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Topic Review
Wave Energy Generation in Brazil
Seas and oceans offer great potential as a widely available source of clean and renewable energy near high energy consumption centers. This source of energy is a valuable option in the energy transition and in energy matrix decarbonization. Wave energy and an oscillating water column (OWC) device stand out as the types of ocean energy with the most potential. An onshore OWC requires locations with rocky outcrops and steeper slopes as the device needs to be physically installed and has lower energy dissipation due to friction with the seabed. However, Brazil has approximately 7490 km of coastlines, with various shoreline geometries and geomorphologies, some of which are very suitable for OWC implementation.
  • 1.8K
  • 27 Oct 2023
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.
  • 1.8K
  • 12 Apr 2023
Topic Review
Hydrogen Energy
This entry explains why the 'hydrogen economy' has been so slow in coming, despite the abundance of hydrogen (H2) on Earth. H2 is either bound up with oxygen in water, or with carbon in fossil fuels, which release CO2 on combustion. For several decades, hydrogen-powered vehicles using fuel cells were seen as the major opportunity for H2. But if H2 is produced from fossil fuels, its use makes little contribution to climate change mitigation, and in any case, electric vehicles are now the main challengers to oil for powering transport. H2 will only come into its own when intermittent renewable energy, mainly wind and solar energy, dominate energy supply, as it makes sense to convert surplus power to H2 for storage or immediate use.  
  • 1.8K
  • 04 Jan 2021
Topic Review
Green and Blue Hydrogen Production in Colombia
Hydrogen is the most abundant element in nature, but it cannot be considered an energy source by itself because it is impossible to find it in its elemental form in nature. Colombia, a privileged country in terms of diversity, availability of natural resources, and geographical location, has set a roadmap for hydrogen as part of the energy transition plan proposed in 2021. To reduce its emissions in the mid-term and foster its economy, hydrogen production should be green and blue, with specific targets set for 2030 for the hydrogen costs and produced quantities. A comparison is made concerning the state-of-the-art production of blue and green hydrogen and how Colombia performs in each pathway.
  • 1.8K
  • 30 Nov 2022
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. 
  • 1.8K
  • 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.
  • 1.8K
  • 16 Dec 2022
Topic Review
Large-Scale CFB Boiler Engineering Tests and Measurement Methods
Circulating fluidized bed (CFB) boilers offer a technically viable and environmentally friendly means for the clean and efficient utilization of solid fuels. However, the complex gas–solid two-phase flow processes within them have hindered a thorough resolution of prediction issues related to coupled combustion, heat transfer, and pollutant generation characteristics. To address the deficiencies in scientific research, meet the practical operational needs of CFB boilers, and comply with new carbon emission policies, conducting full-scale field tests on large-scale CFB boilers is needed, so that the complex gas–solid flow, combustion, and heat transfer mechanisms in the furnace can be comprehended.
  • 1.8K
  • 28 Feb 2024
Topic Review
Commercialization of Electric Vehicles
Electric Vehicles (EVs) are a promising alternative to internal combustion engine vehicles as the city is transitioning to clean energy.
  • 1.8K
  • 10 Feb 2022
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
Indoor Thermal Comfort
A neutral or comfortable environment is an environment that allows metabolic heat production to be balanced with heat exchange (loss and/or gain) from the air around the worker. Outside this situation of balance, there may be adverse situations in which the exchange of heat energy constitutes a risk to the person’s health, since even taking into account the body’s thermoregulation mechanisms, they cannot maintain a constant and adequate internal temperature. Even though the milder climate scenario and constant evolution of thermal building regulation are in light of European initiatives, in Portugal, there are few houses where occupants can remain all the time in perfectly comfortable temperature conditions without resorting to heating or cooling. According to the Long Term Strategy for the Renewal of Buildings (ELPRE), this results from the combination of several factors, namely, low energy use for air conditioning compared to energy needs and aged building stock with poor energy performance. In fact, around 70% of the dwellings currently certified have low energy efficiency (C or less).
  • 1.7K
  • 01 Sep 2022
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.
  • 1.7K
  • 01 Dec 2022
Topic Review
Approaches to Quantifying Carbon Emissions with Human Deaths
When attempting to quantify future harms caused by carbon emissions and to set appropriate energy policies, it has been argued that the most important metric is the number of human deaths caused by climate change. Several studies have attempted to overcome the uncertainties associated with such forecasting. 
  • 1.7K
  • 23 Aug 2023
Topic Review
Delamination-and Electromigration-Related Failures
The reliability of photovoltaic (PV) modules operating under various weather conditions attracts the manufacturer’s concern since several studies reveal a degradation rate higher than 0.8% per year for the silicon-based technology and reached up to 2.76% per year in a harsh climate. The lifetime of the PV modules is decreased because of numerous degradation modes. Electromigration and delamination are two failure modes that play a significant role in PV modules’ output power losses. The correlations of these two phenomena are not sufficiently explained and understood like other failures such as corrosion and potential-induced degradation. 
  • 1.7K
  • 30 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
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
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.
  • 1.7K
  • 01 Nov 2021
Topic Review
Second-Life Batteries
The adoption of electric vehicles (EVs) is increasing due to governmental policies focused on curbing climate change. EV batteries are retired when they are no longer suitable for energy-intensive EV operations. A large number of EV batteries are expected to be retired in the next 5–10 years. These retired batteries have 70–80% average capacity left. Second-life use of these battery packs has the potential to address the increasing energy storage system (ESS) demand for the grid and also to create a circular economy for EV batteries. The needs of modern grids for frequency regulation, power smoothing, and peak shaving can be met using retired batteries.
  • 1.7K
  • 06 Dec 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. 
  • 1.7K
  • 26 Apr 2021
Topic Review
Ammonia Fuel Cells
Ammonia use in maritime applications is considered promising, due to its high energy density, low flammability, easy storage and low production cost. Moreover, ammonia can be used as fuel in a variety of propulsors such as fuel cells and can be produced from renewable sources. 
  • 1.7K
  • 07 Jun 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 .
  • 1.7K
  • 06 Mar 2021
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