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Abstract Propelled by the actual demand from the renewable energy industry, the progress of literature on quantitative forecasting models during the past years is extensive. Research provides a vast output of papers on wind speed, wind power, solar irradiance and solar power forecasting models, accompanied by models for energy load and price forecasting for short-term (e.g. for the intraday trading schemes available at many market places) to medium-term (e.g. for day-ahead trading) usage. While the models themselves are, mostly, rather sophisticated, the statistical evaluation of the results sometimes leaves headroom for improvement. Unfortunately, the latter may occasionally result in the rejection of papers. This review aims at giving support at this point: It provides a guide on how to avoid typical mistakes of presenting and evaluating the results of forecasting models. The best practice of forecasting accuracy evaluation, benchmarking, and graphically/tabularly presenting forecasting results is shown. We discuss techniques, examples, guide to a set of paragon papers, and clarify on a state-of-the-art minimum standard of proceeding with the submission of renewable energy forecasting research papers. Highlights • We provide a baseline for the empirical assessment of renewable energy forecasting. • Prices, wind speed/power solar irradiance or price and load forecasts are covered. • We show how to present and evaluate forecasting results. • Performing and evaluating OOS studies and probabilistic forecasts is shown. [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]

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]

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]

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]

Due to use of fossil fuels for the human activities found a significant effect on the environment as well as people's health. Hence, the researchers from all around the world are searching for the sustainable solution through non-conventional sources of energy like wind, biomass, solar energy etc. Among all non-conventional sources of energy, solar energy is prevalent. Pasteurisation is a process of heating of food or liquid for the killing of bacteria. For pasteurisation of milk, dairy industries require boiler or heat exchanger, and it consumes energy, and sometimes they need fossil fuels. Hence, a primary aim of this review paper is to discuss various research works have conducted by researchers on milk pasteurisation system so an appropriate best solution can be found for sustainable development. [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 number of regional and national power systems with a high share of wind and solar power in the world is quickly increasing. The background for this development is improved technology, decreasing costs, and increased concern regarding environmental problems of competing technologies such as fossil fuels. For the future there are large possibilities for increasing the renewable electricity share. However, variable renewable power production has to be balanced. Demand side flexibility offers an interesting approach to the balancing issues. The aim of this paper is to compare flexibility potentials and how they were estimated in seven Northern European countries in order to compare general challenges and results as well as the connection between used method and results. The total flexibility is estimated to 12–23 GW in a system with a total peak load of 77 GW. [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]

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]

This paper proposes a probabilistic pricing which achieves efficient operation of and investment in ramp-service providers in power systems with a large amount of wind or solar generation. The proposed pricing differs from the existing literature in that it focuses exclusively on the efficient dispatch of electrical energy with no exogenous consideration of the need for reserves or balancing services. The proposed optimal dispatch task determines both the efficient level of any preventive actions taken before a contingency event occurs and the efficient response of the power system - i.e., corrective actions - once an event occurs. We show analytically that the efficient dispatch outcome can be achieved in a decentralized market mechanism provided the market participants are profit-maximizers and price-takers. We show how the total economic benefit of an investment can be decomposed into two components (a) the normal dispatch cost benefit and (b) the economic value of the investment in contributing ramp service to the power system. In order to study different aspects of the probabilistic pricing, the IEEE 30-node example system is deliberately modified. The results show the efficiency of the proposed pricing and the use of the investment model to assess the economic value of ramp-service providers. [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 we study a community or firm considering to diversify its investment in two distinct renewable energy technologies, namely wind and solar PV electricity. We assume technological learning curves as a function of cumulative capital investment. A real options approach is applied as it takes into account uncertainty about prices and learning, as well as irreversibility associated with investment decisions. We investigate three different cases, dealing with uncertainty about future electricity prices, and uncertainty about the speed with which learning drives the costs of wind and solar electricity down. We assess the minimum threshold for the stochastic price and the maximum electricity production cost that makes it optimal for the firm to invest in the two technologies. The results show that the learning rate affects the option to invest in but reducing critical threshold for exercising it. The greater the amount of capital invested, the more learning stimulates earlier exercising of the option to invest. The firm will then anticipate the option to invest and exercise it for lower critical threshold values if all capital is invested in one technology. If capital investment is diversified, the option should be exercised at a higher critical threshold. More uncertainty in energy prices or technology costs postpones the option to invest. Although investing in both solar and wind may be profitable under particular conditions of price and cost uncertainty, the theoretically optimal strategy is generally investing in only one technology, that is, solar or wind, depending on their relative initial costs and learning rates. This suggests that the practice in most countries of diversifying renewable energy may reflect a mistaken strategy. [ABSTRACT FROM AUTHOR]

In this paper, the potential of solar and wind energy-based distributed generation (DG) in Saudi Arabia is simultaneously analyzed with the aim of maximizing the utilization of available resources. It begins with an analysis of DG application potential for wind and solar energy resources in various regions of Saudi Arabia. The progress of DG applications in terms of research, planning, and exploitation of wind and solar energy resources is then presented. An assessment of the DG contribution to the energy sector of Saudi Arabia has been conducted and the barriers and challenges for the implementation of DG systems in the country are discussed with suggested measures to overcome the challenges. The main findings are that with the huge potential of wind and solar resources for DG applications the country has targeted 50 GW of wind and solar capacity by the year 2040. The Saudi government is expected to provide full support in the form of financial incentives for solar and wind energy projects in order to boost renewable energy development. [ABSTRACT FROM AUTHOR]

Greater penetrations of variable renewable generation on some electric grids have resulted in increased levels of curtailment in recent years. Studies of renewable energy grid integration have found that curtailment levels may grow as the penetration of wind and solar energy generation increases. This paper reviews international experience with curtailment of wind and solar energy on bulk power systems in recent years, with a focus on eleven countries in Europe, North America, and Asia. It examines levels of curtailment, the causes of curtailment, curtailment methods and use of market-based dispatch, as well as operational, institutional, and other changes that are being made to reduce renewable energy curtailment. [ABSTRACT FROM AUTHOR]

Conventional power plants suffer from issues like fuel scarcity, availability of site and other environmental concerns. Alternate technologies based on renewable energy sources especially solar, wind and bio-mass are utilised to overcome these problems. Among many options available in solar technology, power generation through CSP (Concentrating Solar Power) could be the most promising one for India in the coming future. In this paper, a brief overview on various CSP technologies and site selection criteria has been outlined. Subsequently, the design considerations for the four major CSP technologies i.e. solar tower, parabolic trough, linear fresnel reflector, and parabolic dish are discussed. Finally, the present status and key issues related to the deployment of CSP based technologies in India are summarised. [ABSTRACT FROM AUTHOR]

Due to the uneven distribution of renewable resources and electricity load centers in China, renewable energy usually needs to be delivered a long distance from the generation base to the load center. However, wind power and photovoltaic (PV) have to be bundled with flexible resources, such as thermal generators, to compensate for the generation uncertainty and variability. Concentrating solar power (CSP) is a controllable generation technology, and it is receiving great attention in the northwest China to be constructed in the 100% renewable energy generation base. This paper proposes a generation portfolio optimization model of a 100% renewable energy base supported by CSP. Firstly, a flexible operation model of CSP based on the interval theory is proposed. Then, a coordinated operation strategy of a 100% renewable energy base organized by CSP, wind power, PV and also energy storage is formulated. On this basis, a generation portfolio optimization model is established with the target of minimizing an extended levelized cost of energy (LCOE) considering the transmission cost. A case study of 100% renewable energy base in Qinghai Province, China, is conducted to verify the effectiveness of the proposed model. It is depicted that CSP plays an important role in the cost-effective portfolio and can be a better alternative to the combination of PV and storage. For the 100% renewable energy base in Qinghai, the LCOE with an optimal CSP, PV, wind, and storage combination is 0.5785 CNY/kWh, which is 20.3% lower than the case without the installation of a CSP station. • Building a 100% renewable energy generation base with a CSP, PV, wind, and storage combination. • A planning model with the target of minimizing an extended LCOE considering transmission cost. • A coordinated operation strategy of a 100% renewable energy base considering CSP's flexibility. • The LCOE of a 100% renewable energy base can drop 20.3% when equipped with CSP in Qinghai. [ABSTRACT FROM AUTHOR]

Smart energy transition includes a widespread deployment of clean energy technologies and intelligent energy management with information and communication technologies (ICTs). In this paper, the smart energy transition is studied from the viewpoint of the technology convergence of renewable energy sources (RESs) and ICTs. Two important, fast-growing and weather-dependent renewable energy generation technologies: wind power and solar PV (photovoltaic) are studied. This paper provides technology convergence analyses of RES and ICT inventions based on international patent data. Digitalisation is changing the whole of society, and according to the results, this transition can also be seen in the studied renewable energy generation technologies. The digitalisation of RES production covers technologies that control, manage and optimise electricity production in different intelligent ways. Differences between wind power and solar PV technologies are found: in the case of wind power, the development from virtually no ICT solutions to partial technology convergence with the ICT sector is straightforward. However, in the case of solar PV, the development of basic technologies has been even faster than the development of the solar PV ICT solutions, which may indicate the immature nature of solar PV technologies during the studied years. The digitalisation of the renewable energy sector poses challenges for RES companies in following and predicting ICT development and opportunities for innovations and collaborations with ICT companies. This conclusion can also be expanded to society and policy levels because focusing on only a narrow field when planning innovation policy instruments can negatively impact the country's competitiveness. • Digitalisation and ICT solutions are impacting on wind power and solar PV technologies. • The prominent RES technologies with ICT solutions control, manage and optimise electricity production. • Wind power patent data shows a straightforward technology convergence trend with ICT. • Basic inventions in solar PV have increased more rapidly than solar PV ICT solutions. • Digitalisation in wind power and solar PV has been driven by the US, Germany, Denmark and Japan. [ABSTRACT FROM AUTHOR]

The paper aims to address the potential of low-carbon and renewable hydrogen in decarbonizing the European energy system; specifically, reducing emissions by 55% in 2030 compared to 1990, and targeting net-zero emissions by 2050. The methodology relies on a cost-optimization modelling approach using three models complementarily: a detailed European TIMES-type model (MIRET-EU); an aggregated model for the European energy system, allowing endogenous cost reductions based on technology deployment in a dynamic programming formulation for investment strategies (Integrate Europe); and a dedicated model for assessing hydrogen import options for Europe (HyPE). Two policy-relevant scenarios have been developed: Technology Diversification (TD) and Renewable Push (RP). Both lead to climate neutrality in Europe in 2050 but the RP scenario differs by setting new reinforced targets for renewable technologies in Europe. Results show that hydrogen production would increase sharply in the coming decades, exceeding 30 million tons (Mt) by 2030 and more than 100 Mt by 2050 in both scenarios. Polyvalence of hydrogen in decarbonizing the European energy system for certain hard-to-abate energy uses in transport and industry is also observed. European hydrogen production relies on a diverse mix including both renewable and low-carbon technologies. It is complemented by hydrogen imports from neighboring regions, that represent between 10 and 15% of total demand in 2050. Access to existing cross-border pipelines is a critical advantage compared to maritime transport. Notably, there are considerable cost reductions due to technology deployment for solar power and hydrogen production by electrolyzers. • European hydrogen demand could exceed 100 million tons per year by 2050. • 15% of H 2 needed to reach carbon neutrality could be imported from outside Europe. • More than half of H 2 is used for transport, the rest is dominated by industry. • 1800 GW of solar and wind power is needed for the roll-out of renewable hydrogen. • Resilience of natural gas in European energy transition by 2050 with uptake of CCS. [ABSTRACT FROM AUTHOR]

Integration of wind- and solar-based generation into the electric grid has significantly grown over the past decade and is expected to grow to unprecedented levels in coming years. Several jurisdictions have set high targets for renewable energy integration. While electric grid operators have managed the variable and non-dispatchable nature of wind and solar power at current levels, large-scale integration of these resources would pose new challenges. In particular, the variable nature of wind and solar may lead to new electric grid operation and planning procedures. Net load in electric grids is defined as the conventional load minus the non-dispatchable generation. Net load is the basis of operation planning in day-to-day delivery of electricity to the consumers. With large-scale integration of wind and solar power, the net load in the system would be significantly affected. In this paper, we focus on characteristics of net load in electric grids when a large amount of wind and solar power generation is integrated into the grid. We use the data from California׳s power system. California intends to produce 33% of its electricity from renewable resources by 2020, 80% of which is expected to come from wind and solar power. We use both historical data and simulated scenarios of future wind and solar power generation. For future scenarios, we use the data provided by National Renewable Energy Laboratory to generate wind and solar power integration scenarios for years 2018 and 2023. The simulated net load data are analyzed from a variety of perspectives, such as average daily shapes, load and net load factor, duration curves, volatility, and hourly ramps. The results showed that compared to conventional load, characteristics of net load would be significantly different and need to be taken into account when designing measures and mechanisms for operating electric grids with high penetration of renewables. [ABSTRACT FROM AUTHOR]

This paper deals with the simultaneous scheduling of electrical vehicles and responsive loads to reduce operation cost and emission in presence of wind and PV powers in microgrid. In the proposed method, the electrical vehicles are used for peak shaving and load curve modification while the responsive loads are employed to supply the reserves needed to compensate the intrinsic uncertainties of wind and PV powers. Furthermore, a developed two-stage model is proposed to determine the expected operation cost of microgrid (energy and reserve). In the first stage, the generation and reserve power costs are minimized while in the second stage, the costs associated with unit scheduling changes resulting from wind and PV power variations are minimized. The proposed model is implemented in a microgrid with various distributed generations. The simulation results have shown that the incorporation of electrical vehicles and responsive loads leads to decrease the system operation costs and emissions while the uncertainties related to wind and PV are compensated. [ABSTRACT FROM AUTHOR]

Renewable energy sources are certain to play a key role in the future energy generation due to the rapid depletion of conventional sources of energy. The solar and wind energy are the major renewable energy sources which have the potential to meet the energy crisis to some extent. However, such sources when explored independently are not completely reliable because of the unpredictable nature. Whereas their use as hybrid energy systems seems to be more reliable and cost effective, due to the complementary nature of these two resources. In this paper an attempt has been made to discuss a systematic review related to hybrid PV/wind energy systems with battery storage. The work as presented in the manuscript will help the researchers to explore such hybrid energy systems for further improvements in terms of designing, analyzing and integrating such systems into the power network. [ABSTRACT FROM AUTHOR]

This paper reviews state-of-the-art on wind speed/power forecasting and solar irradiance forecasting with ensemble methods. The ensemble forecasting methods are grouped into two main categories: competitive ensemble forecasting and cooperative ensemble forecasting. The competitive ensemble forecasting is further categorized based on data diversity and parameter diversity. The cooperative ensemble forecasting is divided according to pre-processing and post-processing. Typical articles are discussed according to each category and their characteristics are highlighted. We also conduct comparisons based on reported results and comparisons based on simulations conducted by us. Suggestions for future research include ensemble of different paradigms and inter-category ensemble methods among others. [ABSTRACT FROM AUTHOR]

As the share of VRE (variable renewable energy) has grown rapidly, curtailment issues have arisen worldwide. This paper evaluates and compares curtailment situations in selected countries using an objective and quantitative evaluation tool named the " C-E map " (curtailment-energy share map). The C-E map is a correlation map between curtailment ratios that mean curtailed wind (or solar) energy per available energy and energy shares of wind (or solar). The C-E map can draw a historical trend curve in a given country/area, as an at-a-glance tool to enable historical and/or international comparison. The C-E map also can classify the given countries/areas into several categories, according to the current levels of curtailment ratio and historical trends. The C-E map helps institutional and objective understanding of curtailment for non-experts including policy makers. • Curtailment is one of the most important issues for wind and solar integration. • Global curtailment data in Europe, North America, China and Japan was evaluated. • Curtailment ratio does not always increase as wind and solar share increases. • Some countries/areas decreased curtailment ratio by enhancing of flexibility resource. • C-E (Curtailment - Energy Share) Map can help to grab historical trend of curtailment. [ABSTRACT FROM AUTHOR]

Renewable energy (RE) trade disputes have been rising in response to certain green industrial policies, i.e., policy mechanisms used to develop domestic RE industries and accrue associated local economic benefits. Since 2011, countries have been increasingly filing trade litigations to counter the use of green industrial policies by their trading partners so that they can expand RE industry competitiveness and the associated manufacturing jobs within their own countries. However, in the absence of systematic studies on the impacts of RE trade duties, evidence regarding their success in achieving these economic goals remains limited. In this paper, the effectiveness of RE trade duties in supporting employment, especially in manufacturing, is assessed. First, the literature on the motivations behind RE trade duties is reviewed, and then the case of trade duties imposed by the US on the imports of solar and wind energy components from China between 2011 and 2019 is examined. Although several factors may drive employment, no evidence is found for the increase in jobs in solar and wind manufacturing in the years after the trade duties were imposed. Meanwhile, downstream jobs in installation, operation and maintenance continued to grow, corresponding to increases in annual installation of solar and wind capacity in the US. These were driven by policy incentives and the declining costs of solar and wind technologies. Overall, this case study highlights the broader implication that trade duties alone are unlikely to promote local manufacturing industries, and countries would benefit from other well-designed policies. • Renewable energy (RE) related trade disputes rising but studies examining effectiveness of trade duties limited. • Literature on the goals behind trade duties on RE components reviewed. • A framework developed to assess the relationship between RE trade duties and manufacturing employment. • Framework applied to examine the case of trade duties by the US on the imports of solar and wind energy components from China. • Trade duties not effective to develop local RE industries; other well-designed policies needed to increase local RE manufacturing jobs. [ABSTRACT FROM AUTHOR]

This paper presents an overview and analysis of the dynamics and unique impacts of variable renewables on the grid, and identifies the bottleneck problems and solutions associated with renewable integration. Variability issues that concern many are not unique to variable renewables. Grid operators have been dealing with demand variability for over a century. With sufficiently accurate forecast for variable renewables, the grid operators can schedule dispatchable generation and/or storage resources to balance demand and supply on a nearly real-time basis. With state-of-the-art wind forecasting technologies and existing generation resources, wind integration has not caused major operational problems for grid systems with a penetration level of up to 37% during some time intervals. Base load generators operate nearly constantly for days or longer and supply a larger share of the electricity mix than what is proportional to their capacity. This will be a limiting factor for high level variable renewables, if current operation continues. The capability to at least partially follow electricity load should be a key performance measure of non-renewable plants if we are serious about high level variable renewables. Specific policy instruments are recommended to incentivize more flexible plant operation and ensure smooth integration of variable renewables. [ABSTRACT FROM AUTHOR]

In this paper we present an up-to-date literature review on employment opportunities associated with the deployment of renewable energy technology. We identified approximately 70 studies and data sources published over the past decade that report analysed or observed employment impacts of renewable energy growth. These publications cover many different countries and several technology options, and present widely varying results derived from distinct methodological approaches. Our first overall conclusion is that there is clear lack of authenticity of findings in this literature, since recursive referencing abounds and relatively few studies yield truly original research. When we omit non-authentic analyses, as well as those that aggregate results in a way that does not allow us to calculate ‘employment factors’ (defined as the number of jobs or amount of work generated per unit of electricity production capacity), the total list of references is brought to 31 independent items. Of these, only 14 references provide separate estimates of the employment factors for the stages of manufacturing and installation, respectively, as opposed to employment factors for these two activities combined. A total of 23 items provide values for operation and maintenance (O&M) employment factors. We observe significant uncertainties in quoted figures for job creation, both across and within publications. [ABSTRACT FROM AUTHOR]

Integrating variable and non-dispatchable renewable power generation into existing power systems will have consequences for their operation and future expansion. These impacts will depend on two factors: (1) the variability of the total renewable power generation on different time scales and (2) the possibilities of accurately forecasting these fluctuations. In this paper, previous research on variability assessment and forecasting of solar, wind, wave and tidal energy resources is reviewed. The aim is to summarize the state of knowledge in each area and to compare the approaches used for the respective resources. For temporal variability, methods and models used for assessing the variability are surveyed, as well as what is known about the variability at individual sites and for larger aggregates of sites. For forecasting, an overview of forecasting methods for the different resources is made, and selected forecasting methods are compared over different time horizons. An important finding is that it is hard to draw strong conclusions from the existing studies due to differences in approaches and presentation of results. There is a need for further, more coherent studies that analyze the variability for the different resources in comparable ways, using data with the same resolution, and for studies that evaluate the smoothing effect and complementarity of combinations of several renewable energy resources. For forecasting, future research should suggest ways to evaluate forecasts from different renewable energy sources in easily comparable ways, using data from the same locations or regions, with the same temporal and spatial resolution, and with comparable metrics for the forecasting errors. [ABSTRACT FROM AUTHOR]

A significant number of Life Cycle Assessment (LCA) analyses of renewable energy technologies is available in the literature, even though there is a lack of consistent conclusions about the life cycle impacts of the different technologies. The reported results vary consistently, according to the size and the technology of the considered plant, thus limiting the utility of LCA to inform policy makers and constituting a barrier to the deployment of a full awareness on sustainable energies. This variability in LCA results, in fact, can generate confusion regarding the actual environmental consequences of implementing renewable technologies. The article reviews approximately 50 papers, related to more than 100 different case studies regarding solar energy (Concentrated Solar Power, Photovoltaic), wind power, hydropower, and geothermal power. A methodology for the harmonization of the results is presented. The detailed data collection and the results normalization and harmonization allowed a more reliable comparison of the various renewable technologies. For most of the considered environmental indicators, wind power technologies turn out to be the low end while geothermal and PV technologies the high end of the impact range where all the other technologies are positioned. [ABSTRACT FROM AUTHOR]

Geothermal, solar and wind are all clean, renewable energies with a huge amount of resources and a great potential of electricity generation. Geothermal energy had definitely dominated the renewable energy market in terms of the installed electricity power about 30 years ago. The unfortunate fact is that the total installed capacity of geothermal electricity has been eclipsed by solar and wind in recent years. In this paper, benefits of using renewable energy resources (RER) have been summarized and attempt has been made to explain the recent trends causing the shift from geothermal energy to solar and wind. Cost, payback time, size of power generation, construction time, resource capacity, characteristics of resource, and other factors were to compare geothermal, solar, and wind power generation systems. Furthermore, historical data from geothermal, solar, and wind industries were collected and analyzed at the global scale. The data from hydropower were also considered in the comparison. Finally, we proposed suggestions for the geothermal industry to catch up with solar and wind industries. [ABSTRACT FROM AUTHOR]

This paper contributes to the development of renewable energy innovation metrics through an exploration of innovation patterns across the European countries in 2010. The identified localized innovation capabilities describe the health of the wind, solar and bioenergy sectors, highlighting a concentrated RES innovation activity within four countries: Germany, France, United Kingdom and Denmark. The association of technological capabilities along the innovation composite indicators allows the extraction of useful insights of the role of environmental policies on employment and technological change. Briefly, the corporate research investment per patent is lower for wind energy (EUR 0.61 million) and higher for PV and biofuels (approximately EUR 1 million). Important lever of innovation capabilities across Europe is identified within public support to deployment, which provides significant insights in terms of economic efficiency of generation technologies; the investigation finds job ratios which are higher for wind and lower for PV technology. As the evolution of the market drives the patterns of innovation activities for all selected technologies, considerable financial consequences are identified in the context of delocalization of clean technology manufacturers. [ABSTRACT FROM AUTHOR]

Environmental and socioeconomic challenges facing many hydrocarbon-rich nations could help them evolve from hydrocarbon-based (black) into renewables-based (green) economies. In this paper, we present a case study for application of this Black Into Green (BIG) method for Iran. We show that with international cooperation Iran could indefinitely meet its energy and freshwater needs by leveraging large-scale renewable energy harvesting systems integrated with seawater pumped storage hydropower, reverse osmosis desalination, and enhanced distribution systems. This BIG transition could be facilitated by allocating a significant portion of Iran's potential hydrocarbon-based income to acquire, develop, and deploy renewable energy technology that utilizes Iran's immense solar and wind energy potential. Our analysis shows that developing just 1% of identified sites would provide over 30 TWh of annual renewable electricity generation and storage, and 221 million m 3 /day of renewably-powered desalination capacity to meet the freshwater needs of over 85% of its population. In addition to providing renewable energy design and manufacturing technology, the international community could also work with Iran to help evolve its nuclear power program toward small modular reactors for baseload power generation. Such an arrangement would contribute to regional and global security, and greatly reduce the Middle East's carbon emissions of which Iran is the largest emitter. Results from this holistic approach could then serve as a model for the world economy to work with other resource-rich nations to reduce their environmental impact while modernizing their economies and helping them achieve the socioeconomic goals outlined in the UN's Brundtland report. • Presents strategy for a sustainable economy to emerge from the COVID-19 pandemic. • Case study for Iran with oil (black) exchanged for renewables (green). • Wind and solar energy with coastal pumped storage hydro and reverse osmosis. • 1% of viable sites could supply Iran with 10% of power and 45% of freshwater needs. • Distributed economic and environmental benefits meet UN sustainable development goals. [ABSTRACT FROM AUTHOR]

Abstract: Currently, many defects have appeared in wind and solar power generation systems. Utilizing the complementary of wind and solar power generation will break the bottleneck of new energy development. How to select the site of wind/solar hybrid power station scientifically is a primary problem. First, the framework of the indicator system is obtained from the literature review and refined according to the resources evaluation standards and different perspectives of the various scholars. Then this paper selects seven wind/solar hybrid power stations which have been put into operation as the case study, weights the indicators through the method of order relations, and evaluates these seven regions via ELECTRE-II. The conclusions are consistent with the related research findings and have better correctness, proving the feasibility and effectiveness of the method. It may provide some theoretical basis for the macro-site selection of wind/solar hybrid power station. [Copyright &y& Elsevier]

Previous studies have noted that, unexpectedly, Germany's dramatic expansion of wind and solar energy coincided with a reduction of short-term balancing reserves. This observation has been dubbed the "German Balancing Paradox". This paper provides further and updated evidence: since 2011, wind and solar energy have nearly doubled while both reserve requirements and reserve use have declined by 50%. The paper quantitatively explores one reason for reduced balancing needs: increased and improved short-term wholesale electricity trading on the intraday market. Trading is now commonly done around the clock and based on quarter-hour, rather than full-hour, contracts. The shift to quarter-hourly products alone explains a decrease in balancing energy by 17%. There is also strong evidence that market parties respond efficiently to imbalance charges, suggesting that incentive-based approaches to electricity balancing work. • Since 2011 wind and solar energy nearly doubled; balancing energy decreased by 50%. • One reason for this is the expansion of short-term electricity trading. • It is now common to trade electricity around the clock, and on a 15-min basis. • In general, the paper finds support for efficient short-term electricity markets. • Good market design allows integrating large volumes of renewable energy at low cost. [ABSTRACT FROM AUTHOR]

Installed capacities of wind and solar power have grown rapidly over recent years, and the pool of literature on very short-term (minutes- to hours-ahead) wind and solar forecasting has grown in line with this. This paper reviews established and emerging approaches to provide an up-to-date view of the field. Knowledge transfer between wind and solar forecasting has benefited the field and is discussed, and new opportunities are identified, particularly regarding use of remote sensing technology. Forecasting methodologies and study design are compared and recommendations for high quality, reproducible results are presented. In particular, the choice of suitable benchmarks and use of sufficiently long datasets is highlighted. A case study of three distinct approaches to probabilistic wind power forecasting is presented using an open dataset. The case study provides an example of exemplary forecast evaluation, and open source code allows for its reproduction and use in future work. • Research in minutes- to hours-ahead wind and solar power forecasting is reviewed. • Knowledge transfer between wind and solar continues to benefit both fields. • An open-source case study of three distinct methods is presented. • Best practice in forecast evaluation is set out in the case study. • Common areas for improvement in research quality are identified. [ABSTRACT FROM AUTHOR]

Renewable energy plays a crucial role in both climate change mitigation and adaptation in highly climate-vulnerable nations such as Nepal. This paper reviews various types of renewable energy technologies and their status, potential for adoption, relationship to climate change, and mitigative and adaptive roles in Nepal. Nepal has installed micro-hydro projects, solar power, improved cooking stoves, biogas technology, improved water mills, and wind energy to mitigate and adapt to climate change. There is a growing potential for renewable energy development in Nepal, such as hydropower, solar, wind energy, biogas, and improved cooking stoves. Roughly 70% of Nepal's energy consumption is generated from traditional energy sources while renewable energy accounts for approximately three percent. The gradual increase in the use of renewable energy has reduced greenhouse gas emissions and enhanced carbon sequestration. By adopting renewable energy technologies, Nepal has reduced emissions by 221,129 tCO 2 e from 2017 to 2018. Nepal's second Nationally Determined Contribution targets a 15% increase in national energy use from renewables with a reduction of 23% of CO 2 emissions by 2030 using biogas and improved cooking systems. Furthermore, a significant increase in the adoption of renewable energy has become a pivotal strategy in adaptation to climate change in social, health, and economic sectors resulting in time savings, alternative income sources, improved health and educational status, local job opportunities, and the promotion of social capital. The benefits of adapting to climate change and mitigating CO 2 emissions via renewable energy are significant at the local, national, and international levels. This study recommends that the government of Nepal focus work on energy policy reviews to address local energy demand and climate change issues by utilizing renewable energy resources at the local level, which has global implications. • Suitable, potential renewable energy technologies in Nepal. • The relationship between energy and climate change. • Relevant data on energy and climate change in tables and figures. • Social, economic, and environmental benefits of renewable energy. • Climate change adaptation and mitigation via renewable energy. [ABSTRACT FROM AUTHOR]

Solar and wind energy are expected to play a key role in creating a climate-neutral Europe by 2050 and decarbonizing energy production in general, albeit requiring significant deployment. This presupposes that the population accepts such energy sources, thus necessitates understanding how people perceive energy systems. Unlike the abundant literature about wind energy, social acceptance of solar energy has received less attention, especially concerning large solar installations. Opinion polls indicate that solar energy enjoys a high level of socio-political acceptance and is preferred to other renewables, although it is unclear whether this acceptance persists as the technology is deployed on a large scale. This paper helps close this gap by describing the results of a representative survey (n = 601) conducted using a between-subject design to examine how attitudes of the public towards solar energy vary based on the size of installations, how the latter compare to attitudes towards wind energy, and what the role of affect is in the former. Results reveal that the stronger preference for solar power decreases to a similar level as that for wind energy when comparing installation of similar sizes, highlighting that solar energy installations may not easily be scaled up. The study also shows that affect plays an important role in forming people's attitudes towards wind and solar, especially concerning large-scale installations. This underlines the need for policymakers and project developers, who aim to deploy renewables on a large scale, to attend to the affective component of decision-making. • Between-subject design survey with a representative sample (n = 601). • Positive attitudes towards solar energy are mediated by installation size. • Solar parks are less positively perceived than rooftop PV installations. • When comparing installations of similar sizes, solar is not more popular than wind energy. • Large installations evoke stronger emotions, which in turn influence attitudes. [ABSTRACT FROM AUTHOR]

The global shipping industry faces huge pressure to reduce its greenhouse (GHG) emissions due to the International Maritime Organization (IMO) has introduced strict regulations to decrease GHG emissions from ships. New energy sources can provide a solution for green shipping because they have the advantages of abundant, renewable and clean. This paper examines the current progress made regarding the integration of new energy sources into conventional ship power systems, including solar energy, wind energy and fuel cells. It also discusses the possibilities for using the aforementioned three new energy sources in ship power systems ranging from technical principles to subsequent applications. Furthermore, basic working theories of new energy sources, application methods, existing new energy ships and core technologies required are summarized in detail. The integration of new energy sources into traditional ship power systems has enormous potential to bring the shipping industry in line with international regulatory requirements and is set to become a key focus of ship-related researches in the immediate future. [ABSTRACT FROM AUTHOR]

China has the world's largest photovoltaic (PV) market, and its cumulative PV installation capacity reached more than 200 GW in 2019. However, a large gap remains to achieve the ambitious target of 1200 GW of wind and solar power installation capacity by 2030. Are there sufficient solar resources, and where should the PV modules be installed? There are no clear answers to these questions. This paper aims to identify the availability and feasibility of developing distributed solar PV (DSPV) systems in China's cities. The results show that China has many DSPV resources, but they are unevenly distributed. The potential for DSPV systems is greatest in eastern and southern China, areas of relatively low solar radiation. Furthermore, the difference in the potential of DSPV development among cities requires targeted policies for different geographical areas. Similarly, the difference in DSPV generation to satisfy the electricity demand in various sectors requires political and industrial efforts to address the mismatch between solar PV power generation capacity, electricity demand, and solar radiation in different regions. • The first study to calculate distributed solar PV (DSPV) potential at city level in China. • China has many DSPV resources, but they are unevenly distributed. • The DSPV resources such as industrial parks, public facilities and rooftops of buildings have been neglected. • Contribute to the decision-making process of the DSPV development by providing a quantitative, city-specific analysis of DSPV power generation. [ABSTRACT FROM AUTHOR]

Impressive growth rates of solar photovoltaics (PV) in higher latitudes are raising concerns about seasonal mismatches between demand and supply. Locating utility-scale PV projects in alpine regions with high solar irradiation could help to meet demand during the winter season. However, similar to wind farms, large solar projects change the landscape and may therefore face social acceptance issues. In contrast to the rich literature on wind energy, social acceptance of solar power has received less attention. This paper helps close this gap with the help of a large-scale survey (N = 1036) that examines the acceptance of alpine solar projects in Switzerland through choice experiments. In addition to attributes that are well established in the social acceptance literature, such as local ownership, along with both distributional and procedural justice, we also investigate the influence of innovative design elements on acceptance. Our findings suggest that local ownership, as well as colored solar panels that reduce the perceived landscape change may increase social acceptance, implying that projects should be kept local and low-key. We also find that acceptance of alpine solar projects is higher among the affected population than among inhabitants of non-alpine regions. • Choice experiment with representative sample of N = 1036. • 64% of respondents would (rather) accept alpine solar projects. • Green PV panels are preferred over conventional panels. • Local ownership increases social acceptance. • Young respondents are more open to innovative design elements. [ABSTRACT FROM AUTHOR]

China has become the world's largest clean energy country in terms of the total installation of wind and photovoltaic power and annual newly installed capacity. However, weather conditions render renewable energy unstable, thereby restricting its application to a power grid; reducing the randomness in wind or photovoltaic power is the major challenge of the utilization of solar and wind energy. This paper systematically reviews the explorations and the practices related to wind and photovoltaic power consumption in China. Considering the difference in the methods of supplementing the variable and intermittent output of wind and PV power, five consumption modes are outlined: distributed energy microgrid absorption, power grid peak shaving operation consumption, wind-photovoltaic-storage consumption, wind-photovoltaic-thermal complementation, and wind-photovoltaic-hydro complementation. The theories, features, current situation and growing trends of each mode are analyzed. Finally, several suggestions, including promoting multi-energy complementary microgrid application and installing large-scale pumped storage hydropower, are provided for improving the efficiency of renewable energy development in China. • Practical variable energy consumption modes are outlined and analyzed. • Small-scale distributed wind and PV power is suitable for microgrid integration. • Medium-sized wind and PV power consumed through the main grid is reasonable. • Large-scale wind and PV can be combined and transmitted with hydro or thermal power. [ABSTRACT FROM AUTHOR]

The Caribbean nation of Suriname has historically depended on a mix of hydropower and oil-based fossil fuels for meeting electricity needs. Continued reliance on fossil fuels poses challenges both for climate change mitigation and for energy security. This paper explores the potential for increasing the share of renewables in Suriname's electricity mix, with a special focus on the complementary role of existing hydropower and future wind power infrastructure. We show that these resources have great synergetic potential for displacing fossil fuel-based power generation. Flexible operation of the Afobaka hydropower plant, newly in full possession of Suriname, allows significant wind power integration without violating grid stability and associated power quality requirements. Considering the trade-off between displacing expensive fossil fuels and limiting wind power curtailment on Suriname's island-like grid, our results suggest that integrating wind power in the Surinamese electricity mix is economically advantageous up to a share of 20–30%, independently of near-term demand growth. These results have wider relevance for climate policy in various Caribbean countries and other island states with existing hydropower infrastructure and substantial wind/solar power potential, for which this study fills an important literature gap. • Suriname's hydropower plant can support substantial grid integration of wind power. • Thermal power could be cost-effectively displaced by hydro-supported wind power. • Suriname could, on average, reach 20%–30% penetration of hydro-supported wind power. • Such strategies could benefit various island states and regions with isolated grids. [ABSTRACT FROM AUTHOR]

Job creation is arguably an important socioeconomic benefit of renewable energy deployment. In turn, this employment creation may be contingent upon the influence of some key factors, including technology learning, trade effects and policies and may affect different renewable energy technologies and activities of the renewable energy value chain in different ways. This paper estimates the gross employment stemming from the deployment of three renewable electricity technologies – photovoltaics (PV), wind on-shore and wind off-shore – up to 2050 for all Member States of the European Union. It uses a novel analytical methodology which is able to capture the influence of technology learning and internal and external trade. Additionally, it provides highly disaggregated results per activity in the supply chain (manufacturing, installation and O&M), year and country for different technology and policy scenarios. The results show that the employment created by those three technologies can be significant but considerable differences across technologies, activities and countries can be observed. In the analyzed period (2014–2050), most employment will be created in the PV sector, in the operation and maintenance activities and it will be highly geographically concentrated in a few countries. However, job creation will strongly depend on the scenarios and assumptions being made. In particular our findings suggest that the availability of carbon capture and storage will have a considerable influence on the number of jobs being created. In contrast, changes in other assumptions have limited effects on the results: a variable (vs. a constant) learning rate, more restrictive emissions targets by 2050 and higher PV costs. • Ex-ante calculation of the employment of wind and PV deployment in 2050 in the EU. • Consideration of different policy scenarios, trade and technology learning effects. • Total employment is expected to increase significantly in the period, driven by PV. • Most jobs are created in the O&M and installation stages. • Job creation is geographically concentrated in a few countries. [ABSTRACT FROM AUTHOR]