The development of solid fuels from biomass sources plays pivotal roles in the global transition towards sustainable energy systems. In this context, optimising solid fuel production processes and understanding the influence of key parameters on fuel quality are crucial. This study examined the development and process optimisation of combined torrefied and pelletised hybrid solid fuels derived from corncob and African birch wood (ABW). Residues of corncob and ABW blends were prepared gravimetrically and evaluated in both raw and torrefied forms to determine optimal combinations with enhanced combustion characteristics. A Box–Behnken experimental design was employed to investigate the effects of key operating parameters on physico-mechanical properties of the pellets. The statistical modelling demonstrated strong linear correlations, with coefficients of determination (R²) of 0.9362 for density, 0.9796 for shatter index, and 0.9736 for water uptake capacity. Analysis of variance confirmed that all continuous variables exerted statistically significant effects on the response variables. Optimal process parameters were identified at a torrefaction temperature of 259.39°C, particle size of 0.5 mm, binder content of 15%, and compacting pressure of 140 MPa. Under these conditions, the model predicted a pellet density of 1466.54 kg/m³, shatter index of 93.69%, and water uptake capacity of 2.37%. These experimental values compared favourably with the predicted outcomes, achieving a desirability factor of 1.00, thereby validating the robustness, reliability, and accuracy of the predictive model. They underscore the potential of combining corncob and ABW residues in the production of high-quality hybrid solid biofuels, with optimised processing conditions significantly enhancing their physico-mechanical performance.
The integration of eco-friendly materials into seawater battery systems represents a sustainable approach to decentralized energy supply for small-scale fisheries. This study aimed to (1) synthesize nitrogen- and phosphorus-doped bamboo-derived graphite (BDG) through a two-step pyrolysis process, (2) fabricate a bamboo-graphite air cathode for magnesium seawater batteries (Mg-SWBs), (3) evaluate its electrochemical properties, and (4) demonstrate battery performance under laboratory seawater conditions by assessing discharge stability and voltage behavior. Bamboo (Dendrocalamus asper) was carbonized using ammonium dihydrogen phosphate (NH₄H₂PO₄) as a dual dopant, followed by cathode fabrication using stainless-steel mesh and polyvinyl acetate binder. Electrochemical performance was characterized using cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Battery performance was evaluated by continuous discharge testing in natural seawater (salinity approximately 35 ppt) under laboratory conditions, where voltage and current were monitored every two hours over a 12 h period. The synthesized BDG exhibited an electrical conductivity of 7.8 × 10⁴ S cm⁻¹, representing approximately 95% of commercial graphite conductivity, with a mesoporous structure (average pore diameter ≈ 3.8 nm) favorable for oxygen reduction reactions. CV analysis demonstrated quasi-reversible redox behavior, while EIS measurements indicated low solution resistance (8.6 Ω) and moderate charge-transfer resistance (34 Ω), confirming efficient electron transport. Continuous discharge testing demonstrated a stable output voltage of 2.0 ± 0.05 V and a power density of 1.9 mW cm⁻² for approximately 10 h, followed by gradual voltage decline caused by magnesium anode passivation. A temporary voltage recovery after a resting period was attributed to chemical relaxation rather than self-recharging. Integration with a DC–DC boost converter increased the usable output voltage to approximately 3.5–3.8 V, enabling continuous operation of an LED lamp. These findings demonstrate that bamboo-derived graphite is a promising low-cost and renewable air-cathode material capable of maintaining stable battery performance under laboratory seawater conditions, supporting sustainable marine energy applications and blue economy initiatives.
Metal hydride based solid state hydrogen storage devices have garnered substantial interest owing to their potential in facilitating clean and efficient energy storage for various applications. However, effective thermal management remains a critical aspect influencing their performance and safety. This review comprehensively explores the thermal management strategies employed in metal hydride-based systems, encompassing heat transfer mechanisms, materials design, and engineering approaches. Various thermal management techniques, including passive and active cooling methods, heat exchangers, and advanced modelling techniques, are studied in detail. Furthermore, challenges and opportunities in enhancing the thermal performance and operational reliability of these systems are discussed. The insights provided in this review aim to contribute to the advancement of metal hydride-based solid-state hydrogen storage devices. By highlighting the significance of thermal management, this review provides actionable insights for researchers and engineers aiming to enhance the efficiency, safety, and real-world applicability of metal hydride hydrogen storage devices, thereby contributing to the broader goal of sustainable energy solutions.
This paper proposes a State of Health (SOH)—aware power management framework for a hybrid renewable energy system integrating solar photovoltaic, wind energy, and battery energy storage systems. Unlike conventional strategies that rely solely on State of Charge, the proposed approach embeds SOH as an active control variable within the power management algorithm to adapt battery dispatch based on degradation state. Real-world solar and wind datasets, along with experimentally obtained battery degradation data, are used for system evaluation. Simulation results demonstrate that incorporating SOH reduces battery stress, limits excessive cycling under degraded conditions, and improves long-term system reliability. The proposed framework enables lifecycle-aware energy management, enhancing the sustainability and operational resilience of hybrid renewable energy systems.
This study presents a comprehensive numerical investigation of magneto hydrodynamic (MHD) hybrid nanofluid flow in a two-dimensional channel featuring a localized wavy section under the influence of a non-uniform magnetic field. The hybrid nanofluid, composed of Fe₃O₄–Al₂O₃ nanoparticles dispersed in water, is modeled as a single-phase fluid under laminar, steady, and incompressible conditions. The applied transverse magnetic field follows an exponential decay along the channel height, inducing a spatially varying Lorentz force and Joule heating effect. The governing equations are solved using the finite volume method implemented in ANSYS Fluent, with the SIMPLE algorithm employed for pressure–velocity coupling. A comparative analysis between smooth (SC) and wavy (WC) channel configurations is conducted to evaluate the impact of Reynolds number (200 ≤ Re ≤ 800) and magnetic field intensity (1 T ≤ B₀ ≤ 8 T) on flow structure, heat transfer, and thermodynamic irreversibility. The results reveal that the magnetic field significantly suppresses fluid velocity within the magnetized region due to Lorentz force damping, while simultaneously enhancing fluid temperature through Joule heating. Overall, the results demonstrate that the combination of localized wall waviness and a non-uniform magnetic field provides an effective strategy for enhancing heat transfer while minimizing thermodynamic irreversibility. This study offers valuable insights for the design of advanced MHD-based cooling systems and energy applications involving hybrid nanofluids.
