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Topic Review
The Lean Blowout Prediction Techniques
The lean blowout is the most critical issue in lean premixed gas turbine combustion. Decades of research into LBO prediction methods have yielded promising results. Predictions can be classified into five categories based on methodology: semi-empirical model, numerical simulation, hybrid, experimental, and data-driven model.
  • 1.7K
  • 30 Nov 2022
Topic Review
Air Addition in Hydraulic Turbines
The use of hydropower is rapidly increasing worldwide, however, achieving maximum efficiency in hydraulic turbines requires operating at the best efficiency point (QBEP). By mitigating the vortex phenomenon, one can reduce pressure pulsation amplitudes and therefore expand the range of stable operation of the hydroturbine. There are two basic approaches to surge mitigation, which are based on the operation turbine principle. The first one involves modifying the existing geometry through geometric optimization, seeking to improve performance over a wider range of operations by changing parametric dimensions. The second approach aims to reduce flow swirl and break up stagnant zones by injecting water or air into the flow.
  • 1.7K
  • 21 Jul 2023
Topic Review
Low-Temperature Solid Oxide Fuel Cells
Solid oxide fuel cells (SOFCs) have been considered as promising candidates to tackle the need for sustainable and efficient energy conversion devices. However, the current operating temperature of SOFCs poses critical challenges relating to the costs of fabrication and materials selection. To overcome these issues, many attempts have been made by the SOFC research and manufacturing communities for lowering the operating temperature to intermediate ranges (600–800 °C) and even lower temperatures (below 600 °C). Despite the interesting success and technical advantages obtained with the low-temperature SOFC, on the other hand, the cell operation at low temperature could noticeably increase the electrolyte ohmic loss and the polarization losses of the electrode that cause a decrease in the overall cell performance and energy conversion efficiency. In addition, the electrolyte ionic conductivity exponentially decreases with a decrease in operating temperature based on the Arrhenius conduction equation for semiconductors. 
  • 1.7K
  • 06 Mar 2021
Topic Review
Formic Acid as Liquid Carrier for H2 Storage
The development of low-carbon technologies that will facilitate the efficient use of hydrogen (H2) as an energy carrier is a critical requirement of contemporary society. To this end, it is anticipated that the cost of H2 production will become a key factor in tandem with production efficiency, process safety, and transport. Much effort has been made to create and develop new, reversible, and sustainable H2 storage systems. Among current techniques, formic acid (FA) has been identified as an efficient energy carrier for H2 storage. Numerous homogeneous catalysts based on transition metals with high activity and selectivity have been reported for selective FA dehydrogenation. 
  • 1.7K
  • 20 Apr 2023
Topic Review
Semi-Closed Oxy–Fuel Combustion Power Cycles with CO2 Recirculation
With the increases in organic fuel prices and growing legislative restrictions aimed at increasing environmental safety and reducing the carbon footprint, the task of increasing thermal power plant efficiency is becoming more and more topical. Transforming combusting fuel thermal energy into electric power more efficiently will allow the reduction of the fuel cost fraction in the cost structure and decrease harmful emissions, especially greenhouse gases, as less fuel will be consumed. There are traditional ways of improving thermal power plant energy efficiency: increasing turbine inlet temperature and utilizing exhaust heat. An alternative way to improve energy efficiency is the use of supercritical CO2 power cycles, which have a number of advantages over traditional ones due to carbon dioxide’s thermophysical properties. In particular, the use of carbon dioxide allows increasing efficiency by reducing compression and friction losses in the wheel spaces of the turbines; in addition, it is known that CO2 turbomachinery has smaller dimensions compared to traditional steam and gas turbines of similar capacity.
  • 1.7K
  • 16 Dec 2022
Topic Review
PAH in Plastic Waste
PAHs are a group of organic compounds made up of simple aromatic rings that have joined together and do not contain heteroatoms or carry any substituents. PAHs are found in oil, coal and tar deposits and also as products of the use of fuels (either fossils or biomass).
  • 1.7K
  • 17 Jun 2021
Topic Review
Spatial Energy Planning
Spatial Energy Planning seems to be an unexploited tool with the potential to provide significant insight into a planning process that could prevent conflicts when integrating renewable energy technologies into electric systems.
  • 1.7K
  • 16 Jun 2021
Topic Review
Electricity Market in Brazil
With the current worsening of climate change-associated risks, the transition to low-carbon energy sources has become a global priority. In this context, the advances in the implementation of smart grids, which, in addition to greater efficiency and resilience, also allow greater penetration of renewable distributed energy resources, are becoming increasingly important. However, the necessary investments will be colossal. Many specialists see the process of opening up the electric energy markets as essential to boosting these new technologies. Greater decentralization of the decision-making process can potentially promote greater scalability. However, not all liberalization reforms have led to good results. Several researchers have been evaluating experiences in different countries. Brazil, a country with continental dimensions and peculiar characteristics, already counts with a mostly renewable electric energy generation mix. In recent decades, however, it has become increasingly dependent on fossil fuel sources. Brazil has been conducting a process of opening the electric energy market since the 1990s. This process has faced a series of barriers. This article presents a critical bibliographic review of the Brazilian Power System history and its ongoing opening process, its possible successes and errors, as well as its perspectives and challenges.
  • 1.7K
  • 18 Jun 2021
Topic Review
Solar Mobility
As proposed by CEA-INES (namely the French National Institute for Solar Energy) [1], the concept of solar mobility seeks a synergy between the following three systems: EVs, PV systems and the electricity network. The basic idea is to combine a standard grid-connected PV system with standard EVs, also connected to the grid [2]. In the extended solar mobility scope, the energy prosumers are equipped with their own renewable energy systems, electrical storage, EVs and other electrical appliances. The buildings are connected into a renewable energy sharing microgrid, in which the surplus renewable production can be delivered from one building to another. Such energy sharing network provides a platform for the buildings in a micro grid to share their surplus renewable energy generations with other buildings, thus helping enhance the overall cluster-level performances. The energy sharing micro grid is also connected to the power grid, in case there is surplus/insufficient cluster-level renewable generations and electricity exchanges with the power grid is needed. The power exchange of the building cluster with the power grid will be metered by advanced metering facilities.
  • 1.7K
  • 28 Jan 2022
Topic Review
Failures of the Photovoltaic Module Components
With the global increase in the deployment of photovoltaic (PV) modules, the need to explore and understand their reported failure mechanisms has become crucial. Despite PV modules being considered reliable devices, failures and extreme degradations often occur. Some degradations and failures within the normal range may be minor and not cause significant harm. Others may initially be mild but can rapidly deteriorate, leading to catastrophic accidents, particularly in harsh environments.
  • 1.7K
  • 12 Mar 2024
Topic Review
Development of the Cogeneration Sector in Spain
Combined Heat and Power (CHP) has been identified by the EU as a powerful resource capable of making substantial contributions to energy savings and reducing GHG emissions. Spain’s effort to promote CHP has been prolific since the 1980s. In this regard, there have been various Laws, Royal Decrees (RDs) and European Union (EU) Directives addressed to reach the national objectives set for the CHP sector. Despite these attempts, the evolution and growth of installed CHP capacity has been irregular, compared to other technologies. Likewise, the academic treatment of the Spanish CHP evolution has not deserved the same attention as other technologies such as wind, photovoltaic and thermal solar systems. As a result, this article is aimed at providing a comprehensive overview of the regulatory frameworks applied to the Spanish CHP sector and analysing the reasons behind the variable evolution of the installed CHP capacity.
  • 1.7K
  • 20 Feb 2024
Topic Review
Sustainable Water and Energy Supply
This entry aims to reveal the economic, technical, and environmental impacts of different system configurations (centralized or decentralized, components, and technologies) on transition plans to achieve a higher share of renewable energy and desalination supplies for regions facing water scarcity. The main contribution of this research is the comparative evaluation of on-grid decentralized or distributed renewable-powered desalination systems for sustainable water and energy supply planning. Applying a novel nexus approach, an interactive multi-period planning model is developed to highlight synergies and to identify conflicts of planning both energy and water sectors at the same time as endogenous subsystems of one overall system. For studying these synergies in this study, the pace of technology deployment and the path of decline in overall costs are assumed to be a function of experience and knowledge as two-factor learning curves. Using data from 81 projects, the levelized cost and capacity factor of utility-scale photovoltaic and wind supplies in the Middle East were calculated. The results indicate that a scenario with a decentralized water sector and renewable-powered multiple-effect distillation technology has the best overall performance among the proposed scenarios. The authors consider that the current study provides novel insights: (1) Designing and planning both the water and energy sectors at the same time, (2) detailed representation of short-term operational aspects in long-run planning of the water and energy sectors to capture the inherent variability of renewable energy resources, (3) modeling the water sector with centralized and decentralized on-grid renewable-powered desalination systems, (4) proposing a new methodology to study the synergies and conflicts of designing the water and energy sectors as an integrated system/separated system, and (5) estimating the two-factor learning curves for wind, photovoltaic, reverse osmosis desalination, and multi-effect distillation desalination industries in the Middle East.
  • 1.6K
  • 27 Oct 2020
Topic Review
Spray Cooling as a High-Efficient Thermal Management Solution
As one of the most promising thermal management solutions, spray cooling has the advantages of high heat-transfer coefficient and maintaining a low temperature of the cooling surface. By summarizing the influential factors and practical applications of spray cooling, the current challenges and bottlenecks were indicated so as to prompt its potential applications in the future.
  • 1.6K
  • 01 Dec 2022
Topic Review
Paramaeters that Affect Biomass Gasification
Gasification is a thermochemical process commonly used for bioenergy production, and it is particularly attractive mainly due to its high efficiency. However, its performance is influenced by parameters such as type of feedstock, size of biomass particle, feed rate, type of reactor, temperature, pressure, equivalence ratio, steam to biomass ratio, gasification agent, catalyst, and residence time.
  • 1.6K
  • 12 Apr 2023
Topic Review
Perovskite Solar Cells with g-C3N4
Perovskite solar cells (PSCs) have attracted great research interest in the scientific community due to their extraordinary optoelectronic properties and the fact that their power conversion efficiency (PCE) has increased rapidly in recent years, surpassing other 3rd generation photovoltaic (PV) technologies. Graphitic carbon nitride (g-C3N4) presents exceptional optical and electronic properties and its use was recently expanded in the field of PSCs. The addition of g-C3N4 in the perovskite absorber and/or the electron transport layer (ETL) resulted in PCEs exceeding 22%, mainly due to defects passivation, improved conductivity and crystallinity as well as low charge carriers’ recombination rate within the device. Significant performance increase, including stability enhancement, was also achieved when g-C3N4 was applied at the PSC interfaces and the observed improvement was attributed to its wetting (hydrophobic/hydrophilic) nature and the fine tuning of the corresponding interface energetics. 
  • 1.6K
  • 26 Apr 2021
Topic Review
Anaerobic Digestion
Anaerobic digestion is a well-known technology with wide application in the treatment of high-strength organic wastes. The oxidation of the organic material is carried out in the absences of oxygen by microorganisms leading to the release of biogas with methane and carbon dioxide being the main components. The microbial process also produces a slurry known as digestate. This stream contains recalcitrant compounds, complex polymeric substances and biomass residual material .
  • 1.6K
  • 06 Mar 2021
Topic Review
Hybrid Ejector-Absorption Refrigeration Systems
Absorption Refrigeration Systems (ARS) are potential alternatives to direct expansion (DX) refrigeration systems. This review focuses on the incorporation of an ejector into absorption refrigeration cycles to constitute Hybrid Ejector-Absorption Refrigeration Systems (HEARS). The ejector adds several advantages to the absorption refrigeration systems depending on its location in the cycle. The two prevalent configurations of HEARS are Triple pressure level (TPL-HEARS), and Low Pressure Condenser (LPC-HEARS). Previous studies revealed the preference of the later configuration as it allows lower circulation ratios, enhances the refrigeration effect, and could achieve a COP up to 1. Moreover, LPC configuration is suitable with single, double, and variable effect absorption systems with a COP of above unity. In turn, the TPL-HEARS notably enhances the absorption process particularly when a variable geometry ejector is utilized. This configuration could obtain a COP around 1.1, but only with high-density refrigerant vapor. Lately, to attain the advantages of both configurations; some studies investigated the viability of adding two ejectors to the cycle. This paper meticulously reviews investigations conducted on the emerging dual ejectors-absorption refrigeration technology. This paper reveals the general performance trend and the maximum attainable COP by each type of hybrid ejector-absorption refrigeration system. DEARS and Ejector-driven absorption refrigeration systems (ED-ARS) could achieve COP that ranges between 1.2 and 1.46. The use of a flash tank and a RHE is essential in NH3/H2O HEARS. At high generator temperatures of (120 – 170 °C), DEARS was found to be the system with the less complexity and best performance. Nevertheless, the performance of the DEARS might drop significantly if the heat source temperature is fluctuating. Thence, the variable effect HEARS is considered the best alternative. The capability of HEARS to be integrated with different power generation cycles is also highlighted. Finally, the review presents possible future research opportunities to improve the absorption refrigeration technology.
  • 1.6K
  • 01 Nov 2021
Topic Review
Serious Energy Games
Serious energy games (SEGs) as interactive experiences that engage users to various energy applications are gaining prominence as an innovative approach, particularly in the realm of energy usage, distributed generation, and interaction with energy markets.
  • 1.6K
  • 10 Oct 2023
Topic Review
Renewable Waste-to-Energy in SEA
Renewable waste-to-energy in Southeast Asia is a kind of renewable and alternative energy gained from waste resource that most Southeast Asian countries explore and utilize not only to minimize the waste crisis but also to meet the actual fossil-free high demand [2] but also to reduce greenhouse gas emissions and other environmental impacts from the energy sector [9] across the region.
  • 1.6K
  • 16 Nov 2020
Topic Review
Environmentally Friendly Vehicle Routing Problem
The growth of environmental awareness and more robust enforcement of numerous regulations to reduce greenhouse gas (GHG) emissions have directed efforts towards addressing current environmental challenges. Considering the Vehicle Routing Problem (VRP), one of the effective strategies to control greenhouse gas emissions is to convert the fossil fuel-powered fleet into Environmentally Friendly Vehicles (EFVs). Given the multitude of constraints and assumptions defined for different types of VRPs, as well as assumptions and operational constraints specific to each type of EFV, many variants of environmentally friendly VRPs (EF-VRP) have been introduced. In this paper, studies conducted on the subject of EF-VRP are reviewed, considering all the road transport EFV types and problem variants, and classifying and discussing with a single holistic vision. The aim of this paper is twofold. First, it determines a classification of EF-VRP studies based on different types of EFVs, i.e., Alternative-Fuel Vehicles (AFVs), Electric Vehicles (EVs) and Hybrid Vehicles (HVs). Second, it presents a comprehensive survey by considering each variant of the classification, technical constraints and solution methods arising in the literature.
  • 1.6K
  • 11 Nov 2020
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