Thermoeconomic analysis of electrically heated molten salt thermal energy storage power generation systems

Electrically heated molten salt thermal energy storage power generation (EH-MSTES-PG) systems offer a promising solution for large-scale, long-duration energy storage. This study establishes an integrated thermo-economic model coupling resistive heating with a Rankine cycle across 50–300 MW scales. A comprehensive life-cycle assessment is performed, including Chinese policy-driven auxiliary revenues alongside time-of-use (TOU) pricing. A novel indicator, Equivalent Conversion Efficiency (ECE), defined as the product of the weighted price ratio and system efficiency, is proposed to evaluate project viability. Results indicate that elevated main steam parameters boost total system efficiency from 38.38% to 42.32%. However, exergy analysis identifies the electric heater as the dominant irreversibility source. Additionally, reducing regenerative stages at intermediate scales notably diminishes steam generator efficiency. Economic evaluation confirms that discharge revenue and charging costs govern viability, collectively accounting for over 73% of total cash flows. Regions with high peak-valley price spreads (represented by Guangdong) exhibit increasing NPV with capacity expansion, significantly outperforming northwestern regions (e.g., Gansu). Significant scale economies are observed, where the 300 MW system achieves the highest Net Present Value (NPV) and exhibits the greatest sensitivity to increases in auxiliary revenue prices. Crucially, a strong nationwide correlation (r > 0.9) is confirmed between ECE and NPV. Analysis establishes that an ECE <100% indicates negative NPV, while an ECE >115% serves as a robust threshold guaranteeing positive lifecycle profitability. These findings provide quantitative criteria for identifying economically viable regions for storage deployment.