International Journal of Energy Research最新文献

Raw biogas (40%–75% CH₄) faces challenges in its adoption due to its low energy density and unpleasant odor in lighting and cooking applications. The objective of this study was to upgrade biogas using low-cost adsorbent materials through column adsorption. The study examined the effect of adsorbent types (commercial activated carbon (CAC), activated carbon from water hyacinth, wood ash (WA), modified clay (MC)), bed heights (4, 8, 12 cm), and gas flow rates (50, 100, 150, 200 mL/min) on biogas upgrading quality. The upgraded biogas was analyzed for CH₄ content, while the spent adsorbent was examined using Fourier transform infrared radiation (FTIR), BET, and scanning electron microscope (SEM) techniques. The breakthrough curve was evaluated at a wide range of flow rates for the optimal adsorbent type and bed height. The adsorption isotherms and kinetics of impurity uptake of activated carbon from water hyacinth were evaluated at a bed height of 12 cm (4.62 g) and flow rate of 50, 100, 150, and 200 mL/min. The results indicated that the BET surface areas of raw adsorbents, including CAC, activated carbon from water hyacinth, WA, and MC, were 789.8, 624.9, 524.8, and 522.5 m²/g, respectively. The upgraded biogas had CH₄ content of 99.0%, 97.8%, 96.3%, and 94.8% for CAC, activated carbon from water hyacinth, WA, and MC, respectively, at an optimal bed height of 12 cm and flow rate of 50 mL/min. The highest removal efficiency and CH₄ content were obtained using activated carbon from water hyacinth, and the values were 96.11% and 97.8%, respectively. The longest breakthrough time was 16 min, and the highest adsorption capacity was 0.82 g of impurities per gram of activated carbon from water hyacinth. Activated carbon from water hyacinth demonstrated comparable removal efficiency of impurities compared to CAC and was superior to WA and MC. The remarkable impurity removal efficiency of adsorbents opens up possibilities for biogas as a cleaner energy source.

Secondary biogas (SBG) represents an environmentally sustainable methane resource formed from the microbial degradation of coal during tectonic uplift. This study simulates the multistage tectonic evolution of coal-bearing basins using a staged nutrient supplementation system, revealing the complex interplay between microbial activity and coal matrix transformation. Over three biodegradation stages, cumulative methane yield increased by 246% (from 201.47 to 696.94 µmol/g), demonstrating the efficacy of staged methanogenesis. A comprehensive analysis of coal properties uncovered the underlying mechanisms: biodegradation shifted carbon preference from n-C₂₇ to n-C₂₂, consuming low- and high-carbon n-alkanes while enriching medium-carbon ones. The coal matrix underwent substantial restructuring, as evidenced by decreasing CH₂/CH₃ ratios; a unimodal aliphatic-to-aromatic tread; and a fluctuating C═O/C═C ratio. Pore structure exhibited a dynamic, bidirectional response—initial compaction followed by microbial-driven expansion—which modulated methane adsorption capacity by altering the specific surface area (SSA). Our results establish that methane production is jointly controlled by three key factors: pore accessibility (via SSA), hydrolytic efficiency (indicated by C═O/C═C), and aromaticity (AR). This work provides a mechanistic model and critical theoretical framework for forecasting SBG generation in geologically complex and multistage tectonic settings.

Inspired by the electrical discharge mechanism of electric fish, we report a bio-inspired power source based on agarose hydrogels. The device generates electrical energy by exploiting ion concentration gradients across high- and low-salinity hydrogels, in combination with polyelectrolyte membrane gels exhibiting ion selectivity based on Donnan exclusion. Systematic optimization of hydrogel composition identified optimal ion concentrations and agarose content that balance energy output and mechanical stability. To further enhance performance, asymmetric redox pairs—ferrocyanide/ferricyanide at the anode and vanadium oxide at the cathode—were introduced, boosting both voltage and current outputs. Additionally, a continuous flow system was incorporated to replenish ionic gradients, addressing limitations from ion gradient depletion during extended operation. Simulations and experimental results confirmed that the flow-assisted configuration maintained stable ion distributions, enabling sustained power output over time. This work demonstrates a safe, scalable, and environmentally friendly platform for water-based energy harvesting, with potential applications in bio-interfacing and soft energy devices.

This work introduces a novel Cu₂ZnSnS₄ (copper zinc tin sulfide [CZTS]) kesterite/coconut shell-derived biomass activated carbon (AC) nanocomposite material (CZTS_0.5:AC_0.5) for supercapacitor application. CZTS was prepared by microwave-assisted synthesis and combined with AC to produce CZTS_0.5:AC_0.5 through mechanical milling and low-temperature annealing at 350°C. X-ray diffraction (XRD) and Raman spectroscopic analyses of CZTS_0.5:AC_0.5 nanocomposite revealed the formation of a multiphase system consisting of residual CZTS and secondary sulfides (zinc sulfide [ZnS], CuS, and SnS), which are embedded within a highly conductive amorphous carbon matrix. High-resolution transmission electron microscopy (HRTEM) results indicate a reduction of the particle size from 55.7 nm (for CZTS) to 21.7 nm (for CZTS_0.5:AC_0.5) due to annealing. The nanostructurization of CZTS_0.5:AC_0.5 created abundant electroactive sites that made the material an efficient charge storage system. Galvanostatic studies of AC//CZTS_0.5:AC_0.5 in a three-electrode configuration produced a specific capacitance (C_sp) of 458.2 Fg⁻¹ at 1 Ag⁻¹. Two-electrode AC//CZTS_0.5:AC_0.5 asymmetric supercapacitor device had a maximum energy density of 12.8 Wh kg⁻¹ and a maximum power density of 890.5 W kg⁻¹. The supercapacitor device exhibited excellent stability with a coulombic efficiency retention of 99.99% and a capacitance retention of 81.4% after 10,000 cycles. The results portray CZTS_0.5:AC_0.5 nanocomposite material as a promising, sustainable electrode material for next-generation supercapacitors.

A geothermal thermosyphon is an outstanding device for roadway snow removal, eliminating energy consumption and mitigating environmental and operational drawbacks of conventional methods, such as road salt and electrical heating. However, for this system to be reliably and effectively implemented on roadways, a more sustainable alternative is required to replace the previously considered working fluids, including ammonia and R134a, which pose toxicity and environmental challenges. Furthermore, a comprehensive investigation is needed to understand its performance during operation, enhance thermal and snow-melting performance, and evaluate its capability to meet actual snow removal standards. This study explored the practical feasibility of the geothermal thermosyphon charged with acetone, the superior alternative to other working fluids, with a lab-scale experimental setup simulating actual snowfall environments. The evaporator surface was modified with thread tapping, which is more productive, economical, and durable than other surface modification methods. The results showed that the snow covering the road improved the thermosyphon heat sink’s performance, increasing geothermal energy absorption. Moreover, the roadway surface temperature stayed above freezing during system operation, confirming its anti-icing ability, not just snow-melting. The threaded evaporator surface significantly improved thermal and snow-melting performance by enhancing film evaporation and increasing heat transfer area, reducing thermal resistance and snow removal time by 69.8% and 24.3%, respectively. Finally, the system explored in this study successfully met snow removal standards for urban roads with 30–60 km/h design speeds in South Korea, demonstrating its feasibility for practical usage on roadways.

Ternary transition metal oxides (TTMOs) have emerged as a new class of electrode materials for high-performance energy storage systems, particularly supercapacitors (SCs) and hybrid battery-capacitor devices. This comprehensive review aims to comprehensively survey recent advances in the design, synthesis, and analysis of TTMOs-based nanostructures for SC electrodes. It begins by outlining the key concepts related to charge storage mechanisms in SC electrodes, electric double-layer (EDL) capacitance, pseudocapacitive (PC), and battery-type (BT) behavior, followed by a clarification of device configurations, including symmetric SC (SSC), asymmetric SC (ASC), and hybrid SC (HSC) devices. This review then examines the fabrication strategies for TTMOs, emphasizing the impact of synthetic approaches on material morphology, crystallinity, and electrochemical performance. Special attention is given to the structure-property relationships that govern ion transport and charge storage dynamics in these materials. The influence of morphological features, including dimensionality, porosity, and hierarchical architecture, on electrochemical behavior is critically analyzed. A comparative evaluation of electrochemical matrices across various TTMO electrodes is presented, highlighting key performance and challenges. Ultimately, the review highlights emerging trends, current limitations, and future research directions that are poised to accelerate the development of next-generation TTMO materials for advanced energy storage technologies.

In the ocean thermal energy conversion (OTEC) system, electrical power is generated by exploiting the temperature difference between cold deep seawater and warm surface water. This study introduces an innovative method that uses a solar collector to increase the temperature of the water entering the evaporator and a wind turbine to increase the useful power, thereby increasing the energy efficiency and power output of the cycle. The research findings indicate that the proposed cycle achieves an average net production power of 36.63 megawatts, with energy productivity and exergy at 9.70% and 29.12%, respectively. Additionally, freshwater production has increased by 170.26% compared to the base cycle. A sensitivity analysis of various parameters was also conducted on the proposed cycle, which demonstrated a reduction of 89.69 tons in carbon dioxide emissions. Finally, to optimize the designed system, the response level multiobjective optimization method has been used to find the best set of objective functions and decision variables. The four objective functions of this optimization included exergy efficiency, total system energy, production work, and system cost rate.

Carbon dioxide (CO₂) emissions pose global challenges, necessitating carbon neutrality in future development. CO₂ capture and energy storage technologies are crucial steps, with calcium looping (CaL) holding significant potential for both. This technology is crucial for achieving carbon neutrality in future strategies. This paper thoroughly reviews the use of CaL in CO₂ capture and storage over the past two decades. It provides an overview of CaL’s application, reviews research progress in CaL-integrated systems, discusses existing limitations, and highlights possibilities for future growth. According to the study, from 2003 to 2023, 692 documents were published on CaL. The annual growth rate of 18.92% indicates rapidly expanding research efforts and increasing recognition of CaL potential. Based on the findings, the field of CaL has evolved from understanding historical carbon cycles to incorporating advanced combustion techniques and renewable resources. Key concepts like “process simulation,” “modeling,” and “life cycle assessment (LCA)” have become more prominent in relation to the subject matter. The study indicates that CaL has significant potential for carbon capture (CC) and storage. However, future research should focus on sorbent development, process optimization, characterization, economic evaluations, and large-scale applications to improve efficiency.

The individual use of organic phase change materials (PCMs) in solar stills has been shown to result in the need for large masses for performance improvements. This paper proposed a novel approach by integrating both paraffin wax and beeswax onto the basin to form a modified solar still (BP-PCMSS), aiming to enhance the performance of a conventional solar still (CSS). A comparative analysis was conducted between the two models, evaluating thermodynamic, economic, environmental, enviroeconomic, and sustainability characteristics. The results revealed that BP-PCMSS provided a yield of 3.1 kg/m² relative to 2.35 kg/m² for CSS, reflecting 31.91% improvement. Thermodynamically, BP-PCMSS improved the energy and exergy efficiency of CSS by 32.14% and 28.57%, respectively. From an economic perspective, BP-PCMSS and CSS had production costs of $0.022/L and $0.027/L, respectively, indicating an 18.52% reduction for BP-PCMSS. The environmental parameter for BP-PCMSS was 7.82 tons of CO₂ mitigation compared to 5.81 tons for CSS, while the enviroeconomic parameter was $113.39 for BP-PCMSS and $84.25 for CSS, reflecting 34.59% improvement in both parameters for BP-PCMSS. Additionally, BP-PCMSS achieved a sustainability index (SI) of 1.028, reflecting a 0.69% improvement compared to CSS (1.021). In conclusion, the proposed dual-PCM approach integrated into the basin offers a more energy-efficient, economical, environmentally sustainable, and overall superior method for improving solar still performance, outperforming the individual application of each PCM.

Power generation is undergoing a major shift with the rise of renewable energy, and DC microgrids are emerging as key players in transforming electricity generation, distribution, and management. Implementing droop control causes inherent voltage fluctuation at the DC bus. This study presents a distributed secondary control technique for a standalone solar photovoltaic (PV) and battery energy storage-based DC microgrid. The scheme ensures bus voltage recovery, state of charge (SoC) balancing, and power allocation among multiple energy storage units by integrating current and voltage error corrections within the designed control loop. A novel hybrid whale optimization (WO) algorithm and the gray wolf optimization (GWO) algorithm approach are introduced to optimize the parameters of the proposed control scheme, ensuring the proposed control meets its objectives. State-space modeling of the DC microgrid was formulated, incorporating eigenvalue observation analysis to assess the impact of the optimized control on the system’s stability. A real-time testing framework designed with MATLAB/Simulink is implemented within the Speedgoat real-time machine, enabling the validation of the control technique under realistic operating conditions. The findings indicate that by facilitating power exchange and communication between neighboring energy storage units, the proposed control scheme ensures an accurate and well-balanced power distribution across the system. Furthermore, the implementation of this strategy effectively stabilizes the DC bus voltage, mitigating fluctuations and enhancing overall microgrid performance.