Optimal location of slope solid gravity energy storage using geographic information systems and multi-criteria analysis

Sloped solid gravity energy storage (S-SGES) exploits natural slopes to achieve high efficiency, long life, low cost and low environmental impact. These advantages enable S-SGES to smooth wind and solar power fluctuations and support their large-scale grid integration. However, large-scale deployment is constrained by the absence of systematic site-selection approaches adapted to its unique technical features. Drawing on the shared principles of pumped hydro energy storage (PHES) and extensive PHES siting experience, this study develops a dedicated two-stage geographic information system–multi-criteria decision-making (GIS-MCDM) framework for S-SGES. In the first stage, a terrain-based topology explicitly considering inclined transportation routes and stacking zones is constructed, and seven terrain and infrastructure constraints are applied to identify geographically suitable sites. In the second stage, a three-dimensional indicator system covering electrical, economic and social criteria is established. The Analytic Hierarchy Process (AHP) yields dimension weights of 44.95%, 33.11% and 22.94% for electrical, economic and social aspects, respectively; at the criterion level, Grid reliability (C13) attains the highest weight (28.52%), while Employment (C32) is least important (2.50%), quantitatively highlighting the dominance of grid-related factors in S-SGES siting. A case study in Guizhou Province, China, shows that the top-ranked site P4 in Qiandongnan achieves a composite score of 9.06, outperforming the second-best site P2 (8.08) by 0.98 points, i.e. about 12%. Sensitivity analysis with ±30% perturbations of key indicator weights confirms that the ranking of P4 remains stable, demonstrating the robustness of the proposed framework. A prototype S-SGES system under construction at site P4 provides ongoing engineering validation. Methodologically, this work (i) tailors the GIS screening logic to slope-based gravity systems, (ii) reforms the evaluation index system and weights to emphasize grid reliability and power-system integration, and (iii) offers a systematic and transferable GIS-MCDM approach that extends PHES-oriented siting methods to emerging gravity energy storage technologies.