment in wind power energy R&D in Korea and optimal deployment timing of wind power technology by using the real option approach. The real option model adopted in this paper assumes that a decision maker has a compound option to abandon, deployment, or continue the R&D. As a result by using empirical data of Korea, it is found that there exists a considerable amount of positive economic value of investments in wind power energy R&D. [ABSTRACT FROM AUTHOR]

In the United Kingdom wind power is recognised as the main source of renewable energy to achieve the European Union 2020 renewable energy targets. Currently over 50% of renewable power is generated from onshore wind with a large number of offshore wind projects in development. Recently the government has re-iterated its commitment to offshore wind power and has announced that offshore wind subsidies are to increase from £135/MWh to £140/MWh until 2019. This paper provides a detailed overview of the offshore wind power industry in the United Kingdom in terms of market growth, policy development and offshore wind farm costs. The paper clearly shows that the United Kingdom is the world leader for installed offshore wind power capacity as pro-active policies and procedures have made it the most attractive location to develop offshore wind farm arrays. The key finding is that the United Kingdom has the potential to continue to lead the world in offshore wind power as it has over 48 GW of offshore wind power projects at different stages of operation and development. The growth of offshore wind power in the United Kingdom has seen offshore wind farm costs rise and level off at approximately £3 million/MW, which are higher than onshore wind costs at £1.5-2 million/MW. Considering the recent increase in offshore wind power subsidies and plans for 48 GW of offshore wind power could see more offshore wind power becoming increasingly financially competitive with onshore wind power. Therefore offshore wind power is likely to become a significant source of electricity in the United Kingdom beyond 2020. [ABSTRACT FROM AUTHOR]

Solar and wind energy are inherently time-varying sources of energy on scales from minutes to seasons. Thus, the incorporation of such intermittent and stochastic renewable energy systems (ISRES) into an electricity grid provides some new challenges in managing a stable and safe energy supply, in using energy storage and/or 'back-up' energy from other sources. In such cases, the ability to accurately forecast the output of “unpredictable” energy facilities is essential for ensuring an optimal management of the energy production means. This review syntheses the reasons to predict solar or wind fluctuations, it shows that variability and stochastic variation of renewable sources have a cost, sometimes high. It provides useful information on the intermittence cost and on the decreasing of this cost due to an efficient forecasting of the source fluctuation; this paper is for engineers and researchers who are not necessarily familiar with the issue of the notions of cost and economy and justify future investments in the ISRES production forecasting. [ABSTRACT FROM AUTHOR]

In this paper a spatio-temporal analysis of wind power resource in the Iberian Peninsula is presented. The study uses the Second-Order Data-Coupled Clustering (SODCC) algorithm over reanalysis data in the for the period 1979 – 2014. Several characteristics of the method are detailed, such as the data-coupled clustering approach of SODCC, that ensures the non-singularity of the signal subspace within each cluster. The performance of the proposed approach and specific results obtained have been discussed in a case study in the Iberian Peninsula. In these results it is possible to identify different spatio-temporal patterns of the wind data statistics depending on the initialization year. Moreover, this work also shows that there is a close relationship between these spatio-temporal patterns with the wind energy production of the area under study, so the proposed analysis can be extended to wind farms efficiency production at the time scales considered. [ABSTRACT FROM AUTHOR]

In this paper, we undertake an integrated financial, economic, stakeholder analysis of a grid-connected onshore wind project that is owned and operated by an independent power producer (IPP) in Santiago Island, Cape Verde. This IPP project has received considerable positive publicity and has won many awards. Cape Verde has a very good wind resource, but it suffers from high transportation costs for petroleum fuels due to its location. Hence, it would appear to be an ideal site for an IPP investment in a wind farm. This analysis is conducted from the perspectives of the electric utility, the country’s economy, the government, and the private sector investor. The key question is whether the design of the power purchase agreement (PPA) can simultaneously yield a high enough cash flow for the project to be bankable while at the same time yielding a positive net financial and economic present value to the electric utility and the country respectively. The analysis shows that a negotiated PPA results in a negative outcome for the economy of Cape Verde in almost all circumstances. In contrast, the owners of the IPP are guaranteed, under all circumstances, a very substantial return on their investment. [ABSTRACT FROM AUTHOR]

In recent years, international working groups, mainly from the International Electrotechnical Commission (IEC) and the Western Electricity Coordinating Council (WECC), have made a major effort to develop generic —also known as simplified or standard— dynamic wind turbine models to be used for power system stability analysis. These models are required by power system operators to conduct the planning and operation activities of their networks since the use of detailed manufacturer models is not practical. This paper presents a comprehensive review of the work done in this field, based on the results obtained by IEC and WECC working groups in the course of their research, which have motivated the publication of the IEC 61400-27 in February 2015. The final published versions of the generic models developed according to the existing four wind turbine technology types are detailed, highlighting the subsequent changes made during the development phase. The main differences between IEC and WECC generic models are also analyzed. Not only is the final model structure presented but we also provide a complete description of the physical behavior of wind turbines facing power system stability problems. Results are thus of great interest to grid operators, software developers, wind farm owners and researchers focused on the integration of wind energy into power systems. [ABSTRACT FROM AUTHOR]

Renewable energy sector is undergoing rapid expansion as the global focus is shifting towards cleaner, reliable and sustainable resources. As the new installation of these resources are well underway, there is tremendous potential for exploring these to more advanced control algorithms. Model predictive control is gaining immense popularity because of its flexible controllability, its ability to be used in any of application irrespective of its field as well as the availability of fast processors. This paper presents a systematic review on Photo-voltaic (PV) and wind energy systems controlled by Model predictive control approach. The work presented here will help the researchers to further explore the flexibility of this controller for design, analysis and implementation in renewable energy systems. [ABSTRACT FROM AUTHOR]

This paper reports recent efforts made by the mining industry in adapting and applying photovoltaic (PV) and wind power systems at operating and abandoned mines around the world. Several applications of PV systems have been found at operating mines such as the Goldstrike mine in USA, Chuquicamata mine in Chile, Weipa and DeGrussa mines in Australia, Thaba mine in South Africa, and the Rosebel mine in Suriname. A few PV systems were also identified at abandoned mines in USA, Germany, Canada, and Korea. Applications of wind power systems in operating mines were investigated, including those at the Veladero mine in Argentina, Diavik and Raglan mines in Canada; and the Los Pelambres mine in Chile. In addition, some large-scale wind farms constructed at abandoned mines in the USA (i.e., Dave Johnston, Somerset, and Buffalo Mountain) were studied. From the review, we learned that PV and wind power systems have been utilized at mines operating in remote areas to resolve energy supply problems, and at abandoned mines to foster substitute industries able to benefit from exhausted mines. Because the utilization of PV and wind power systems by the mining industry will have positive effects in both environmental and economic terms, it is expected to continue to spread. [ABSTRACT FROM AUTHOR]

The accurate power generation forecast of multiple renewable energy sources is significant for the power scheduling of renewable energy systems. However, previous studies focused more on the prediction of a single energy source, ignoring the relationship among different energy sources, and failing to predict accurate power generation for all energy sources simultaneously. This paper proposes a hybrid framework for the power generation forecast of multiple renewable energy sources to overcome deficiencies. A Convolutional Neural Network (CNN) is developed to extract the local correlations among multiple energy sources, the Attention-based Long Short-Term Memory (A-LSTM) network is developed to capture the nonlinear time-series characteristics of weather conditions and individual energy, and the Auto-Regression model is applied to extract the linear time-series characteristics of each energy source. The accuracy and practicality of the proposed method are verified by taking a renewable energy system as an example. The results show that the hybrid framework is more accurate than other advanced models, such as artificial neural networks and decision trees. Mean absolute errors of the proposed method are reduced by 13.4%, 22.9%, and 27.1% for solar PV, solar thermal, and wind power compared with A-LSTM. The sensitivity analysis has been conducted to test the effectiveness of each component of the proposed hybrid framework to prove the significance of energy correlation patterns with higher accuracy and stability compared with the other two patterns. [Display omitted] • Propose a hybrid framework for power forecast of multiple renewable energy sources. • Improve forecast accuracy by considering energy correlation patterns. • Sensitivity analysis is conducted to discuss each information pattern. • Method verified by a real renewable energy system case. [ABSTRACT FROM AUTHOR]

Abstract: Wind power is one of the fastest-growing technologies for renewable energy generation. Unfortunately, in the recent years some cases of degradation on certain telecommunication systems have arisen due to the presence of wind farms, and expensive and technically complex corrective measurements have been needed. This paper presents a comprehensive review on the impact of wind turbines on the telecommunication services. The paper describes the potential affections to several telecommunication services, the methodology to evaluate this impact, and mitigation measures to be taken in case of potential degradation, both preventive and corrective. The telecommunication services included in this review are those that have demonstrated to be more sensitive to nearby wind turbines: weather, air traffic control and marine radars, radio navigation systems, terrestrial television and fixed radio links. The methods described in the paper allow a thorough case-by-case analysis before the wind farm is installed, taking into account the particular features of each installation and the involved services. The prediction of the potential impact makes it possible to propose alternative solutions in order to assure the coexistence between the wind turbines and the telecommunication services. [Copyright &y& Elsevier]

Abstract: Hybrid energy systems are being utilized for supplying electrical energy in urban, rural and remote areas to overcome the intermittence of solar and wind resources. A hybrid renewable energy system incorporates two or more electricity generation options based on renewable energy or fossil fuel unit. The techno-economic analysis of the hybrid system is essential for the efficient utilization of renewable energy resources. Due to multiple generation systems, hybrid system analysis, is quite complex and requires to be analyzed thoroughly. This requires software tools for the design, analysis, optimization, and economic viability of the systems. In this paper, 19 softwares with their main features and current status are presented. The softwares studied are HOMER, Hybrid2, RETScreen, iHOGA, INSEL, TRNSYS, iGRHYSO, HYBRIDS, RAPSIM, SOMES, SOLSTOR, HySim, HybSim, IPSYS, HySys, Dymola/Modelica, ARES, SOLSIM, and HYBRID DESIGNER. The research work related to hybrid systems carried out using these softwares at different locations worldwide is also reviewed. The main objective of the paper is to provide the current status of these softwares to provide basic insight for a researcher to identify and utilize suitable tool for research and development studies of hybrid systems. The capabilities of different softwares are also highlighted. The limitations, availability and areas of further research have also been identified. [Copyright &y& Elsevier]

Abstract: Wind energy has been considered as an important substitution of fossil-based energy for future society. However large-scale integration of wind power will introduce great risks to both power system planning and operation due to its stochastic nature. By adopting power system reliability theory, the risks can be quantitatively estimated so that numerous publications have been published to study reliability impacts caused by wind power. This paper thoroughly investigates the features of existing reliability models of wind power, reliability assessment algorithms and its applications in wind power related decision making problems. The paper also reveals significant differences existed in reliability models and algorithms between planning and operational phase of power systems, which are neglected in existing review articles. [Copyright &y& Elsevier]

Abstract: With the support of national policies, China's renewable energy generation industry has experienced a rapid development period and entered the world forefront level, especially in the aspects of installed capacity and speed of newly installed capacity. However, with the rapid development of renewable energy, the power generation industry is facing more and more challenges, particularly in investment and financing. As for wind power industry, there are also some problems such as single financing channels, blindness of projects investment and so on, which will result in financing difficulties for some advanced projects. In addition, the problems for the investment of photovoltaic (PV) power generation leads to vicious competition and a tumble in international market, thus the overcapacity of China's entire PV industry emerges. Generally speaking, the renewable energy industry is facing a seemingly contradictory predicament of funding deficiencies and blind investment, which is derived from the government-centered renewable energy investment and financing. This government-centered mode has promoted the development of renewable energy industry in the early stage, but it cannot be adapted to the requirements of sustainable development. In view of these, the problems of renewable energy investment and financing are deeply studied in this paper. This paper proceeds as follows: Firstly, the overview of the development of China's renewable energy industry is briefly introduced. Secondly, the status quo of China's renewable energy investment and financing is explored in detail based on overview of the following five perspectives: investment situation; investment and financing bodies; investment and financing means; sources of funding and financing channels. Secondly, the patterns and characteristics of renewable energy financing are summarized and a comparative analysis of wind power and photovoltaic power generation financing means is carried out. Finally, renewable energy investment and financing issues are discussed and further feasible proposals are put forward. In all, this paper is of great significance in the sustainable and healthy development of China's renewable energy. [Copyright &y& Elsevier]