Objective In vertical gravity energy storage systems, the mass block serves as the core medium for the conversion between gravitational potential energy and electricity. Its physical structure and associated storage system are key components of the total life-cycle cost. Therefore, developing an economic model for the mass blocks is essential for the overall economic analysis of the system.

Method This paper established a mathematical cost model for the mass blocks and their dedicated storage structure, the "bottom chamber." The model comprehensively considered the influence of key system parameters—such as energy capacity, power rating, round-trip efficiency, shaft depth, and descent velocity—on the costs of both the mass blocks and the bottom chamber. The analysis investigated how the unit cost and density of various materials (concrete, scrap steel, mine tailings, and granite) affected these costs. Furthermore, it detailed how cost variations were correlated with the specific types and corresponding properties of concrete and mine tailings. The study also quantified the different degrees to which material unit cost and density impacted the costs of the mass blocks versus the bottom chamber.

Result The analysis reveals that for a given system configuration (i.e., fixed energy capacity, power rating, efficiency, shaft depth, and descent velocity), the material density of the mass blocks solely affects the cost of the bottom chamber, showing an inverse relationship. Conversely, the material's unit cost only influences the cost of the mass blocks themselves, exhibiting a linear correlation.

Conclusion The cost models developed for the mass blocks and the bottom chamber provide a valuable reference for the design, construction, and financial assessment of vertical shaft gravity energy storage systems.