Search

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

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

Deep electrification powered by renewable sources has emerged as a pivotal strategy for achieving ambitious CO 2 emission reduction targets. However, the true impact of electrification on decarbonization remains inadequately measured because the whole energy chain has not yet been fully considered. This study combines Societal Exergy Accounting and Logarithmic Mean Divisia decomposition analysis to quantify the main drivers of relative (de)carbonization in Portugal from 1960 to 2016. The results reveal a significant increase in the carbon intensity of useful exergy from 250 to 380 tons CO 2 /TJ during the late 1990s, followed by a decline to 280 tons CO 2 /TJ in the 2000s. These changes were driven by fossil fuel dependency and the efficiency and structure of the energy system. Decarbonization was facilitated by electrification when the following three conditions were met: (1) end-use electrification was at least a third of total useful exergy consumed, (2) renewable resources were at least a third of overall mix (above 33%) and (3) natural gas was at least a third of the mix of fossil fuels used for electricity generation. (above 30%). Policies promoting fossil fuel use for economic development led to the peak in carbon intensity of useful exergy in the 1990s while investments in renewable resources for electroproduction facilitated effective relative decarbonization later. Based on the current structure and efficiency of the energy system, policy recommendations include prioritizing investments in renewables, enhancing final-useful efficiency, and promoting the electrification of mechanical drive end-uses. [Display omitted] • Carbon intensity of useful exergy ACI useful is a better measure of decarbonization. • ACI useful encompasses the entire energy system focusing on biophysical aspects only. • ACI useful was driven by fossil fuel dependency and efficiency of the energy system. • Electricity decarbonized when electric end-uses and renewables were more than 1/3. • Energy policies were not effective in increasing final-useful exergy efficiency. [ABSTRACT FROM AUTHOR]

Photovoltaic systems (PV), particularly solar photovoltaics, are gaining popularity as renewable energy sources. The rapid deployment of PV systems has attracted substantial investments, with around $170 billion projected by 2025. However, challenges like dust accumulation, solar radiation, and temperature rise hinder PV efficiency. Elevated temperatures, exceeding standard levels, notably decrease voltage output and overall electricity generation efficiency. This review provides a comprehensive overview of recent cooling techniques adopted to enhance solar PV performance. Beginning with an introduction to global warming's impact and renewable energy's significance, the article explores cooling methodologies for solar PVs. These encompass Absorption & adsorption-based, PV/T hybrid, Microtechnology-based, and Water and air-based cooling systems. The review concludes this section with a detailed table comparing cooling technologies' performance, benefits, and challenges. The review then delves into four primary cooling techniques: Active cooling, Passive cooling, Nanofluid-based cooling, and Thermoelectric cooling. Passive cooling, which effectively reduces PV system temperature without external energy sources, is highlighted. Modalities of Passive cooling methods, such as Radiative cooling, Evaporative cooling, Liquid immersions, and Material coatings, are elaborated. Concluding, the article addresses challenges, opportunities, and future prospects related to diverse cooling techniques' utilisation, aiming to elevate solar PV system efficiency. [Display omitted] • Different photovoltaic cooling technologies, and their recent developments were examined. • Advantages, challenges, and research gaps in various cooling methods were analysed. • Nanotechnology-based PV cooling systems, and their effectiveness were discussed. [ABSTRACT FROM AUTHOR]

The increasing share of renewable energy sources in the global electricity generation defines the need for effective and flexible energy storage solutions. PHES with their technically matured plant design and wide economical potential can generally match those needs. But especially for lowland countries, where low-head PHES applications are needed, the current turbomachinery technologies offer no viable solutions for LH-PHES to be a competitive energy storage technology in the context of realizing the European Green Deal. The new developments in low-head hydraulic turbomachineries, smart operation schemes and powerful site identification algorithms can shape these plants towards a viable future technology. Therefore, this study demonstrates that, through a novel design of a contra-rotating, variable-speed, reversible pump-turbine especially designed for low-head operation, PHES can operate over a wide range of hydraulic heads and discharges at very high efficiencies. Additionally, it shows that, with the use of more than one CR-RPT unit in parallel action, different power settings can be selected to achieve high efficiency with fast reaction times. Furthermore, the newly developed operation simulation code is used to support the RPT design developments considering the most compact plant design, which is achieved by Prototype 0 at LAT of 31 m and dam diameter of 1600 m. Thus, the investment costs are minimized while the revenue is maximized through the delivery of grid services tailored to suit the market needs. Moreover, the novel development of a smart site identification algorithm, supports RPT design development at high potential offshore sites (in the Greater North Sea). • Review of current methods and criteria for potential and design of low-head PHES. • PHES as powerful technology for a stable grid supporting an increased share of RES. • New pump-turbine designs make PHES highly efficient at a wide head operation range. • A new developed detailed operation model is able to find the most compact PHES. • Operation model coupled to site identification algorithm spots viable offshore sites. [ABSTRACT FROM AUTHOR]

Solar Chimney Power Plants (SCPP) are among the promising solar thermal electricity generation technologies. Equipped with a Thermal Energy Storage (TES) system, such technologies can overcome variations in the main driving factors such as solar radiation and ambient air temperature. This article presents a comprehensive semi-analytical model of a TES to predict the time-dependent performance of an SCPP. By introducing a Quality Factor of power generation (QF) that includes energy conversion efficiency and capacity factor, the effects of 15 TES materials have been studied on the plant performance. Results indicate no significant difference between water TES and clay or soil type, and water-filled bags or tubes are relatively ineffective in improving performance compared to them. Among the various TES materials analyzed, a type of wet soil, i.e., the specific wet mixture of clay, sand, and silt in closed and dark-colored bags, show excellent performance in both QF enhancement and having low Heat Penetration Depth (HPD) simultaneously. The QF and HPD are directly affected by thermal effusivity and thermal diffusivity, respectively. Implementing wet soil TES for the studied power plant (Manzanares) enhances the QF from 7.46 % (for limestone soil) to 10.95 %. Water-filled bags demonstrate a heat penetration depth of 0.4 m, while wet soil exhibits a slightly greater depth of 0.5 m. Furthermore, water-filled bags experience a broader temperature range of 40 °C, whereas wet soil undergoes a comparatively smaller temperature variation of 26 °C. Furthermore, the capacity factor raises from 41.18 % to 61.07 % when utilizing wet soil TES compared to water-filled bags. • Solar Chimney Power Plant (SCPP) time-dependent performance modeling. • Investigation of various Thermal Energy Storage (TES) materials on an SCPP. • The similarity of water storage effect with other materials like clay and soil. • Achieving optimal quality factor of power generation with a type of wet soil TES. • Having the lowest heat penetration depth with the same performance for wet soil TES. [ABSTRACT FROM AUTHOR]

Hydropower is the third largest supplier of global electricity generation trailing behind coal and natural gas. It serves as the backbone of low-carbon electricity generation, supplying 55% more than nuclear and greater than the combination of solar and wind energy. With a growing emphasis on cleaner, carbon neutral and economical energy production, it is important to shift the focus to accelerate the growth of large hydropower generating stations, including pumped storage power plants. International energy agency statistics estimate that the projected increase in installed capacity towards 2030 is 230 GW, representing a 17% growth in hydropower for this decade. This work attempts to project the potential of existing hydel power plants through technological updates and modernization. The capabilities of these hydropower generating stations are strongly conditioned by the characteristics of turbine, generator, transformer, and power electronic converter. In recent years, new techniques have been developed to improve the output controllability of hydropower generating systems at better efficiency and facilitate their integration with different forms of renewable energies and develop new ways of balancing supply and demand. A major revamping is expected for 40% of the major hydropower plants that have served as the backbone of low-carbon electricity generation for the past 45–60 years, representing a potential of 476 GW. Capability enhancement will rejuvenate the potential of old hydropower plants. This investigation aims to review current research and development trends along with potential future research fields to identify the best-combined operation strategy to optimize the capabilities of hydropower generating stations. [Display omitted] • Hydropower generation is critical to global decarbonization efforts. • Improve existing capabilities to achieve sustainability. • Technology adoption, upgradation and renewable energy integration is mandatory in the present scenario. • Bulk energy storage systems should be installed to ensure grid stability. [ABSTRACT FROM AUTHOR]

The system inertia is gradually decreasing and frequency security issues are becoming more prominent with the increasing penetration of wind power. To ensure the safety and stability of power system, many countries have updated their grid codes to reinforce the frequency regulation requirements (FRRs) for wind power plants (WPPs). However, most review articles on grid codes cover all grid-integration metrics, while the review of FRRs is inadequate and incomplete; moreover, it shall be updated to accommodate the state-of-the-art grid codes. To cope with it, this study presents a comprehensive review of FRRs for WPPs in modern grid codes, covering 12 representative countries or organizations such as those with the highest development level, the fastest development speed, and the largest installations in wind power. The FRRs in their grid codes for wind power integration are compared and analyzed from three aspects: frequency operating range, primary frequency response and inertia response. Based on the comparative analysis, combined with relevant policy documents, some future trends related to FRRs are concluded. Furthermore, electricity generation sources in each country are analyzed to enrich the understanding of the reasons behind the differences in FRRs. The review helps the transmission system operator to compare and analyze international grid codes and optimize their own grid codes. Moreover, it enables wind turbine manufacturers to master the latest grid codes and grasp the future trends, and helps research focus on practical needs and solve the pain points of wind power development. [Display omitted] • Frequency regulation requirements for wind power integration are reinforced. • A comprehensive comparison of 12 representative grid codes is presented. • Three key aspects in frequency regulation requirements are compared and analyzed. • Future trends related to frequency regulation requirements are concluded. [ABSTRACT FROM AUTHOR]

Sugarcane mills currently use sugarcane bagasse to cogenerate heat and electricity, supplying the process with mechanical, thermal and electrical energy. Some of these plants are able to produce surplus electricity to export to the national grid. With the improvement in collection techniques, sugarcane straw has also become available and has been used in some mills as fuel for steam boilers, mixed with sugarcane bagasse. However, due to different traits compared to bagasse, the use of sugarcane straw may pose additional problems of incrustation and corrosion on heat exchange surfaces. Several alternatives and technologies have been studied and tried out in order to increase the production of surplus electricity. Among others, biomass integrated gasifier–gas turbine combined cycle (BIGCC) is a promising technology. However, several attempts have resulted in failure, whether on a pilot or industrial scale. Biomass gasification integrated with internal combustion engines can become an opportunity for generation of small power capacity (<15 MW) and integrated to sugarcane mills. This paper analyzes the difficulties and barriers to increasing electricity generation in the sugarcane industry through studies, projects and experimental and industrial-scale installations that have already been carried out. • Bagasse and cane straw show great potential for electricity generation. • Sugarcane industry in Brazil accounts for 6.4% of the electricity generated. • Biomass integrated gasification and combined cycle can increase electricity generation. • Technological and economic challenges are major barriers to the development of BIGCC. • No BIGCC project already implemented is currently in commercial operation. [ABSTRACT FROM AUTHOR]

In recent decades, investing in renewable and eco-friendly energy technologies, such as replacing clean energy systems instead of traditional ones and equipment management, is an interesting and practical topic in all sectors. This research analyzes the optimization of a hydro plant, wind turbines, and photovoltaic (PV) panels with a careful examination of three scenarios in the Hinnoya region, Norway. Three consumption scenarios—including an industrial/domestic load scenario, transportation load, and household load alone—for this region are considered. HOMER software is used to simulate and analyze the techno-economic performance of solar panels/wind turbines/grid/batteries and converters. The results of this research show that using renewable and eco-friendly systems in accordance with the region's potential leads to a lower cost of electricity generation. The COE production is at least 50% less than the normal sales price of the electricity grid. The use of electric grid exchanges results in energy modification at night. The potential for the use of onshore wind turbines is more than offshore turbines. The results also indicate that using renewable systems in the household field can reduce the COE by nearly 70% (0.0296 €/kWh), and in other energy fields (transportation and industrial) can diminish the COE by nearly 50% (0.055 €/kWh). Thus, increasing the percentage of employing renewable and eco-friendly energy systems leads to reduce greenhouse gas (GHG) emissions (particularly carbon dioxide). • 3E analyses are done for the RES connected to the local electricity grid in Norway. • Three consumption scenarios; industrial, domestic, and transportation loads are considered. • Using electric grid exchanges results in energy modification at night. • The potential for the use of onshore wind turbines is more than offshore turbines. • Using RES reduce the cost of energy by 0.0296 €/kWh for domestic and 0.055 €/kWh for transportation and industry. [ABSTRACT FROM AUTHOR]

Nowadays, wind energy is taking on primary role within renewable energies scenario. However, impact of wind energy industry on the environment still requires to be fully understood and better quantified. This study provides an updated review of Life Cycle Assessment (LCA) studies of electricity produced from onshore and offshore wind turbines (WTs). Special emphasis is put on results harmonization and simplified LCA models existing in the literature. The synthesis of the results is performed for wide range of WTs capacities, providing an exhaustive and general frame of the environmental impacts of WTs systems. Moreover, new simplified LCA models, which make use of a non-linear regression, were developed in this work for the following impact categories: Acidification Potential (AP), Eutrophication Potential (EP), Global Warming Potential (GWP) and Cumulative Energy Demand (CED) and for onshore (1–5000 kW) and offshore (500–8000 kW) WTs. Nonlinear data fitting models are provided with a sufficiently high correlation coefficient for total life cycle impacts. Moreover, the proposed simplified LCA models predict the final results with acceptable uncertainty. This indicates that the one-term power series describes the behavior of the impact indicators accurately, providing a useful correlation to estimate the life cycle environmental performance for a specific turbine model with a given nominal power. Furthermore, obtained simplified LCA models were generalized for different site-specific wind conditions, i.e. wind speeds and wind classes. By analyzing all the considered impact indicators for electricity generation, we notice that the highest values of life cycle impacts of electricity, for a particular WT correspond to the highest wind velocities. This is particularly valid for low nominal power turbines, which seem to be significantly affected by wind conditions. The trends exhibit an asymptotic behavior, indicating that, on the contrary, wind conditions are a minor contributor to the environmental impact of large-scale systems. Image 1 • Systematic review of LCA works on wind energy systems is performed. • Simplified LCA models for GWP, AP, EP and CED impacts are developed. • Synthesis and generalization of the results are provided. [ABSTRACT FROM AUTHOR]

Photovoltaic (PV) energy has been identified as one of the main energy sources in transition from generation of electricity from non-renewable sources to renewable sources. In the Southern region of Brazil, despite the favorable conditions for implementation of distributed generation of photovoltaic energy, the installed capacity is much lower than the existing generation potential, evidencing the presence of factors that hinder the greater adoption and diffusion of this technology. Thus, this article identifies the panorama of distributed generation of photovoltaic energy and barriers that compromise its greater diffusion in the Southern region of Brazil, based on existing literature and qualitative interviews with professionals of the electricity sector. Results showed that this source of solar energy is expected to grow, but much remains to be done to consolidate it in the energy matrix, given the existence of technical, economic, social, managerial and political barriers. Among the main barriers identified are the poor quality of photovoltaic systems, the high cost of initial investment, the dependence on financing for purchase of solar panels, consumer culture, lack of knowledge about photovoltaic technology, the inefficient after-sales services, the dependence on imports of solar panels from China and lack of policies to encourage photovoltaic generation. The results of this study allow the understanding of the diffusion of the distributed generation of photovoltaic energy in countries of emerging economies or in regions where the implementation of PV systems is still incipient. Image 1 • In Southern Brazil, the installed capacity of PV energy is lower than its potential. • The scenario and the barriers for PV adoption in Southern Brazil are presented. • Data from semi-structure interviews with specialists are compared to the literature. • Identified barriers were classified in five dimensions. • Results allow to understand distributed PV generation in emerging economies. [ABSTRACT FROM AUTHOR]

Agricultural and livestock/slaughterhouse wastes are produced in huge quantities and could be promising sources for electricity generation to partially reduce dependence on fossil-oriented electricity. In light of that, the state of the production for these wastes in different parts of the globe was first presented. Subsequently, various waste-to-energy technologies and their electricity generation feasibility from both environmental and economic perspectives were reviewed. Finally, electricity generation and greenhouse gas (GHG) reduction potentials through anaerobic digestion of the above-mentioned wastes generated in each province of Iran in 2016 were investigated as a case study. Accordingly, Khuzestan province with the highest amount of agro-wastes (7.61 million tons) and Sistan and Baluchestan province with the highest amount of livestock/slaughterhouse wastes (10.69 million tons) had the maximum electricity generation potentials of 82.83 MW and 164.23 MW, respectively. Moreover, the country's total potentials for electricity generation from these wastes was determined at 2848.26 MW. Based on the life cycle assessment (LCA) results, a minimum of 10,693.5 thousand tons CO 2 eq/yr could be avoided by valorizing these wastes into electricity in Iran. This would be translated into 1.5% reduction of Iran's annual GHG emissions; a promising achievement given Iran's international GHGs reduction commitment. Moreover, if a short-term time horizon would be considered for electricity generation from these wastes, the reduction rate could reach 24,153 thousand tons CO 2 eq/yr, i.e., 3.39% reduction of Iran's annual GHG emissions. To the best of our knowledge, this is the first report scrutinizing electricity generation potentials from both agricultural and livestock/slaughterhouse wastes in Iran while assessing the consequent GHG emission reduction potentials. The outcomes of the study could assist policy makers with decisions aimed at taking advantage of these resources while the platform introduced pave the way for other researchers to conduct similar studies in different parts of the world. Image 1 • Global agricultural/livestock/slaughterhouse wastes generation was reviewed. • Electricity generation potentials from waste biomass in Iran were reviewed. • GHG emission reduction potentials from waste biomass in Iran were reviewed. • Electricity generation potentials in Iran were estimated at 2848.26 MW. • At least 10.7 MT CO 2 eq/yr could be avoided by managing these wastes feedstocks. [ABSTRACT FROM AUTHOR]

Transparent, consistent accounting of climate-related energy targets is a fundamental building block to the architecture of international climate agreements. Many of these climate targets focus on the transition of the energy system which has led to the development of various energy transition scenarios. Now that fossil resources are being replaced by non-combustible and renewable energy sources a re-assessment of the applicability of the current set of metrics on which these energy scenarios are based is necessary. Now that energy derived from renewable and non-combustible resources with abundant availability but limited instantaneous availability becomes more prominent the ongoing electrification of the energy system combined with the decarbonisation of the electricity system has caused the current set of energy scenario metrics to become ambiguous. More specifically we show that Total Primary Energy (TPE) and its related indicators, Energy Efficiency (EE), Energy Intensity (EI) as well as the key metric Electricity Generation Capacity (EGC) have become unrepresentative, potentially misleading and for a large part irrelevant. This is problematic as these metrics steer climate policy and investment decisions based on statistical artefacts rather than valid representation of the energy system. This study concludes with a set of requirements on energy scenarios to overcome these problems that will lead energy scenarios to focus on Total Final Consumption within a mix of related energy metrics. • Decarbonisation of the energy system has caused energy scenario metrics to become ambiguous. • We show that TPE and EGC have become potentially misleading and for a large part irrelevant. • This is problematic as these metrics steer policy and investments based on statistical artefacts. • We conclude with a set of requirements that will lead scenarios to focus on Total Final Consumption. [ABSTRACT FROM AUTHOR]

There is an evident food, water and energy crisis worldwide. Up to a quarter of the global population has no reliable access to any of these basic supplies. The published literature reveals that research is being carried out on sustainable and comprehensive energy transitions. Simultaneously, research on different aspects of agriculture, such as energy intensity and water use are constantly investigated, mostly at local or regional level. However, the published literature has not yet addressed a recently developed model of agriculture, the container sized agricultural units, which can be integrated to energy production facilities providing an opportunity for a symbiotic relation whereby both systems benefit. Results show that using only 5% of the projected electricity generation (2527 TWh el) from biomass, utility-scale photovoltaic, wind and waste-to-energy for proposed cases, a total of 55.4 million container-sized agricultural units can be powered globally by 2050, providing the recommended vegetable intake to 24.4% of the projected global population. The proposed approach eliminates the need of pesticides and herbicides, and reduces water, land and fertilizer use, while decreasing the need for transportation. Additionally, the CO 2 emissions from point sources, such as power plants, can be captured and used to increase the yield of the agricultural units by up to 30%. • Energy can bridge the global alimentary gap through new enhanced agriculture. • A new unit, the VEGY, is created to represent the recommended vegetable intake. • In 2050, 3.6% of the global energy generation could cover 24.4% of VEGY production. • The proposed solution could preserve 14.5 billion m3 of water and 9600 km2 of land. [ABSTRACT FROM AUTHOR]

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

Abstract The electricity sector in the Galapagos Islands is heavily dependent on fossil fuels for electricity generation but only a few renewable sources are used for such a purpose in this archipelago. Therefore, this work aims to present the current status of its electricity sector and show estimates for the upcoming years, discuss exploited and unexploited renewable resources, and put forward a proposal for a hybrid system to generate renewable power. Currently, thermoelectric power plants run on diesel are the main source of electricity generation in the archipelago due to supplying 85% of the total power installed in the islands (27.6 MW), and the remaining 15% (7.3 MW) is from renewable sources, such as the wind (10.8%), sun (4.1%), and vegetable oils (0.1%). In the upcoming years, there will be a growth in the use of these renewable resources if an additional capacity of 28.5 MW is installed. The gross electric output generated by this sector in the last twelve months (March 2017 - February 2018) was 53.80 GWh, which has allowed a return on revenues of over five million dollars at an average cost of US $0.10/kWh. Based on the existing renewable resources in the Galapagos Islands, the implementation of a hybrid solar/biogas power generation system is an attractive alternative to support the zero-fossil fuel initiative, diversify the energy matrix, and promote local development. However, sustainable development policies, energy efficiency programs and foreign investment funds to carry out new projects are required to ensure a bright future for the electricity sector in the Galapagos. Highlights • Galapagos Islands are heavily dependent on fossil fuels for electricity generation. • Solar energy has become the main renewable source of electricity generation. • An additional power of 28.5 MW generated from renewable sources will be installed by 2025. • Biogas, geothermal energy, and wave power are unexploited sources in the Galapagos Islands. • A solar/biogas power system appears as an attractive alternative to support the zero-fossil fuel initiative. [ABSTRACT FROM AUTHOR]

Sedimentation poses a significant threat to the long-term sustainability of hydropower generation. However, there is a lack of studies examining the relationship between sediment trapping efficiency and electricity generation on a basin-wide scale over time. This study aims to assess the efficiency of hydropower production in terms of reservoir sediment trapping. Modified Brune's method examined the relationship between trapped sediments in reservoirs and hydropower production, considering sediment projections for the near future. We divided the cases of existing and planned reservoirs in the mainstream river and subbasins to assess cumulative sediment trapping. Using the Lancang-Mekong River Basin as a case study, the following main findings were observed. Firstly, the existing reservoirs, under baseline conditions (2018), had the potential to trap approximately 60.9% or 82 Mt/yr of the total sediment load. Secondly, around 69% or 110 Mt/yr of the total sediments could be significantly trapped when considering the existing reservoirs and those planned according to the development plan of riparian countries. Thirdly, the hydropower production efficiency of most reservoirs in 2030 and 2040 experienced a significant decline of approximately 10%–20% and more than 30%, respectively. Therefore, sediment management is crucial for maintaining efficient hydropower production and achieving sustainable hydropower development through effective planning strategies. • The integrated approach for analysing reservoir TE and HPP under sediment projections in future conditions is proposed and assessed. • All mainstream reservoirs of the UMB could potentially trap sediments in the range of 70%–90% behind the storage, which was reflected as the sediment impact for the downstream part. • The HPP efficiency in the mainstream and subbasin reservoirs decreased the electricity production because most of the reservoirs had a vaguely active storage capacity for HPP. [ABSTRACT FROM AUTHOR]

Climate change significantly impacts hydrological systems resulting in hydropower generation uncertainties. In this study, a high-resolution glacio-hydrological model is coupled with an hourly-resolution power grid model to evaluate the climate change influences on hydropower generation across Nepal. Four climate future scenarios namely Cold-Dry, Warm-Dry, Cold-Wet, and Warm-Wet are developed to compare the changes in water availability and optimal power system with historical climate. The total flow increases for the wet scenarios (+11.4% under Cold-Wet for the Koshi basin), compared to the dry scenarios (−24.6% under Warm-Dry for the Karnali basin) for all the major river basins in Nepal. The results illustrate the distribution and magnitude of changes in total water availability and power generation are not proportional for dry and wet scenarios as a ∼20% reduction of water availability in the dry scenarios only results in a ∼2–3% decrease in electricity generation. The capacity requirements of hydro storage decrease by 7.2 GW for Cold-Wet and 6.8 GW for Warm-Wet scenarios compared to historical climate indicating higher capacity requirements in dry scenarios. Larger impacts observed at higher altitudes suggest more attentive adaptation strategies in developing climate-resilient hydropower systems. Results suggest that Nepal should not be entirely focused on exploiting its hydropower potential but rather diversifying the generation mix including solar PV and hydrogen technology. For the least-cost power system expansion, the Warm-Wet climate appears to be the most desirable and a cost savings of about 3.76 billion USD in hydropower development can be realized if better adaptation strategies are employed. [Display omitted] • Climate change impacts on hydro-dominated power systems in a high-mountain country. • Coupling of glacio-hydrological model and a high spatial-temporal power grid model. • Adaptation strategies for surplus electricity management are more critical in wet scenarios. • Storage hydro capacity needs drop by 7.2 in Cold-Wet & 6.8 GW in Warm-Wet scenarios. • Employing adaptation strategies results in cost savings of about 3.76 billion USD. [ABSTRACT FROM AUTHOR]

Concerns regarding the negative impact of fossil fuels on the environment have led to a global shift towards sustainable energy systems. This study reviewed recent studies on renewable energy composition and electrification abatement in 26 future scenarios of Canada. There is a trend to move from a comprehensive forecasting analysis of multiple energy sectors to a detailed transition analysis of individual sectors, providing more precise recommendations for achieving emission targets. In 2050, the shares of hydropower and nuclear power fluctuate little between scenarios, accounting for about 60% and 20%, respectively. The balance between variable renewables and natural gas remains unclear to fill the gap from the replacement of coal-fired power by 2030. The capacity demand for solar and wind under the 2050 GHG-100% scenario is doubled compared to the results of the 2050 existing policy scenario, which is beyond what is currently planned by government policies. This increased demand for renewable energy sources requires inter-provincial cooperation in electricity planning for countries with mismatches between renewable energy potential and high energy consumption areas. The result highlights the insufficient carbon price signal for coal, which is only 1/7 of that in the road transport sector, emphasizing the need for stronger carbon pricing policies to meet the targets of the Paris Agreement. This study provides valuable insights into the prospects of renewable energy and electrification abatement in Canada, highlighting the need for inter-provincial cooperation, precise transition analysis, and effective carbon pricing policies. [Display omitted] • Energy transition scenario analysis moves from multiple to individual sectors. • The share of hydro power and nuclear power fluctuates modestly in scenarios. • The future demand for solar and wind energy capacity has been underestimated. • The electrification abatements based on renewable energy were assessed. • Compared to the other sectors, the coal sector needs an effective carbon pricing. [ABSTRACT FROM AUTHOR]

Hydrogen is becoming increasingly popular as a clean, secure, and affordable energy source for the future. This study develops an approach for designing a PV–battery–electrolyzer–fuel cell energy system that utilizes hydrogen as a long-term storage medium and battery as a short-term storage medium. The system is designed to supply load demand primarily through direct electricity generation in the summer, and indirect electricity generation through hydrogen in the winter. The sizing of system components is based on the direct electricity and indirect hydrogen demand, with a key input parameter being the load sizing factor, which determines the extent to which hydrogen is used to meet seasonal imbalance. Technical and financial indicators are used to assess the performance of the designed system. Simulation results indicate that the energy system can effectively balance the seasonal variation of renewable generation and load demand with the use of hydrogen. Additionally, guidelines for achieving self-sufficiency and system sustainability for providing enough power in the following years are provided to determine the appropriate component size. The sensitivity analysis indicates that the energy system can achieve self-sufficiency and system sustainability with a proper load sizing factor from a technical perspective. From an economic perspective, the levelized cost of energy is relatively high because of the high costs of hydrogen-related components at this moment. However, it has great economic potential for future self-sufficient energy systems with the maturity of hydrogen technologies. • An approach is proposed to size a PV–battery–electrolyzer–fuel cell energy system. • Hydrogen is considered the long-term energy storage medium. • Techno-economic performance of the energy system is analyzed with a case study. • The introduction of hydrogen increases the reliability of energy supply. • Load sizing factor of <1 is sufficient. [ABSTRACT FROM AUTHOR]

Abstract Increasing flexibility in electricity systems with high-shares of volatile renewable generation is on top of the European policy making agenda. Large-scale pumped hydro storages are appropriate technology candidates to accomplish this. Therefore, they are one of the focus technologies of the European Commission in the Projects of Common Interest discussion. In order to get listed a thorough system benefit analysis has to be conducted. This paper investigates a comprehensive socio-economic benefit analysis of storage technologies according to the indicators expected by the European Commission. The dispatch model EDisOn + Balancing is applied, which includes the functionalities depicting balancing mechanisms. Additionally, the profitability analysis tries to sort out the most convincing business cases where storage technologies contributing to more flexibility in the electricity system can sustain in the long-run. A simulation tool has been developed to model and quantify flexibility options, and to evaluate the profitability from the owner's point-of-view. The results show that in Central Europe with increasing storage capacities the necessity of reserve capacity and investments in peaking units decreases while maintaining a high security of supply level. In addition to electricity generation and balancing cost reductions, shedding of renewables and significant amounts of environmental damage costs of up to 1300 MEuro/a can be avoided. The profitability study shows that a reduction of minimum load or retrofitting hydro reservoir storages with pump mode increase the hours of participation in balancing markets and machine utilisation, e.g. operating hours and frequency of machine starts. With the latter also wear of machines increases. Therefore, it is important to find the optimum in terms of machine starts and market benefits. Several benefits are presented per installed capacity to provide scalability and transferability of outcomes for other applications. Furthermore, the analyses make an important contribution to the European Projects of Common Interest discussion. Highlights • Planned hydro projects in AT till 2030 avoid environmental damage costs of 1300 MEuro/a in CE. • 3.5 GW turbine capacity in addition replaces 1 GW of thermal power capacity. • Reducing minimum load of PHS by 50. [ABSTRACT FROM AUTHOR]

Abstract This paper provides a critical literature review of the impact of snow accumulations on photovoltaic (PV) system electricity generation. The review quantifies the impact of snow, identifies factors that influence the generation loss, examines existing snow impact estimation techniques, and identifies mitigation strategies to reduce the impact of snow accumulations. Reported annual and monthly electricity generation losses resulting from snow accumulations on photovoltaic systems show that annual electricity generation losses were less than 10% in most climates; however, monthly generation losses throughout the winter were generally higher than 25%. The influences of climatic characteristics and system characteristics on the impact of snow were examined individually, and the codependence between influence factors was also discussed where relevant. Estimation techniques for electricity generation loss due to snow cover were summarized. Relatively accurate estimates are achievable by several models when considering ambient temperature, solar irradiance, and snow depth. Ten mitigation methods were identified as having the potential to reduce the impact of snow on PV system electricity generation and were discussed qualitatively. This review provides system designers and operators with the information required to identify how to manage the effect of snow on PV systems and highlights the need for researchers to develop ways to reduce and predict the impact. Highlights • Electricity generation loss due to snow on PV systems is generally less than 10%. • Winter month generation loss due to snow is generally higher than 25%. • Climate and system characteristics have a significant impact on loss. • Threshold type snow coverage prediction models are most effective. • No method currently exists to mitigate the impact of snow on PV panels. [ABSTRACT FROM AUTHOR]

Abstract This paper evaluates the potential for co-location of offshore wind turbines at sites being developed for tidal stream arrays as a method for reducing the cost of electricity. It is shown that for a typical tidal site, MeyGen in the Pentland Firth, UK, increasing the wind turbine capacity reduces the cost of electricity compared to operating tidal stream arrays alone. This is due to increased energy yield combined with reduction of capital expenditure based on the use of common grid connection and shared support structures. Assessment is made using tidal, wave and wind resource data for a three year period. The overturning moment about the base of a monopile supporting a wind turbine with two tidal turbines is only 8% larger than for a wind turbine alone in a strong current typical of tidal farms. The increased cost of infrastructure is small relative to the increased energy yield and for all array configurations of practical interest, the levelised capital cost of energy is estimated to be 10–12% less from a co-located farm than from a tidal turbine farm alone. Highlights • Cost of electricity by co-locating wind turbines with tidal stream arrays is evaluated. • Energy yield and peak loads are modelled for array layouts in the Pentland Firth. • Peak loads for a shared support are 60% greater than typical offshore wind turbines. • For the same cost, co-location generates 20% more yield than tidal-only arrays. • Co-location offers 10–12% lower levelised cost compared to a comparable tidal array. [ABSTRACT FROM AUTHOR]

Abstract Biogas production from animal manure produced in farms in the Canary Islands may represent an additional energy source for producing heat and/or electricity. Data of different animal farms distributed all around the islands were used for evaluating the potential biogas generation and contribution to the production of renewable energy in the Canary Islands. Total manure production is 495,622 tons per year. Results show that animal manure as a source of biogas may be associated with an overall biogas potential of 27.1 Mm3 year−1 with an equivalent installed power capacity of 6.8 MW e. Considering 0.5 t day−1 manure as the lowest limit for implementing biogas projects, 546 farms raising different animal types (poultry, sheep, swine, cows or goats) have potential for producing and using their own biogas for generating heat and/or electricity with electrical powers ranging from 3 to 185 kW e. Potential GHG emissions savings due to the production of biogas from animal manure could reach yearly 55,745.1 tons of carbon dioxide equivalents, including both substitution of fossil fuels and appropriate management of animal manure. The application of appropriate policies described in this study should contribute to overcome main challenges identified for the development of the biogas industry in the Canary Islands, which are related to the small size of the livestock holdings, the lack of a culture of association in the livestock sector and the lack of specific subsidies for biogas production. This study could be used as a basis for further studies in other European outermost regions with similar characteristics to the Canary Islands, such as Madeira and Azores. Graphical abstract fx1 Highlights • Manure production on the Canary Islands amounts to 495,622 t year−1. • Potential biogas production is 27.1 millions of m3 year−1. • Biogas potential can contribute up to 14.6 toe year−1 and 6.8 MWe. • Potential electricity is 0.68% and 8.56% of total and renewable electricity of 2016. • Potential GHG emissions savings could reach 55,745.1 tCO 2 e year−1. [ABSTRACT FROM AUTHOR]

Abstract The purpose of this paper is to highlight the most demanding aspects of grid interconnection of marine energy installations while at the same time providing an updated overview and comparative analysis of the connection requirements of eight European Grid Codes. Therefore, the major issues related to marine energy installations will be summarized as well as the requirements of this type of generation. Besides, the extent to which current Grid Codes include marine energy technologies will be analysed jointly with the need of harmonization of different Grid Codes into a generalised European grid code. Apart from this, several future trends of marine energy technology and its interconnection will be provided for the final discussion. Highlights • Capacity limits and critical power quality issues where not originally planned. • Impacts: limited dispatchability, electrical grid stress, high penetration effects. • Long submarine cables reduce precise voltage or reactive power control capability. • European Grid codes compared: only in UK and Germany offshore treated separately. • ENTSO-E effort for harmonization by setting common requirements for grid connection. [ABSTRACT FROM AUTHOR]

Abstract The investment in renewable energy sources power generation is coming into a stall in face of the removal of incentives in most of the European countries. The technological maturity of wind and solar power generation is the justification basis and market integration of extensive amounts of renewable energy is seen with concern by electricity systems stakeholders. Given the low marginal cost of renewable power generation, the available load in the spot electricity market for conventional and dispatchable power plants is diminishing, the so-called Merit-Order Effect. In this study, we estimate the value of the Merit-Order Effect due to wind and solar power generation in the Iberian electricity market with historical bid supply and demand offers from 2008 to 2017. The estimated values are then used to value determinants and volatility through GARCH econometric modelling. Results demonstrate that the Merit-Order Effect in Iberia is influenced negatively by the residual load and positively by demand, wind power and solar power. Additionally, the high Merit-Order Effect volatility found, mirrors the behavior of spot electricity market. Highlights • The MOE is negatively influenced by the residual load and positively by demand, wind and solar power. • High MOE volatility mirrors the intermittent behavior of non-dispatchable RES power generation. • Lack of signals to invest in new generation capacity, renewable or not. • Without new investment in capacity, the electricity sector is likely to fall into supply shortage. [ABSTRACT FROM AUTHOR]

Abstract African countries are in a unique position to reap the socio-economic and environmental benefits of renewable resources as a means for meeting increasing energy demand in a sustainable way. A critical obstacle for the deployment of renewable energy technologies in Africa is the difficulty of attracting sufficient and affordable finance. This paper compares the impact of financial conditions on the cost of electricity generation across six renewable and three fossil-based technologies in 46 African countries. The results show large cost variations and highlight the extent to which renewables are disadvantaged by current financial practices. The energy-economy-environment model TIAM-ECN is used to show how lowering financing costs results in a much higher deployment of renewables. For example, solar PV could account for 10–15% of total electricity generation by 2050, even without explicit climate policy, thanks to financial de-risking programmes. The results demonstrate that changes in financing schemes could outweigh the impact of technology learning. This paper also demonstrates that, once ambitious climate policies are in place, reducing financing costs for renewables could be an efficient way to lower greenhouse gas emissions. Financial de-risking is thus a key ingredient for unlocking the renewable energy potential in Africa. Highlights • We show how renewables are disadvantaged by today's financial practices in Africa. • We show how lower financing costs result in a higher deployment of renewables. • PV can account for 10–15% of electricity generation by 2050 without climate policy. • Changes in financing schemes could outweigh the impact of technology learning. • Financial de-risking is key for unlocking the renewable energy potential in Africa. [ABSTRACT FROM AUTHOR]

Abstract Logarithmic mean Divisia for index decomposition analysis (IDA-LMDI) has been applied to evaluate the aggregate carbon emission intensity of electricity (ACI) evolution considering explaining factors as fuel mix, thermal efficiency, fossil share and geographical effects. However, the capacity factor of the generation system has not been duly considered in previous LMDI formulations. The capacity factor provides a perception of the time of use of the generation infrastructure. Despite LMDI analysis have been widely applied to explain the electricity-related CO 2 emissions changes in many countries and regions of the world, Latin America & the Caribbean (LAC) power sector has not been analyzed yet. Since 1990 the global ACI declined around 5% whereas the ACI of LAC is just going in the opposite direction with a significant increase of 10%. To fill the research gap, this paper presents a new and general temporal IDA-LMDI formulation in order to expressly include the effect of capacity factors and analyze the evolution of LAC's ACI between 1990 and 2015. Results reveal the increase of the ACI in the region is due to structural reasons, mainly in Brazil. Intensity factors as thermal efficiency and fossil mix were also substantially improved, mainly in Mexico, but not enough to cut down the regional ACI increase. As a key result, it is shown that the capacity factors of fossil-based generation –mainly in Venezuela, Mexico and Brazil– are a relevant driving force behind the ACI increase. As Brazil is the largest producer and its capacity factor is relatively low compared to other LAC countries, the increasingly dispatch of fuel-fired power plants to cover base-load may boost the ACI of the region in the future jeopardizing the compliance of the climate goals. Highlights • A new IDA-LMDI method for aggregate carbon intensity (ACI) analysis is presented. • The method is based upon the inclusion of the generating plant capacity factor. • The ACI of the Latin American countries was analyzed over 25 years. • Brazil's thermal capacity factor had a central role on the increase of regional ACI. • The ACI's increasing trend, mainly in Brazil, can threaten the regional climate goals. [ABSTRACT FROM AUTHOR]

Abstract Long-time search for green energy as a replacement of the depleting conventional sources to the eternal power demand still remains as an unanswered question. But the steady growth in the contribution of solar energy towards the electrical power generation for the past three decades have persuaded many researchers to consider it as a viable option. However, the power harnessed from solar PV is low due to its less conversion efficiency. Therefore, it is necessary to perform some critical analysis on the factors improving the efficiency of the solar PV system. In this paper, an attempt is made in performing a detailed comprehensive review on the factors affecting the efficiency of solar cell. A detailed review is carried out on basic material used for solar cells, Maximum Power Point Tracking (MPPT) Techniques and the DC-DC converters used for power conversion. Highlights • Efficiency of PV system depending on materials used for manufacturing. • Efficiency of PV system depending on Maximum power point tracking techniques. • Comparative analysis of MPPT techniques on various factors. • Efficiency of PV system depending on Converter topologies employed. [ABSTRACT FROM AUTHOR]

Abstract This review collates energy assessment data for the most common electricity generation methods and evaluates five Energy Ratios. The considered ratios are Energy Return on Investment (EROI) – standard and external, Energy Payback Time (EPT), Primary Energy Factor (PEF), and Resource Utilisation Factor (RUF). A common energy analysis framework, together with three energy accounting methods based on energy value, exergy, and primary energy, are described. The concept of the time-value for energy as an analogy to the time-value for money is proposed and has a significant impact on the calculated Energy Ratios. In total, this review brings together data for 45 electricity generation projects. Based on the Energy Return on Investment (external), the generation methods fall into three tiers: (1) nuclear, natural gas combined cycle, and geothermal (in New Zealand) with ratios > 30, (2) hydro, wind, and geothermal (in Iceland) with ratios between 5–30, and (3) solar PV with ratios less than 5. High Energy Return on Investment ratios correspond to short Energy Payback Times and vice versa. Energy Ratio performance levels for renewable energy generation sources – hydro, wind, geothermal and solar – heavily rely on the quality of the primary natural resource available. This review recommends Energy Return on Investment (external) and Resource Utilisation Factor as the most useful metrics for inclusion in full sustainability assessment. Highlights • Determines five Energy Ratios for 45 electricity generation projects. • Introduces the concept of time-value for energy for capital energy investments. • Nuclear, natural gas and geothermal power stations achieve high Energy Ratios. • Geothermal, hydro, wind performances strongly depend on available resources. • Solar PV has the least attractive Energy Ratios due to high embedded energy. [ABSTRACT FROM AUTHOR]

Abstract Power-to-gas is a key area of interest for decarbonisation and increasing flexibility in energy systems, as it has the potential both to absorb renewable electricity at times of excess supply and to provide backup energy at times of excess demand. By integrating power-to-gas with the natural gas grid, it is possible to exploit the inherent linepack flexibility of the grid, and shift some electricity variability onto the gas grid. Furthermore, provided the gas injected into the gas grid is low-carbon, such as hydrogen from renewable power-to-gas, then overall greenhouse gas emissions from the gas grid can be reduced. This work presents the first review of power-to-gas to consider real-life projects, economic assessments and systems modelling studies, and to compare them based on scope, assumptions and outcomes. The review focuses on power-to-gas for injection into the gas grid, as this application has specific economic, technical and modelling opportunities and challenges. The review identified significant interest in, and potential for, power-to-gas in combination with the gas grid, however there are still challenges to overcome to find profitable business cases and manage local and system-wide technical issues. Whilst significant modelling of power-to-gas has been undertaken, more is needed to fully understand the impacts of power-to-gas and gas grid injection on the operational behaviour of the gas grid, taking into account dynamic and spatial effects. Highlights • Review found great interest in power-to-gas (P2G) & H 2 injection into the gas grid (HIGG). • Strong potential for P2G & HIGG to increase penetration of renewables in energy system. • Studies generally agree that efficiency of P2G and HIGG will increase by 2030. • Electricity balancing market and government support will drive viable business cases. • There is a lack of whole-systems optimisation studies with HIGG and linepack storage. [ABSTRACT FROM AUTHOR]

Abstract As for other renewable energy sources in Germany like wind or photovoltaics, biogas has rapidly expanded in the past fifteen years. The installed electricity capacity for German biogas plants increased from 0.2 GW el in 2001 up to about 4.2 GW el by the end of the year 2016. This expansion has been supported in particular by the Renewable Energy Sources Act (EEG) through electricity Feed-In-Tariffs (FITs). However, major uncertainties are linked to the future capacity expansion in particular due to volatile electricity and energy crops prices. Taking into account this situation this paper analyzes possible future developments of the German biogas plant capacity up to 2030. For this purpose, a regional optimization model is employed, with the objective of determining the optimal economic development of the future biogas plants under different legal framework conditions. The base scenario with a constant energy crops cost evolution shows that the EEG 2012 framework -if maintained- would have fostered the development of agricultural plants, especially co-digestion plants valorizing energy crops and manure. The new EEG 2014 stops the expansion of energy crops mono-digestion plants, which will no longer be built due to an unprofitable situation. The German biogas market will thus face a paradigm shift and move towards the increase of biowaste and small-scale manure plants. Further scenarios quantify the impact of a strong variation of three main fundamental drivers, namely the energy crop costs, the EPEX-Peak electricity price and the biowaste valorization revenues, on future capacity developments. Based on the model results recommendations in direction of plant operators and policy-makers are formulated aiming at a more sustainable electricity production from biogas. Further work should consist in integrating the present analysis in national bioenergy models under the EEG 2017 legal framework. [ABSTRACT FROM AUTHOR]

Abstract Fuel cells and solar energy are promising candidates for electricity generation. It is forecast that fuel cells and solar power systems will play an important role in reducing the greenhouse gas footprint and replacing fossil fuels. Therefore, the limitations of fuel cells and solar power systems, such as low efficiency, high cost, and low reliability, must be addressed appropriately to enable their full potentials. Metal foam is a new class of material that has gained immense attention due to its excellent properties suitable for a wide range of applications. Its unique characteristics distinguish it from typical solid metals. The properties of metal foam can be modified during the fabrication stage by manipulating its physical structure. The goal of this paper is to review the application of metal foam in fuel cells and solar power systems. Besides, the performance of metal foam in fuel cells and solar systems is also discussed. Metal foam has been applied to the electrodes, gas diffusion layer and flow field of fuel cells to enhance performance, especially in regard to current density and flow distribution. Furthermore, metal foam is a heat exchanger for the solar energy harvesting system to improve its efficiency. Superior performances in experimental testing allows the possibility of commercialization of metal foam products in the renewable energy field. Highlights • This article reviews the past research on metal foam in fuel cell and solar power systems. • Metal foam applications on bipolar plates, electrodes and the gas diffusion layer in a fuel cell. • Metal foam as a thermal management system in solar power systems. • Barriers and future perspectives of metal foam applications in fuel cells and solar power systems. [ABSTRACT FROM AUTHOR]

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

Chile is one of the world largest copper producing countries, housing significant mineral reserves, and accounting for over 30% of national electricity consumption. Currently, the total installed electricity generation capacity amounts to over 20 GW and is expected to double within the next two decades. Since electricity generation is a well-known source of environmental impacts throughout its lifecycle, there is a permanent need to evaluate potential environmental burdens of alternative courses of action. Unfortunately , systematic information on the environmental performance of current electricity generation in the country is lacking. Therefore, this paper reports the potential environmental burdens of the Chilean electricity generation system over the last two decades, to account for temporal effects and serve as a baseline to which compare different strategies, following a cradle-to-gate approach based on ISO 14.040–44:2006 standards. The system limits included fuels extraction and transportation processes, and construction materials, as well as electricity generation, considering as a functional unit 1 kWh. Plant operation, thermal efficiency and infrastructure requirements were modelled based on primary data, whereas fuels extraction, refining, and manufacturing of construction materials were obtained from Ecoinvent databases. Changes in water availability, commercial constrains in natural gas supply, investment in renewable energy technologies, among others, have led to significant changes in the environmental profile along time. Results obtained here show stricter environmental legislation and more efficient environmental control technologies need to be introduced to promote improvements in environmental performance, with particular focus on human health and ecotoxic effects in coal-fired power plants. Finally, new electricity generation capacity based on solar, wind, and other renewable sources should be encouraged to reduce the environmental footprint of electricity generation, thus fostering the competitiveness of Chilean exports. This work provides a sound baseline for the assessment of future development scenarios, constituting an interesting case study for comparative studies. [ABSTRACT FROM AUTHOR]

Malaysia's framework for energy development was established in the early 1970s. Henceforth, many successive policies were introduced as potential resources for electricity generation and utilization. Currently, as a signatory to the United Nations Framework Convention on Climate Change, Malaysia is sparing a number of effort to comply with the policy to meet the challenges of mitigating over-dependence on fossil fuels, reducing carbon levels, and achieving sustainable national development. This paper reviews the baseline studies on electrical energy policies and the measurement indicators used in Malaysia's electric power system. This research involves a comprehensive survey of electrical energy policies in Malaysia that focus on issues pertaining to energy supply, utilization, its environmental impact and considerations, renewable energy (RE) policies, production and consumption, energy efficiency, and feed-in tariffs. Fourteen energy indicators for sustainable development in Malaysia were investigated through the identification of energy policies in significant areas, such as reliability, safety, adequacy and cost-effectiveness of energy supply; increasing energy efficiency; minimizing environmental impact; and enhancing quality of life in terms of social well-being. The policies and the indicators are classified into different sustainable dimensions and summarized in tables along with the corresponding key references. In this study, future energy planning and options, especially in nuclear and RE programs, as well as the conflict between them, are illustrated through the overall performance relative to targets and benchmarks for past and future projections up to the year 2030. This review seeks to examine the past, present, and future policies and indicators to provide a sufficient overview of Malaysian energy policies for optimizing sustainable development. The goal is for this review to lead to increased efforts to accommodate the increasing demand for the management and utilization of RE, promote energy efficiency, and improve performance in achieving sustainable national development. [ABSTRACT FROM AUTHOR]

Renewable Energy Sources have been growing rapidly over the last few years. The spreading of renewables has become stronger due to the increased air pollution, which is largely believed to be irreversible for the environment. On the other hand, the penetration of renewable energy technologies causes major problems to the stability of the grid. Along with the fluctuations of the renewable energy technologies production, storage is important for power and voltage smoothing. Energy storage is also important for energy management, frequency regulation, peak shaving, load leveling, seasonal storage and standby generation during a fault. Thus, storage technologies have gained an increased attention and have become more than a necessity nowadays. This paper presents an up to date comprehensive overview of energy storage technologies. It incorporates characteristics and functionalities of each storage technology, as well as their advantages and disadvantages compared with other storage technologies. Comparison tables with several characteristics of each storage method are included, while different applications of energy storage technologies are described as well. Finally, several hybrid energy storage applications are analyzed and different combinations of energy storage technologies are reviewed. [ABSTRACT FROM AUTHOR]

This paper evaluates the net effect of renewable energy policy in Spain from 2002 to 2017 and calculates its cost-effectiveness in terms of CO 2 emission reductions in the production of electricity. Our conclusions indicate that although the phasing out of Feed-in Tariffs reduced the regulatory costs, it also limited renewable participation in the electricity market, leading to an increased electricity price and higher emissions. According to our results, the joint effect of (i) the value of avoided emissions due to renewable energy participation and (ii) the merit order effect was able to compensate for the regulatory costs (subsidies) up until 2010, while the sign of the net effect was reversed from 2011 to 2017. Finally, we find that the economic implications of emission reductions are highly dependent on how the social cost of carbon is measured. [ABSTRACT FROM AUTHOR]

This paper presents a detailed review of the energy potential from residual biomass for distributed generation in Brazil, presenting the potential by macro-region of the different types of residues generated in the agricultural, forestry, livestock, industrial and urban sectors. The focus of this research is to map and point out, through bibliographic research, the great potential of biomass in the Brazilian market for the production of biogas and consequently the use for electric power generation in the country and especially in the state of Paraná. Therefore, it should be emphasized that the methodology used is based on a bibliographic research from databases and recent research using a survey carried out by the ITAIPU Technological Park (PTI) in partnership with SENAI/PR, using the FIEP Observatories. As result, this research describes through data collection a favorable scenario for the technical feasibility of the use of biomass for the energetic use of biogas for power generation. The distributed generation of electricity from the use of biomass could help Brazil in the preservation of the environment as well as contribute to the diversification of the energy matrix, economic development and broadening access to energy in isolated communities. [ABSTRACT FROM AUTHOR]

As Iran is rich in oil and gas resources, renewable energy was known as a luxurious source of electric power generation for a long time. New policies and targeted subsidy reform plan for fossil fuel products have changed the view of decision-makers and energy sector investors toward renewable energy resources. According to the climatological studies, two-thirds of Iran's land has three hundred sunny days which indicates great potentials for providing solar energy. This paper deals with small-scale solar energy potentials in different cities of Iran. The considered solar systems are based on the combination of photovoltaic panels in order to obtain the nominal values of 1, 5 and 10 kW for 15 selected cities of Iran. Design of the photovoltaic (PV) systems is carried out based on optimum fixed tilt angles of the panels and efficiency variation due to the temperature changes of different locations. The final decision on financial assessment of the mentioned solar PV projects is based on different concepts of engineering economy such as rate of return (ROR), present worth of benefit and cost (PWB, PWC), extra investment analysis, levelized cost of energy (LCOE). The amount of calculated income and the expected benefit are also investigated under certainty and uncertainty of guaranteed solar electricity purchase tariff in a 30-year project lifetime. [ABSTRACT FROM AUTHOR]

More and more wind farms are reaching the end of their useful lifetimes, so it is necessary to consider the need and/or suitability of dismantling or repowering them. This paper presents an analysis from the point of view of the potential environmental impact and benefit of a wind farm repowering process. The study has been performed by developing a life cycle assessment model of the repowering process of an old wind farm with low-power wind turbines. The results show the advantages of repowering wind farms of this type, especially in terms of increased capacity for electrical power generation from renewable sources and extending the useful lifetimes of wind farms. The main impact of the repowering process comes from the wind turbines, which show values of 2.43E + 07 kg CO 2 eq. in the Global Warming category, followed by the substation and electrical line (5.14E + 05 kg CO 2 eq.). These impacts are clearly offset by the benefits of increasing electrical power generation from renewable sources, which show values of − 9.03E + 08 kg CO 2 eq. Therefore, from the point of view of the decision-making process, the repowering of old wind farms with low-power wind turbines provides environmental benefits that must be taken into account when evaluating the future of wind farms approaching the end of their useful lifetimes. [ABSTRACT FROM AUTHOR]

Operational research (OR) methods have been successfully applied in many industrial process. The objective of this work is to discuss the application of computational tools and OR to the study and optimisation of industrial co-generation systems. After reviewing the literature a collection of technical data on co-generation systems is made and a complete OR model (objective function and constraints) for the co-generation problems is done. In order to find the optimal solutions for the co-generation systems a computer code that solves the resulting linear programming problem was developed. The first problem presented consists in a work production system, here considered as electrical power, and heat through multi-stage turbines and condenser, respectively. The second one is a simplified system of co-generation, which will be generated electrical power from a turbine in multi-stage and heat by two heat exchangers. Finally, it was possible to note that the computational tools combined with operational research have proven to be effective in solving industrial co-generation problems. [ABSTRACT FROM AUTHOR]

A recent article ‘Burden of proof: A comprehensive review of the feasibility of 100% renewable-electricity systems’ claims that many studies of 100% renewable electricity systems do not demonstrate sufficient technical feasibility, according to the criteria of the article's authors (henceforth ‘the authors’). Here we analyse the authors’ methodology and find it problematic. The feasibility criteria chosen by the authors are important, but are also easily addressed at low economic cost, while not affecting the main conclusions of the reviewed studies and certainly not affecting their technical feasibility. A more thorough review reveals that all of the issues have already been addressed in the engineering and modelling literature. Nuclear power, which the authors have evaluated positively elsewhere, faces other, genuine feasibility problems, such as the finiteness of uranium resources and a reliance on unproven technologies in the medium- to long-term. Energy systems based on renewables, on the other hand, are not only feasible, but already economically viable and decreasing in cost every year. [ABSTRACT FROM AUTHOR]

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

The environmental awareness and sustainability concerns have reached an unprecedented level of importance that is leading to, among other things, constant improvements in the traditional methods of energy conversion. One of those improvements involves the use of micro-CHP (combined heat and power production) systems for residential applications since the potential in terms of primary energy savings and GHG (greenhouse gases) reductions is considered to be enormous. Among the different technologies available for micro-CHP systems, ORC based ones seem the most suitable and promising option due to its simplicity and its ability to retrofit current heating systems used in residential dwellings. This work reviews the use of ORC for micro-CHP applications taking into account the intrinsic requirements of the residential sector. One of those requirements is the ability to face highly variable thermal demand loads for which a short response time is necessary to ensure. The present research analyzes how manufacturers and the researcher centers are dealing with this key requirement. One of the findings of this work is that the referred requirement is essentially dependent on the ORC-evaporator design and how the primary energy reaches the power cycle, while the remaining ORC main components (expander, pump and condenser) play a minor role on that ability. Additionally, this research also offers an analysis of the micro-CHP potential and of the ORC market evolution, presenting a historical perspective of the technology, current main manufacturers, main application areas and a comparison between the use of an organic fluid and water/steam as working fluid for Rankine cycles. [ABSTRACT FROM AUTHOR]

In present day scenario, the focus is reallocating towards integration of small and medium scale power plants based on renewable energy sources into the power distribution system. Solar is the fastest growing form of renewable energy and a single phase voltage source inverter is used to interface photovoltaic based plants with the distribution system. The grid integrated inverter has stringent control requirements. A current controller is employed to mitigate the harmonics in the current injected into the grid and regulate the power exchange between the plant and the grid. This paper presents a review of the current control strategies implemented for a single phase grid tied photovoltaic inverter. A comparative performance evaluation of the current control techniques is also presented through simulation and experimental results. [ABSTRACT FROM AUTHOR]

A technical, financial, economic and environmental analysis of geothermal power plant developments in the Ecuadorian context was analysed by RETScreen-International Geothermal Project Model. Three different scenarios were considered. Scenario I and II considered incentives of 132.1 USD/MWh for electricity generation and grants of 3 million USD. Scenario III considered the geothermal project with an electricity export price of 49.3 USD/MWh. Scenario III was further divided into IIIA and IIIB case studies. Scenario IIIA considered a 3 million USD grant while Scenario IIIB considered an income of 8.9 USD/MWh for selling heat in direct applications. Modelling results showed that binary power cycle was the most suitable geothermal technology to produce electricity along with aquaculture and greenhouse heating for direct use applications in all scenarios. Financial analyses showed that the debt payment would be 5.36 million USD/year under in Scenario I and III. The corresponding values for Scenario II was 7.06 million USD/year. Net Present Value was positive for all studied scenarios except for Scenario IIIA. The equity paybacks were 3.2, 3.7, 16 and 5.6 years for Scenario I, Scenario II, Scenario IIIA and Scenario IIIB, respectively. Overall, Scenario II was identified as the most feasible project due to positive NPV with short payback period. Interestingly, Scenario IIIB could become financially attractive by selling heat for direct applications. Direct applications, public incentives and clean funding mechanisms are essential for the success of geothermal energy projects in the Ecuadorian context. The total initial investment for a 22 MW geothermal power plant was 114.3 million USD (at 2017 costs). Economic analysis showed an annual savings of 24.3 million USD by avoiding fossil fuel electricity generation. More than 184,000 tCO 2 eq. could be avoided annually. Thus, greenhouse emissions avoided by using geothermal energy would bring out environmental benefits and improve the socio-economic benefits in communities. [ABSTRACT FROM AUTHOR]

The evolution of existing electricity grids to smart grids is aimed at accommodating increasing shares of renewable generation thus contributing for the de-carbonization of economy, offering more diversified services to consumers, enhancing different types of markets (energy, capacity, ancillary services) and improving the system's overall efficiency. As the economic characteristics of the electricity sector tend to discourage investments in smart grids, many countries have adopted incentive policies to foster the deployment of new technologies, which vary according to the particular characteristics of each country. Therefore, the design of specific public policies for Brazil must consider not only the motivations involved, but also the existing challenges for the implementation of smart grids and the socio-economic context. Moreover, the relevance of the proposed policies can be seen from different perspectives. This justifies the need to elicit information from multiple stakeholders for decision support purposes. This paper presents and assesses a set of policies identified by different stakeholders as having a potential to foster the development of smart grids in Brazil. The methodology to shape this set of policies consisted of a thorough literature review of international experiences, combined with meetings with experts in several domains. Then, these policies were assessed by applying a Delphi questionnaire aiming at measuring their effectiveness in fulfilling the objectives associated with investments in smart grids. A first conclusion is that all policies were assessed as having a positive impact taking into account each of the objectives, differing only in the priority to be assigned to each one. The policies that were considered more relevant were: "Incentive Policies for Promoting Demand-Side Management, Distributed Generation and Storage", "Regulatory Changes to Foster Innovation in the Energy Sector" and "Regulation of New Business Models". Among the policies with the worst scores, "Mandatory Rollout of Smart Meters" and "Establishing Quality Standards for the Telecommunications Industry" were ranked as the two lower-ranked policies, i.e., they were assigned lower priority under all objectives. [ABSTRACT FROM AUTHOR]

In order to fulfill the goals of sustainable development and emission reduction, as the main contributor to emissions, optimizing the electric structure is imperative for Chinese electric power industry. In the "thirteenth five-year" period, China has implemented tradable green certificates (TGC) and carbon emissions trading (CET) in the electricity market to accelerate the development of renewable energy. In this study, we analyze and simulate the dual effects of TGC and CET on the electricity market based on the theories and models of equilibrium and system dynamics. The obtained results show that: (1) The increase of renewable portfolio standards and carbon price is advantageous to the expansion of green electricity. The higher the portfolio standard and the carbon price are, the better the electric structure optimization could be. (2) The proportion of renewable energy power generation is expected to achieve the goal of ‘renewable energy thirteenth five-year development planning’ by 2020 (Goal: 680 million kW, 1.9 trillion kW h, 27% of all electricity generated). (3) The CO 2 emission in the electric power industry will be controlled, meanwhile effectively promoting the realization of national CO 2 emission-reduction target by 2020 (Target: below 1.6298 ton CO 2 emission/10,000 yuan). (4) TGC system and CET system are incentive compatible in China. Finally, we propose some policy recommendations on the mechanism design and implementation for these two systems. [ABSTRACT FROM AUTHOR]