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To facilitate a successful integration of distributed energy resources into the electricity generation mix, new forms of energy markets must be considered. Concepts such as Peer-to-peer energy trading (P2P), transactive energy (TE) and community/collective self-consumption (CSC) are frequently mentioned as solutions to this challenge. Despite increasing interest from industry, policy, and academia, the field lacks a shared understanding of this class of models. This need is addressed by presenting sets of shared and distinct characteristics which define P2P, TE and CSC. Our analysis is based on a series of expert group interviews with regulators, industry, and academics across 13 countries, and a systematic and targeted literature review of 133 papers. Findings show that P2P/TE/CSC models can be described as sub-markets that operate within or alongside traditional energy markets and enable trading or sharing of energy using an automated approach. They focus on promoting and supporting local energy generation and consumption using price negotiation mechanisms that reflect the aims of the market. The paper also presents sets of characteristics which differentiate P2P, TE, and CSC from one another and sets out guiding definitions to be used as a reference point. The main differences between these models stem from the goal they are trying to achieve and the contexts they are deployed in. Findings from this analysis can support development of a shared understanding of this class of models across multiple disciplinary perspectives and applications. • Decentralised energy trading models lack a unified definition. • Expert interviews and literature review identify defining characteristics. • Decentralised models can operate as sub-markets alongside traditional markets. • Distinctions between models stem from their goal and the contexts they are deployed in. [ABSTRACT FROM AUTHOR]

The residential sector is well known to be one of the main energy consumers worldwide. The purpose of this study is to select the best renewable energy alternatives for electricity generation in a residential building by using a new integrated fuzzy multi-criteria group decision-making method. In renewable energy decision-making problems, the preferences of experts and decision-makers are generally uncertain. Furthermore, it is challenging to quantify the reel performance of renewable energy alternatives using a set of exact values. Fuzzy logic is commonly applied to deal with those uncertainties. The method proposed in this paper combines different methods. First, the Delphi method is used in order to select a preliminary set of renewable energy alternatives for electricity generation as well as a preliminary set of criteria (economic, environmental, social, etc.). Then, the questionnaire is used to study the renewable energy alternatives preferences of the residents of the residential building'. Later, the FAHP (Fuzzy Analytical Hierarchy Process) is implemented to obtain the weighs of the criteria taking into consideration uncertainties in expert's judgments. Finally, the FPROMETHEE (Fuzzy Preference Ranking Organization Method for Enrichment Evaluation) global ranking is performed in order to get a complete ranking of the renewable energy alternatives taking into account uncertainties related to the alternatives' evaluations. The originality of this paper comes from the application of the proposed integrated Delphi- FAHP- FPROMETHEE methodology for the selection of the best renewable energy alternatives for electricity generation in a residential building. A case study has validated the effectiveness and the applicability of the proposed method. The results reveal that the proposed integrated method helps to formulate the problem and is particularly effective in handling uncertain data. It facilitates the selection of the best renewable energy alternatives in a manner that is participatory, comprehensive, robust, and reliable. • This paper presents a new methodology for the selection of the best renewable energy alternatives in a residential building. • A new fuzzy integrated Delphi- FAHP- FPROMETHEE methodology has been applied. • The sensitivity analysis indicates that the proposed methodology is stable with respect to decision-makers' preferences. [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]

The Chinese government has made significant effort to promote biomass based electricity generation in recent years. Yet, little is known about consumers’ preferences for biomass electricity and associated environmental impacts. This paper uses discrete choice experiments (DCE) to investigate Chinese consumers’ preference for electricity generated from various biomass sources. Based on 548 responses, the paper finds that Chinese households are willing to pay a premium of around 27 Yuan per month or 0.20 Yuan per kilowatt hour (kWh) to replace coal-fired electricity. Among the various biomass sources, electricity generated from agricultural and forestry biomass is most preferred, followed by biogas electricity and waste-to-energy. It is also found that respondents have a significant willingness to pay for reducing haze. Consumers’ household structure and environmental awareness also affect their preference for biomass electricity. These results have significant implications for the prioritization, design and communication of biomass promoting schemes. [ABSTRACT FROM AUTHOR]

Fault current studies are often required to determine the proper settings for the overcurrent relays. The conventional synchronous generators are known to exhibit high current magnitude during fault, which present an ideal scenario for fault isolation using the cost-effective overcurrent relays. On the other hand, the fault current magnitude from renewable based generation such as solar photovoltaic (PV) is intentionally limited due to the constraints in the power electronic components. Therefore, dispute pertaining to the feasibility of overcurrent relay in inverter based distributed generations (IBDG) applications arises. These disputes mainly arise due to the unavailability of firm understanding of the fault current characteristics from the IBDGs. The problem is further compounded with the availability of numerous possible fault current controls, where various fault current characteristics can be obtained from the IBDGs. In light of this problem, this paper aims to establish the various possible IBDG fault current characteristics, with special attention paid to compliance to the latest grid codes requirements such as low voltage ride through (LVRT) with reactive current injection (RCI). Five different types of RCI controls are analyzed as follows: variable active current control, constant active power control, constant reactive power control, constant active current control, and maximum current control. From the established fault current characteristics in this paper, the disputes pertaining to the feasibility of overcurrent relay for IBDG applications can be resolved and the suitable types of RCI control that allow satisfactory performance of overcurrent relays can be identified. [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]

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]

This paper presents a comprehensive practical diagnosis methodology for the detection and identification of faults in Air-Cooled Polymer Electrolyte Fuel Cells (AC-PEFCs). The proper operation of an AC-PEFC depends on many factors to ensure the electrochemical process in the stack and the electricity generation from hydrogen and air. However, the stack performance depends on several factors like state of its cells, stack cooling state, stack operating and non-operating time, hydrogen and air supply pressure, hydrogen and airflow rates, and load demand. So, the diagnosis methodologies development is very helpful as part of the AC-PEFCs advanced monitoring and control systems, and of course for predictive maintenance. The developed diagnosis methodology in this paper can be understood like a diagnosis tree , in the sense that it implies an structured framework tests over the AC-PEFC: hydrogen line, air/cooling subsystem, electrical circuit and even in the stack itself. The developed diagnosis methodology allows to analysis and improving the performance of an AC-PEFC, and consequently its durability, helping to achieve this challenge, perhaps the main, to bring the fuel cells into the market. [ABSTRACT FROM AUTHOR]

The energy situation of the African island states which include Cape Verde, São Tomé and Príncipe, Comoros, Guinea-Bissau, Madagascar, Mauritius and Seychelles are overwhelmingly dependent on fossil fuels with paradoxically high potential of renewable energy which are sparsely developed. This paper lay emphasis on the present electricity situation in these countries and highlights the potential of renewable energy resources on their territories. Among Africa islands, demographic and economic features are dissimilar and their power sector is complex by unique challenges. It is seen that there is a critical lack of electricity in Guinea-Bissau and Madagascar, which are 21% and 13% respectively, due to political instability and high spending on diesel. Moreover, the electricity consumption per capita is alarming in Guinea-Bissau, Comoros and Madagascar where it is below the average consumption for low income countries. Sustainable energy supply can be achieved by renewable energy sources, however, not all renewable resources are technically and economically feasible for development in these countries, for example wind in Comoros and hydro in Mauritius have little potential – which this paper elaborated further. Based on these analysis, a roadmap was developed, on to how to address some of the energy issues in these countries and accelerate the uptake of renewable energy. Through energy governance reform, political decision makers can drive change within their government, especially when a reform entails opening market opportunities and stimulating private participation and exerting pressure on existing government agencies to work efficiently. [ABSTRACT FROM AUTHOR]

Cameroon has an abundant reserve of energy resources, such as crude oil, natural gas, hydropower, biomass, solar, wind and geothermal energies. However, these resources are still weakly valorised. The country relies mainly on hydropower energy for electricity generation (73%) with persistent power outages throughout the country especially in the dry seasons when water levels are low. Electricity access is about 65–88% in urban areas and around 14% for rural populations. Cameroon has experienced a strong economic growth (growth rate of 5.9% in 2015), accompanied by a rapid increase in electricity demand (1455 MW in 2014). Electricity needs are expected to continue rising over the next decade to reach 5000 MW by 2020 and 6000 MW by 2030. This paper seeks to address energy issues (reliability, accessibility and security) in Cameroon and brings to light the potential and meaningful contributions of renewables in solving energy concern. In order to achieve this objective, an overview, of the energy sector (energy source, access, demand, supply and distribution) is given followed by a review of renewable energy potential, policy, benefits and barriers. In addition, this paper introduces the energy roadmap to achieve a universal access to electricity, which will pave the way for the country emergence by 2035. It is found that energy sector of Cameroon holds promising possibilities of development and diversification given the country's energy potential. With adequate policy, standards, regulations, awareness, capacity building and off-grid renewable energy investments measures, it is possible for Cameroon to meet the future energy targets and ensure meaningful development throughout the country. [ABSTRACT FROM AUTHOR]

There is a growing body of research into the potential security risks and trade-offs which may emerge over the long-term development of energy systems. As part of this body of research, this paper aims to develop and demonstrate a set of indicators for assessing the security of long-term national electricity scenarios. This paper extends the empirical work of existing frameworks by including reliability and cost parameters alongside a range of other important aspects of energy security such as diversity, trade and acceptability, and by using both qualitative and quantitative indicators without aggregation in order to identify trade-offs. This paper uses the indicators to assess the energy security implications of three plausible long-term scenarios for the UK electricity system. The results indicate that a major risk may be experienced by a lack of flexible, responsive supply capacity in low-carbon electricity pathways. Reducing overall energy demand is found to be the most beneficial policy for improving energy security in terms of generating benefits in multiple dimensions. The paper finds that energy security is often conceptualised as the avoidance of causes of insecurity (such as insecure fuel imports), but that an equally important aspect of security lies in maximising responses to insecurity, for example by increasing the flexibility and responsiveness of both supply and demand. [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]

The output of solar photovoltaic (SPV) system depends on various factors like bypass diode configuration, array size, array configuration, shade intensity, etc. besides the environmental conditions. Further, partial shaded conditions increase the mismatch losses and reduce the output of the photovoltaic (PV) array significantly. The size of the PV array is to be increased under such circumstances to meet the desired specifications. This, in turn, increases the return of investment period that makes power generation by PV systems less attractive. This paper focuses on the various techniques that could negate the impact of partial shading and enhance the output under such conditions. In order to improve the power extraction under partial shaded conditions, various solutions modifying either the power processing architecture or the PV generator architecture have already been proposed. This paper reviews the latter approach and proposes a static architecture to negate the impact of partial shading and enhance the energy yield under non-uniform irradiation conditions. [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]

Conventional petrol vehicles emit a substantial quantity of greenhouse gases, leading to increasingly serious global warming problems. The expansion and development of renewable power generation technologies is conducive in promoting the use of electric vehicles, which are more environmentally friendly. This paper proposes a multi-objective power expansion model considering renewable energy policy objectives. The model regards the problem as a multi-period optimisation task, taking the newly installed capacity and the power generation capacity of each power generation technology as decision variables, and simulating the uncertain factors in the planning process using Geometric Brownian Motion and Monte Carlo approaches. The optimisation objective of the model is to minimise expected costs, reduce risk and environmental impacts, and incorporate changing policy objectives into the constraints to meet policy makers' expectations for renewable energy development. Then, a decentralised target search-based multi-objective evolutionary algorithm is proposed to solve the model. Its effectiveness is verified by a numerical example using real data from the Chinese power system. The experimental results show that the proposed algorithm exhibits improved performance compared with benchmark algorithms and provides high quality and diverse Pareto-optimal solutions to decision makers. Finally, the optimal plans for power expansion and generation mix under different preferences and policy objectives are discussed and corresponding recommendations are made. [Display omitted] • Planning for the expansion of power generation under uncertainties is determined. • Strategies for the expansion of power generation towards renewable energy are optimised. • A novel multi-objective evolutionary algorithm with a constraint handling method is developed. • The impact of multiple renewable energy policies on power generation expansion planning is discussed. [ABSTRACT FROM AUTHOR]

In order to meet global sustainability goals, in particular, the rapid decarbonisation of the energy sector in combination with geopolitical energy security issues, as well as further improvement in regional air quality-the so-called renewable energy sources are becoming increasingly critical and important. Photovoltaic power (PV) generation is clearly the most widely deployed (non-hydro) renewable energy source globally, which still has a significant growth potential in many countries, including Hungary. However, due to the intermittent nature and the strong dependency of photovoltaic power production on meteorological factors, continuous adjustment of electric power in the electric grid is needed. This, in turn, requires the most accurate forecast of the photovoltaic energy to be produced in the ultra-short term (15 min) and short term (1 day) in order to minimise last-minute and high-price energy acquisition or unplanned kicks-in of gas-fired auxiliary power plants. In this paper, we evaluate the impacts of large-scale dust transport episodes on the accuracy of forecasts of PV power generation. The numbers and intensities of Saharan dust storm events reaching Central Europe have increased over the last decade, hitting a new record in 2022 with 16 (!) African dust episodes observed over Hungary. We have shown that the semi-direct effect of atmospheric dust particles on high-level cloud formation rather than their direct irradiance-reducing effect is responsible for the reduced accuracies of e short-term (24-h) PV energy production forecasts during these events. • 16 Saharan dust events (SDEs) were identified in Hungary in 2022. • SDEs caused photovoltaic (PV) generation drops and forecast errors. • Indirect effect of dust on irradiance (through cloud formation) was the dominant. [ABSTRACT FROM AUTHOR]

In this paper, the potential of municipal solid waste (MSW) for electricity production in twelve selected metropolises in Nigeria using Landfill Gas to Energy (LFGTE), Incineration (INC) and Anaerobic Digestion (AD) technologies is presented with the aim of evaluating the energy potential for each location as well as determining the economic viability of possible waste to energy project. Waste profile of each location was determined using population data obtained from National Population Commission (NPC) located in Ibadan and the per capita waste generation gathered from literature. The economic viability of the projects was determined using levelised cost of energy (LCOE) and Net Present Value (NPV) methods. Some of the key results revealed that Port Harcourt (M6), Abuja (M7), Benin (M5) and Ilorin (M8) are potentially feasible and economically viable for waste-to-energy project. However, Abakaliki (M4), Bauchi (M9) and Jalingo (M10) are less viable for such a project. INC and LFGTE technologies provide the best technological option for waste-to-energy project in term of quantity of electricity that can be generated in the cities located in the Northern part of Nigeria based on the kind of wastes that are being generated at the locations while AD present itself as the technology of choice in the cities located in the Southern region. However, from the point view of economic viability, AD is the best option in all the locations followed by LFGTE. INC technology present the highest LCOE and hence less economical for electricity generation in all the locations. This paper is useful to the investors, policy makers, scientist etc. as it could serve as a source of scientific information for decision making which could lead to optimal investment in waste-to-energy project in Nigeria. [ABSTRACT FROM AUTHOR]

One of the major consequences of evolutionary growth of industrial era is the continuously growing rate of energy consumption across the world. In the industrialized countries, the concern about economies accompanied by the environmental perspective is a significant driver for inventions of efficient and cost effective modular energy delivering structures. DGs with their heterogeneous forms are likely to be increased in utilization as an outstanding alternative solution to the prevailing energy crises. The advent of DG penetration is leading to fundamental changes in distribution network exploitation and exploration. Nonetheless the DG installation and exploitation has been debated in distribution networks, the fact is that, practically the Distribution Network Operators (DNOs) has limited control or influence over DG allocation and design. Their owners and investors depending on site and fuel availability finalize DG placement. The prime objective to achieve the most from DG installation, owes special attention of DNOs towards DG placement and sizing. This objective encompasses two major sub problems: which may be the optimal location for DG installation and with which capacity? Enormous quality literature is available enlightening this area. This paper presents a state of art of DG deployment techniques and their influence on the ongoing research efforts in this field. To relieve the imminent researchers from the difficulties of availing appropriate guidance, an elfin attempt has put forward through this paper by presenting significant information of research work done in this field. [ABSTRACT FROM AUTHOR]

Electric Vehicles (EV) are emerging due to ever increasing concerns on the energy issues and greenhouse gas effects. Also, due to the depletion of fossil fuels, electricity generated from Renewable Energy Sources (RES) like Photovoltaic (PV) arrays and Wind Turbine Generators (WTG) are used for charging the EV batteries which reduces the utility grid overload. A review on different power converter topologies which can be used in PV-EV and WTG-EV battery chargers are presented in this paper. Also, this paper reviews the various power converters which can be employed for interfacing RES-EV battery charger with the utility grid. This paper enlightens the researchers in the selection of appropriate power converters suitable for the stand-alone and grid-connected RES-EV battery charging systems. [ABSTRACT FROM AUTHOR]

Fuel cell technology can be traced back to 1839 when British scientist Sir William Grove discovered that it was possible to generate electricity by the reaction between hydrogen and oxygen gases. However, fuel cell still cannot compete with internal combustion engines although they have many advantages including zero carbon emissions. Fossil fuels are cheaper and present very high volumetric energy densities compared with the hydrogen gas. Furthermore, hydrogen storage as a liquid is still a huge challenge. Another important disadvantage is the lifespan of the fuel cell because of their durability, reliability and maintainability. Prognostics is an emerging technology in sustainability of engineering systems through failure prevention, reliability assessment and remaining useful lifetime estimation. Prognostics and health monitoring can play a critical role in enhancing the durability, reliability and maintainability of the fuel cell system. This paper presents a review on the current state-of-the-art in prognostics and health monitoring of Proton Exchange Membrane Fuel Cell (PEMFC), aiming at identifying research and development opportunities in these fields. This paper also highlights the importance of incorporating prognostics and failure modes, mechanisms and effects analysis (FMMEA) in PEMFC to give them sustainable competitive advantage when compared with other non-clean energy solutions. [ABSTRACT FROM AUTHOR]

Polish economy is still undergoing the transformation process and seeks to converge with the most developed economies in Europe. While many economic reforms have been made, the generating sector was left to its own devices and lack of the investments caused that electricity supply in Poland is ineffective and not secure. The coal is a primary fuel and it constitutes over 80% of the energy mix. Thus, with energy mix restructuration ahead, the ambitious and balanced energy policy is highly required. The article aims to present the 2050 Energy Policy for Poland, which should facilitate the transformation of coal-based electricity generation system towards more sustainable and diversified energy mix. Comprehensive description and review of the current conditions of energy sector in Poland are accompanied with strengths and problems that need to be solved, taking into account European requirements. Additionally, in the paper the authors describe the development process of the Polish Energy Policy as they actively participated in the calculations of optimal energy mix for Poland. The manuscript presents the eMix model (energy mix optimization tool) developed by the authors, that constituted a background for Ministry of Economy to create Energy Policy. Hundreds of simulations scenarios were performed for the Ministry of Economy to provide the clear view of the electricity generation sector and to understand the impacts of all external stimuli to the mix. Assumptions for the model and results of calculations according to the policy scenarios are presented in the paper. Finally, the authors evaluate the final decisions of the policy makers, integrated in the Polish Energy Policy 2050, taking into account the challenges for the Polish power sector. [ABSTRACT FROM AUTHOR]

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

This paper presents a state of art literature review of slip power recovery scheme (SPRS) as an adjustable speed alternating current (AC) drive with various control methodologies for performance enhancement of electric drives. Starting from the brief history of components of control methodologies for SPRS to various control techniques including inverter control, chopper control, field oriented control, vector control, matrix converter control, microprocessor control, sliding mode control, digital signal processing control, neural network control, fuzzy logic control, and optimal control have been reviewed in this paper. The literature related to harmonic analysis of SPRS and use of SPRS in wind power generation has also been reviewed in this research paper. The paper is focused on providing a comprehensive perspective on the state of art of SPRS to the researchers, manufacturers, industries, and application engineers dealing with adjustable speed SPRS drives. The contributions of various researchers in this area have been presented in a classified manner which will serve the reader as a quick, useful, and ready reference. The issues related to control techniques with emphasis on induction machine drive have been highlighted and rigorously examined in this paper. [ABSTRACT FROM AUTHOR]

Bangladesh is a hugely populated country in South Asia. The country produces its electricity mainly from natural gas followed by liquid fuels. Although the installed electricity generation capacity of the country has been increased to 12,261 MW, there is scarcity of electricity in the hot summer season which is a barrier to industrial development as well as socio-economic development. Combustion of fossil fuels releases greenhouse gases (GHGs) into the atmosphere which causes global warming. Bangladesh can be badly affected by greenhouse effect and global warming. These problems can be mitigated by incorporating renewable energy sources (e.g., solar, wind, hydro, biomass, etc.) to the country's electricity generation. Renewable energy resources are considered as clean and can serve the electricity demand in the remote areas where grid connection is not possible. The potential of solar energy and biomass is enormous in Bangladesh and people have already started to harness energy from these sources. The government and the policy makers should come forward to encourage the people of rural areas as well as urban areas to use renewable based electricity. The government of Bangladesh has set up a plan to generate 5% of the country's total electricity from renewable sources within 2015 and 10% within 2020. However, within 2015 the country has been able to generate only 3.5% of the total electricity from renewable sources. This paper presents a thorough review of the current status and future potentials of renewable energy sector in Bangladesh. In this paper the updated information is provided for the overall renewable energy sector of the country. [ABSTRACT FROM AUTHOR]

There are many advantages of vertical axis wind turbines (VAWTs) compared with horizontal axis wind turbines (HAWTs). Research has shown that VAWTs are more suitable for turbulent wind flow and urban applications. However, the efficiency and low self-start ability of VAWTs are always the main drawbacks especially for the lift-type VAWTs. Unlike HAWTs, the rotor blades for VAWTs do not always provide positive torque during operation. Many innovative designs have been implemented to improve the performance of VAWTs, and this includes different configurations and blade profiles. This paper extensively reviews various flow augmentation systems and attempts to provide information to researchers on current augmentation techniques and other relevant research. The flow augmentation system is able to increase the coefficient of power, C P , hence improving the output power of different types of VAWTs. Some augmentation systems are able to increase the maximum power output by up to 910%. The methods and designs used to increase upwind velocity and to reduce negative torque created on the wind turbine have been discussed in detail. Additionally, the flow augmentation devices that are integrated with building structures are also reported in this paper. [ABSTRACT FROM AUTHOR]

When talking about energy conservation, "Rebound Effect" (RE) is always concerned, which defined as the increasing energy consumption relative to the counterfactual predicted by technological progress because of efficiency induced decrease in the real price of energy services. In this paper, we try to find a way to figure out the RE through calculating the substitution relations accord with the definition. Based on the trans-log cost function and considering the asymmetric impact on energy-cost share equation, the paper applies Allen-Uzawa substitution elasticity to establish the price-oriented analysis diagram of fossil-energy consumption RE. Using time series data, applying the joint method of the dynamic OLS (DOLS) and the seemingly unrelated regressions (SUR), the RE in China's electricity generation sector is estimated. The results showed that the RE is 11.6% in China's electricity generation sector if allowing for asymmetric price effects, which indicates that China's power generation sector generally displays a feature of energy saving. [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 quality and composition of biomass as used in Portugal's thermal power plants is highly variable. The biomass consists mainly of residual forest biomass derived from forestry operations and wood waste from industrial processes, in particular paper and pulp industry. Its quality and composition is influenced by the presence of moisture and inert fragments, the latter being incorporated during collection or as a consequence of adherence to the biomass prior to collection. This variability presents difficulties for the thermal power plants; besides being an additional operational cost, the presence of large amounts of water and inerts in biomass used as a fuel, can result in problems related to the instability of the combustion and the accumulation of ash or rock that have to be removed and discarded. The objective of this paper is to review the main parameters that influence the quality of biomass, while analysing the current state-of-the-art power generation from the biomass sector in Portugal, as a new contribution to earlier studies. [ABSTRACT FROM AUTHOR]

Today solar power is still dominantly presented to be expensive source of electricity. However, the profitability of solar and other electricity generation technologies is typically evaluated with the Levelized Cost of Electricity (LCOE) approach. This paper questions the traditional investment evaluation logics of power production (LCOE) in the interesting case of rooftop PVs and based on customer value generation logics presents a new approach for evaluating the profitability of rooftop PV investments. The approach recognizes the value that PVs produce to real estate owners and utilize basic real estate investment models to evaluate the profitability of PVs. The results imply that, if PVs are considered as a part of the underlying property, rooftop PV systems are already today profitable in many European cities and can provide substantial returns on investment for property owners. More interestingly, the results imply that rooftop PV investments are most profitable in the dense urban cores instead of more remote (industrial) locations, and thus the current trend of urbanization seems to further strengthen the profitability of rooftop solar power. This paper points out that spatial locations drive the economic analysis of real estate, and thus it is likely that it will drive the economic analysis of decentralized on-site energy investments as well. [ABSTRACT FROM AUTHOR]

Unit Commitment (UC) is an optimization problem used to determine the operation schedule of the generating units at every hour interval with varying loads and generations under different generational, environmental and technical constraints. With the significant increase of Renewable Energy Sources (RES) integration into the power networks, effects posed by these system changes to the UC are actively being studied and investigated by global researchers and operation engineers. To this end, this paper firstly provides a literature survey of UC concept, objectives and constraints. Different UC models developed for addressing RES impacts are also reviewed. Moreover, many algorithms have been proposed in the past few decades to optimize the UC problem. This work explores the necessity for alternative optimization approaches for UC solution. In doing that, the work uncovers the advantages and disadvantages of the existing methodologies so that future algorithms could be designed in retaining the advantages of the existing methodologies while avoiding the presented weaknesses. In addition, installation of energy storage devices to balance the fluctuation in power generation and their associated impacts on UC models are reviewed. The contents of this paper provide ready-to-refer and ready-to-use information for the researchers working in the field of UC. [ABSTRACT FROM AUTHOR]

The production of electricity from hydropower results in several environmental impacts that, in only some instances, have been analysed from an economic valuation approach. Moreover, as environmental impacts largely depend on the specific characteristics of the case study, benefit transfer techniques are inadequate for valuation. The present paper demonstrates through the review of valuation studies on the environmental impacts of this technology, and the analysis of the different environmental impacts associated with hydropower for specific case studies that in fact benefit transfer should not be applied as each hydropower plant has specific and different impacts. The paper demonstrates the importance of a case study approach, for defining priorities with respect to alternative hydropower production facilities. Finally, the paper demonstrates that choice experiments are particularly suited for valuing the identified environmental impacts, being relevant for policy planning purposes. [ABSTRACT FROM AUTHOR]

The paper discusses the possibilities of multi-criteria optimisation of a multi-layer perceptron (MLP) model applied to the short-term (intra- and next-day) wind power forecasting problem. The paper comprises two main parts: a theoretical background and study case using data (wind power production and historical weather forecast) obtained from two wind farms (at different power capacity levels). The problem stated in this paper is to formulate a method allowing for the estimation of a set of prediction models meeting the selected three model learning criteria: n BIAS , n MAE and n RMSE . The two-step NISE method has been used in order to estimate the non-dominated forecast evaluation set. The available data have been divided into three subsets for model learning, testing and validation. Than, a set of prediction model variants has been investigated considering different types of data subsets used for stopping the MLP learning process as well as calculating the forecast error. Additionally, different structures of MLP and learning algorithms have been analysed. Finally the paper is ended with a summary and conclusions. [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]

China's wind power installed capacity is the largest in the world, but the utilization of wind power equipment is not very good, far behind USA. In this paper, the development of China's wind power is reviewed, and the present wind power curtailment restricts the sound development of China's wind power industry. The characteristics of China's wind farm are summered. With the insatiability and intermittence, wind power is not welcome to China's electric grid, and large-scale wind power construction does not match with the existing power grid, therefore, wind power curtailment is serious and the level of wind power utilization is very low. To solve the wind power curtailment rationing problem, in this paper, combined with the characteristics of China's wind farm operation, the wind power utilization level evaluation index system has been built, reflecting the wind resource characteristics, wind power equipment type, wind power output, wind power curtailment, grid technology, operation management and so on. Taking Hami wind farm in Xinjiang province as an example, wind power utilization level is evaluated comprehensively, combined the improved analytic hierarchy process (IAHP) analysis and fuzzy comprehensive evaluation method (FCEM). The results show that the establishment of wind power utilization level comprehensive evaluation index system is helpful to find the main factors which effect the level of wind power utilization and improve the wind power field operation, which can provide reference for the planning and design of wind farm, and the results have certain value on theoretical significance and engineering application. [ABSTRACT FROM AUTHOR]

The utilization of solar energy based technologies has attracted increased interest in recent times in order to satisfy the various energy demands of our society. This paper presents a thorough review of the open literature on solar energy based heat and power plants. In order to limit the scope of the review, only fully renewable plants with at least the production of electricity and heat/hot water for end use are considered. These include solar photovoltaic and solar thermal based plants with both concentrating and non-concentrating collectors in both solar-only and solar-hybrid configurations. The paper also presents a selection of case studies for the evaluation of solar energy based combined heat and power generation possibility in Denmark. The considered technologies for the case studies are (1) solar photovoltaic modules, (2) solar flat plate collectors, (3) a ground source heat pump, (4) a biomass burner, and (5) an organic Rankine cycle. The various cases are compared on the basis of economic profitability and environmental performance. The results from the case studies indicate that it is economically and environmentally beneficial to invest in both small and large capacity solar-biomass hybrid plants for combined heat and power production in the Nordic climatic conditions. The results also suggest that the configuration with an organic Rankine cycle with solar thermal collectors and a biomass burner is particularly attractive for large capacity plants. [ABSTRACT FROM AUTHOR]

The centralised power grid bears a heavy burden in a time when consumers expect an uninterrupted reliable power supply, a reduction in carbon emissions, increased efficiency within the national grid and power supplied to remote communities. As expectations increase, it becomes the task of power systems research and design to develop new structures to meet these demands. This has led to alternatives being sought for centralised power generation, which is prone to outages (due to long distance transmission), is a substantial contributor to global carbon emissions, has large transmission losses and is often not a practical solution when supplying remote communities. Distributed generation (DG) looks to remedy these inadequacies by producing power close to its point of consumption, often utilising carbon neutral, renewable energy (RE) sources (sun, wind). To maximise the efficient use of DG, control structures are used to balance the intermittent RE power production with consumer power consumption. One such structure is used to implement control of small scale DG, at a single house/small building level: the nanogrid. This paper explores the current nanogrid research, it collates the existing definitions and uses the knowledge to give a concise definition of a nanogrid. It then discusses the control topologies and techniques which enable the intelligent control of the nanogrid, before presenting the hardware platform used to ensure the efficient operation of a small scale DG system. The paper then considers the interconnection of multiple nanogrids forming a network (microgrid), facilitating the sharing of power between individual nanogrids. The future developments are then explored before the paper's conclusions are presented. [ABSTRACT FROM AUTHOR]

The Photovoltaic (PV) monitoring system collects and analyzes number of parameters being measured in a PV plant to monitor and/or evaluate its performance. In order to ensure the reliable and stable operation of any PV system, an effective monitoring system is essential. Moreover, the monitoring system keeps track on various electricity generation indices and fault occurrences. The cost and complexity of existing PV monitoring systems restricts their use to large scale PV plants. Over the past decade, different aspects of PV monitoring systems were reported in wide range of literature. In this paper, a comprehensive review of various PV monitoring systems is presented for the first time. This includes the detailed overview of all the major PV monitoring evaluation techniques in terms of their relative performances. Major aspects of PV monitoring systems which examines in this paper are: sensors and their working principles, controller used in data acquisition systems, data transmission methods, and data storage and analysis. The acquaintance of all these aspects are crucial for the development of effective, low cost, and viable PV monitoring systems for small and medium scale PV plants without compromising on the desired performance. [ABSTRACT FROM AUTHOR]

Contingent valuation is widely used due to its flexibility in valuing a wide variety of non-market goods. Although this method has important benefits, its validity and reliability are often criticised. This paper reviews the literature on the use of contingent valuation for measuring willingness to pay (WTP) for electricity generated from renewable energy sources (green electricity). A literature review, conducted on a sample of 57 peer-reviewed studies, shows that the vast majority of contingent evaluation studies stems from developed economies. Furthermore, most frequently used WTP elicitation techniques are open-ended and dichotomous choice approaches, which tend to produce varying levels of WTP. Studies dealing with the antecedents of WTP are predominantly inspired by the theory of reasoned action or by its extension, the theory of planned behaviour. This paper identifies six common errors in contingent valuation methods and discusses a number of remedies to deal with these errors in WTP research. [ABSTRACT FROM AUTHOR]

Nowadays, renewable energies are more preferable to fossil fuels because of being free, widely available and producing minimal pollution. One of the disadvantages of renewable energy systems is that using only one type of renewable energy cannot guarantee a continuous power generation. To overcome this problem, two or more renewable energy systems should be used simultaneously to compensate for times when one of them is not available or the renewable system should be used aligned with the generator. In addition, another weakness is that they are not accessible in every geographical position and location. It is clear that renewable energy systems can be exploited to their fullest capacity when used in the proper place. Therefore, given the importance of finding suitable places for co-utilization of several renewable energies, present paper attempted to find the ideal locations for construction of hybrid solar-wind power stations in Middle-East using Boolean model in GIS software. The Boolean method is, in a way, a more stringent method compared to the other positioning methods. Therefore, the selected locations will definitely have greater energy potential by using the Boolean method. Data obtained by RETScreen4 software from 400 stations in Middle-East were used for collecting monthly weather information. Results of the current paper may be helpful in creating prospects for sustainable energy development for systems based on natural resources and facilitating the national power transmission and sustainable environmental policies. [ABSTRACT FROM AUTHOR]

The penetration of photovoltaics (PV’s) in electric power generation is continually increasing. Tracking maximum power point in PV systems is an important task and represents a challenging problem. In maximum power point tracking (MPPT), the duty cycle of DC-DC converter is adjusted in a way that maximum achievable power is extracted from PV system. In this paper, the existing MPPT strategies are classified into two main categories and the strategies of each category are reviewed. Based on the conducted review, some directions for future research are recommended. The author strongly believes that this paper will be helpful for researchers and engineers in the field of PV systems. [ABSTRACT FROM AUTHOR]

Renewables around the globe, provide fuel diversification, energy security and produce little or no emissions during the electricity generation. The unavailability of rotating masses prohibits on-grid renewable energy generation systems from providing inertia during a frequency disruption. This would be extremely unsettling and impactful when the proportion of energy in the grid due to renewables is high. India currently, has a 28.04% share of on-grid renewable energy. The grid infrastructure systems of India would face severe challenges when the share of on-grid renewables leaps past 50% in the future. Thus, this paper primarily addresses the repercussions of increasing share of on-grid renewables in terms of inertia and frequency response in India. The energy scenario of 2040 in India under 80% proliferation of on-grid renewables has been well reviewed in this paper. The novelty of this paper is the narrative literature review of the Indian Electricity Grid Code (IEGC) on frequency response which is unique and exclusive to this manuscript. It demonstrates the current strategies prevalent in the grid system of India towards frequency response and inertia support. This paper also explains the diverse control strategies and energy storage technologies required for adoption with the on-grid renewables in India for frequency response. The other novelty in this paper is the insight about the inertia lost due to an on-grid 100-kW p solar photovoltaic system to explain the readers about the impact when the integration is hundreds to thousands of kilowatts. • Share of renewables in the Indian grid network is 28.04% (113.226 GW) as of 2022. • India aspires to achieve 54% share of on-grid renewables by 2030 and 80% by 2040. • Indian Electricity Grid Code indicates need for expansion in active power reserves. • India requires diverse control strategies and energy storages for inertia support. • On-grid 100-kW p solar photovoltaic system loses inertia of 100-kW for 4.44 s. [ABSTRACT FROM AUTHOR]

The application of a gas-fired CCHP can effectively solve seasonal shortages of electricity and gas. To realize providing investment decision for gas-fired CCHP in Beijing, first, the paper analyses the status of gas-fired CCHP systems in Beijing; second, the technology structure and economic benefits of gas-fired CCHP systems are analyzed; third, a technical economic evaluation framework of a gas-fired CCHP is built, which analyses the cascade utilization and energy saving effects of a heat and power energy system in a gas-fired CCHP system. Analysis of the gas-fired CCHP system economy and the factors that influence the economic performance is also performed, as well as a sensitivity analysis. In addition, the paper also analyses an energy efficiency sharing model of a cooling, heating and power system that considers the grid enterprises’ economic efficiency. Finally, an empirical analysis of a trigeneration project control center in the Beijing Gas Group is carried out. Research results show that gas-fired CCHP system is good to both customers and beneficial, fuel price and electricity price will influence revenue of Gas-fired CCHP system greatly, a reasonable energy efficiency sharing ratio will help to the recovery of investment in Gas-fired CCHP. [ABSTRACT FROM AUTHOR]

Variability and intermittency are some of the main features that characterize renewable energy sources. Intermittency usually includes both predictable and unpredictable variations. The many drawbacks of intermittency of renewable sources can be overcome by considering some special design considerations. Integrating more than one renewable energy source and including backup sources and storage systems are among the few measures to overcome these drawbacks. These additional design considerations usually increase the overall cost of the renewable system. Furthermore, the presence of more than one energy supply/storage system requires the control of energy flow among the various sources. Therefore, optimizing the size of the components and adopting an energy management strategy (EMS) are essential to decreasing the cost of the system and limiting its negative effects. The energy management strategy is commonly integrated with optimization to ensure the continuity of load supply and to decrease the cost of energy production. Therefore, energy management is a term that collects all the systematic procedures to control and minimize the quantity and the cost of energy used to provide a certain application with its requirements. The energy management strategy usually depends on the type of energy system and its components. Various approaches and techniques have been used to develop a successful energy management strategy. In this paper, a comprehensive review of the approaches proposed and used by authors of many papers is conducted. These approaches include both the standalone hybrid renewable energy systems and the grid-connected hybrid renewable systems. More attention is focused on popularly used techniques to address the features of each system. The selected papers in this review cover the various configurations of the hybrid renewable energy systems for electric power generation only. [ABSTRACT FROM AUTHOR]

Stand-alone micro-grids (MGs) and grid-connected MGs with high penetration level of Distributed Generation (DG) are growing at a fast rate. In these grids, the power quality disturbances such as harmonics, inter-harmonics and deviation from the fundamental frequency are widespread. The influence of these disturbances on two categories of digital metering algorithms is evaluated in this paper. The first category is related to the measurement of the fundamental frequency component of current and voltage signals, which are used as inputs of the digital protection algorithms. Most of the relays only use fundamental frequency component of their input voltage and current signals to fulfill the desired protective functions. The accuracy of the protective relays highly depends on the performance of the applied algorithms for extracting the fundamental components. The second evaluated category is related to the reactive power calculation algorithms, which are used in the static VAr compensator (SVC) control system. Utilizing SVC is growing due to the DGs such as wind turbines magnify voltage fluctuations called flicker. Since the SVC compensates only the reactive power related to the fundamental frequency component, the reactive power signal should not be sensitive to the harmonics. In addition, the reactive power calculation should be fast enough that SVC can follow the abrupt changes to mitigate the flicker, efficiently. In this paper, frequency deviation, harmonic, and inter-harmonic phenomena are considered as the most causes for power quality problems. Their influence in digital metering algorithms is evaluated. It is confirmed that defining new indices is mandatory to fully reflect algorithms׳ accuracy and efficiency. Furthermore, the field measurements of instantaneous voltage and current of a wind farm and electric arc furnaces are used for the evaluation. [ABSTRACT FROM AUTHOR]

This investigation is to review advanced technologies for modeling and control of reactor cores in nuclear power plants for electricity generation. A reactor core in a nuclear power plant is the key part as the hot source with radioactivity nuclear fuel, which possesses security risks and economic potential. Incapacity of a nuclear power plant to carry out desired control of its core can result in either higher operating costs or a reduction in system security and reliability, and the implementation of desirable control for the core can improve security and effectiveness of the nuclear power plant. Generally speaking, the reactor core control contains the power (or coolant temperature) control and axial power difference (namely power distribution) control of the core. The core power control is to regulate the core power, and the core load following control is to regulate the core power and axial power difference simultaneously. Modeling reactor cores is the inevitable preliminary work for research of reactor core control. Over the decades, continuous work has been devoted to the research of including modeling, power and load following control for reactor cores. In this paper, the review on advanced technologies for modeling, power and load following control of reactor cores is presented. Modeling approaches for reactor cores are reviewed such as the point reactor core modeling. Power control methods for reactor cores are reviewed such as the feedback control with a state observer. Load following control techniques for reactor cores are reviewed such as Mode A, Mode G, Mode T, Mechanical Shim and advanced control methods of containing multivariable frequency control, etc. The review in this paper can contribute to comprehend the past work with respective advantages, and then exploit novel research directions for development of nuclear power plants. [ABSTRACT FROM AUTHOR]

Despite the historical priority to grid-based electrification in South Asia, two out of every five people in the region still live without access to electricity. Due to various limitations of conventional grid-based rural electrification, as brought out by a number of studies and reports, demand for alternative models such as renewable energy based off-grid and distributed generation solutions are gaining increasing attention globally. However, due to the absence of any study that could juxtapose these two modes in terms of their merits and demerits, it is difficult to infer on their relative superiority or inferiority. In view of that, this paper makes an attempt to connect the dots by carrying out an extensive review of the literature, to analyse the role of grid and off-grid options in facilitating rural electrification, and come out with a comparative assessment of their costs and impacts on the South Asian countries. The paper infers that instead of considering each of the modes of electrification in a standalone manner and perceiving them as mutually exclusive or competing with one another, as usually perceived in the policy sphere, off-grid electrification can actually be considered as a complementary mode and should ideally be integrated with grid expansion to serve the bigger cause of ensuring universal and sustainable rural electrification in South Asia. [ABSTRACT FROM AUTHOR]

Wind turbine wakes are one of the most important aspects in wind power meteorology because they decrease the power production and increase the loading of downstream wind turbines. Therefore, there is a continuous need to find a ‘good’ wake model to properly plan wind power plant-level control strategies, predict the performance and understand the fatigue loads of turbines. In this paper, six widely used approaches of wake modelling (Jensen, Larsen, Dynamic Wake Meandering, Fuga and, Ellipsys3D LES and RANS together with their interpretations) that were developed at Technical University of Denmark, are described and the model subcomponents are analysed. The models are evaluated using data from the Sexbierum (onshore) and the Lillgrund (offshore) wind farms to understand how to best utilize them. The paper provides a comprehensive conceptual background to wake modelling combined with the overview of the state-of-the-art models including their implementations on operating wind farms. [ABSTRACT FROM AUTHOR]

The use of an ammonia-fed solid oxide fuel cell (SOFC) is the most efficient method of generating power. In terms of CO 2 emission, ammonia is a good indirect hydrogen storage material because it does not contain carbon and therefore will not release CO 2 when used as fuel in a fuel cell or gas turbine. Using ammonia like hydrogen directly in a fuel-cell system provides high power density. Compared with other fuel cells, the ammonia-fed SOFC has many advantages. The availability of NH 3 is one of the main reasons for the high output. This paper presents a comparative study of the working principles, analyses, applications, advantages and disadvantages of various technologies available for ammonia fuel cells. The aim of the paper is to review and describe the suitability of ammonia as a fuel for the next generation of fuel cells, including direct ammonia-fed SOFCs, the development of different types of fuel cells using ammonia as a fuel, and the potential applications of ammonia-fed fuel cells. [ABSTRACT FROM AUTHOR]

The hydrokinetic energy conversion system has capabilities to supply inevitable and secured power which is obtained from free stream like ocean, river, and man-made channel etc. So far, researchers have done different work on resource availability, design parameter, electricity generation cost, reactivity of plant, its impact on environmental separately. In this paper an attempt is made to review the technology, performance, design optimization, reliability, techno-economic analysis and environmental impact of the hydrokinetic energy conversion systems altogether to establish the relationship between the above said aspects towards the viability of power project. After conducting these reviews it has become clear that in order to avoid cavitation, coefficient of pressure should be less than cavitation coefficient especially at leading edge of hydrokinetic turbine blade. Moreover, to avoid stall and separation, angle of attack should be kept as less as possible. By implementing hydrofoil blade profile, performance of the hydrokinetic turbine can be improved. Sometimes, implementation of double blade hydrofoil may be beneficial and increase the coefficient of lift more than that of the single blade hydrofoil. Apart from the above considerations it is to be noted that deployment of turbine near bed level should be avoided as it brings down available power, increase hydrodynamic loading, turbulence level, and fouling by sediments. Moreover to increase the performance arm and end plate can be incorporated in hydrokinetic turbine design. It is also observed that hybrid conversion system is also viable in order to reduce power generation cost. This paper will help researchers to identify areas of design parameter of hydrokinetic turbine that need to improve and encourage the project developer, funding and financial institution, policy maker or government officials, and local community, to provide knowledge about hydrokinetic energy conversion system for executing the project and compete with the existing market. [ABSTRACT FROM AUTHOR]

Biofuels productions from microalgae received wide attention recently and have high potential to replace fossil fuels. This paper served as a platform to critically review current production technologies of microalgae, ranging from cultivation, harvesting, extraction and several biofuels conversion processes. In addition, due to the high photosynthetic efficiency of microalgae, mass cultivation of microalgae is believed to be able to efficiently reduce the carbon dioxide emission to atmosphere and thus, reducing the impact of global warming. This is because microalgae have high growth rate and is able to develop maximum of 70% of lipid content within their cells depending on species. Apart from that, microalgae have the ability to survive under harsh condition and occupied smaller cultivation land area than other land crops. The harvested microalgae biomass can be used for electrical generation, while its crude lipid can be used as transportation fuel as it has 80% average energy content of petroleum. In the present paper, a detailed discussion to produce biodiesel, fuel gas, bio-oil, methane, hydrogen and alcohol from microalgae biomass are also included. Besides, updated research, challenges and the way forward of microalgae biofuels are also presented. In future, biofuels production from microalgae can be economical viable at some scale, which is then profitable in terms of economics and also environment. [ABSTRACT FROM AUTHOR]