857 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 seasonalscale 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 component of material weight exceeds motion resistances (Kawalec et al., 2020). Modern industrial implementations commonly achieve regeneration via variable frequency drives using active front-end converters that support bidirectional power flow and stable control under generating conditions (Chelopo & Gupta, 2025). The feasibility of applying a reversible conveyor specifically as a storage plant in abandoned open pits has also been recently demonstrated conceptually, highlighting the relevance of slope angle, losses, and load throughput as critical design parameters (Galetakis et al., 2023). From a systems perspective, a CB-GES plant comprises: (i) an upper and lower storage area (stockpiles), (ii) a reversible conveyor line with mechanical support structure and idler sets, (iii) controlled loading/unloading equipment (feeders, hoppers, reclaimers), and (iv) an electro-mechanical conversion unit including motor–generator and power electronics for grid connection. The conveyor’s controllability is crucial since power output can be modulated by adjusting belt speed and the mass flow rate, allowing the plant to provide dispatchable services over a wide operating covering. However, the same controllability must maintain safe belt tensions, stable material transport, and acceptable braking behavior during transient events such as start/stop sequences, since dynamic stability is a known design challenge for downhill conveyors (Chelopo & Gupta, 2025).
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