International Journal of Energy Research

This research showcases the seamless integration of solid oxide fuel cells (SOFC) with waste heat recovery systems, utilizing liquefied petroleum gas (LPG) as the primary fuel source. The focus of the study is on efficiently harnessing the cold energy from the LPG supply to produce substantial power for the entire system. To optimize energy utilization, a gas turbine (GT) and steam Rankine cycle (SRC) are integrated to effectively convert waste heat from the system into useful work and power. Additionally, a waste heat boiler (WHB) is incorporated to provide superheated vapor steam for seafarer accommodation. A detailed thermodynamic analysis and investigation of the proposed integrated system are performed. The simulations and optimizations of combined system are conducted using ASPEN HYSYS V12.1. Thermodynamic equations based on the fundamental laws of thermodynamics are employed to estimate system performance indicators, and the exergy destruction in major components is assessed to optimize the system’s design and operation. The proposed system exhibits impressive energy and exergy efficiencies, calculated at 52.65% and 51.10%, respectively. Moreover, the waste heat recovery combined cycles contribute an additional 1,759.73 kW, equivalent to 31.65% of the total system output. The innovative models are validated against experimental data from the literature, demonstrating strong agreement. Furthermore, a comprehensive parametric study investigates the influence of varying the current density from 900 to 1,950 A/m², leading to a total energy efficiency variation of 41.59%, ranging from 82.45% to 40.86%. The organic Rankine cycle (ORC) performs exceptionally well, capitalizing on both cold energy and high-temperature waste heat to achieve high energy recovery efficiency. The WHB is capable of providing 8,200 kg/h of superheated vapor stream at 151°C and 499 kPa for seafarer accommodation and heating purposes. The economic viability analysis is conducted to assess the potential for investment, maintenance costs, and the payback period associated with the proposed system.

Solar greenhouse technology emerges as a solution that intensifies crop yields and allows utilities to generate energy from photovoltaic cells. Here, we demonstrate a photonic crystal-integrated solar cell that selectively transmits photosynthetic light for plant cultivation and reflects the remaining light to the adjacent solar cells to generate electricity. The photonic crystal is fabricated using an e-beam evaporation method by nonperiodic stacking of TiO₂ and SiO₂ layers to transmit light at 400–500 nm (blue) and 600–700 nm (red) and reflect green (500–600 nm), ultraviolet, and infrared light. The photonic crystal-integrated solar cell is constructed with the vertically arranged copper indium gallium diselenide (CIGS) solar cell and the tilted photonic crystal with respect to the CIGS cell. By controlling the tilting angle of the photonic crystal film, it achieves the generated electric power of 40.2 W m^-2 and the irradiance of 124.6 W m^-2 for transmitted photosynthetic lights (400–500 and 600–700 nm). In contrast, a conventional horizontal CIGS cell shows a power generation of 55.6 W m^-2 without any light transmission. This work provides a new optical strategy and design principle for the development of a wavelength-selective semitransparent solar cell.

Carbon corrosion in a catalyst layer (CL) deteriorates the performance and durability of proton-exchange membrane fuel cells (PEMFCs), which are closely related to water management within these cells. This study investigates the characteristics of water behavior of two gas diffusion layers (GDLs) and compares their influence on degrees of degradation in the CL. First, the properties of the GDLs, including their thickness, pore size distribution, gas permeability, electrical resistance, contact angle, and polytetrafluoroethylene (PTFE) content, are evaluated. The dynamic behavior of liquid water is observed using a visualization cell and synchrotron X-ray imaging. Second, a modified accelerated stress test (AST), which includes a water generation reaction within the catalyst support protocol of the US Department of Energy (DOE), is performed. For assessing the degradation, we utilize polarization curves, electrochemical impedance spectroscopy, cyclic voltammetry, scanning electron microscopy, and field emission transmission electron microscopy. The results reveal that, even though GDL B contains a higher hydrophobic content than GDL A, it exhibits lower water discharge, indicating a reduced performance at high relative humidity (RH) levels. This is attributed to a low capillary pressure gradient, which is influenced not only by PTFE but also by the overall pore structure (i.e., porosity and pore size). Consequently, a high capillary pressure gradient can enhance water discharge and thereby mitigate carbon corrosion and Pt agglomeration in the CL. In addition, the application of the modified AST induces carbon corrosion with fewer cycles than that achieved using the DOE carbon support protocol.

Date palm fiber (DPF) holds great potential for composite materials, but its flammability limits its practical applications. In this study, DPF was modified using a pad-drying method to impregnate it with a 5 wt.% solution of ammonium dihydrogen phosphate (ADP). These treated fibers were then utilized to fabricate poly(β-hydroxybutyrate)- (PHB-) based composites. The resulting thermal insulators were comprehensively evaluated for their flammability, physical, mechanical, and thermophysical properties, as well as morphological and thermal stability characteristics. The findings revealed a significant reduction in flame spread and smoke suppression; however, the concentration used is not sufficient to achieve the desired rating grades. The thermal insulation capacity of the modified fiber composites was substantially enhanced, particularly with the 40% PHB/DPF-ADP composite displaying the lowest thermal conductivity at 0.0564 W/m.K. Moreover, the presence of gaps and voids at the interface led to a reduction in tensile strength to 4-7 MPa. Additionally, the modified fiber composites exhibited significantly reduced water absorption (~0.76%), attributed to the formation of a highly water-resistant substance containing a furan compound. This work provides a simple and effective approach for achieving durable flame retardancy and long-term thermal insulation performance, offering promising opportunities for the practical application of biobased PHB composites.

Hierarchical porous carbon materials have received significant attention for application in catalytic water splitting because of their high efficiency, cost-effectiveness, and biocompatibility. In this study, laser-induced graphene (LIG) was fabricated on a carbon film- (CF-) type substrate for an efficient hydrogen evolution reaction (HER). The LIG-CF electrode was fabricated via laser-induced graphitization on a commercial polyimide (PI) film, followed by the pyrolysis of the LIG on the PI film (LIG-PI). During pyrolysis, the microscopic and material properties of the LIG remained intact, as verified through various characterizations. The as-prepared all-carbon electrode was then utilized as an electrode for the HER study in a 1.0 M KOH electrolyte and compared with LIG-PI and Pt electrodes. In the HER experiments, the optimized LIG-CF electrode exhibited excellent catalytic performance with zero-onset potential, and the potentials required to achieve high current densities of 10 and 20 mA/cm² were 134 and 139 mV (vs. reversible hydrogen electrode (RHE)), respectively. The excellent performance of the LIG-CF electrode originates from the hierarchical porous structure of the LIG material, which serves as an electrochemically active site, and carbon substrate that facilitates the fast transport of ions at the electrode/electrolyte interface. Additionally, the carbon substrate shortens the transportation length of electrons which played a significant role for the enhanced performance of the LIG-CF electrode.

The high level of integration of distributed generation systems (DGSs), especially distributed wind and solar, significantly affects the flexibility and controllability of the power system. Aggregating local DGSs and shared energy storage systems (ESSs) within an energy community offers an economically and environmentally viable solution. However, the coupling of shared ESSs with the energy community, while considering subjectivity, is often overlooked. Therefore, this study introduces a two-layer optimization framework that enables DGSs to trade energy freely, voluntarily, and independently and to share ESSs within the energy community, considering participants’ subjectivity. The upper layer optimizes the size of shared ESSs, while the lower layer, structured as a two-layer model, simulates participant interactions. The numerical case shows that, compared to DGSs operating individually, the shared ESS case indicates that community self-sufficiency and self-consumption rates increase by 16.22% and 21.98%, respectively. Additionally, the annual operating cost is reduced by approximately 27.10%, and CO₂ emissions are decreased by about 33.24%. Considering DGS’ subjectivity, the self-sufficiency and self-consumption rates are 3.04% lower, and the total operating costs and CO₂ emissions are 3.26% and 6.86% higher, respectively.