SIMULATION-BASED PERFORMANCE ASSESSMENT OF ROCK-BED SENSIBLE THERMAL ENERGY STORAGE FOR OFF-GRID SOLAR ELECTRICITY GENERATION IN NORTH-EASTERN NIGERIA
Keywords:
Rock-bed, thermal energy storage, sensible heat storage, solar thermal electricityAbstract
Limited access to reliable electricity remains a major development challenge in North-Eastern Nigeria despite the region’s high solar energy potential. This study presents a simulation-based assessment of a rock-bed sensible thermal energy storage (SHS) system integrated into a 100 kWh decentralized solar thermal electricity generation configuration for off-grid applications. A transient MATLAB/Simulink model incorporating region-specific solar irradiance and ambient temperature data was developed to evaluate charging–discharging behavior, thermocline evolution, and system-level performance under representative operating conditions. Simulation results indicate a maximum recoverable stored thermal energy of approximately 210 kWh per cycle within the rock-bed TES unit. When integrated with direct solar thermal input to the power conversion block, the overall hybrid system delivers a total daily usable energy output of approximately 497 kWh. These values correspond to different system boundaries—stored TES output versus combined direct-plus-stored solar contribution—and therefore do not imply energy amplification beyond storage capacity. The system achieved an average thermal storage efficiency of 75–78%, consistent with reported packed-bed TES performance ranges. Sensitivity analysis identifies specific heat capacity as the dominant material parameter affecting stored energy, while heat transfer fluid mass flow rate primarily governs discharge stability. A preliminary techno-economic screening based on simplified cost assumptions suggests competitive performance; however, comprehensive capital, balance-of-plant, and financing costs were not fully modeled and are required for investment-level feasibility evaluation.
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