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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.
  • 1.9K
  • 21 Jul 2023
Topic Review
Whey for Bioethanol Production by Yeast
Concerns about fossil fuel depletion and the environmental effects of greenhouse gas emissions have led to widespread fermentation-based production of bioethanol from corn starch or sugarcane. However, competition for arable land with food production has led to the extensive investigation of lignocellulosic sources and waste products of the food industry as alternative sources of fermentable sugars. In particular, whey, a lactose-rich, inexpensive byproduct of dairy production, is available in stable, high quantities worldwide. Therefore, whey is indeed an ideal alternative feedstock for fuel ethanol feedstock because it can provide a remarkable 6–10 million tons of lactose annually. However, despite the availability of this massive, underutilized resource, it faces challenges in being adopted at a commercial scale since S. cerevisiae, the most common fermentative species for transforming sugars to ethanol, lacks the enzyme required for lactose utilization and thus cannot ferment whey into ethanol without further metabolic engineering. 
  • 1.8K
  • 27 Apr 2022
Topic Review
LHTES
Latent heat thermal energy storage systems (LHTES) are useful for solar energy storage and many other applications, but there is an issue with phase change materials (PCMs) having low thermal conductivity. This can be enhanced with fins, metal foam, heat pipes, multiple PCMs, and nanoparticles (NPs). This entry focuses on nano-enhanced PCM (NePCM) alone and with additional enhancements. Low, middle, and high temperature PCM are classified, and the achievements and limitations of works are assessed. The review is categorized based upon enhancements: solely NPs, NPs and fins, NPs and heat pipes, NPs with highly conductive porous materials, NPs and multiple PCMs, and nano-encapsulated PCMs. Both experimental and numerical methods are considered, focusing on how well NPs enhanced the system. Generally, NPs have been proven to enhance PCM, with some types more effective than others. Middle and high temperatures are lacking compared to low temperature, as well as combined enhancement studies. Al2O3, copper, and carbon are some of the most studied NP materials, and paraffin PCM is the most common by far.
  • 1.8K
  • 07 Jul 2021
Topic Review
Hazards of the Ammonia Bunkering Process
Ammonia is thought to be a potential alternative for hydrogen storage in the future, allowing for CO2-free energy systems. Ammonia’s beneficial characteristics with regard to hydrogen storage include its high volumetric hydrogen density, low storage pressure, and long-term stability. However, ammonia is characterized by toxicity, flammability, and corrosiveness, making safety a challenge compared to other alternative fuels. In specific circumstances, leakage from ammonia bunkering can cause risks, dispersion, and unsafe areas due to its flammability and toxicity. To avoid dispersion, fire, and explosion hazards on ships, it is crucial to conduct thorough risk analyses.
  • 1.8K
  • 30 May 2023
Topic Review
Perovskite Solid-State Electrolytes for Lithium Metal Batteries
Solid-state lithium metal batteries (LMBs) have become increasingly important in recent years due to their potential to offer higher energy density and enhanced safety compared to conventional liquid electrolyte-based lithium-ion batteries (LIBs). However, they require highly functional solid-state electrolytes (SSEs) and, therefore, many inorganic materials such as oxides of perovskite La2/3−xLi3xTiO3 (LLTO) and garnets La3Li7Zr2O12 (LLZO), sulfides Li10GeP2S12 (LGPS), and phosphates Li1+xAlxTi2−x(PO4)3x (LATP) are under investigation. Among these oxide materials, LLTO exhibits superior safety, wider electrochemical window (8 V vs. Li/Li+), and higher bulk conductivity values reaching in excess of 10−3 S cm−1 at ambient temperature, which is close to organic liquid-state electrolytes presently used in LIBs. 
  • 1.8K
  • 23 Nov 2021
Topic Review
Technical and Economic Viability of Underground Hydrogen Storage
The concept of underground hydrogen storage (UHS) is less known than its natural gas counterpart, which is expected due to its less significant role in the past. Despite this, the insights gained with natural gas can be applied to hydrogen storage due to the shared cavern design and operation.
  • 1.8K
  • 11 Dec 2023
Topic Review
Fuel Cells
Fast start-up, high efficiency, no toxic emissions into the atmosphere and good modularity are the key advantages of fuel cell applications. Despite the merits associated with fuel cells, the high cost of the technology remains a key factor impeding its widespread commercialization.
  • 1.8K
  • 13 Jan 2021
Topic Review
Microbial Technologies Applied Biofuel Production
The use of fossil energy sources has a negative impact on the economic and socio-political stability of specific regions and countries, causing environmental changes due to the emission of greenhouse gases. Moreover, the stocks of mineral energy are limited, causing the demand for new types and forms of energy. Biomass is a renewable energy source and represents an alternative to fossil energy sources. Microorganisms produce energy from the substrate and biomass, i.e., from substances in the microenvironment, to maintain their metabolism and life. However, specialized microorganisms also produce specific metabolites under almost abiotic circumstances that often do not have the immediate task of sustaining their own lives. Microorganisms can change the current paradigm, energy–environment, and open up countless opportunities for producing new energy sources, especially hydrogen, which is an ideal energy source for all systems (biological, physical, technological). Developing such energy production technologies can significantly change the already achieved critical level of greenhouse gases that significantly affect the climate.
  • 1.8K
  • 20 Sep 2022
Topic Review
Hydrogen Production by Wastewater Alkaline Electro-Oxidation
The electro-oxidation of olive mill and biodiesel wastewaters in an alkaline medium with the aim of hydrogen production and simultaneous reduction in the organic pollution content are presented. The process is performed, at laboratory scale, in an own-design single cavity electrolyzer with graphite electrodes and no membrane. The system and the procedures to generate hydrogen under ambient conditions are described. The gas flow generated is analyzed through gas chromatography. The wastewater balance in the liquid electrolyte shows a reduction in the chemical oxygen demand (COD) pointing to a decrease in the organic content. The experimental results confirm the production of hydrogen with different purity levels and the simultaneous reduction in organic contaminants. This wastewater treatment appears as a feasible process to obtain hydrogen at ambient conditions powered with renewable energy sources, resulting in a more competitive hydrogen cost.
  • 1.8K
  • 15 Sep 2022
Topic Review
Produced Water Treatment
Flowback-produced water (FP) is a waste fluid associated with hydraulic fracturing in unconventional oil and gas development (UOG). Initially, FP reflects the composition of the hydraulic fracturing fluid, which is referred as flowback water (FBW). After the initial months of well production, the waste fluid is predominantly representative of the formation and is known as produced water (PW). 
  • 1.8K
  • 08 Jul 2022
Topic Review
Bubble Dynamics in Proton Exchange Membrane Water Electrolysis
Water electrolysis using a proton exchange membrane (PEM) holds substantial promise to produce green hydrogen with zero carbon discharge. Although various techniques are available to produce hydrogen gas, the water electrolysis process tends to be more cost-effective with greater advantages for energy storage devices. However, one of the challenges associated with PEM water electrolysis is the accumulation of gas bubbles, which can impair cell performance and result in lower hydrogen output. Achieving an in-depth knowledge of bubble dynamics during electrolysis is essential for optimal cell performance.
  • 1.8K
  • 10 Jan 2024
Topic Review
Exploration and Use of Lithium in Oman
Oman has huge potential for lithium exploitation and production, considering the enormous quantities of spodumene and seawater salt with high-grade lithium available, developing efficient regulations and rules to protect investors’ rights, and reducing the environmental risks associated with the production and recycling of lithium-ion batteries. 
  • 1.8K
  • 29 Jan 2024
Topic Review
Hybrid Renewable Energy System
The HRES is a cyber–physical system that can be divided into two layers: the power infrastructure and the communication infrastructure layers, as shown in Figure 1. The power infrastructure layer consists of different energy sources (e.g., wind turbines, photovoltaics, diesel generators, and batteries), transformers, feeders, converters, and electrical connections. The communication infrastructure layer supports the physical infrastructure by an underlying communication network, linking between sensors and actuators nodes. This enables the local control center to manage the system operation. In this integration, ICTs play an essential role in allowing the transition from the conventional power grid to the future smart grid by supporting the integration of HRES.
  • 1.8K
  • 06 Sep 2021
Topic Review
Perovskite Solar Cell
Organic-inorganic hybrid perovskite materials have attracted tremendous attention as a key material in various optoelectronic devices. Distinctive optoelectronic properties, such as a tunable energy band position, long carrier diffusion lengths, and high charge carrier mobility, have allowed rapid progress in various perovskite-based optoelectronic devices (solar cells, photodetectors, light emitting diodes (LEDs), and lasers). Interestingly, the developments of each field are based on different characteristics of perovskite materials which are suitable for their own applications. 
  • 1.8K
  • 20 Jan 2021
Topic Review
Time Series Aggregation for ESMs
Due to the high degree of intermittency of renewable energy sources and the growing interdependences amongst formerly separated energy pathways, the modeling of adequate energy systems is crucial to evaluate existing energy systems and to forecast viable future ones. However, this corresponds to the rising complexity of energy system models (ESMs) and often results in computationally intractable programs. To overcome this problem, time series aggregation is frequently used to reduce ESM complexity. As these methods aim at the reduction of input data and preserving the main information about the time series, but are not based on mathematically equivalent transformations, the performance of each method depends on the justifiability of its assumptions.
  • 1.8K
  • 29 Sep 2021
Topic Review
Iron Ore Reduction with Hydrogen
The steel industry represents about 7% of the world’s anthropogenic CO2 emissions due to the high use of fossil fuels. The CO2-lean direct reduction of iron ore with hydrogen is considered to offer a high potential to reduce CO2 emissions, and this direct reduction of Fe2O3 powder is investigated in this research.
  • 1.8K
  • 18 Sep 2021
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.
  • 1.8K
  • 30 Nov 2022
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
Power Battery Thermal Management System
The battery thermal management system is a key skill that has been widely used in power battery cooling and preheating. It can ensure that the power battery operates safely and stably at a suitable temperature.
  • 1.8K
  • 28 Mar 2022
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
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