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The palm oil industry generates significant amounts of solid wastes. The solid wastes, also known as oil palm biomass, includes the trunk (OPT) and fronds (OPT) from the plantation, and empty fruit bunch (EFB), mesocarp fibre (MF) and palm kernel shell (PKS) from the processing mills. Oil palm biomass is not effectively recycled for other applications, and existing disposal practices can cause adverse impacts on the environment. As oil palm biomass is a readily available lignocellulosic biomass, it has the potential to be a low-cost feedstock for conversion into higher value products. The first part of this study provides a comprehensive review of utilisation of oil palm biomass for the production of biofuels, chemicals and biomaterials through direct utilisation and physical conversion, biochemical conversion, thermochemical conversion and synthesis of lignin-based materials. The second part of this study discusses the opportunity for biorefinery development based on existing bioproducts from oil palm biomass, for the production of advanced fuels and platform chemicals that have not been explored in oil palm biomass research. This study proposes integrated biorefinery concepts via the integration of existing oil palm biomass biorefinery products with thermochemical process for upgrading the bioproducts into higher values products. The high-value products integrated biorefinery products include advanced biofuels, fuel additives and platform chemicals. The integrated biorefinery development for oil palm biomass processing is expected to improve the economics of the production of biomass-derived renewable energy and enhance the sustainability of palm oil industry.

The gradual shift of transportation fuels from oil based fuels to alternative fuel resources and worldwide demand for energy has been the impetus for research to produce alcohol biofuels from renewable resources which focus on utilizing simple sugars from lignocellulosic biomass, the largest known renewable carbohydrate source as an alternative. Currently, the usage of bioethanol and biodiesel do not cover an increasing demand for biofuels. Hence, there is an extensive need for advanced biofuels with superior fuel properties. Biobutanol is regarded to be an excellent biofuel compared to bioethanol in terms of energy density and hygroscopicity, could be produced through acetone-butanol-ethanol (ABE) fermentation process. Even though the ABE fermentation is one of the oldest large-scale fermentation processes, biobutanol yield by anaerobic fermentation remains sub-optimal. For sustainable industrial scale of biobutanol production, a number of obstacles need to be addressed including choice of feedstock, low product yield, product toxicity to strain, multiple end-products and downstream processing of alcohol mixtures plus the metabolic engineering for improvement of fermentation process and products. Studies on the kinetic and physiological models for fermentation using lignocellulosic biomass provide useful information for process optimization. Simultaneous saccharification and fermentation (SSF) with in-situ product removal techniques have been developed to improve production economics due to the lower biobutanol yield in the fermentation broth. The present review is attempting to provide an overall outlook on the discoveries and strategies that are being developed for biobutanol production from lignocellulosic biomass.

Due to the massive entrance of new renewable energies such as wind or solar, hydraulic turbines have to work far from its designed point and withstanding multiple transients, such as starts and stops, that shorten the useful life of the machine and cause fatigue damages. The present paper reviews the complex problem of fatigue in Francis turbines particularly focused on the experimental data available for static and dynamic stresses. For this purpose, many researches, which include different Francis turbines covering a wide range of design head and power, have been considered. The experimental stresses characteristics measured with strain gauges installed on the turbine runner and obtained from previous works have been analyzed for the different operating conditions and transient states occurring in the normal life of actual Francis units. The actual computational capabilities and techniques typically used to estimate such stresses have been discussed in detail. Potential future techniques to simplify complex strain measurements on the turbine runner, computational and statistical methods to estimate turbine stresses are reviewed in this paper. Finally, the relative damage of the different operating conditions and useful life estimation of the turbine, based on past strain measurements of the runner, are addressed.

To stop the spread of COVID-19, governments have implemented confinement measures unprecedented in modern society. One of the main consequences has been the paralysis of commercial and industrial sectors worldwide, primary electricity consumers. This paper examines the impact of these measures on the electricity sector through a literature review accompanied by fieldwork on the impact of COVID-19 in Ibero-America and its energy regulatory response. First, we will review the causes of the reduction in electricity demand due to the confinement measures and their technical and financial consequences in the electricity sector. Second, we will examine the impact of COVID-19 on the wind and solar PV energy sectors, mainly affected by the paralysis of production and export of materials and components. Third, we will revise the regulatory measures implemented by the countries to avoid the interruption of electricity supply to households. This paper will end by reviewing economic recovery plans and their relationship to the energy transition. Although there are no fundamental differences between developed and developing countries in their regulatory reaction to this crisis in the energy sector, there are significant differences in economic recovery planning. While developed countries aim for a green economic recovery and the creation of green jobs, developing countries are allocating least resources to social protection and general economic stimulus programs, postponing climate objectives. In Latin America, this adds to the high levels of debt faced by utilities and the possible resurgence of social crises that were stopped by the COVID-19 outbreak, making a green recovery even more difficult., Graphical abstract Image 1

This paper presents a thorough review of 75 modelling tools currently used for analysing energy and electricity systems. Increased activity within model development in recent years has led to several new models and modelling capabilities, partly motivated by the need to better represent the integration of variable renewables. The purpose of this paper is to give an updated overview of currently available modelling tools, their capabilities and to serve as an aid for modellers in their process of identifying and choosing an appropriate model. A broad spectrum of modelling tools, ranging from small-scale power system analysis tools to global long-term energy models, has been assessed. Key information regarding the general logic, spatiotemporal resolution as well as the technological and economic features of the models is presented in three comprehensive tables. This information has been validated and updated by model developers or affiliated contact persons, and is state-of-the-art as of the submission date. With the available suite of modelling tools, most challenges of today's electricity system can be assessed. For a future with an increasing share of variable renewables and increasing electrification of the energy system, there are some challenges such as how to represent short-term variability in long-term studies, incorporate the effect of climate change and ensure openness and transparency in modelling studies.

By year 2030, the world's energy demand is expected to increase by over 60% of current demand. Thus, the potential of renewable energy should be investigated. Renewable energy is the energy from natural and unnatural available forms including wind, biomass, solar, and waste heat energy generated through various human activities. Solar energy is an available and clean form of renewable energy used as an alternative to fossil fuel in generating energy. However, the maximum extraction of thermal energy from the sun is most challenging. This study focuses on energy generation using the parabolic trough collector (PTC). This review contains geometrical analysis including the thermal approach of the PTC model, heat transfer, and method of enhancing thermal efficiency on the PTC receiver. This paper also includes performance analysis, thermal efficiency, and applications of the solar-powered PTC and the history of PTC evolution. The PTC applications include desalination process, air heating system, power plants, refrigeration, and industrial heating purposes. This paper benefits researcher that focus on the solar-powered PTC.

Solar thermal technology to supply process heat in different industrial sectors has become very promising in recent years. Industries can reduce their consumption of fossil fuels by replacing them with solar process heat with non-conventional system integration and using clean energy. In this paper, a systematic review of 10 countries is presented which demonstrated extensive use of solar industrial process heating systems in their manufacturing sectors. This country-wise analysis is then used to compare with current Australian scenario and identify future prospects of integrating solar process heating in Australian industrial sectors. The choice of countries is based on a database where promising industrial sectors and solar process heating applications are currently using incident solar energy. These are analyzed for their potential of integration to developing solar heat in industrial processes (SHIP) and a number of potential industrial sectors that have the highest potential like Motor vehicles, Textiles, Printing, Wood, Paper, Fabricated metal, Rubber and plastics, chemicals, Food, beverages, electrical equipment, machinery, and equipment are being identified. An overview of available studies is discussed in this paper focused on specific countries and the industrial heat demand of existing operational plants. Future trends due to solar energy potential are also outlined.

This paper focuses on feature selection problems that arise in renewable energy applications. Feature selection is an important problem in machine learning, both in classification and regression problems. In renewable energy systems, feature selection appears related to prediction systems in the most important sources such as wind, solar and marine resources. The objective of the paper is twofold: first, a review of the most important prediction systems for renewable energy applications involving feature selection is carried out. Analysis and discussion of different feature selection problems in prediction systems are considered. We show that wrapper FSP approaches are those mostly used due to their higher performance. They include a diversity of algorithms, prevailing fast-training approaches. The lack of an uniform framework for FSP and the diversity of tackled problems impede a systematic assessment of the performance and properties of the applied methods. Thus, the simultaneously use of several global search mechanisms should be the preferred option. In a second part of the paper, we explore this possibility, by introducing a novel approach for feature selection based on a novel meta-heuristic, the Coral Reefs Optimization algorithm with Substrate Layer. This approach is able to combine different search mechanisms into a single algorithm, providing a global search procedure of high quality. We use an Extreme Learning Machine for prediction within this novel approach. The performance of the system is evaluated in a problem of wind speed prediction from numerical models input, using real data from a wind farm in Spain, where comparison with alternative regression algorithms is carried out. Improvements up to 20% in hourly and daily wind speed prediction are obtained with the proposed system versus the algorithms without the feature selection process considered., This work has been partially supported by Comunidad de Madrid, under project number S2013/ICE-2933, and by project TIN2014-54583-C2-2-R of the Spanish Ministerial Commission of Science and Technology (MICYT).

Source at https://doi.org/10.1016/j.rser.2018.02.034. Photovoltaics (PV) and electric vehicles (EVs) are promising technologies for increasing energy efficiency and the share of renewable energy sources in power and transport systems. As regards the deployment, use and system integration of these technologies, spatio-temporal modeling of PV power production and EV charging is of importance for several purposes such as urban planning and power grid design and operation. There is an abundance of studies and reviews on modeling of PV power production and EV charging available in the literature. However, there is a lack of studies that review the opportunities for combined modeling of the power consumption and production associated with these technologies. This paper aims to fill this research gap by presenting a review of previous research regarding modeling of spatio-temporal PV power production and charging load of EVs. The paper provides a summary of previous work in both fields and the combination of the fields. Finally, research gaps that need to be further explored are identified. This survey revealed some research gaps that need to be further addressed. Improving the accuracy of PV power production ramp-rate modeling in addition to quantifying the aggregate clear-sky index on city-scale are two priorities for the PV potential studies. For the EV charging load models, differences in model assumptions, such as charging locations, charging powers and charging profiles, need to be studied more extensively. Moreover, there is an imminent need for metering the load of charging stations. This is essential in developing accurate models and time series forecasting techniques. For studies exploring both the PV and EV impacts, local weak points in a spatial network need to be discovered, especially for the city-scale studies. Cooperation between eminent researchers in the PV and EV fields might propagate state-of-the-art models from the separate fields to the combined studies.

This paper examines the main non-technical factors that influence social and market acceptance of solar photovoltaic panels and heat pumps in buildings. The paper discusses results from a literature review and a survey of European stakeholders. Statistical analysis results of survey data identify the most common barriers to adoption of renewables as: limited information about the technology, financial concerns, and sociodemographic factors. Survey results indicate variability in market and social acceptance of renewables between stakeholders and countries. The investment cost of the technologies is identified as a barrier to adoption for all countries. Legal and organizational issues are identified as barriers in Spain. Economic and legal barriers are identified as barriers in Latvia and Belgium. The respondents from Germany only identify investment cost as a barrier. Economic aspects are identified as the main barriers among public building owners and the general public. Businesspeople identified the largest number of barriers, including economic aspects, lack of information, trust, business models, and legal issues, while private building owners identified the least number of barriers, with concerns only related to economic aspects. Results of this study provide valuable information for policymaking focused on increasing the adoption of renewables in the building sector. Additionally, this study identifies the need to increase environmental awareness among citizens and increase the availability of information about technologies to stakeholders. Citizens should be informed about the recoupment of the investment costs of the technologies to offset the perception of high investment costs, long payback time, and lack of proper business models.

In the last decade, there have been several initiatives for the deployment of cross-Mediterranean HVDC (High Voltage Direct Current) links to enable the transmission of electrical power from renewable energy sources between North Africa and Europe. These initiatives were mainly driven by the potential economic, environmental and technical benefits of these HVDC interconnections. In previous studies on these projects, some technical aspects of critical importance have not been addressed or studied in sufficient detail. One of these key aspects relates to the impact and possible benefit of these HVDC links on the dynamic performance of the European system which is the major focus of this paper. Several issues relating to the dynamic performance of the system are addressed here. Based on the experience gained from existing AC/DC projects around the world, this paper shows that the HVDC links between North Africa and Europe can greatly improve the dynamic performance of the European system especially in the southern regions. In addition, some challenges on the operation and control of these HVDC links are highlighted and solutions to overcome these challenges are proposed. This review paper, therefore, serves as a preliminary study for further detailed investigation of specific impacts or benefits of these interconnections on the overall performance of the European system.

Highlights • 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. 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.

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

Fiji is an island country with just over 300 small islands and approximately 853,000 people. It is a small island developing state (SIDS) that is heavily dependent on imported fossil fuel for its energy needs. The paper attempts to determine the past and current energy situation in Fiji, challenges faced and strategizes to overcome these challenges. In 2014, Fiji generated 859 GW h of grid electricity from 259.8 MW of power plants. Here, 45.4% of grid electricity was produced by hydro, 50.9% by diesel generators and the remaining by biomass. However, Fiji's transport sector is completely dependent on fossil fuels with fuel import bill equivalent to an average 58% of export earnings and taking up 21% of total import bill. The smallness of Fiji and dispersed islands within Fiji group leads to many challenges to have accessible, affordable and sustainable energy supply. These challenges are comprehensively discussed in this paper. Strategies such as increasing private-public partnership in renewable energy projects, changing customer behavior, setting up a credible feed-in tariff structure, developing locally owned business in renewable energy and energy efficiency, setting up of risk mitigation facilities and strengthening institutions supporting energy sector are discussed to overcome or minimize challenges.

Nowadays, some Multi-terminal DC (MTDC) systems are in operation around the world. Soon, MTDC grids will be built and overlay the present AC grids. The main driver for the construction of such a grid is to facilitate large-scale integration of remote renewable energy sources to existing AC grids and to develop the energy market. This paper presents a comprehensive analogy between the control and operation aspects of the emerging MTDC grids to those of the traditional AC power grids. Similarities and difference between the two technologies are presented and highlighted. Based on the performed detailed overview, even though a three-layered control system, i.e., primary, secondary, and tertiary control layers is state-of-the-art in large-scale AC power systems, a two-layered control system will satisfy MTDC grids control and operation requirements. This paper also addresses some control and operational issues and limitations of MTDC grids.

As an important renewable energy source, the scale of wind energy utilization is growing rapidly worldwide in recent decades. The increasing capacity of both onshore and offshore wind power generation calls for higher requirements for the power level and reliability of generators and converters. Compared to the traditional three-phase wind power generation, multiphase wind power generation systems have obvious advantages in low-voltage high-power operation, enhanced fault-tolerant ability and increased degrees of control freedom, which help them gaining increasing popularity in modern wind power generation. This paper presents an overview on the multiphase energy conversion of wind power generation and introduces the pertinent technology advances, including the design of multiphase wind turbine generators, multiphase converter topologies, modeling and control of multiphase generators. Besides, this paper offers prospects of novel solutions brought by the redundant control freedom in multiphase system to cope with some difficult technical problems, such as Common-Mode Voltage (CMV) suppression, Low Voltage Ride Through (LVRT), and vibration & noise reduction.

Liquid Air Energy Storage (LAES) systems are thermal energy storage systems which take electrical and thermal energy as inputs, create a thermal energy reservoir, and regenerate electrical and thermal energy output on demand. These systems have been suggested for use in grid scale energy storage, demand side management and for facilitating an increase in renewable power integration into the current power network. This paper presents a comprehensive review of LAES systems, ranging from the first known mention of LAES systems in literature to the most recent studies. This review covers liquefaction systems, power generation systems, integrated systems (combining LAES with other industrial processes) and physical LAES plant demonstrations. Although significant analysis of LAES systems has been done to date, there remains a gap between published LAES literature, and how LAES systems would operate optimally at large scale. To bridge this gap, future LAES research should involve multivariate analysis of LAES systems under dynamic, transient conditions, with the aim of identifying and potential design implications, and to further assess the operational and economic viability of LAES systems in use at large scale. This paper aims to achieve a holistic, critical review of all published work relating to LAES systems.

Global steel production is currently dependent on coal and capital-intensive production facilities with long economic lifetimes. While the Paris Agreement means carbon neutrality must be reached globally by 2050–2070, with negative emissions thereafter, coal-based steel production today accounts for around 8% of global energy-related CO2 emissions. Its production may stabilize or even decline in industrialized countries, but it will increase significantly in the emerging economies. In the past, the focus of CO2 reduction for steel has been on moderate emissions reductions through energy efficiency measures and on exploring carbon capture and storage. However, as (1) the cost of renewable electricity is declining rapidly, (2) carbon capture and storage has not materialized yet, and (3) and more and more countries set deep emission reduction targets, electricity- and hydrogen-based steelmaking has gathered substantial momentum over the past half-decade. Given the short time frame and the sector's deep carbon lock-in, there is an urgent need to understand the national climate and energy policy as well as the current implementation of low-CO2 and renewable electricity that would enable a shift from coal-based to electricity-based steelmaking. In this paper, we first identify the countries that are likely to be major steel producers in the future and thus major CO2-emitters. Then we map medium- and long-term CO2 reduction and renewable targets as well as the current share of low-CO2 and renewable electricity by country. Based on these data, we develop a set of indicators that map the readiness of steel-producing countries for a sustainable transition. Our findings show that although binding long-term CO2 reduction targets are being implemented, medium-term CO2 reduction do not yet affect coal based steel production. Overall, the global steel industry seems not be on track yet, though differences between steel producing countries are large. Common shortcomings across countries are a lack of access to renewable electricity and a lack of demanding medium-term CO2 reduction targets. The paper ends with recommendations on how to enable a low-carbon transition of the global steel industry in line with the Paris Agreement.

Flexibility coming from consumers in residential and service sectors has received significant attention to deal with uncertainty and variability of renewable energy sources. Since these consumers are too small individually to participate in the electricity markets, their assets can be pooled by an aggregator. The aggregator can implement business models by trading flexibility obtained from these consumers’ assets in different electricity markets. However, the aggregator and the consumers are only motivated to implement a business model, if it is economically feasible. The economic feasibility of a business model depends on (1) financial aspects: how much profit the aggregator makes, and how much money the consumers save, and (2) operational aspects: how the consumers’ assets are operated to increase the financial aspects. This paper aims to provide insights in these operational and financial aspects of the aggregator's business models in residential and service sectors. For this purpose, a literature review is conducted, and a framework is presented to analyze the selected papers on these operational and financial aspects. Based on this analysis, different strategies for the aggregator to implement business models are determined. Moreover, knowledge gaps are identified and several recommendations for future research are provided.

This paper is an updated, but totally new, version of “A review on phase change materials (PCMs) integrated in building walls”, an article published in 2011 in Renewable and Sustainable Energy Reviews. Both numerical and experimental studies on building walls containing PCMs during the last ten years (2011–2020) are reviewed. The paper also summarizes the main PCMs used in this application and the recent progress in the integration techniques of PCMs in building construction elements. Most of the proposed studies (about 66%) are focused on PCM in walls. In addition, more than half of these studies are numerical where several assumptions are made such as the neglected of both the occupant presence in the building and its behaviour. Based on this review, it is concluded that the used PCMs in building walls showed good potential for reducing both indoor air temperature fluctuations and energy consumption. However, further numerical and experimental studies are needed that take other aspects into consideration, such as the real use of buildings with the occupant behaviour, the economic viability and the environmental impact. This review paper will help scientific researchers and engineers to update the integration techniques of PCM in building walls and to define potential future research works.

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.

European Commission has set clear targets for 2020 regarding energy and environment policy; these targets include 20% cut in greenhouse gas emissions against the 1990 levels. It is believed that adopted strategy has encouraged the renewable energy applications during the last two decades. Moreover, measurement deviations of carbon dioxide flux occurring in respiration chambers has been seen of a great importance to explain the biochemical parameters affecting the climate change issue. This is attributed on many occasions to chamber design constraints and the way they are coupled with the studied site location. This is illustrated by external disturbances whereby when they happen while gas measurements are taken measurement deviations become more evident. This paper surveys the different soil physical, biological and geotechnical parameters and links them to meteorological ones. Consequently it explores their direct and indirect effects to the produced soil efflux. Furthermore this paper proposes several soil temperature models according to the studied case constraints to see what affects soil efflux production. Moreover a clear understanding of what affects the measurement process was achieved through surveying all the internal and external pressure parameters and how they influence the chamber in relation to time. The conclusion is that respiration chamber designers need to preserve chamber internal temperature and pressure to be equal to the outer atmosphere for the case of stabile external conditions. For the case of unstable external conditions design counter measures are incorporated. Furthermore the appropriate gas sensor needs to be selected professionally with emphasis on the importance of installation location inside the chamber. Likewise soil bacterial type and soil temperature also has an influence on efflux production.

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.

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

This review paper examines pathways towards solar energy in China by examining two different solar energy technologies, namely solar photovoltaic (PV) and solar water heaters (SWH). The paper investigates these two case studies to understand how different pathways for low carbon innovation are promoted and challenged by China's changing financing and policy-making, and how they relate to changing practices among producers and consumers. The paper finds two distinct approaches to solar energy. Chinese solar PV is predominantly produced for the export market, relies on intellectual property-intensive technology and has received much financial and political support from the central and provincial governments. On the other side, solar water heaters are an indigenous Chinese technology that is found everywhere across China, especially in rural areas. They have developed from grass-roots levels to mass products with very little central government support. Although being largely absent from high-level discussions and policies, solar water heaters could contribute a lot to China's low carbon transitions that are driven at the local level.

The harmful effects of carbon emissions and carbon dioxide caused by over dependence on oil is a global issue, which is currently being addressed by encouraging renewable energy (RE) resources contribution to the energy mix. Encouraging RE is important in order to solve the unsustainable nature of electricity generation especially in the sub-Saharan African countries. One of the REs that have vast potential especially in sub-Saharan Africa is the solar energy. This paper provides an overview of the solar photovoltaic (PV) developments in selected countries of sub-Saharan Africa – in terms of research, installed capacity, solar radiation level, RE policies and the percentage of solar PV in the future energy mix of these countries. Finally, this paper identified the barriers to RE deployment and proposed scaling-up solar PV as one of the solution in the development of energy mix in these countries.

Recent interest in the integration of renewable energy sources (RES) into the power grid has raised concerns in synchronization of the various RES. Grid variables such as voltage, phase angle and frequency should be continuously monitored to guarantee correct operation and synchronization of power converters connected to the power grid. Numerous synchronization methods have been presented over the years to address issues such as unbalanced condition and frequency variation. This paper presents a review of past studies on synchronization methods for grid-connected converters together with their control and modeling techniques. Various estimation techniques for phase angle, frequency and harmonic are discussed and examined. Key challenges for a smart and efficient synchronization are briefly overviewed and possible future works are also recommended. A consolidated review is the particular focus of this paper, as is the provision of information on the best method for synchronizing grid-connected converters.

When choosing policy mechanisms to design and deploy energy policies, policymakers typically seek cost-effective ones, linking cost effectiveness to the lowest cost of support for RES-E generation and/or consumer costs. The objectives of this paper are to analyze the cost-effectiveness of renewable portfolio standards (RPS), feed-in tariffs (FIT) and auctions in the short and long term, considering both technology-neutral and technology-specific approaches. Results show that RPS and auctions are more cost-effective than feed-in tariffs (FIT) in the short term if cost-effectiveness is defined as minimizing consumer costs. Also, if one or more emerging technologies with higher levelized life cycle costs (LCC), low cumulative production and high experience elasticity are considered in the pool of RES-E policy design, a technology-neutral approach in the short-term could lock out these emerging technologies, avoiding a long term LCC reduction. In this case, a technology-specific policy used in the short-term would reflect lower total generation policy costs in the long term if compared with a technology-neutral policy in both short and long term. This paper calls this phenomenon the paradox of technology-neutral and technology-specific policies in the long term. Considering the results, this paper suggests a mix of technology-neutral and technology-specific policies using RPS or auction mechanisms to promote RES-E.

This paper presents an overview of the regulatory framework for wind energy in European Union Member States. The analysis covers three main aspects of regulatory framework: support schemes, electrical grid issues and potential barriers for wind power deployment. The aim is not just to provide an updated picture of current (early-2015) regulatory framework, but also to analyse the past evolution and trends (in order to achieve the targets of renewable energy share set for 2020). Each country implements a specific regulatory framework driven by several factors: their own renewable energy targets, local availability of renewable resources, energy mix structure, existing infrastructures as well as other factors such as public perception or geographical distribution of electricity generation and consumption points. The results presented in this paper show a trend for increasing the market exposure of wind generators; feed-in premiums and competitive bidding procedures to establish the support level are gaining prominence in the last few years. In relation to grid issues, it is a common practice that new wind generators only bear the grid extension costs to the closest connection point; priority or guaranteed access is granted in most Member States and wind generators are usually not demanded to meet balancing requirements (this is expected to change in the next few years following the new guidelines provided by the European Commission). The analysis of potential barriers for wind energy deployment shows that the stability of regulatory framework is one of the most important concerns for investors. Finally, actual deployment over the last few years has been linked with evolution of regulatory frameworks. This analysis shows that some Member States have shown a strong commitment supporting wind energy; however, in other countries the support has not been enough to stimulate the desired level of investment.

The application of renewable energy such as solar photovoltaic (PV), wind and fuel cells is becoming increasingly popular because of the environmental awareness and advances in technology coupled with decreasing manufacturing cost. Power electronic converters are usually used to convert the power from the renewable sources to match the load demand and grid requirement to improve the dynamic and steady-state characteristics of these green generation systems, to provide the maximum power point tracking (MPPT) control, and to integrate the energy storage system to solve the challenge of the intermittent nature of the renewable energy and the unpredictability of the load demand. In order to improve the efficiency and the power density of the overall circuit, the use of a three-port DC–DC converter, which includes a DC input port for the renewable source, a bidirectional DC input port for the energy storage system, and a DC output port for supplying the load, is a preferable solution to the traditional method using two DC–DC converters: one for the renewable sources and another for the energy storage system. In recent years, many DC–DC three-port converters have been proposed and reported in the literature. Each of these converters has its own topology and operating principle, which results in different complexities, different numbers of components, different reliability and efficiency. In this paper, a comparison of the features of different topologies of three-port DC–DC converters that have been proposed by different research groups is reviewed briefly. This review can be used as a guide for the appropriate selection of the suitable topology to meet the particular requirement of a system. The paper also discusses the potential research extension of the topologies from three-port DC–DC converters to three-port DC–AC inverters and how the voltage gain of the non-isolated three-port DC–DC converter can be improved.

Environmental change created worldwide interest in investing in renewable energy. Less reliance on fossil fuels would have a substantial influence on investors for alternative energy, especially renewable energy. The literature has concentrated on empirical studies of herding behaviour in finance, but not in renewable energy. This paper fills the gap by investigating herding in renewable energy, using daily closing prices in renewable and fossil fuel energy stock returns in the USA, Europe, and Asia, for March 24, 2000–May 29, 2020, which covers the Global Financial Crisis (GFC) (2007–2009), the coronavirus crises of SARS (2003). And the ongoing COVID-19 (2019–2020) pandemic. The paper shows that: (1) for low extreme oil returns, investors are more likely to display herding in the stock market; (2) for SARS and COVID-19, herding is more likely during extremely high oil returns after the GFC; and (3) herding is more likely during periods of extremely low oil returns during the coronavirus crises. These results suggest that after the GFC, investors are more sensitive to asset losses, so they will be more likely to display herding in the stock market. However, during SARS and COVID-19, investors panic so they may unwisely sell their assets. There are strong cross-sector herding spillover effects from US fossil fuel energy to renewable energy, especially before the GFC, while the US fossil fuel energy market has a significant influence on the Europe and Asia renewable energy returns during COVID-19. During SARS, which was not a pandemic, US fossil fuels only had an impact on US renewable energy returns., Highlights • Environmental change has led to investing in renewable energy as an alternative to fossil fuels. • The literature has concentrated on herding behaviour in finance, but not in renewable energy, so this paper investigates herding in renewable energy for the USA, Europe, and Asia, for the period March 24, 2000–May 29, 2020 that covers the GFC, SARS, and COVID-19. • For (1) low extreme oil returns, herding is more likely in the stock market; (2) SARS and COVID-19, herding is more likely during extremely high oil returns after the GFC; and (3) extremely low oil returns during SARS and COVID-19, herding is more likely. • After the GFC, investors are more likely to display herding in the stock market but, during SARS and COVID-19, investors may unwisely sell their assets. • There are strong cross-sector herding spillover effects from US fossil fuel energy to renewable energy, especially before the GFC.

This paper offers perspectives on the development of low-carbon energy technology in Brazil, pinpointing changes that have occurred since our former publication in 2011. It takes a fresh approach in terms of how likely Brazil will achieve its Nationally Determined Contributions Commitments in the energy sector. Many countries have implemented national climate policies to accomplish their pledged NDC and contribute to the temperature objectives of the Paris Agreement on climate change. Based on official reports and databases of energy development projections in Brazil and the socioeconomic context, we discuss what can be expected for the future of the Brazilian energy sector, the probability of implementing selected technologies, and the prospects of reaching the NDC targets for 2025 and 2030. In addition, this paper provides an overview of the current stage of development of these technologies, main directions, and bottlenecks in Brazil. Analyses have shown that the Brazilian renewable matrix tends to remain significant, driven by the development of solar and mostly small hydroelectric power sources, as well as different types of biomass. In addition, the system will include the replacement of thermoelectric plants powered by diesel and fuel oil by natural gas plants. The prospects for Brazil's official energy plan for 2027 are aligned with the reference technology scenario, which represents the business as usual scenario. Despite this, low-carbon technologies could be implemented far beyond the NDC's goals, given the abundance of renewable natural resources in the country., Highlights • Prospects for low-carbon technologies in Brazil are lacking. • RenovaBio Law may promote bioelectricity production from sugarcane bagasse. • Small hydro will play an important role in the achievement of Brazilian NDC for the hydroelectric sector. • Wind power is developing rapidly, but still substantial room for growth. • Solar power is developing slower than expected.

This paper provides an overview of available innovative shape morphing building skins and their design principles. In particular, the proposed review deals with comfort-related issues associated with dynamic solar shading devices, building integration of smart materials, and morphological analyses related to the most recent shape morphing solar skins. In the first part of the paper, an introduction to the typologies of movement in architecture, its concept and application are presented. An explanation of biomimetic principles together with an overview of user’s response to dynamic shading devices is also provided. This is followed by the description of the design principles for shape morphing solar shadings with particular focus on energy and comfort aspects, smart materials and biomimetic principles for efficient movements. A review of most recent developments on the topics of comfort, users’ response and control of dynamic shading devices, is presented and summarized in a comparison table. The main technical and mechanical properties of the most diffused smart materials (Shape Memory Alloys, Shape Memory Polymers and Shape Memory Hybrids) that can be used for innovative shape morphing solar skins are illustrated in detail and compared. Biomimetic principles for efficient movements complete this part of the work. The principles illustrated in the previous part of this paper are then used to critically analyse the most recent examples of building integrated shape morphing shadings.

© 2015 Elsevier Ltd. The inertia of today's power system decreases as more and more converter connected generation units and load are integrated in the power system. This results in a power system which behaves differently from before which causes concerns for many grid operators. Therefore, a detailed study is needed to investigate the relevance of this inertia in the operation, control and stability of the system. Moreover, a new definition of the term system inertia is necessary since is it expected that in the future also the renewable electricity generation units will deliver the so-called virtual (synthetic) inertia. In this paper a review of the research related to inertia in a power system is given. Both the challenges as the solutions from an operator point of view to control a system with low inertia are discussed. Also a new definition of inertia is proposed to incorporate the different forms of inertia which are each described in more detail. From recent studies, it can be concluded that the influence of reduced inertia on frequency stability is generally considered as the main challenge for system operators, but with the additional measures listed in this paper, this impact can be mitigated. publisher: Elsevier articletitle: The relevance of inertia in power systems journaltitle: Renewable and Sustainable Energy Reviews articlelink: http://dx.doi.org/10.1016/j.rser.2015.11.016 content_type: article copyright: Copyright © 2015 Elsevier Ltd. All rights reserved. ispartof: Renewable & Sustainable Energy Reviews vol:55 pages:999-1009 status: published

© 2015 Elsevier Ltd. All rights reserved. This paper assesses competing outlooks for energy mix in the Association of Southeast Asian Nations (ASEAN), highlighting the paradox of its fossil fuel-dominated outlooks when contrasted with its aspirations to move toward a green energy mix, and reviews green energy strategies using the strengths, weaknesses, opportunities, and threats (SWOT) analysis method. The paper argues that despite the looming brown outlooks due to the expected surge of coal, the ASEAN region has many advantages in providing cleaner energy for its green vision. However, reduction of CO2 emissions has not been explicitly set in the region's policy agenda and thus green energy potential is underdeveloped. To achieve a greener energy mix, ASEAN needs to make further efforts such as cleaner use and removal of subsidies of fossil fuels, promotion of renewables and energy efficiency, regional market integration and connectivity, and execution of existing plans by nations. Ultimately, each of these strategies will require sustained leadership, political determination, and concrete actions from stakeholders, in particular, national governments across the region.

A sustainable energy system can be treated as a development of the distributed generation concept. It meets energy demands locally from renewable energy or/and high-efficiency polygeneration production technologies, and is characterized by energy and cost efficiency, reliability, and environmental-friendliness.Distributed energy systems typically use renewable energy resources to supply all energy demands, such as heat, cooling, and electric power in an integrated way. However, it seems that too much emphasis is placed on power and associated renewable energy-based power technologies for dealing with sustainability issues in public discussion and the research community. Often, equally important thermal energy (heat and cooling) and polygeneration are ignored. Polygeneration is an energy- efficient technology for generating simultaneously heat and power as well as other energy products in a single integrated process. Energy efficiency contributes significantly to CO2 emission reduction. This paper discusses the role of polygeneration in a distributed energy system and the contributions of polygeneration to the development of sustainable energy systems. The paper also stresses that efficient decision support tools for sustainable polygeneration systems are important to achieve sustainability. First, the joint characteristic of a polygeneration plant that defines the dependency between different energy products is reviewed. Then, typical methods for dealing with polygeneration systems are reviewed. The review attempts to highlight the complexity of polygeneration systems and potential of polygeneration systems to adjust output of different energy products. Next, the challenges of sustainable polygeneration energy systems are discussed. Then some practices for operating polygeneration plants are discussed.

LBNL-XXXX Costs and Benefits of Renewables Portfolio Standards in the United States by Galen Barbose, 1 Jenny Heeter, 2 Lori Bird, 2 Samantha Weaver, 1 Francisco Flores-Espino 2 , and Ryan Wiser 1 Lawrence Berkeley National Laboratory National Renewable Energy Laboratory Corresponding Author Galen Barbose, Research Scientist Electricity Markets and Policy Group Environmental Energy Technologies Division Lawrence Berkeley National Laboratory 1 Cyclotron Road, MS 90R4000 Berkeley, CA 94720 Phone: (510) 984-3453/Email: GLBarbose@lbl.gov Abstract As state-level renewable portfolio standards (RPS) have driven large increases in U.S. renewable generation capacity, states have sought to quantify the costs and benefits of these policies. This paper examines recent costs and benefits of RPS implementation, focusing on the net (or incremental) cost to utilities of renewables used for compliance with RPS targets during the years 2010-2012. Incremental RPS cost estimates are developed using a wide variety of methods and assumptions, which makes comparisons among states imperfect. For states with restructured electricity markets, we use a standardized method to calculate incremental costs based on renewable energy certificate prices, alternative compliance payment levels, and compliance obligations. For states with traditionally regulated electricity markets, we rely on estimates produced by utilities and regulators, whose methods and underlying assumptions vary widely. We find that recent estimated incremental RPS costs were equivalent to less than 2% of retail rates in 17 states and about 2%–4% in eight states, or -$4/MWh to $48/MWh of renewable energy required across all states (for the most recent year available in each state). Estimated RPS costs in most states were well below the respective cost caps, although a few states are currently operating at or near their cap. 1. Introduction Twenty-nine states, Washington DC, and Puerto Rico have adopted renewables portfolio standards (RPS), helping drive a roughly eight-fold increase in U.S. renewable generation capacity over the past decade. Concern over the impact of these policies on electricity prices and economic growth, however, has spurred recent legislation in at least a dozen states to repeal, reduce, or freeze existing RPS requirements. At the same time, other recent legislative proposals have sought to expand state RPS policies. Understanding the actual historical costs—and benefits—of RPS policies is critical to informing these legislative debates, but the subject is inadequately understood. This paper examines historical costs of RPS implementation, drawing on a recent joint report by Lawrence Berkeley National Laboratory and the National Renewable Energy Laboratory, Estimating the Costs and Benefits of Complying with Renewable Portfolio Standards: Reviewing Experience to Date (Heeter et al. 2014). 1 We summarize the methods state agencies and utilities have used to assess RPS costs, compare incremental RPS compliance costs to date, and evaluate the potential for increases in RPS compliance costs as legislative targets rise and cost caps in some states potentially become binding. The aforementioned report also synthesizes recent estimates of broader societal benefits from formal state-agency evaluations— including estimates of health and emission reduction benefits, economic development benefits, and wholesale electricity market price reductions—though those findings are not included in the present paper. Compared to the summary of estimated RPS costs, the summary of RPS benefits is more limited, as relatively few states have undertaken detailed benefits estimates, and then only for a few types of potential policy impacts. In some cases, the same impacts may be captured in the assessment of costs. For these reasons, and because methodologies and level of rigor vary widely, direct comparisons between the estimates of benefits and costs are challenging. 2. Methods and Data Sources for Estimating Incremental RPS Compliance Costs RPS compliance costs may be defined as either “gross costs” or “incremental costs.” Gross costs consist of the total cost of procuring renewables to meet the RPS, while incremental costs (also referred to as “net” or “above market” costs) represent This report is publically available at http://emp.lbl.gov/publications. Participation by Lawrence Berkeley National Laboratory was supported by the Office of Energy Efficiency and Renewable Energy (Solar Technologies Office) of the U.S. Department of Energy under Lawrence Berkeley National Laboratory Contract No. DE-AC02-05CH1131.

Wind energy is an important contributor of modern power systems as a renewable energy source. However, wind energy poses new challenges because of its unique characteristics, such as limited predictability, short-term and long-term variability and close-to-zero marginal cost. This paper puts forward the critical aspects of wind energy systems in respect to the transformation of the power system into a "smart grid". Issues discussed include the electro-mechanical matters like the selection of wind turbine technology, the structure of wind system, the robustness of mechanical parts (gear box and blades) and fault diagnosis. In addition, the system operational challenges such as complexity, instability, unbalance loading, grid interactive problems and impact of wind energy on power system are discussed in this paper. Moreover, the economical subjects such as investment costs and energy management, communication requirements, and security are involved as important titles. Finally, environmental aspects of wind energy are also highlighted to show that the wind energy is an environmentally friendly energy source since it is sustainable, clean and safe. (C) 2015 Elsevier Ltd. All rights reserved.

Confronted by increasingly tight budgets and a broad range of alternative options, policy makers need empirical methods to evaluate the effectiveness of policies aimed at supporting the diffusion of renewable energy sources (RES). Rigorous empirical studies of renewable energy policy effectiveness have typically relied on panel data models to identify the most effective mechanisms. A common characteristic of some of these studies, which has important econometric implications, is that they assume that the contribution of RES to total electricity generation will be stationary around a mean. This paper reviews such assumptions and rigorously tests the time series properties of the contribution of RES in the energy mix for the presence of a unit root. To that end, we use both individual and panel unit root tests to determine whether the series exhibit non-stationary behavior at the country level as well as for the panel as a whole. The analysis, applied to a panel of 19 OECD countries over the period 1990–2012, provides strong evidence that the time series of the renewable share of electricity output are not stationary in 17 of the 19 countries examined. This finding has important implications for energy policy assessment and energy policy making, which are discussed in the paper.

The use of renewable energy is projected to increase substantially in the European Union to reach a share of 20% in final energy consumption and 10% renewable energy in transport by 2020. The renewable energy contribution is further expected to increase to 55%–75% of gross final energy consumption in 2050. According to the latest reports, the European Union has made significant progress since 2005 and is on track to reach its 2020 renewable energy targets. This paper provides a review of the policy framework for renewable energy in the European Union and an analysis of the progress made by the use of renewable energy as well as the expected developments until 2020 and beyond. It focusses on the contribution of bioenergy, the major source among renewables in the European Union. As biomass availability is a critical issue for the bioenergy production, this paper provides an analysis of the biomass demand for reaching the 2020 targets, in relation with the expected domestic supply and biomass potential.

The development and exploitation of sustainable and environmentally friendly energy sources are required in order to resolve global energy shortages and to reduce the reliance of many countries on fossil fuel combustion. Salinity gradient energy has been considered a potential candidate for renewable energy due to the abundance of saline waters that could be combined with less saline solutions across the globe. Pressure Retarded Osmosis (PRO) is one of the technologies to harness salinity gradient energy. Apart from zero carbon dioxide emission, PRO is capable of producing power with less periodicity, abundance and low environmental impacts. One of the preconditions for the technical and financial feasibility of PRO, however, is the development of a PRO-specific membrane—one that meets the conditions that none of the current commercially-available membranes have met so far. The current paper discusses the progress made in PRO membrane development, particularly during the past decade, and analyses the challenges that are still hindering the implementation of PRO at large scales. Also, this paper explores possibilities for the implementation of PRO by analysing various combinations of existent solutions of various salt concentrations. Australia has been chosen to demonstrate some potential applications of PRO. This vast country has extensive reserves of saline waters that could be paired with less concentrated solutions to generate power. For each combination of solutions, a conceptual idea is presented, and an estimate of power production is given. Also, advantages and disadvantages of each scheme are discussed. The ideas and estimates can be easily extrapolated, with minor adjustments, to other countries with similar conditions. It is hoped that this publication will be valuable to those nations that have similar policies as Australia’s, with government incentives for the development and implementation of new technologies to explore new renewable energy sources.

The present global energy scenario, in which fossil fuels play a preponderant role, faces significant energy and environmental challenges. To help address these challenges, countries across the world are increasing the contribution made by renewable energy (RE) resources to their energy supplies. Feed-in Tariff (FiT) is one of the most effective incentive policies used to promote the RE sector especially at the micro-generation level. The key objective of the FiT schemes is to provide financial support to residential, industrial and commercial consumers to encourage them to become RE producers. Solar photovoltaic (PV) is one of the most promising RE technologies. This paper provides an overview of the solar PV developments in the Association of South East Asian Nation (ASEAN) countries. It reflects upon the RE trends in the world as well as providing an introduction to the ASEAN countries. It reviews the progress of solar PV in each of the ASEAN countries especially in terms of RE policies, growth in terms of PV installations and research and development activities. Finally, the paper presents conclusions and a set of recommendations. Out of the 10 ASEAN countries, 5 have implemented FiT as a key policy incentive to stimulate the progress of RE. It is found that the ASEAN countries have great potential for solar PV in term of their annual solar insolation levels, which ranging from 1460 to 1892 kWh/m2 per year.

It is widely acknowledged that many renewable energy technologies cannot (yet) compete with incumbent (fossil fuel) options e.g. in terms of price. Transitions literature argues that sustainable innovations can nevertheless break out of their ‘niches’ if properly shielded, nurtured and empowered. Most studies using this perspective have focused on how innovation champions engage in shielding, nurturing and empowering (SNE) activities: none have so far focused specifically on the role that policy plays in relation to these three processes. This paper therefore aims to analyze the way in which policy constrains and enables the shielding, nurturing and empowering of renewable energy innovations. To do so, it presents a qualitative review of the development of offshore wind power (OWP) in The Netherlands over the past four decades. Based on interpretation of a wide variety of written sources (academic histories, reports, policy documents, parliamentary debate transcripts, news media) and nine semi-structured interviews, it discerns six periods of relative stability in the history of Dutch offshore wind. It then analyzes the effects of various policies on the shielding, nurturing and empowering of offshore wind in these periods. The paper contributes to transitions literature (1) by providing an analysis of how policies can enable and constrain the shielding, nurturing and empowering of renewable energy innovations, and (2) by bringing together, for the first time, fragmented accounts of the surprisingly long history of Dutch offshore wind development and implementation. Both contributions are timely, given the recent reprioritization of OWP on the Dutch policy agenda.

For decades, Ghana’s economy has been fuelled by abundant inexpensive hydropower. As a developing economy, Ghana’s electricity demand has long been relatively low, though rising in recent times due to increasing economic growth, urbanization and industrial activities. However, the rapid demand growth, as well as periodic hydrological shocks, leaves the country increasingly reliant on expensive oil and gas-based generation power plants, with a resultant drain on the national economy. The main electricity generation company, the Volta River Authority, is not able to generate enough electricity for all the demand sectors. The electricity supply-demand margins - the difference between peak demand and available supply - of the country fall short of the recommended engineering practice and thus presents a high supply security risk. The country has been experiencing an increase in the frequency of power cuts over the last ten years. It is clear that Ghana will have to expand and diversify its generation capacity in order to improve supply security. This paper provides a review of the assessed potential renewable energy resources, their current exploitation status, and their potential contribution to the electricity supply of the country. The paper also presents the barriers to their utilization and the existing policy and regulatory instruments to overcome those barriers, plus the current and expected future impacts of these instruments. The results show that Ghana has several RES, such as wind, solar PV, mini hydro and modern biomass that can be exploited for electricity production. While their exploitation for electricity generation is currently very low, providing just 0.13% of the country’s generation, the review shows a great potential for RES generation to increase substantially over the next decade, looking at the government commitment and legal frameworks that are being put in place.

Microgrids have emerged as a prospective framework that integrates renewable energy sources, energy storage systems, and loads. They can be addressed as a local distribution system with distributed generators (DGs) and have the potential to improve power quality, reliability, and energy efficiency to their consumers in a grid-connected or islanded mode. However, in order to implement microgrids or distribution systems with DGs, some challenges should be faced, especially concerning protection issues. The possible operating modes and the presence of distributed energy resources may make conventional protection schemes ineffective. Therefore, new protection schemes have been developed in the context of microgrids, including the cases of distribution systems with DGs. Thus, this paper presents a comprehensive survey aiming at studies considering this kind of protection. Emphasis has been given to studies associated with adaptive protection, considered by some researchers as a promising solution for microgrid protection. For this purpose, firstly, a microgrid structure is briefly presented. Afterwards, some challenges related to the protection of these systems are also addressed. Moreover, a brief overview of adaptive protection is provided, and then the newly developed schemes found in the technical literature are described. It is worth mentioning that a bibliometric analysis is also presented in this paper, highlighting a substantial growth in publications concerning adaptive protection. Nevertheless, it can be observed that more effort is still needed to obtain a complete solution for the protection of microgrids and distribution systems with DGs. Further attention to matters such as communication failures, cyberattacks, and the presence of energy storage systems should emerge in the next few years.

Remote area power supply (RAPS) systems are being used for many years to supply power to rural or remote communities where the utility grid is not accessible. In order to avoid the high operating cost and environmental impact caused by conventional generators, renewable energy resources are currently being utilised in RAPS systems. However, the intermittency of such renewable energy resources greatly impacts on planning and operation of RAPS systems. This paper aims to present a comprehensive review with regard to the RAPS system planning and operation techniques published in the literature. This paper summarises different modelling approaches associated with the RAPS system architectures, pre-feasibility studies for energy potential analysis, component modelling, unit size optimisation approaches, and system control aspects. In addition, technical challenges associated with RAPS systems, such as system sizing, voltage and frequency control and coordination of different system components are also highlighted in the paper. Moreover, further research avenues with regard to various different aspects of RAPS systems are also delineated in the paper.

This paper presents an overview of the Malawi energy situation and the potential of renewable energy resources including solar, wind, biomass, hydro and geothermal. Despite a range of efforts by local and international stakeholders to increase access to modern energy sources in the country, 89 per cent of Malawi׳s energy is still sourced from traditional biomass mainly fuel wood. Only 8 per cent of the population in Malawi have access to electricity but installed capacity of electricity generation is lower than demand. This leads to load shedding by the electricity supplier; consequently electricity supply in Malawi is unreliable and micro and macroeconomic activities are significantly affected. Solar, non-traditional biomass (crop residues and forest residues not burnt on three stone fireplaces, and biogas), hydro, wind and geothermal are potential energy resources that could enhance Malawi׳s energy security. However, unreliable financing mechanisms for large scale energy projects; shortage of trained human resource; lack of coordination among local institutions; unclear regulation enforcement; and sometimes political governance impede sustainable delivery of energy projects. The Malawi energy policy targets and drivers are also discussed in the paper. Based on the prevailing energy situation, a PESTLE analysis is provided in this paper outlining a novel thinking for addressing the political (P), economic (E), social (S), technological (T), legal (L), and environmental (E) challenges that constrain the development of renewable energy technologies in Malawi.

A smart grid is a system that uses information and communication technologies to integrate, in an intelligent way, the behaviour and actions of all users connected to the electrical power system. For this purpose, information about the electrical network, such as the current, the voltage or the power, is gathered together over time so that the behaviour of suppliers and consumers can be observed and automatically coordinated. Smart grids are becoming an important element in the configuration of future electrical power systems. A lot of research has been done on using smart grids to achieve highly efficient and user-friendly electrical power systems. Many new methods have been introduced to solve the difficulties energy providers face when transforming conventional electrical networks into smart grids. These difficulties include the integration of renewable energy and different grid systems at national and international levels due to changes in frequency, voltage and in the synchronisation mechanism. This paper provides an outline of the European smart grid projects and gives an overview of the current infrastructure and smart grid applications of the Turkish Electricity Production Company (EUAS), Turkish Electricity Transmission Company (TEIAS), and Turkish Electricity Distribution Company (TEDAS). In this paper the feasibility of the further steps required is described and some assessments are made and suggestions given on smart grid developments in general., JRC.F.3-Energy security

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

Research on climate change impacts on renewable energy is becoming increasingly relevant due to the vulnerability of the sector and to the continual development of methodologies and availability of data. Public and private decision-making needs specific research. However, many gaps still exist in certain geographical regions and technologies. Providing economic estimates with a value chain perspective are also missing from most papers. This paper addresses the most relevant studies that project quantitative estimates of climate change impacts on solar, wind, hydro and other renewable generation technologies. Summary tables of impacts and projections are provided so that researchers, governments and the private sector may have an accurate view of the state-of-the-art on this topic.