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    Enhancing clay properties with eggshell powder: A sustainable alternative for soil stabilization
    (2026-07-01)
    Munirwan, Reza Pahlevi
    ;
    Taib, Aizat Mohd
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    Jaya, Ramadhansyah Putra
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    Yuliana, Yuliana
    ;
    Kamchoom, Viroon
    Poultry waste is increasing rapidly in many countries as urbanization and industrialization rise and create environmental and economic issues. Eggshell waste deteriorates infrastructures but could effectively stabilize clay soil. This study investigates the performance of eggshell powder (ESP) as a stabilizing agent for clay soil, emphasizing its effects on the mechanical properties of clay and its suitability for construction. The methodology involved preparing soil and ESP samples, followed by standard Proctor compaction tests, direct shear tests, and microstructural analysis. Various percentages of eggshell powder (0%, 3%, 6%, and 9%) were added to the clay soil. The results revealed that the addition of ESP improved the plasticity, compaction behavior, and shear strength of soil. The results showed that the plasticity index decreased from 30.45% (untreated soil) to 21.78% at 6% ESP, and the liquid limit reduced from 65.28% to 57.80%, enhancing soil workability and reducing swelling. Additionally, soil cohesion increased substantially from 82.7 kN/m² (untreated soil) to 144.5 kN/m² at 9% ESP, while the internal friction angle improved from 18° to 25°, contributing to its overall strength and stability. The microstructural analysis confirmed these findings, showing a denser soil matrix and stronger inter-particle bonds. This study concludes that ESP is a promising alternative to traditional soil stabilizers, offering environmental benefits by utilizing waste material and reducing the need for cement and lime. The use of ESP in soil stabilization contributes to sustainable construction practices and presents a viable solution for improving the performance of clay soils in construction.
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    Biodiesel production from spent coffee grounds via ethanolic extraction and supercritical ethanol transesterification: technoeconomic analysis and life cycle assessment
    (2026-01-01)
    Supang, Wirasinee
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    Ngamprasertsith, Somkiat
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    Nimmanterdwong, Prathana
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    Sakdasri, Winatta
    ;
    Hunsub, Panusorn
    Previous studies have developed biodiesel production methods from spent coffee grounds (SCGs) via ethanolic extraction and supercritical ethanol transesterification (EE-SET) to minimize the energy consumption associated with solvent evaporation. In this study, we perform a technoeconomic analysis (TEA) and a life cycle assessment (LCA) to evaluate the profitability and sustainability of EE-SET. The material and energy balances in the TEA and LCA were derived from Aspen Plus<sup>®</sup> V12 based on experimental data from previous research. The results from the base case indicated that EE-SET was unprofitable and posed a considerable environmental burden by disposing of defatted SCG (DSCG) as solid waste due to two main issues. First, the amount of DSCG was 4.8 times greater than the total biodiesel and glycerol produced. Second, landfilling DSCG incurred waste treatment costs and induced greenhouse gas (GHG) emissions simultaneously. Selling DSCG as a feedstock for solid fuel pellets offers an effective strategy for achieving profitability and sustainability. As such, EE-SET addresses the economic drawback of generating profit from selling DSCG while reducing waste treatment costs. Using DSCG as a solid fuel for environmental benefits increases ash disposal credit and substantially reduces GHG emissions. The incorporation of pelletizing units or biomass power plants into EE-SET represents a promising avenue for future research.
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    Thermodynamic and Emission Performance of SOFC-GT Hybrids with Dual Recirculation Strategies
    (2026-01-01)
    Pholboorn, Suthin
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    Patcharavorachot, Yaneeporn
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    Saebea, Dang
    ;
    Arpornwichanop, Amornchai
    Solid oxide fuel cell–gas turbine (SOFC-GT) hybrid systems offer high efficiency and low emissions for sustainable power generation. This study compares two SOFC-GT configurations with different exhaust gas recirculation strategies: SOFC-GT-RAN (anode recirculation) and SOFC-GT-RAB (afterburner recirculation). Both systems were modeled in Aspen Plus using methane with 10% pre-reforming. Parametric analyses were conducted to examine the influence of fuel utilization, steam-to-carbon ratio, SOFC operating temperature, and recirculation ratio on system performance. The results show that SOFC-GT-RAN consistently outperforms SOFC-GT-RAB in terms of power output, efficiency, and CO<inf>2</inf> emissions. At optimal conditions (SOFC temperature = 1173 K, fuel utilization = 0.90, steam-to-carbon ratio = 2.0, anode recirculation ratio = 0.30, afterburner recirculation ratio = 0.10), SOFC-GT-RAN achieved SOFC and net powers of 208.51 kW and 207.47 kW, compared to 156.43 kW and 158.01 kW for SOFC-GT-RAB. Energy and exergy efficiencies were 93.18% and 89.81% for RAN, substantially higher than 70.96% and 68.40% for RAB. Moreover, CO<inf>2</inf> emissions were lower for RAN (205.98 kg/MWh) than for RAB (268.82 kg/MWh). These findings confirm that anode exhaust gas recirculation provides superior technical and environmental performance, highlighting SOFC-GT-RAN as a promising pathway for efficient and clean hybrid power generation.
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