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An enormous gap exists between Africa's current electrification rate and the 2030 UN goal to ensure universal access to modern energy. A study by Sanoh et al. published in Renewable Energy in 2014 [1] is a rare example of finding a cost minimal solution for the Africa-wide generation and transmission network. Unfortunately, however, the paper exhibits a number of relatively serious flaws that demand attention given the alarming paucity of such research on Africa. Five issues of the study by Sanoh et al. are identified and discussed in this commentary paper. Specifically, the study does not account for capacity factors when deriving required capacity additions, misses transmission losses when sizing generation capacity, models country-level import constraints incorrectly, introduces a supply option redundancy, and reports optimisation results that can be shown to be mathematically sub-optimal. As a result of some of these issues, the Sanoh et al. significantly underreport the required capacity to meet additional African demand in 2025. In addition to discussing these flaws, this paper provides potential approaches to avoid each of the five issues. [ABSTRACT FROM AUTHOR]

The challenge of global warming requires deep decarbonization of the electricity system, which can be achieved with a higher share of renewables in the electricity mix. However, the driving mechanism for renewable penetration in electricity production has not been clearly revealed so far. Using the data of the European Union (EU) during 2001–2017, this paper aims to investigate the spatial-temporal heterogeneity and dynamic evolution mechanism of renewable electricity penetration. To this end, from the investment-production-consumption perspective, renewable electricity generation is decomposed into seven factors through temporal and spatial factor decomposition methods. Then, this paper integrates the factor decomposition results into a coupling elasticity analysis to study the dynamic evolution mechanism of renewable penetration in electricity production. The results are as follows. (1) Investment structure contributes the most to increasing renewable electricity generation, while the energy intensity effect and renewable generation-to-capacity ratio effect are the main reasons for the reduction in renewable electricity generation. The effect of technological structure is minor. (2) The economic scale effect and the investment structure effect are dominating factors accounting for the regional difference of renewable power generation between the EU countries and the benchmark region. (3) The progress of renewable electricity penetration accelerates over time for the EU, western EU, and eastern EU. The Western EU has realized remarkable progress in facilitating renewable electricity penetration during 2009–2017. (4) On the whole, the investment effect makes the largest contribution to promoting renewable electricity penetration, while the production effect is the major inhibiting factor, showing that there is considerable potential in renewable generation efficiency improvement in the EU. This paper provides insightful implications for energy policies aimed at the shift towards a low-carbon electricity system in the EU, which also gives a reference for other economies. [ABSTRACT FROM AUTHOR]

The difference between the scheduled and actual generation of electricity leads to disruption on the balancing markets that must be paid at the deficit or surplus price. To smooth and simplify the market interactions, each license holder (producer, large consumer, supplier, grid operator) must be a member of a Balancing Responsible Party (BRP). We propose an improvement of the method for transparently and equidistantly setting the imbalance, cost - revenue allocation at the level of BRPs to increase the competitiveness among them. The proposed allocation method is compared with two existing methods implemented by two representative BRPs in Romania. The novelty of our approach consists in fairly rewarding the BRP members that reduce the cost or penalizing those members that diminish the revenue using indirect cost and revenue and implementing the penalty/reward principle. In this paper, we prove that BRP members benefit from cooperating and BRP minimizes the costs of imbalances between the schedule and real-time electricity delivery. The gain of BRP members (BRPi) may vary from 19 to 226%. Furthermore, we simulate that by adjusting the initial imbalance with only 2 or 3 units (equivalent with a smaller imbalance), the costs considerably decrease by 23.7%, 35.6% respectively. • Balancing Responsible Party (BRP). • Cost-revenue of allocation methods. • Implementation of principle penalty/reward using direct and indirect cost and revenue. • Fairly rewarding the BRP members that reduces the cost or penalizing those that diminish the revenue. [ABSTRACT FROM AUTHOR]

This article analyzed the location and concentration of forest bioelectricity in Brazil, from 2000 to 2019, available from the National Electric Energy Agency (ANEEL) and used the following indicators: Location Quotient (QL), Concentration Index [CR (k)], Herfindahl-Hirschman Index (HHI), Hoover Index (H) and Coefficient of Gini (G). The main results showed that the supply of electricity from Brazilian forest biomass increased from 562.90 MW and 11 thermoelectric plants in 2000 to 3532.61 MW and 115 thermoelectric plants in 2019, providing an average growth of 10.15% yy of the granted installed power and 13.20% p.a. of thermoelectric power plants. The QL inferred a high concentration of energy supply from black liquor (Rio Grande do Sul, Paraná, Espírito Santo, Bahia, Maranhão and Mato Grosso do Sul) and forest residues in several states, mainly in the North region. At the state level, the CR (4), CR (8) and HHI indexes indicated a deconcentration trend. The identification of the location and concentration pattern that the greatest offer was associated with industrial pulp and paper complexes. These results can indicate to investors the impact of electric power generation in the sector and the most relevant location for the installation of new thermoelectric plants. [ABSTRACT FROM AUTHOR]

This paper investigates and optimises the thermal performance of deep closed-loop heat exchanger (DCHE) systems by applying a computational numerical approach. The investigated DCHE configuration accounts for two deep vertical boreholes, an injection and a production well, connected by a horizontal borehole at depth and an insulated pipeline at the surface, establishing an effective closed-loop system. First, a parametric sensitivity study explores the effects of the environmental, design and operating variables on the production temperature. The simulation uses realistic geological and geothermal conditions, depths, circulation rates and injection temperatures. Two complex numerical models are then solved for site-specific DCHEs in different geological scenarios: a foreland basin and a convergent margin hosting low-to-intermediate and high-temperature geothermal resources, respectively. Production temperatures beyond 40–60 °C and 100 °C, sustainable for both heat and electric power generation, are obtained, depending on the geothermal conditions and closed-loop dimensions. Furthermore, circulation rates of 0.02–0.04 m3 s−1 are cost-effective, and the system's efficiency and sustainability increase when a fluctuating and periodic heat extraction strategy is employed. When efficiently operated, DCHEs are a viable solution for renewable energy production and should be integrated into the local heat market and distribution network infrastructure. Earth and Planetary Sciences; Energy; Environmental Sciences • Reuse of dry and depleted abandoned wells to boost geothermal energy production. • Deep closed-loop heat exchanger (DCHE) as innovative technological solution. • Computational numerical approach for DCHE performance optimisation. • Sustainable closed-loop configuration for synthetic and real case studies. • Long-term DCHE thermal performance improvement by monthly rotation practice. [ABSTRACT FROM AUTHOR]

At present, energy represents a key element in the social and economic development of a territory. This is particularly true for fragile territories that are not interconnected, such as small island states. As is true for many of the Small Island Developing States (SIDS) worldwide, the energy situation of the Comoros is substantially based on fossil fuel imports. The socioeconomic development of this archipelago is overwhelmingly dependent on energy security from sustainability, availability and affordability perspectives. As a forward-looking response to energy vulnerability, the deployment of renewables to diversify the generation of electricity appears to be an essential prerequisite for guaranteeing a sustainable future. Nevertheless, despite a high potential for renewable energy, only 3.8% of the electricity supply in the Comoros is provided by hydropower. This paper provides a comprehensive overview of the energy situation throughout the Comoros and focuses on renewable energy opportunities to facilitate the supply of green power. This study ultimately shows that renewable energies are rarely exploited despite the powerful potential of different resources. Finally, this paper attempts to provide recommendations for the Comoros to pursue a more sustainable future. • Analysis of the current energy situation of Comoros. • Defining renewable potential and ongoing actions. • Analysis of the specific barriers and policy to the development of RES in the Comoros. [ABSTRACT FROM AUTHOR]

This paper presents an overview of current electricity generation and consumption patterns in the Arctic. Based on published data and new data collection this paper provides an overview of the installed capacity per energy source. A more detailed view of electricity systems is also presented, showing how different types of resources can be used and combined within Arctic communities. The paper briefly discusses which aspects of transmission systems are of special interest under the harsh climatic conditions of the Arctic. A description is given of the various electricity generation technologies that have been proven to be effective for use in Arctic environment, and those that are currently in use, including diesel, hydropower, photovoltaic, and wind power, in addition to discussion of different back-up options. Furthermore, for a more holistic view concerning such energy systems the socio-economic dimension is addressed with a focus on energy security, through an investigation of energy availability and affordability in the Arctic. The availability of energy in the harsh Arctic environments can be crucial for survival and affordability, and can have a huge impact among low-income communities. • Overview of current electricity generation and consumption patterns in the Arctic. • Potential use of different energy resources in the Arctic. • Arctic Energy security. • Socio-economic dimension of energy systems in the Arctic. [ABSTRACT FROM AUTHOR]

As countries implement renewable energy policies, it's important to understand the impacts of policies on sustainability. Population, economic and production changes affects in land use, water consumption and emissions along with trade-offs for limited resources to achieve food and energy security. Thailand faces increasing electricity imports and agricultural production, causing residue burning, a resource utilized for electricity generation. Thailand implemented a renewable energy policy and another to curb sugarcane residue burning addressing above challenges. The paper uses an extended input-output model in Thailand and the Northeast to understand impacts of these policies on output, labor income, employment, land and water use, etc. The study concludes these policies lead to supplementary increase in income, employment and value added contributing towards achieving SDGs through energy security, climate action, decent work and economic growth. At a national level, renewable energy policy is unable to capture a large potential of biomass electricity, while the no burn policy is better able to achieve sustainability through total output, income, employment, and water use. The renewable energy policy in Northeast Thailand is better able to capture the electricity potential. The Northeast also sees land use shifts from rice to cane, which could cause food security challenges. • Thailand faces growing challenges with energy security and crop residue burning. • To address the challenges, they implemented RE policies and crop burning policies. • The study uses extended input-output models in Thailand and Northeast Thailand. • We see positive effects of the policies on the economy, society and environment. • The policies fall short in capturing the full potential of biomass electricity. [ABSTRACT FROM AUTHOR]

Several studies calculate the potential of renewable energies throughout the world. However, these studies vary in the underlying assumptions and do not consider several technologies within a uniform methodology, which affects comparability. In this paper, we calculate the worldwide potentials of ground-mounted photovoltaic (PV), concentrated solar power (CSP), and wind onshore and offshore on a 6.5 by 6.5 km grid. The results consist of installable capacity, generated electricity, and specific cost of electricity generation. Our methodology combines high-resolution data for land uses, slope, and hourly weather data with a thorough analysis of different factors for wind power, like hub heights and rotor diameters, and solar power plants, like tilt angle, and temperature-related loss of efficiency. The results show that the summed-up potential capacity of ground-mounted PV surpasses the amount of CSP, wind onshore and offshore combined with 450 TW. Given the cost-potential curve, ground-mounted PV reaches 560,000 TWh at costs below 20 €/MWh, which is twice the projected worldwide primary energy supply of the World Energy Outlook 2022 for the year 2050 with 205,557 TWh. The calculated results can function as input factors for energy system models, which are an important tool to analyse the energy transition. • Model-based global renewable potential calculation. • Calculation of capacity, electricity generation and costs for four technologies. • Results show technical potentials of 662,740 TWh for ground-mounted PV. • Ground-mounted PV shows potentials of 560,000 TWh at costs below 20 €/MWh. • Most cost efficient ground-mounted PV and CSP potentials can be found in Chile. [ABSTRACT FROM AUTHOR]

This paper combines underwater concentrating photovoltaic and air gap membrane distillation, enabling the simultaneous production of electricity and potable water in underwater environments. Given its submerged nature and absence of land occupation, it proves particularly advantageous for land-deficient regions with limited access to electricity and potable water, such as islands and Coastal cities. It primarily comprises innovatively designed underwater solar concentrators featuring extensive light interception angles, photovoltaic modules, and membrane distillation units. It utilizes exhausted heat from photovoltaic modules to separate clean water from seawater via membrane distillation process. Furthermore, it is engineered to prevent any contact between metal materials and seawater, thereby mitigating the risk of corrosion. An experimental setup with photovoltaic cells' areas of 0.006 m2 is developed and tested in the laboratory and under real weather conditions to assess its performance. The steady-state experimental findings indicate that as solar irradiation increases from 500 W/m2 to 900 W/m2, its electricity generation efficiency ranges from 9.0% to 9.7%, while the water yield efficiency ranges from 32.8% to 35.1%. Besides, outdoor experiments demonstrate that its power output during normal incidence ranges from 38.89 W/m2-85.56 W/m2, with an average electrical efficiency of 10.5%. Its average potable water yield reaches 0.537 kg/m2/h and average water production efficiency reaches 48.3%. [ABSTRACT FROM AUTHOR]

Decentralised grid-connected photovoltaic systems (DGCPS) have proved to be an alternative to traditional electricity generation because they have introduced advantages to power systems, such as reducing electrical losses, relieving transmission and distribution lines, and provisioning ancillary services. Despite all these benefits, a new class of problem concerning DGCPS has been reported in the literature. From the utilities' point of view, the installation of a DGCPS may lead to an apparent degradation of the load power factor. This effect does not have physical causes, i.e. equipment malfunction or overuse of reactive power by the load, although it may lead to reactive power excess charging (RPEC). Since these charges could lengthen the payback of PV installations, this paper aims to assess three strategies to tackle this issue. The first strategy, which has demonstrated to be best for prosumers, is a new regulatory scheme for reactive power monitoring in consumer units with DGCPS. The other two solutions are classical approaches based on reactive power compensation from PV inverters or capacitor banks. For these two last solutions, this paper provides an innovative and optimized way of operation that can adjust the load power factor measured by the utility in real-time, minimizing economic losses. Image 1 • We tackle the apparent degradation of the power factor that is caused by PV systems. • The proposed solutions can avoid reactive power excess charges for PV owners. • We got an ideal power factor for PV inverters to minimize active power curtailments. • PV systems can reduce the apparent power in the grid and reduce electrical losses. [ABSTRACT FROM AUTHOR]

The microbial fuel cell (MFC) is an electrochemical electricity generation device that uses microorganisms to degrade organic matter to produce electrical energy. However, due to the limited charge generated by microorganisms, the output power of MFC is relatively low. Additionally, as a traditional MFC, it cannot store charge. In this paper, we designed and developed a dual-function capacitive MFC anode, which could generate electricity and store energy simultaneously. The capacitive anode was prepared by the direct growth of polypyrrole and ferric oxide on the carbon felt matrix, and the two materials played a synergistic effect. The power density of MFC equipped with the CF/PPy/Fe 3 O 4 -modified anode reached 6.61 W/m3, 29.8% higher than that of the CF/Fe 3 O 4 anode. When in the charging-discharging 45 min test(C45/D45), the total charge Q t released by the CF/PPy/Fe 3 O 4 anode was increased by 1431.74 C/m2 compared with the CF/Fe 3 O 4 anode. In this paper, the method of preparing a dual-function capacitive bioanode could store the electricity generated by microorganisms in the capacitive anode, which greatly improved the current output of MFC and solved its low output power problem. Schematic diagram of microbial fuel cell structure. [Display omitted] [ABSTRACT FROM AUTHOR]

The choice of a power plant in different nations depends on the required resources availability, abundance, and reliability. It is evident that renewable energy generation resources provide a more sustainable solution than the fossil fuels. However, as a complete system, renewable energy generation systems also have some overall environmental impacts on humankind and ecosystems. The main objective of this paper is to addresses the environmental effects caused by different types of renewable energy generation systems through process-based life-cycle impact analysis. A comparative study is carried out among different renewable energy generation technologies which include wind, photovoltaic, biomass, and hydro power. Life-cycle impact analysis has been carried out by Institute of Environmental Sciences (CML), Eco-indicator 99, Cumulative Energy Demand (CED) and Ecopoints 97 approaches. The superiority of this work is creating a comprehensive life-cycle inventory following a reliable global database, assessing the impacts for about 10 midpoint impact categories and three endpoint indicators, and taking account of the fossil-fuel-based energy consumption rate of each plant. The key findings reveal that photovoltaic power plants have the highest environmental impacts in the types of ozone layer depletion, fresh water aquatic ecotoxicity and marine aquatic ecotoxicity, while biomass plants impact on the categories of abiotic depletion, global warming, photochemical oxidation, acidification, and eutrophication. Moreover, the wind power plants have the more significant environmental effect on human toxicity and terrestrial ecotoxicity types. Overall, hydropower plants are found to be much more environment-friendly than other renewable electricity generation systems. [ABSTRACT FROM AUTHOR]

Traditional building integrated photovoltaic (BIPV) windows face the problems of low efficiency and unsatisfactory daylighting. Given this, this paper proposes a solar louver to harvest solar energy in the vertical building space for on-site electricity and heat generation. The solar louver is composed of concentrating photovoltaic-thermal (CPV-T) modules and allows users to adjust interior daylight according to individual demand. The design scheme of the CPV-T module and the solar louver is introduced. The CPV-T module's optical characteristics are revealed by optical simulations. The results illustrate that the CPV-T module can concentrate sunlight at the incident angle between 5° and 75° and holds the maximum concentration ratio of 3.14. Moreover, its concentration ratio can exceed 2.5 over the range of light incident angles between 15° and 45°. A prototype of the solar louver is manufactured and experimentally studied under actual weather conditions to illustrate its electricity and thermal collection performance. The results show that within the light incident angle of 20°–50°, the solar louver can maintain electrical efficiency above 4.18% and thermal collection efficiency above 55.6%. Additionally, the effective working hour is greater than 6 h, which provides a possibility to be used on buildings. • A solar louver composed of concentrating photovoltaic-thermal modules is proposed. • The louver's concentration ratio can exceed 2.5 in light incident angle of 15°–45°. • The louver allows user to adjust daylighting without reducing solar energy capture. • Its effectiveness is demonstrated by experiment with energy efficiency over 59.7%. [ABSTRACT FROM AUTHOR]

Short-term forecasting of electricity generation from variable renewable energy sources is not an end in itself but should provide some net benefit to its user. In the case of electricity trading, which is in the focus of this paper, the benefit can be quantified in terms of an improved economic outcome. Although some effort has been made to evaluate and to improve the profitability of electricity forecasts, the understanding of the underlying effects has remained incomplete so far. In this paper, we develop a more comprehensive theoretical framework of the connection between the statistical and the economic properties of day-ahead electricity forecasts. We find that, apart from the accuracy and the bias, which have already been extensively researched, the correlation between the forecast errors and the market price spread determines the economic implications - a phenomenon which we refer to as 'correlation effect'. Our analysis is completed by a case study on solar electricity forecasting in Germany which illustrates the relevance and the limits of both our theoretical framework and the correlation effect. • The economics of short-term electricity forecasts are studied analytically and empirically. • The value and the risk of forecast-based electricity trading are evaluated. • We find that the economics depend on the correlation of forecast errors with prices. • Hence, the most accurate forecast is not necessarily the most accurate. [ABSTRACT FROM AUTHOR]

Bionic flapping hydrofoils can be utilized for either energy extraction or propulsion, which has attracted the interest of many researchers. This paper proposes a semi-active flapping hydrofoil device connected to a spring damper power takeoff (PTO) that can simultaneously capture wave energy and propel under ocean wave excitation. The effects of various PTO stiffnesses, PTO damping, and torsional stiffnesses on energy capture and propulsion are investigated using CFD simulation. The performance maps of power generation and propulsion are presented. Compared with the traditional semi-active flapping hydrofoil, the study discovered that the proposed dual-function flapping hydrofoil system could achieve higher overall efficiency. With increasing PTO damping, the overall efficiency initially rises and then falls. After optimizing the PTO parameters, it is possible to increase the overall efficiency by 32 %–86 %. By adjusting the PTO damping, the proportion of energy absorbed for electricity generation and propulsion can be redistributed. Larger torsional stiffness can compensate for the reduction in energy capture and has slight influence on propulsion power. The proposed flapping hydrofoil is expected to be implemented in small wave-powered marine robots, enabling wave propulsion and wave power generation simultaneously. [Display omitted] [ABSTRACT FROM AUTHOR]

Photovoltaic/Thermal (PV/T) systems are getting attention due to limitations in rooftop space, especially in apartment buildings. Those buildings must improve electricity generation from photovoltaic (PV) systems and hot water for domestic use. PV/T systems were investigated experimentally for Jordanian weather in this paper. Thermal and exergy efficiency was evaluated for commercially available PV/T panels under different connection configurations, open-loop, and closed-loop connections. Results showed a significant effect for the PV/T panel for Jordanian weather. Closed-loop performance can be improved if the heat collected by PV/T is extracted from the tank. Finally, the total efficiency of the PV/T system in an open-loop configuration is significantly higher, 76 %, than in a closed-loop one, 58 %, due to the improvement in thermal efficiency. [ABSTRACT FROM AUTHOR]

Bionic flapping hydrofoils can be utilized for either energy extraction or propulsion, which has attracted the interest of many researchers. This paper proposes a semi-active flapping hydrofoil device connected to a spring damper power takeoff (PTO) that can simultaneously capture wave energy and propel under ocean wave excitation. The effects of various PTO stiffnesses, PTO damping, and torsional stiffnesses on energy capture and propulsion are investigated using CFD simulation. The performance maps of power generation and propulsion are presented. Compared with the traditional semi-active flapping hydrofoil, the study discovered that the proposed dual-function flapping hydrofoil system could achieve higher overall efficiency. With increasing PTO damping, the overall efficiency initially rises and then falls. After optimizing the PTO parameters, it is possible to increase the overall efficiency by 32 %–86 %. By adjusting the PTO damping, the proportion of energy absorbed for electricity generation and propulsion can be redistributed. Larger torsional stiffness can compensate for the reduction in energy capture and has slight influence on propulsion power. The proposed flapping hydrofoil is expected to be implemented in small wave-powered marine robots, enabling wave propulsion and wave power generation simultaneously. [Display omitted] [ABSTRACT FROM AUTHOR]

Photovoltaic/Thermal (PV/T) systems are getting attention due to limitations in rooftop space, especially in apartment buildings. Those buildings must improve electricity generation from photovoltaic (PV) systems and hot water for domestic use. PV/T systems were investigated experimentally for Jordanian weather in this paper. Thermal and exergy efficiency was evaluated for commercially available PV/T panels under different connection configurations, open-loop, and closed-loop connections. Results showed a significant effect for the PV/T panel for Jordanian weather. Closed-loop performance can be improved if the heat collected by PV/T is extracted from the tank. Finally, the total efficiency of the PV/T system in an open-loop configuration is significantly higher, 76 %, than in a closed-loop one, 58 %, due to the improvement in thermal efficiency. [ABSTRACT FROM AUTHOR]

As the quality of life continues to improve, the requirement for district heating is gradually growing, contributing to problems of climate change and environmental degradation. The electricity consumption and heat losses in thermal stations are significant. To address these issues, a novel self-sufficient thermal station in electric power is proposed in this paper. The techno-economic and environmental performances of the novel electricity self-sufficient thermal station under operating conditions is analyzed employing a mathematical model. The results show that the higher the temperature of the primary heating network supply water, the better the overall performance of the system. Additionally, a lower point pinch temperature difference is beneficial for improving the performance of the system. At the primary heating network supply water temperature of 100 °C and the evaporating temperature of 69 °C, the PBP obtains the minimal value of 6.53 years. The annual saving coal can reach 73.21 t and reducing CO 2 emissions can reach 199.55 t. Therefore, the novel electricity self-sufficient thermal station can meet certain technical requirements for combined heating and power generation while demonstrating superior economic capability. [ABSTRACT FROM AUTHOR]

Long-term solar irradiance prediction can be more effective to plan and manage solar power systems. Existing methods have demonstrated the effectiveness of decomposing time series to enhance solar irradiance prediction models. However, these methods still have limitations in extracting potential sequence information from complex data sources. This makes the long-term prediction of irradiance still uncertain. In this paper, an improved complete ensemble empirical mode decomposition adaptive noise (ICEEMDAN) combined with TimesNet (ICEEMDAN-TimesNet) method is proposed. The ICEEMDAN method decomposes the subsequence features of the original irradiance, and the multidimensional spatial mapping of the data in the TimesNet model ensures that the model can efficiently extract historical information for the week-ahead hourly prediction of irradiance. In order to explore the performance of ICEEMDAN-TimesNet in the solar irradiance prediction task, several multi-step prediction models were established for comparison. Overall, the ICEEMDAN-TimesNet framework can report satisfactory testing results. The prediction curve is fitted to the trend of irradiance change which can play an excellent guiding role in scheduling electricity generation. [ABSTRACT FROM AUTHOR]

Despite the importance of cost of capital and expected returns from investing on renewable electricity generation in Africa on one hand and the implications of such investments on economic, social and environmental factors on the other. These concepts are not well understood by non-finance and finance actors respectively. Studies that analyze renewable energy-growth nexus at regional and global level are lacking. Instead, existing studies emphasize on individual countries or panel of countries. The paper undertakes comparisons of costs and returns of selected renewable energy technologies in Africa and presents estimates of its impact on Africa's economic growth between 1990 and 2014. Even with abundant renewable resources and well performing technologies measured using levelized cost of electricity and expected internal rate of return, investment on renewable electricity generation is quite low. Findings from Autoregressive Distributed Lag approach and cointegration established a long run relationship among hydro power generation, carbon emissions and electricity consumption. Error Correction Model results suggest that investment in renewable generations excluding hydro power generation is boosted by economic growth, so long as development of such renewables corresponds with lesser carbon emissions. To accelerate renewable development, SSA countries will need to deploy initiatives that enhances national economic growth. [ABSTRACT FROM AUTHOR]

Electricity generation by means of renewable energy such as solar energy has paid great attention over recent decades. In this paper, a comprehensive study on the effect of geometric parameters such as collector roof angle (β), chimney divergent angle (α) and wind velocity on the performance of solar chimney power plant (SCPP) is carried out. A new mathematical model for airflow through all components of SCPP including collector, turbine and chimney is presented. In order to validate the present model, the geometry and operating conditions same as ones in SCPP prototype built in Manzanares are considered in the present model and comparing the obtained results with the measured data of SCPP prototype verifies the accuracy of the present model. The parametric study is carried out at various α and β. Results show that the power output of SCPP increases with decreasing β at a specified α. In addition, it is proposed that the ratio of turbine pressure drop to total pressure potential is chosen in the range of 0.7–0.85 to attain the optimum performance of SCPP. Furthermore, results demonstrate that an increase in wind velocity has a remarkable positive effect on power generation. [Display omitted] • Comprehensive theoretical modeling of SCPP is carried out. • The simultaneous effect of geometric parameters and wind velocity are investigated. • The maximum power output increases as the area of collector inlet increases. • The performance of SCPP enhances with increasing the chimney divergent angle. • Power output becomes higher with increasing wind velocity. [ABSTRACT FROM AUTHOR]

Swedish government's target is to have 100% renewable electricity production by 2040. Currently, hydropower contributes the majority of renewable electricity generation of the country. The wind power capacity has increased significantly in the past decade. In this paper, practical data is used to study the possibility of reaching the 100% renewable electricity generation goal by replacing existing thermal generations with wind power generations. It is found that the Swedish electricity generation system can reach 100% renewable by tripling the existing wind power capacity combined with the existing hydropower in the country. Based on current growth rate of wind power installation, the goal could be reached within 20 years. Hourly simulation shows that 100% renewable energy generation system composed by wind power and hydropower satisfy hourly operation requirements. • Sweden can reach 100% renewable generation by tripling existing wind capacity. • Sweden can reach 100% renewable generation goal within 20 years. • Coordinating hydropower and wind power satisfies hourly operation requirement. [ABSTRACT FROM AUTHOR]

Renewable energies (RE) in Chile and around the world have experienced outstanding growth in recent years. However, RE technologies such as solar photovoltaic and wind generate an imbalance between generation (offer) and consumption (demand) because of their intermittent and variable nature. Moreover, RE's natural variability makes it necessary for conventional technologies to play a significant role in adjusting for the imbalance in the electric system frequency. As variable RE penetration grows, the need for frequency regulation will increase and, depending on how those higher costs are financed, this could lead to a disincentive to invest in conventional plants that provide that service. In this paper we study the impact of increased photovoltaic energy penetration, the leading RE in Chile, on the profitability of different conventional generation technologies. Specifically, we analyze the role that the frequency control remuneration mechanism has on that impact. For this purpose, four different solar photovoltaic penetration scenarios are simulated in Chile's Northern System, comparing two payment criteria for frequency regulation services: i) a cost-based pricing system whose payments relate to the incurred costs and ii) a market-based pricing system where the marginal cost of providing the services is paid. The results show that as installed photovoltaic capacity increases, the average marginal cost of energy (operation cost) decreases due to a displacement of more expensive power plants, but at the same time, investment cost may increase. In the long run, contract prices change as a result of falling operational costs and rising investment cost, resulting in changes in the profitability of all technologies. Finally, while both cost-based and market-based systems reward the ability to regulate frequency, the technologies performing the regulation receive different payments for the service, affecting both their profitability and the incentives for investment. • High penetration rates of intermittent renewable energies require more frequency regulation services. • Depending on the type of regulation, incentives to invest in technologies providing ancillary services might diminish. • Incentives to invest do not change between a regulatory scheme markedbased compare to one cost-based. • Profitability of the natural gas power plants is the one increasing most under market-based regulation. • Under market-based regulation the profitability of photovoltaic and eolic power plants decreases. [ABSTRACT FROM AUTHOR]

Renewable electricity generations are promising to address the global energy issue while they also place great pressure on the reliability of power grids due to their intermittent nature. In recent years, existing heating, ventilation and air-conditioning (HVAC) systems in buildings have attracted increasing attention to implement continuous demand response in providing frequency regulation service, which can enhance instantaneous power balance and reliability of power grids without extra huge investment. When providing frequency regulation service, the power use of HVAC systems would follow the regulation signals. On the other hand, these signals, acting as continuous disturbances, affect naturally the building indoor environment control at the demand side. In this paper, a novel control strategy is proposed, which can prevent the sacrifice of the building indoor environment when providing the service. The core element of this control strategy is a frequency disturbance compensation scheme, which is developed based on the concept of "disturbance-observer-based control". Experimental results show that the use of the proposed strategy can achieve significant improvement in the building indoor environment control without sacrificing the quality of frequency regulation service. In addition, the wear level of the valve was not affected significantly when adopting the frequency disturbance compensation scheme. • A control strategy of HVAC systems is proposed for power grid frequency regulation. • Experimental tests are conducted to validate this proposed novel control strategy. • It works effectively in preventing the impacts on indoor environment control. • It can also ensure the high quality of frequency regulation service to power grids. • The valve wear level is not affected significantly when adopting the novel strategy. [ABSTRACT FROM AUTHOR]

Solar dish (SD) technology is recognized as one of the most efficient solar thermal technologies for electricity generation. Moreover, SD technology has proven its suitability and reliability in solar energy potentials areas that are scarce to have water. In this regard, Egyptian western desert occupies an area of more than 65% of the total area of Egypt. It receives some of the highest solar radiation in the world (up to 3.0 MWh/m2/year), making it a prime location for the exploitation of this technology. Then, it is worth to investigate the opportunities of SD power plant for electricity generation. This paper investigates the techno-economic performance of SD power plant under Egypt desert weather condition. Accordingly, the proposed power plant is modeled and simulated using System Advisor Model (SAM). The annual energy and the levelized costs of electricity (LCOE) are calculated based on the annual simulations of 50 MW installed capacity. The profitability of proposed power plant is assessed based on Egypt's feed in tariff of concentrated solar power (CSP) projects. The proposed location of this power plant is Benban solar power park, near Aswan city in the south of Egypt. This is because the nature of the place is convenient and configured for building solar power plant, as well as its proximity to the Egyptian electricity grid. Furthermore, a sensitivity analysis is conducted to investigate the effect of the main economic variables of the proposed power plant on the LCOE and NPV. The results show that annual energy output of 50 MW is estimated to 105 GWh/year. The LCOE is estimated to 13.38 ¢/kWh. The avoided GHG emissions and fossil fuels usage are equal to about 45 million tons of CO 2 emissions and 21.64 thousand tons of equivalent oil (toe) per year (respectively). Furthermore, the results indicate that LCOE and NPV are very highly sensitive to the collector cost. • A Solar Dish/Stirling power plant is technically and economically investigated. • The solar dish power plant is modeled and simulated in SAM. • The levelized cost of electricity of the power plant estimated to be 13.38 ¢/kWh. • LCOE and NPV are very highly sensitive to the collector cost. [ABSTRACT FROM AUTHOR]

Abstract To satisfy the huge energy demand of China, a rapid development rate of hydropower system was undertaken over the past decades. Currently, thousands of hydropower reservoirs with a total installed capacity of more than 330 GW have provided approximately 20% of China's gross electricity generation, ranked number 1 in the world. Besides, it is foreseeable that in the coming decades, the same development speed of hydropower will be maintained in order to effectively handle the increasing environment and energy problem. The dimensionality problem caused by booming system scale, unprecedented development speed and operational complexity are posing a giant challenge to the operation of large-scale hydropower system in China. Thus, after giving an overview of China's large-scale hydropower system, this paper deeply analyses the key operation characteristics leading to the dimensionality problem and highlights the possible dimensionality reduction strategies to sharply alleviate the optimization difficulty, providing necessary technical support to achieve the goal of energy conservation and emission reduction of China. To sum up, this paper could be a good and inspiring example, contributing to the sustainable development of worldwide countries with a high proportion of hydropower integration. Highlights • An unprecedented large-scale hydropower system is forming in China. • The main operation characteristics of large-scale hydropower system are given. • The dimensionality problem is a great challenge to China's hydropower operation. • Several dimensionality reduction strategies are used to reduce modeling difficulty. [ABSTRACT FROM AUTHOR]

Abstract Reliability improvement of wind turbine power generation is the key issue that can turn the wind power into one of the main power sources to respond to the world power demands. The likelihood of fault occurrence on wind turbine components is unavoidable, especially for large rotor modern wind turbines, operating in harsh offshore environments. Accordingly, the maintenance need increases due to unanticipated faults, which in turn, leads to higher energy cost and less reliable power generation. In this regard, model-based fault detection and fault tolerant control techniques have been extensively investigated in the last decade, for achieving good performance. In this way, the reliability, availability and safety features of the wind turbine power generation are also enhanced. Thus, in this paper a comprehensive review of the most-recent model-based fault detection and fault tolerant control schemes for wind turbine power generation is presented, focusing on the advantages, capabilities and limitations. Note that the so-called data-driven or signal-based methodologies, which rely on the analysis of the signals directly generated from the monitored system, are not reviewed in this paper. This review is organized in a tutorial manner, to be a suitable reference for further research for the wind turbine's reliability improvement. Highlights • Wind turbine model representation for FDI purposes associated with all considered faults. • A Comprehensive review of all available FDI methods applicable to wind turbines. • Application of FDI methods on wind turbine components, comparing their advantage and disadvantages. • A comprehensive review of FTC techniques with wind turbine operational objectives point of view. • Future trends of wind turbine FDI and FTC approach towards the reliability improvement. [ABSTRACT FROM AUTHOR]

Abstract This paper concerns the prediction of the power output performances of an oscillating surge wave energy converter in irregular waves. The generated power has been calculated using a new methodology by incorporating a stochastic Lagrange wave model into a non-linear filter which takes also hydrodynamic forces into account. It is shown that the stochastic Lagrange wave model in this paper can be utilized to generate irregular waves with realistic crest-trough and front-back asymmetries, and when used in combination with the non-linear filter will produce more accurate power output predictions than the traditional Gaussian wave model can do. The research findings in this paper demonstrate that the stochastic Lagrange wave model together with a non-linear filter can be utilized as a robust tool for engineers in their design, analysis and optimization of wave energy converters. Highlights • The power performances of a wave energy converter are investigated. • The generated power is calculated using a new methodology. • A stochastic Lagrange wave model is utilized. • A non-linear filter is utilized. • The new methodology is demonstrated to be robust. [ABSTRACT FROM AUTHOR]

Abstract Recently, electricity generation from solar photovoltaic (PV) has gained popularity throughout the world due to its profuse availability and eco-friendly nature. Consequently, extraction of maximum power from solar PV energy systems was the point of interest in the current researches. Various techniques have been proposed to track the maximum power point (MPP) from solar PV energy systems under variable environmental conditions. Conventional maximum power point tracking (MPPT) techniques have demonstrated the ability to track MPP with uniform solar irradiance. However, the ability of these techniques to track the accurate MPP with the condition of partial shading (PS) is not guaranteed. Hence, this paper intended to present novel optimization techniques to mitigate the PS effect and proficiently track the global maximum power point (GMPP). Grey Wolf Optimization (GWO), Moth-Flame Optimization (MFO), Salp Swarm Algorithm (SSA) and Hybrid Particle Swarm Optimization-Gravitational Search Algorithm (PSO-GSA) techniques have been proposed to handle this dilemma. The proposed techniques have been simulated and analyzed using MATLAB/SIMULINK. Furthermore, these techniques have been compared with the conventional PSO algorithm for validation. Statistical and sensitivity analysis have been established to compare the performance, check the stability, and determine the best technique out of the proposed techniques. Results showed the superiority of GWO in the speed of convergence and the time to catch GMPP. Moreover, the sensitivity analysis demonstrated the stability, successfully rate, and tracking efficiency of PSO-GSA technique. Finally, this paper gives an open reference to these optimizers to attempt mass research works in PV systems under PS. Highlights • Implementation of distinctive meta-heuristic optimization algorithms for increasing the PV system efficiency under PSC. • The proposed algorithms are GWO, MFO, PSO-GSA, and SSA. • Determination of the GMPP from the multiple local peaks caused by different irradiances. • Comparing the proposed algorithms with PSO algorithm for approval. • Introducing statistical and sensitivity analysis to compare the performance and check the stability of proposed algorithms. [ABSTRACT FROM AUTHOR]

Selecting a renewable energy source portfolio is an uncertain multi-criteria decision-making (MCDM) problem. In particular, it involves searching for the best portfolio of renewable energy that meets the decision maker’s preferences by considering and leveraging conflicting criteria such as technical, environmental, societal, and economic. To tackle such complex problems, this paper proposes an efficient method, called multi-segment fuzzy goal programming (MS-FGP), which addresses decision-making problems with high levels of uncertainty. The paper makes the following contributions: i) extends the conventional fuzzy goal programming (FGP) model to solve a wide range of uncertainties decision-making problems and ii) proposes a method based on a recent development in the FGP area that considers all types of fuzzy goals in real-world problems. The model is validated by applying it to a real-world scenario: optimizing the renewable portfolio for electricity generation in Italy. These renewables are solar photovoltaic (PV), wind, biomass, and tidal currents. The results show that the proposed methodology can assist decision makers in determining the most sustainable renewable energy source portfolio for electricity generation under uncertain conditions and in imprecise environments. [ABSTRACT FROM AUTHOR]

In this paper, a novel concept of small isolated electric power generation from pumped-hydro energy storage (PHES) using wind as primary energy is proposed for rural and remote areas where the wells are available. A suitable well is utilized as the lower reservoir of the PHES system, while the upper reservoir needed for the water storage is made on the ground. In this scheme, the wind turbine, unlike other PHES schemes is not used for rotating the electric generator at all, but to rotate the hydraulic pump, which is used to suck the water from the well and to store it in the upper reservoir. The water head created in this way is utilized to run a pico-hydro turbine coupled with a generator for generating electric power. The mathematical modelling of the system has also been developed in the paper. For the validation of the model, the simulation is carried out using the actual wind speed data. The attractive features of the scheme are its low cost, simplicity, reliability and continuity in power supply at constant voltage irrespective of wind speed variations. [ABSTRACT FROM AUTHOR]

This is the second of three papers that propose and study a new concept of mooring turbine generators with the aim of resolving key difficulties in realizing ocean current power generation. The concept of Cross-stream Active Mooring (CSAM) features a hydro sail system that allows deployment of generator turbines, from anchoring points on shore or on shallow seafloors, across current stream to access current core flowing over deep seas or over seabed not suitable for anchoring construction. The CSAM can increase system power capacity by changing horizontal positions of generator turbines to track meandering current core, and can also change system depth to avoid storms. New anchoring designs of improved efficiency and implementation methods for resolving seafloor geological issues in the Kuroshio off southeast Taiwan are also included. This second paper discusses conceptual design and construction of the tethers, mooring implementations and reduction of flow drag, mooring of power cable and design of linear array and 2D formation. Model tests were conducted to demonstrate and observe the feasibility of the basic concept and its stability. Formation stability under the influences of waves and other possible perturbations was analyzed and discussed. [ABSTRACT FROM AUTHOR]

This paper shows the on-going experimental campaign carried out over a small size vertical axis wind turbine in the facility of the Savona Harbor. Investigations mainly concern two issues: power production assessment and full-scale structural behavior. The first one highlights the importance of a deep knowledge of the local orography and of the wind characteristics (e.g., turbulence intensity); in the absence of reliable wind data it is impossible to properly estimate the performance of the system. The latter allows to identify the possible critical aspects of the structural system (e.g., in terms of resonance conditions) and to investigate the actual dynamic behavior (e.g., in terms of dissipative capacity), necessary for assessing the useful life. The paper points out how these two issues are closely related. Results obtained can provide indications suitable for improving future installations. [ABSTRACT FROM AUTHOR]

In the field of energy, hydrogen as an energetic vector is becoming increasingly important. Specifically, fuel cells powered by hydrogen are becoming an alternative in automotive and other fields because of their ability to produce electricity without any pollution. Therefore, at this time there is a very active research field. A fuel cell can be described as a scale down industrial plant that consists of different subsystems whose purpose is to make the stack works properly. Air Cooled Polymer Electrolyte Fuel Cells (AC-PEFC) are receiving special attention due to their potential to integrate the oxidant and cooling subsystems into one, which in term gives the fuel cells their capability to reduce its weight, volume, cost and control complexity. In these fuel cells, the Oxidant/Cooling subsystem is of crucial importance and along with three others ( Fuel , Electrical and Control subsystems) make up the Balance of Plant (BoP), which together with the stack comprise the full fuel cell system. The aim of this paper is to present a comprehensive experimental study of an AC-PEFC paying particular attention to the Oxidant/Cooling subsystem configuration. According to the scientific literature, this subsystem has not received the same attention as other subsystems like the Fuel and Control subsystems. However, a suitable design and size is critical for the proper functioning of the stack. The analysis carried out in this paper tries to solve some problems that can appear if the design of the Oxidant/Cooling subsystem has not been optimized. These problems are related to important aspects such as the performance and the efficiency of the whole system and temperature distribution over the stack. [ABSTRACT FROM AUTHOR]

Wave energy is one of the most concentrated ocean renewable energy resources. Although wave energy has been studied extensively for more than four decades, there is no large commercial installation for wave energy production or a consensus framework on how to exploit this resource. Wave energy is a complex resource that directly depends on two meteorological parameters, which produced significant fluctuations of wave energy in both temporal and spatial criteria. This paper presents a new concept called Energy Event, to analyze meteorological data generated by WaveWatch III over 36 years in the U.S. to characterize and assess wave energy behavior using the peak-over-threshold methodology. This methodology used extreme statistics, segmented the wave energy with different thresholds, and assessed wave energy production on a temporal and spatial framework. Three areas were studied in this paper, including the Gulf of Mexico, the East and West U.S. Coasts. The results indicated that wave energy behaved as a two-state energy system with each state having independent characteristics. The main difference among the three studied areas was the constant baseline of wave power density, with the West Coast having the highest constant baseline and the Gulf of Mexico having the lowest baseline. [ABSTRACT FROM AUTHOR]

Photovoltaic/thermal (PV/T) systems allows for simultaneous electricity and heat generation. The energy output characteristics of PV/T systems are well-suited to complement the proton exchange membrane electrolytic water hydrogen production technology (PEMWE). In this paper, the performance of photovoltaic/thermal powered proton exchange membrane water electrolysis cogeneration system (PV/T-PEMWE) under different connection modes is compared. By establishing the mathematical model of PV/T-PEMWE system under indirect connection mode, direct connection mode and the optimized connection mode based on maximum power tracking, the dynamic performance is compared and analyzed. In addition, the influence of number of PV/T modules on the energy output of the system is also discussed. And the performance of PV-PEMWE and PV/T-PEMWE with the same area and optimized connection mode is compared under identical meteorological conditions. The results indicate that the hydrogen production efficiency of the systems with different connection modes, ranked from high to low, is as follows: indirect connection, optimized connection, direct connection. The operating voltage range of PV/T-PEMWE system is close to that of PV-PEMWE system, while the operating current in PV-PEMWE system is noticeably higher than that in PV/T-PEMWE system. The hydrogen production efficiency of PV-PEMWE system and PV/T-PEMWE reaches peak value at 12:00 and 14:00 respectively. [ABSTRACT FROM AUTHOR]

Pakistan is facing severe electricity crisis due to lack of investment in power sector, depleting gas resources and dependency on imported oil. Utilization of indigenous and renewable energy resources is the best way to compensate energy need and reduce fossil consumption. Being an agrarian country, huge amount of agricultural residue is generated each year, which can be used as a cheap input to generate electricity. Aim of this research is to assess the total potential of electricity that can be generated from Agricultural Residue (AR) in Pakistan. The paper focuses on district-wise resource assessment for electricity generation in the province of Punjab. Estimated 60 Mega Tonne (Mt) of AR is generated in Punjab every year from 5 major crops (wheat, sugarcane, rice, maize, and cotton). AR is used for various purposes but still large amount of residue is left unused and burnt openly in the fields. As a methodology, certain factors are used to calculate the Net Available Residue (NAR). This research shows that a lot of potential is available in Pakistan to generate electricity form biomass, in total around 1700 MW electricity can be generated from agricultural residues of 4 main crops (Maize, Cotton, Wheat and Rice). It is also found that maize stalk producing districts of central Punjab are the best location for installing BPP and also it is cheapest to produce electricity from maize stalk with LCOE of 6.8 cents/kWh. • The assessment of the power generation from Agricultural Residue (AR) in Punjab, Pakistan is performed. • District-wise resource assessment for electricity generation is done in the province of Punjab. • Estimated 60 Mega Tonne of AR is generated in Punjab every year from 5 major crops. • In total around 1700 MW electricity can be generated from agricultural residues of 4 main crops. • Maize stalk producing districts of central Punjab are the best location for installing BPP. [ABSTRACT FROM AUTHOR]

Accurate and reliable solar irradiance forecasting can bring significant benefits for managing electricity generation and distributing modern smart grid. However, the characteristics of instability, intermittence, and randomness make an accurate prediction of solar irradiance very difficult. To exploit fully solar irradiance by the successful scheduling of electricity generation and smart grid, this work proposes a new CEEMDAN–CNN–LSTM model for hourly irradiance forecasting. Firstly, complete ensemble empirical mode decomposition adaptive noise (CEEMDAN) is employed to decompose original historical data into a set of constitutive series to extract data features. Secondly, a deep learning network based on convolutional neural network (CNN) and long short-term memory network (LSTM) is used to forecast solar irradiance in the next hour. Moreover, in this paper, the various CNN-LSTM-based strategies for solar irradiance forecasts are systemically investigated. Four real-world datasets on different climate types are employed to evaluate the full potential of the proposed model. Multiple comparative experiments show that the proposed CEEMDAN–CNN–LSTM model can accurately forecast the solar irradiance and outperform a large number of alternative methods. An average RMSE of 38.49 W/m2 indicates that CEEMDAN–CNN–LSTM model has a relatively stable prediction performance in different climatic conditions. • A novel deep learning-based model is used to forecast multi-region solar irradiance. • CEEMDAN is used to decompose the original data in different climate regions. • Five types of CNN-LSTM are designed for multiple feature inputs. • The proposed model shows better accuracy than other state-of-the-art models. [ABSTRACT FROM AUTHOR]

Concerns over climate change have led governments around the world to establish a range of renewable, low-carbon energy goals. Plans for meeting these targets vary widely in their ambition, specificity, and time horizons. Wind and solar electricity generation will feature prominently in future energy systems that meet these renewable, low-carbon energy goals. Implementing largescale wind and solar PV infrastructure configurations in a timely fashion will require cooperation between and among electric grid stakeholders and communities that host the infrastructure. This paper presents methods for constructing a diverse range of wind and solar PV energy infrastructure pathways that meet statutory energy goals, measuring their land use impacts, and assessing their performance relative to electricity demand. A case study on the state of Vermont's statutory energy goals from its 2016 Comprehensive Energy Plan is presented as an example. While total wind and solar PV infrastructure requirements would increase several-fold, Vermont's statutory energy goals can be met while occupying less than 1% of the state's land area. Vermont electricity demand was most effectively met by balanced configurations of wind and solar PV similar to the state's present wind and solar PV resources, while 100% wind or 100% solar PV configurations were less effective. • Most statutory energy goals do not prescribe implementation pathways. • Large-scale wind and solar PV deployments will expand electric grid land use impacts. • The state of Vermont can meet its 40% by 2035 goal with less than 1% of its land. • Wind turbines offer attractive performance per unit direct land use versus solar PV. • Direct land use only captures one aspect of the grid's total landscape impacts. [ABSTRACT FROM AUTHOR]

This paper deals with the environmental assessment of two electricity scenarios in Sicily, for 2030, characterized by a high exploitation of renewable energy sources in order to quantify the potential contribution of the local strategies in the achievement of the European climate policies and the potential improvement in the future electricity mix, compared to the current one (2014). In order to match these goals, authors integrate the Life Cycle Assessment with a scenario analysis. The future electricity mix scenarios, characterized by a share of renewables (57% for 2030-BS scenario and 51% for 2030-DS scenario) show a reduction of the greenhouse gases emissions per kWh of electricity generated, compared to the current one in which renewables account for 24%. Greenhouse gases emissions decrease by 39.9% in 2030-BS and by 32.9% in 2030-DS. However, the analysis highlights that the state of development of technologies does not allow improvements in a whole set of impacts categories. Particularly, freshwater ecotoxicity increases by around 30% and resources depletion by more than 100%. Results of this study can be used by local authorities as knowledge base in the definition and "ex-ante" evaluation of site-specific low-carbon energy strategies in Sicily. • The scenario analysis integrated with the LCA methodology was presented. • Electricity generation scenarios in 2030 in the Italian context was build. • Marginal electricity generation technologies were identified based on site-specific data. • A high penetration of renewables in the electricity generation mix allows decreasing a wide range of environmental impacts; Improving renewable technologies is paramount for better resource efficiency A high penetration of renewables in the electricity generation mix allows decreasing a wide range of environmental impacts; Improving renewable technologies is paramount for better resource efficiency and toxicity control. [ABSTRACT FROM AUTHOR]

The penetration of renewable energy sources for electricity generation is critical to decarbonize electricity systems, a main goal in the context of the energy transition. Among renewable energies capacity additions, wind energy has played a dominant role in the European Union and elsewhere, fuelled by technology cost reductions and public promotion schemes. In turn, wind deployment has led to considerable socioeconomic and environmental benefits in terms of CO 2 emissions reductions, avoidance of fossil fuels and employment creation. The aim of this paper is to assess those socioeconomic and environmental benefits of wind energy deployment in the European Union and their evolution over time. Based on two novel methodologies, which allow a disaggregated analysis per country and stage of the supply chain (only for employment creation), an ex-post calculation of those benefits over the 2008–2016 period has been carried out. Our results show that, overall, those benefits are considerable and have increased over time. However, some benefits are more relevant than others. In fact, the monetary calculation of the fossil fuel savings is twice the benefits in terms of CO 2 emissions abatement. Their relevance also differs across countries and, for employment creation, across distinct stages of the value chain. • Ex-post calculation of the benefits of wind energy in the EU in the period 2008–2016. • Assessment of the emission reductions, avoidance of fossil fuels and employment creation. • The monetary quantification of the fossil fuel savings is twice the benefits of CO 2 emissions abatement. • More than 2.5 million jobs created in the period 2008–2016 in the EU28. • Policy costs are higher than benefits from CO 2 and fossil fuel reductions. [ABSTRACT FROM AUTHOR]

Currently, photovoltaic (PV) installations target a maximization of annual energy yield. However, as the grid penetration of PV is increasing, PV electricity generation will need to match better with local load profiles. Especially the seasonal variabilities remain challenging. While wind and PV tend to have complementary seasonal variability, wind turbine installation faces limitations especially in densely populated areas. In this paper, we discuss how this challenge may be addressed with climate- and consumption-specific PV module technology. In particular, we demonstrate how the temperature coefficient of a PV system can impact the energy yield throughout the year. In colder climates, higher temperature coefficients allow for a better energy balance, favoring production in colder seasons without a significant reduction of yearly energy yield. Simulations for locations at high latitude, and colder climates, indicate that higher temperature coefficients and improved low-light behavior not only enable a higher energy yield in cold seasons, but also negligible losses in the overall yearly energy yield compared to lower temperature coefficients and slightly better low-light behavior. Simulations show that these results can be obtained using commercial PV modules. More broadly, they indicate how PV module technology may be optimized depending on the location and climate. • Detailed energy yield simulations are carried out for 4 locations and climates. • A high temperature coefficient may improve seasonal production in cold climates. • Yearly energy yield is not necessarily sacrificed, even for commercial modules. • Next to temperature coefficients, also low-light behaviour is important. • Climate-specific modules could be considered for future grid-friendly PV systems. [ABSTRACT FROM AUTHOR]

Critical mechanical faults in wind turbine systems lead to considerable downtime and repair costs. Improving the detection and diagnosis of such faults thus brings about significant cost reductions for operations and maintenance (O&M) and electricity production. One of the most common defects in drivetrains are rolling element bearing faults. Detecting the faults in their incipient phase can prevent a more catastrophic breakdown and save a company time and money. This paper focuses on separating the bearing fault signals from masking signals coming from drivetrain elements like gears or shafts. The separation is based on the assumption that signal components of gears or shafts are deterministic and appear as clear peaks in the frequency spectrum, whereas bearing signals are stochastic due to random jitter on their fundamental period and can be classified as cyclostationary. A technique that recently gained more attention for separating these two types of signals is the cepstral editing procedure and it is investigated further in this paper as an automated procedure. The performance of the developed methods is validated on experimental data from the National Renewable Energy Laboratory (NREL) in the context of the wind turbine gearbox condition monitoring round robin study. [ABSTRACT FROM AUTHOR]

Solar thermal power plants using dish-engine systems have conventionally used multiple dishes of an optimum size. In a few recent developments, dish sizes up to 500 m 2 have been attempted in order to scale up power generation. Although using very large dishes may have a few advantages, the cost implications need to be analyzed before implementing such designs. An optimum dish size may provide the key advantage for dish-engine power plants to compete with grid power, but determining it poses a serious challenge. As dish-engine power plants call for heavy investments, it becomes important to design dishes to endure excessive wind loads, to prevent an overnight obliteration. A simple cost model is presented in this paper, in which the structural problem is modeled mathematically and optimized for minimum cost subject to wind-load resistance constraints. This paper demonstrates how cost optimization can be used as an effective decision making tool for selecting the right dish size. The optimization results indicate that very large dishes of conventional designs may not be cost-effective if they have to withstand heavy wind loads. [ABSTRACT FROM AUTHOR]

Wind profile, wake effect, and wind turbine outage create considerable impact on the energy production of a wind farm. This paper proposes a Markovian wind farm generation model that incorporates these factors. This model considers the wind farm as a generating unit with multiple generation states. The probability, frequency of occurrence, and transition rate of each state can be obtained using the collected wind profile data and wind turbine reliability parameters. The power output of each state is calculated using Jensen wake model and enumerated wind farm layouts. The proposed model is verified by a sequential Monte Carlo simulation approach using a test wind farm and recorded wind profile data from four different sites in North Dakota, USA. A state merging technique is developed to enable the application of the proposed model to adequacy assessment. The Roy Billiton Test System with a test wind farm is used to demonstrate the application of the proposed model and the procedure to adequacy assessment. Moreover, this paper investigates the influence of wake effect, peak load, seasonal wind pattern, wind turbine reliability parameters, and wind turbine type on system adequacy. [ABSTRACT FROM AUTHOR]

This paper describes a wind power system which controls the active and reactive generated powers as well as it performs the function of filtering the harmonic components of the grid currents. From the grid side converter, the harmonic filtering is achieved by an algorithm proposed by compensation of harmonics. This technique ensures the improvement of power quality. The machine side converter controls the active and reactive powers that are delivered to the electric grid by the stator flux oriented control. The design methodology of the controllers used is presented. This paper is distinguished by three key contributions. The first contribution of this article is the tutorial character, it should assist in the development of future work. The second is the analysis of the harmonic filtering behavior for some operating points of the DFIG/APF system. The third is the application of the precise model of the DC link voltage dynamics, allowing verifying the stability of the system control for each DFIG/APF (active power filter) operating point. Simulation and experimental results confirm the effectiveness of the proposed research. [ABSTRACT FROM AUTHOR]

Worldwide electricity generation is featured by the growth of intermittent renewable energies. In this context, hydropower plays a fundamental role because it provides flexibility to the power grid and ensures its stability. The new grid requirements have led hydropower units to working under a wider range of loads and with more start/stop sequences. Pelton turbines are the most suitable for high heads and have a large regulation capacity. In operation, the runner is impinged by high-speed water jets, and, thus, subjected to strong pulsating forces. As a consequence, the structure presents large deformations and high stresses, especially on the buckets. This situation can be much aggravated if the frequency and shape of the excitation is resonant with those of the structure. Therefore, the modal response of the turbine must be thoroughly studied and the most dangerous frequencies avoided. In this paper, a detailed analysis of the modal behavior of Pelton turbines is presented. Four prototypes have been studied for such purpose. The first one has been modeled numerically and analyzed experimentally. Following a systematic investigation, the effect on the modal shapes and the frequencies of the different parts comprising the turbine has been evaluated. The single bucket and the whole runner have been studied. Finally, another turbine installed in the same power plant has been analyzed to determine the effect of the mechanical design on the frequencies. In addition, two prototypes belonging to other power plants have been studied to see the effects of the hydrodynamic design on the modal behavior. [ABSTRACT FROM AUTHOR]

Biogas is a practical way of recycling bio-wastes that can be utilized as a fuel for co-generation of electricity and heat. Livestock and agriculture-based resources have considerable potential for bio-power generation mainly due to their comparatively low cost. However, the contribution of agricultural residues has been neglected within this context in Iran. This study aims to assess Iran's potentials in bio-power generation from both animal and agriculture-based resources to provide an accurate/realistic estimate of the resource availability. The studied energy crops were wheat, rice, barley, maize, potato, apple, grape, alfalfa and other industrial crops including sugar cane and sugar beet. The total amount of agricultural waste is assessed to be 24.3 million tones that can be considered potential feedstock to produce 6,542 million m3 of biogas, 2,443 million liters of bio-butanol, and 2,082 million m3 of bio-hydrogen. In addition, the biogas potential from livestock and slaughter wastes is estimated to be 11,523.84 and 16,026 million m3/year, respectively. The findings indicated that there is considerable potential for bio-power generation in Iran. The analysis estimated that Iran's total potential for bio-power generation from these organic matters was around 62,808 × 106 kWhyear−1, accounting for 27% of the total electricity consumption in the country. The greenhouse gas emission mitigation from bio-based electricity generation would be about 4,096 thousand tons of CO 2 -eq/year, which account for up to 0.6% of Iran's annual greenhouse gas emissions. To the best of the author's knowledge, this is the first report assessing the emission inventory and emission allocation of CO 2 from both livestock manure and the open burning of crop residues in Iran. This paper provides valuable insights and information for policy-makers to formulate long-term energy policy by taking advantage of these bio-wastes in Iran as a case study. Image 103442 • Agricultural & livestock wastes production in Iran was assessed. • Bio-power generation potential in Iran was reviewed. • Approximately 62 TWh of bio-power can be obtained from these renewable wastes. • The greenhouse gas emission mitigation was estimated to be 4000 ktons of CO 2 eq/year. [ABSTRACT FROM AUTHOR]