research communities highlight the importance of diversifying storage selections to reduce supplychain exposure and enable storage durations that are challenging for conventional battery systems (U.S. DOE, 2024). In parallel, European deployment is accelerating, strengthening the need for scalable solutions compatible with different topographies and existing infrastructures (European Commission, 2024). Within this landscape, gravity energy storage (GES) has emerged as a promising solution of mechanical storage technologies, relying on reversible conversion between electricity and gravitational potential energy. Recent reviews classify GES concepts across modular and integrated architectures and identify techno-economic competitiveness in applications where large height differences or existing structures can be leveraged (Cai et al., 2024). Integrated concepts are particularly attractive because they exploit pre-existing topography or industrial assets, enabling lower storage-cost and potentially seasonal-scale storage services (Hunt et al., 2025). Mine repurposing has therefore gained attention as a transition strategy, with abandoned extractive sites increasingly discussed as host environments for renewable generation and storage. Therefore, research has focused on pumped storage hydropower (PSH) using open pits or mine voids, including work highlighting geotechnical sensitivities and slope stability constraints under fluctuating reservoir levels (Liu et al., 2022). Less explored, however, are concepts that couple GES directly to bulk granular materials and conveying infrastructure already common in surface mines. Notably, downhill regenerative conveyor systems demonstrate that gravitational potential of transported mass can be recovered as electricity and exported to the grid (Kawalec et al., 2020; Galetakis et al., 2023). Based on these principles, this study introduces and evaluates a Conveyor Belt-based Gravity Energy Storage (CB-GES) concept designed specifically for decommissioned open-pit landscapes, providing a scalable way from “pits to power” for both energy transition and site rehabilitation. 2. CB-GES SYSTEM DESCRIPTION AND MODELLING The Conveyor Belt–based Gravity Energy Storage (CB-GES) system is considered as a mechanically simple, infrastructure-compatible storage technology that can be integrated into the steep topography of decommissioned open-pit mines. In contrast to liquid-based gravity storage such as pumped storage hydropower (PSH), which requires water reservoirs and introduces geotechnical concerns associated with cyclic water-level variation (Liu et al., 2022), CB-GES stores energy by moving granular solid material (e.g., sand, gravel, crushed rock) between two stockpiles at different elevations. The approach is consistent with the broader family of solid gravity energy storage (SGES) concepts that aim to reduce geographic constraints and avoid reliance on water availability. A key benefit in post-mining contexts is the presence of both steep terrain (large vertical drop) and abundant granular solid material availability, which facilitates the implementation of storage systems with minimal civil engineering requirements. As shown in Figure 1, CB-GES operates in two reversible modes, “charging” and “discharging”. During “charging”, surplus electricity drives a conveyor belt uphill, transporting granular material from a lower stockpile to an upper stockpile, thereby converting electrical energy into gravitational potential energy. In “discharging”, the material flow direction is reversed, and the descending material causes the conveyor drive to operate regeneratively, converting mechanical power back into electricity and exporting it to the grid. This operating principle is based on established practice in downhill regenerative belt conveying, where gravity-driven transport can produce net electrical power if the downslope
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