Energy Generation Technologies Research Articles

Analysis of the SWOT matrix as a strategy for implementing the Ap-Th1000 Reactor in Brazil

This article analyzes the SWOT Matrix for the implementation of the AP-Th1000 reactor with thorium fuel, aiming at a future replacement of the current nuclear reactors that use uranium as fuel by thorium. There was a need for an in-depth study of the national and international literature linked to the Brazilian reality. After that, specific meetings were held to detect all possible situations of the 4 main points of the SWOT matrix. During the sessions, which averaged 1 hour, the authors' industrial and academic expertise was demonstrated in competencies such as creativity, collaboration, effective communication, openness and tolerance, quick thinking, synthesis ability, problem focus, and flexibility during the discussions of over 50 items found in the analysis of the 4 points of the SWOT matrix. Each meeting was divided into three parts. The first part, which would be the Creative phase; and a second part, which would be the Critical phase; and, finally, the third phase, where ideas are filtered for the permanence of those that were better founded and of better acceptance. Then, the aspects listed were classified into 4 categories: Strengths (S), Weaknesses (W), Opportunities (O), and Threats (T). After the classification, a ranking of priorities was made, in descending order of importance, according to the authors, of the weaknesses and threats, neutralization suggestions were made. Finally, the data obtained were analyzed. We concluded through the SWOT analysis, we can observe an expressive amount of benefits of using the AP1000 reactor with MOX of Thorium and Uranium in the development of nuclear energy generation technologies in Brazil.

Ammonia nitrogen removal from coal gasification wastewater using a falling-film dielectric barrier discharge reactor: Process optimization and toxicity analysis

The continuous use of coal gasification technology for green energy generation to supplement the dwindling energy reserves generates significant amounts of wastewater containing ammonia nitrogen, posing a significant risk to the finite drinking water sources and aquatic lives. Herein, two falling-film dielectric barrier discharge (DBD) reactors with copper and titanium high-voltage electrodes, respectively, were designed to remove ammonia nitrogen (NH3−N) and chemical oxygen demand (COD) simultaneously from coal gasification wastewater. The operational parameters were screened using the Plackett-Burman design, and the significant parameters were further optimized via the response surface methodology. The results showed that the power parameter significantly influenced NH3-N removal, and COD removal was influenced considerably by power and treatment time. Under the optimum conditions (treatment time = 20.32 min, pH = 3, airflow rate = 1 L/min, power = 116 W, and recirculating flow rate = 50.02 mL/min), a removal ratio of 62.33 % and 37.35 % was achieved for NH3-N and COD for the reactor with the copper electrode, and 67.66 % and 44.90 % for NH3-N, and COD for the reactor with the titanium electrode. Additionally, the concentrations of O3, ·OH, and H2O2 produced by the reactors were quantified, and their crucial roles in the removal process of NH3-N were evaluated. Although smaller concentrations of NO2− and NO3− were detected in the treated wastewater, over 97 % of N2 selectivity encompassed NH3-N removal. Finally, acute phytotoxicity tests were performed, and the results indicated that at 100 mL/L dosage, the treated wastewater from both reactors did not restrict Barbarea verna growth.

Highly Integrated Perovskite Solar Cells‐Based Photorechargeable System with Excellent Photoelectric Conversion and Energy Storage Ability

Perovskite solar cells have emerged as a promising technology for renewable energy generation. However, the successful integration of perovskite solar cells with energy storage devices to establish high‐efficiency and long‐term stable photorechargeable systems remains a persistent challenge. Issues such as electrical mismatch and restricted integration levels contribute to elevated internal resistance, leading to suboptimal overall efficiency (ηoverall) within photorechargeable systems. Additionally, the compatibility of perovskite solar cells with electrolytes from energy storage devices poses another significant concern regarding their stability. To address these limitations, we demonstrate a highly integrated photorechargeable system that combines perovskite solar cells with a solid‐state zinc‐ion hybrid capacitor using a streamlined process. Our study employs a novel ultraviolet‐cured ionogel electrolyte to prevent moisture‐induced degradation of the perovskite layer in integrated photorechargeable system, enabling perovskite solar cells to achieve maximum power conversion efficiencies and facilitating the monolithic design of the system with minimal energy loss. By precisely matching voltages between the two modules and leveraging the superior energy storage efficiency, our integrated photorechargeable system achieves a remarkable ηoverall of 10.01% while maintaining excellent cycling stability. This innovative design and the comprehensive investigations of the dynamic photocharging process in monolithic systems, not only offer a reliable and enduring power source but also provide guidelines for future development of self‐power off‐grid electronics.

Energy efficiency of hydrogen production via gasification from lignocellulosic residual biomass blend

Facing the challenges of environmental sustainability and energy security caused by anthropogenic carbon emissions, there is a need to adopt cleaner energy generation technologies, leveraging Colombia's existing national resources. In this context, hydrogen emerges as a promising source of renewable energy. Therefore, this project explores the use of a blend of residual lignocellulosic biomass as raw material for hydrogen production through gasification for energy purposes. Initially, a screening of residual lignocellulosic biomass in the study region was conducted, a blend was selected, and a simulation of the synthesis gas production process was carried out prospectively using Aspen Plus Dynamics® software. The results revealed that, by using the selected biomass blend, a synthesis gas with a hydrogen molar fraction of 38.7% and an ER of 0.19 was obtained. According to sensitivity analyses, the optimal parameters identified to achieve this hydrogen concentration were: gasification temperature of 707°C, oxygen flows of 484 kg/h, steam at 420 kg/h, and gasification pressure of 1 atm. These findings support the potential of the studied lignocellulosic biomass blend as an alternative for hydrogen production, while also offering an opportunity for the valorization of lignocellulosic residual biomass.

Multicomponent nickel-molybdenum-tungsten-based nanorods for stable and efficient alkaline seawater splitting

The electrolysis of seawater for hydrogen production holds promise as a sustainable technology for energy generation. Developing water-splitting catalysts with low overpotential and stable operation in seawater is essential. In this study, we employed a hydrothermal method to synthesize NiMoWOX microrods (NiMoWOX@NF). Subsequently, an annealing process yielded a composite N-doped carbon-coated Ni3N/MoO2/WO2 nanorods (NC@Ni3N/MoO2/WO2@NF), preserving the ultrahigh-specific surface area of the original structure. A two-electrode electrolytic cell was assembled using NC@Ni3N/MoO2/WO2@NF as the cathode and NiMoWOX@NF as the anode, demonstrating exceptional performance in seawater splitting. The cell operated at a voltage of 1.51 V with a current density of 100 mA·cm−2 in an alkaline seawater solution. Furthermore, the NC@Ni3N/MoO2/WO2@NF || NiMoWOX@NF electrolytic cell exhibited remarkable stability, running continuously for over 120 h at a current of 1100 mA·cm−2 without any observable delay. These experimental results are corroborated by density functional theory calculations. The NC@Ni3N/MoO2/WO2@NF || NiMoWOX@NF electrolyzer emerges as a promising option for industrial-scale hydrogen production through seawater electrolysis.

Critical material requirements and recycling opportunities for US wind and solar power generation

AbstractThe deployment of renewable energy generation technologies, driven primarily by concerns over catastrophic climate change, is expected to increase rapidly in the United States. Rapid increases in the deployment of wind and solar energy will translate to increases in critical material requirements, causing concern that demand could outstrip supply, leading to mineral price volatility and potentially slowing the energy transition. This study presents a detailed demand‐side model for wind and solar in the United States using dynamic material flow analysis to calculate the requirements for 15 elements: Cr, Zn, Ga, Se, Mo, Ag, Cd, In, Sn, Te, Pr, Nd, Tb, Dy, and Pb. Results show that transitioning to a completely decarbonized US energy system by 2050 could require a five‐to‐sevenfold increase in critical material flow‐into‐use compared with business as usual (BAU), with some materials requiring much larger increases. Rare earth elements (REEs) could require 60–300 times greater material flows into the US power sector in 2050 than in 2021, representing 13%–49% of the total global REE supply. Te requirements for reaching net zero by 2050 could exceed current supply, posing challenges for widespread deployment of cadmium‐telluride solar. We also investigate several strategies for reducing material requirements, including closed‐loop recycling, material intensity reduction, and changing market share of subtechnologies (e.g., using crystalline silicon solar panels instead of cadmium telluride). Although these strategies can significantly reduce critical material requirements by up to 40% on average, aggressive decarbonization will still require a substantial amount of critical material.

Hydrogen energy storage integrated grid: A bibliometric analysis for sustainable energy production

Hydrogen energy storage and grid integration are emerging as key technologies for efficient energy generation and decarbonization, addressing the unpredictability of renewable sources like wind and solar. Hydrogen serves as a flexible energy carrier, enabling storage and conversion back to energy, and supporting various applications. Since there is a lack of bibliometric investigation in the grid-connected hydrogen energy storage system, this review conducted the bibliometric analysis and analyzed the role of hydrogen in enhancing grid-connected systems' sustainability and flexibility, based on data from the Scopus database. The principal search terms that have been used to identify the publications are “Hydrogen AND Storage AND ("Grid-connected" OR "On-grid" OR “Grid-tied” OR “Integrated grid” OR “Grid integration”)” and several keywords have also been utilized in the filter including “Hydrogen Storage”, “Hydrogen”, “Hydrogen Production” and “Grid-connected”. The chosen documents type is only comprised of ‘Article’ and ‘Review’. By conducting an analysis of publication trends, citation patterns, co-authorship, and keyword usage, significant and informative observations regarding the development of grid-connected hydrogen storage system research from 2013 to 2023 (up until November) were unveiled. Notably, 86.55% of the articles focused on simulation study, while the rest are focusing in experimental work, reviews, and technical overview of integrated-grid hydrogen storage system. China is establishing itself as prominent participant, while International Journal of Hydrogen Energy is recognized as a notable medium for distributing research on the integrated-grid hydrogen storage system. Compressed hydrogen tank emerges as a prominent type of storage because of its less energy requirement to increase the density of hydrogen that allow more efficient transportation for hydrogen. The review also underlines numerous factors, issues, challenges, and difficulties that next-generation hydrogen energy storage production should overcome with regards to system sustainability.

A Machine Learning Frontier for Predicting LCOE of Photovoltaic System Economics

In this research article, the objective is to determine the return on investment (ROI) of photovoltaic (PV) power plants by employing machine learning (ML) techniques. Special focus is done on the levelized cost of electricity (LCOE) as a pivotal economic parameter crucial for facilitating economic decision‐making and enabling quantitative comparisons among different energy generation technologies. Traditional methods of calculating LCOE often rely on fixed singular input values, which may fall short in addressing uncertainties associated with assessing the financial feasibility of PV projects. In response, a dynamic model that integrates essential demographic, energy, and policy data, is introduced encompassing factors such as interest rates, inflation rates, and energy yield, which are anticipated to undergo changes over the lifetime of a PV system. This dynamic model provides a more accurate estimation of LCOE. The comparative analysis of ML algorithms indicates that the auto‐regression integration moving average (ARIMA) model exhibits a high accuracy of 93.8% in predicting consumer electricity prices. The validation of the model is highlighted through two case studies in the United States and the Philippines underscores the potential impact on LCOE values. For instance, in California, LCOE values could vary by nearly 30% (5.03 cents kWh−1 for singular values vs 7.09 cents kWh−1 using our ML model), influencing the perceived risk or economic feasibility of a PV power plant. Additionally, the ML model estimates the ROI for a grid‐connected PV plant in the Philippines at 5.37 years, in contrast to 4.23 years using traditional methods.

Energy systems capacity planning under high renewable penetration considering concentrating solar power

With the rapid development of renewable generation and the promotion of “Clean Heating”, the uncertainty of renewables as well as rising energy demand has posed significant problems to the energy system’s economical and flexible operation. As a renewable energy generation technology, concentrating solar power (CSP) with thermal energy storage (TES) offers a promising approach by providing operational flexibility and thermal energy supply to the energy system. We propose a long-term high-resolution planning model considering the operational characteristics of CSP and improved flexibility constraints of energy systems under high renewable penetration to meet the electricity and heat demand simultaneously in this paper. By applying the proposed model to a typical “Clean Heating” area in China, it demonstrates that the optimal deployment by integrating CSP can reduce the peak-valley depth of coal units, minimize the renewable curtailment and carbon emissions by 37.64 % and 19.05 % respectively with more than 5.98 % cost reduction at 85 % renewable penetration compared with the base scenario, which provides an economic and stable zero-carbon pathway for multi-energy systems.

Research on driving mechanism and prediction of electric power carbon emission in Gansu Province under dual-carbon target

The electric power industry is a key industry for the country to achieve the double carbon target. Its low carbon development has a double effect on this industry and helps other industries to achieve the carbon peak target. This paper firstly uses the IPCC inventory method to calculate carbon emissions in the production phase of the power industry in Gansu Province from 2000 to 2019, followed by the ridge regression method and the STIRPAT model to analyse the quantitative impact of six major drivers on carbon emissions, and finally, the scenario analysis method is used to forecast carbon emissions in this phase. The results show that the carbon emissions of Gansu Province show a trend of rising and then falling, and reached a peak of 65.66 million tons in 2013. For every 1% increase in population effect, urbanisation level, affluence, clean energy generation share, technology level and industrial structure, carbon emissions will grow by 4.939%, 0.625%, 0.224%, − 0.259%, 0.063% and 0.022% respectively. Because of the clean energy advantage in Gansu Province, the low-carbon development scenario will continue to have low carbon emissions during the scenario cycle, which can be reduced to 53.454 million tons in 2030; the baseline scenario will achieve a carbon peak in 2025, with a peak of 62.627 million tons; the economic development scenario has not achieved carbon peak during the scenario cycle, and carbon emissions will increase to 73.223 million tons in 2030.

Design optimization for an integrated tri-generation of heat, electricity, and hydrogen powered by biomass in cold climates

For green hydrogen energy systems driven by renewables, despite the complexities in design and operations, uncertainties related to availability of infrastructures or seasonality of resources are significant as well as the uncertainties in technical side such as adoption of technologies for energy generation, conversion, and storage. Such uncertainties put the economy and sustainability of these systems under shadows. Consequently, it has been attempted to balance and offset the impacts of uncertainties by means of providing the side products such as hydrogen. An enviro-economic optimization considering reliability, availability, and maintenance of a biomass-gasification-driven combined heating, hydrogen, and electricity system is considered in this study. The emission penalty cost as well as the electricity and hydrogen generation revenues are also pinpointed as part of the objective function which is the total cost. Such costs incorporate capital cost for purchase and installation of all modules, primary fuel (High Heat Value Woods) purchase, and transportation costs. Probabilistic approach using Weibull function is used for modeling reliability for the whole system. The most optimal values for total cost, hydrogen and electrical modules incomes, rated capacities, utilization times, reliability and maintainability indicators such as mean time to failure and maintenance intervals for modules are derived and compared. The sensitivity to performance parameters and sizing characteristics of those three modules are also investigated. The results support this notion that if there are opportunities to sell hydrogen, it is advantageous to integrate hydrogen module to the heating and power co-generation. The results show that minimum cost is obtained by devoting less rated capacities and utilization times to electricity modules in favor of increasing the hydrogen module utilization times and flow rates.

An Active Injected Location Method for DC Fault of Wind Power Based on Parallel Energy Absorption Module

In recent years, the widespread adoption of wind power has been facilitated by the rapid advancements in new energy generation technology. The precise identification and efficient management of DC faults in onshore wind farms has gained increasing significance. To address issues such as limited functionality, low device utilization, and the inefficient use of fault energy prevalent in current fault location methods applied in wind power flexible grid-connected systems, this study explores the storage and reuse technology of fault energy. The article proposes a topology structure designed to absorb and reuse fault energy under multiple DC faults, aiming to overcome the challenges posed by single-function methods. The structure and control strategy of this topology are clearly delineated, and the design methodology for topology electrical parameters is thoroughly investigated. Simulation studies were conducted to validate the electrical characteristics of the employed devices and assess the operational effectiveness of the proposed topology within wind power grid-connected systems. In comparison with conventional fault location methods, the proposed scheme exhibits multiple energy absorption functions for DC faults and fault location capabilities, especially in the presence of permanent DC faults. As a result, this approach maximizes the utilization of DC fault energy, ensuring higher device efficiency and a broader spectrum of functionalities.

Simultaneous solar steam and electricity generation from biochar based photothermal membranes

Clean water and energy are essential for reducing poverty, fostering economic growth and sustainable development while mitigating CO2 emissions. Considering that, solar-powered interfacial vapor or steam generation is sustainable and promising environmental technology for both water purification and energy generation while being CO2-free. Despite continuous research progress, most of the solar absorbers to capture sunlight following heat conversion for steam generation are generally made from expensive nanostructures, which in part prevents their widespread manufacturing for useful applications. Herein, we experimentally demonstrate a biomass-derived carbon composite membrane that nearly covers the entire sunlight spectrum as a solar absorber with an estimated absorptivity of 90%. As a result, the light absorbed yields a surface temperature of 55 °C at the surface of the B700 and 33 °C for water. Evaporation rates up to 1.26 and 1.16 kg/(m2 h) and solar-to-vapor efficiencies of 80 and 74% were recorded in presence of sodium chloride with two different types of biochar B700 and B300 based photothermal membranes, respectively, under 1 sun illumination. The water evaporation in presence of mixed sodium chloride/magnesium chloride reached up to 1.21 and 1.05 kg/(m2 h) with 77 and 69% efficiency with B700 and B300; due to different solar absorber geometry. Furthermore, by merging the thermoelectric technology, we exploit the concept of hybrid clean water and energy generation. At a relative humidity of 60%, the thermoelectric device may generate approximately 0.9 W/m2 power density. These results highlight the interactive effects of biochar and polyvinylidene fluoride with porous hierarchies and enhanced absorption of sunlight, thus enabling a considerable elevation of temperature with great potential for clean water and energy. Overall biochar photothermal membrane represents a significant advancement as low-cost sustainable technology, addressing both water and energy challenges by providing efficient, environmentally friendly solution for freshwater production and clean power generation.

Thermodynamic assessment of a novel solar powered trigeneration system for combined power generation, heating, and cooling

Solar power tower (SPT) technology is the mature technology among the various concentrated solar technologies for energy generation. Therefore, it is necessary to develop the efficient energy generation system that utilizes the SPT plant. In the current study, a novel trigeneration system was presented to utilize the SPT for combined power generation, heating, and cooling. The trigeneration system consists a helium Brayton cycle and organic Rankine cycle (ORC) with ejector refrigeration system for recovering the waste heat. The power was produced by the helium Brayton cycle and ORC turbine whereas, cooling and heating was produced simultaneously by the condenser and evaporator respectively. For building applications such as hospitals and hostels, the heating and cooling effects were generated at 50°C and 10°C respectively. Finally, the optimal system exhibits exergy and energy efficiency of 25.12% and 23.3%, respectively, when all the studied parameters are taken into consideration. Apart from this power output, heating and cooling productions were observed as 14,998, 60.52 and 8.25 kW and respectively at the 2.3 of compressor pressure ratio, 197.2°C of inlet temperature of ORC turbine.

Implementation and optimization of hydraulic wave energy generation system.

Wave energy is one of the primary sources of marine energy, representing a readily available and inexhaustible form of renewable clean energy. In recent years, wave energy generation has garnered increasing attention from researchers. To study wave energy generation technology, we have constructed a real wave energy generation system and designed wave simulation and hydraulic energy storage systems. The wave simulation system is mainly composed of a frequency converter and an electric boost pump, while the hydraulic energy storage system consists of a hydraulic control unit and hydraulic motors. Corresponding mathematical models have been established to investigate the characteristics of wave energy generation. Specifically, a mathematical model for wave input using the double-parameter JONSWAP wave spectrum has been created for wave simulation in the wave simulation system. For the hydraulic energy storage system, known as the Power Take Off (PTO) system, mathematical models have been developed for double-acting hydraulic cylinders, energy storage devices, and precise displacement hydraulic motors, taking into consideration fluid Reynolds numbers and leakage. During the generation of wave energy, there is a problem of prolonged power interruption when wave conditions are unfavorable, which hinders continuous power generation. To address this issue, a system structure with an energy storage unit and two parallel generator sets, as well as a power operation optimization scheme, have been proposed. This system structure and optimization approach efficiently and reasonably utilize wave energy, achieving the goal of uninterrupted power supply in the hydraulic wave energy generation system.

Dissipative MHD flow of ternary‐hybrid nanofluid over an inclined stretching sheet with heat source and mass flux due to temperature gradient

AbstractAn analysis has been made to illuminate the unsteady MHD slip flow of ternary‐hybrid nanofluid of water conveying spherical Cu, cylindrical Al2O3, and platelet Ag nanoparticles over an inclined stretching sheet. The above complex scenario explores how the presence of a magnetic field affects the behavior of ternary‐hybrid nanofluid over an inclined stretching surface. Understanding this interaction is crucial in advanced thermal systems like cooling mechanisms and energy generation technologies. The study can provide insights into optimizing heat transfer rates, enhancing thermal conductivity and improving efficiency in practical applications by manipulating the flow characteristics and temperature distribution in the system. The heat transfer has been analyzed incorporating Darcy dissipation and heat source in the presence of 1st order velocity slip. The presence of Soret effect makes the study more congenial. Using similarity transformation technique, the governing partial differential equations are converted into a system of ordinary differential equations. The reduced system is dealt with 4th order Runge–Kutta method with shooting technique. The comparison with earlier results gives a reliability of present results. The important findings are: velocity of the flow decelerates for higher values of 1st order slip parameter, velocity of the flow increases with increase in Soret number, increasing values of chemical reaction parameter lead to lower concentration in both the cases, that is, with or without velocity slip.

CTAB-Assisted Synthesis of FeNi Alloy Nanoparticles: Effective and Stable Electrocatalysts for Urea Oxidation Reactions.

Development of highly efficient electrocatalysts for treating urea-rich wastewater is an important problem in environmental management and energy production. In this work, an iron-nickel alloy (Fe-Ni alloy) was synthesized via soft-template cetyltrimethylammonium bromide (CTAB)-assisted precipitation using low-temperature calcination. The as-synthesized nanoalloy was characterized by X-ray diffraction (XRD), which revealed the formation of a face-centered cubic (FCC) structure of the Fe-Ni alloy; field emission-scanning electron microscopic (FE-SEM) analysis revealed the spherical shape of the Fe-Ni alloy; high-resolution transmission electron microscopy (HR-TEM) revealed the average size to be ∼33.09 nm; and X-ray photoelectron spectroscopy (XPS) showed the presence of Fe, Ni, C, and O components and their chemical composition and valence states in the Fe-Ni alloy. The electrochemical urea oxidation reaction (UOR) was investigated by conducting linear sweep voltammetry (LSV) tests on the synthesized electrocatalysts with different Ni/Fe ratios in alkaline electrolytes with urea. The potential required to reach a current density of 10 mA cm-2 is 1.27 V vs RHE, which demonstrates the higher electrochemical activity of the Fe-Ni alloy compared to other individual compounds. This could be due to CTAB which improved the structural stability and synergetic and electronic effects in the nanoscale. This study will further contribute to renewable energy generation technology with long-term energy sustainability and also opens up great potential for reducing water pollution.

Investigation of the Enhancement of Heat Transfer in a Flat Plate Solar Collector With a Corrugated Tube Under Thermosiphon Effect

Abstract The development of new technologies for energy generation and use has been increasing significantly. In this projection, the use of flat solar collectors to convert solar energy into thermal energy through water heating for residential and commercial purposes has grown due to the potential reduction of up to 40% in electrical energy consumption promoted by these devices. A promising but underexplored area in engineering is the study of the intensification of heat transfer in these devices by changing the dimensional and constructive characteristics of the elevation tubes, especially through a numerical approach by passive systems that operate under the thermosiphon effect. Thus, this work aims to investigate, by using computational fluid dynamics (CFD), the heat transfer process in a flat plate solar collector with a concentric plate to the elevation tube, evaluating different diameters, angles of inclination, and slope corrugation profiles subjected to a constant heat flux. The numerical modeling considers a single-phase, incompressible, permanent, three-dimensional, and laminar flow, in addition to the Boussinesq approximation. The results showed that significant increases in the heat transfer rate can be achieved with absorber plates in comparison to those configurations without absorber plates. Moreover, the increase in the tube diameter allowed gains of up to 5.1% in the heat transfer rate, while the increase in the angle of inclination did not promote significant improvements. The triangular profile R10 P20 configuration increased the Nusselt number by 8%, while the R5 P20 configuration promoted a 25% gain in thermo-hydraulic performance.

Synergistic dynamics unveiled: Interplay between rare earth prices, clean energy innovations, and tech companies' market resilience amidst the Covid-19 pandemic and Russia-Ukraine conflict

Rare earth elements play a crucial role in supporting low-carbon energy generation technologies, such as electric motors in electric vehicles and the production of wind turbines. Additionally, these elements are utilized in a wide range of products manufactured by tech companies, including smartphones, aerospace components, and microelectronics. This paper aims to investigate the interplay between rare earth element prices (REMX), clean energy innovations (NEX), and the market of tech companies (PSE) from February 2018 to February 2023. To analyze the interdependencies between these markets, the study employs the cross-quantilogram (CQ) and wavelet local multiple correlation (WLMC) techniques. The findings of the investigation reveal a positive correlation between rare earth elements and the clean energy market, but only when both markets are in their respective extreme quantiles (10th and 90th). However, when the clean energy market is in a lower quantile and REMX is in a higher one for an extended period, there is either no significant interdependence or a negative relationship. Furthermore, the study identifies a positive co-movement between PSE and REMX in the short, intermediate, and extremely long-term. However, this relationship turns negative in the long run. The values of the coefficients fluctuate over time, particularly at larger scale periods of 8–16 when using the WLMC procedure. These findings have notable implications for stakeholders, including investors, managers, and policymakers, who are linked to the field of mineral resources and industries reliant on rare earth element-based technologies.

Comparative analysis of conventional and microwave pyrolysis of raw materials with different degree of metamorphism

The growth in anthropogenic impact on the environment caused mainly by energy activities and combustion of traditional fossil hydrocarbon sources necessitates the search for alternative energy generation technologies. Thermal processing of organic raw materials allows obtaining energy valuable products with less environmental impact. However, it strongly depends on the mechanism of thermal effect on the raw material and its characteristics. This paper compares two types of pyrolysis, including conventional one with heating of the entire reactor volume and microwave one with local impact of electromagnetic waves on the sample, for fuels with different degree of metamorphism. Comparative experiments indicate that the yield of high-calorie carbonaceous residue rises with an increase in geological age of fuels for both pyrolysis types, while the amount of solid products for conventional pyrolysis is 1.2–2.6 times higher than for microwave one. In its turn, regardless of the degree of metamorphism, microwave pyrolysis demonstrates advantages from the position of obtaining high-calorie gaseous products (from 18.6 to 28.0 MJ/m3) with low CO2 component ballast (<10 %). Such fundamental differences are due to the nature and speed of ongoing thermal reactions. The presented results can serve as a basis for choosing the method of processing of organic raw materials depending on the intended purpose of the final products.