Analytical and quantitative assessment of capital expenditures for construction of an aboveground suspended weight energy storage

Abstract

The capital expenditures to energy capacity ratio (capex) stands as a key competitive metric for energy storage systems. This paper presents an evaluation of this indicator for an aboveground suspended weight energy storage system. For the first time, an analytical foundational correlation was found between capital expenditures of gravity energy storage, its energy capacity, and storage power. The correlation reveals that capex can be expressed as the sum of three components: one inversely proportional to discharge duration, another inversely proportional to the square root of energy capacity, and a constant term. By using established construction and power element prices the study demonstrates that capex can be reduced to less than 600 $/kW·h for discharge durations of 4 h or more, and can decrease to nearly 450 $/kW·h for a 10-h discharge duration. Employing the computed capex an evaluation of the total cost of ownership was conducted and juxtaposed with lithium-ion energy storage. The gains from adopting gravity technology become significant starting from the initial replacement of degraded Li-ion batteries. This scenario results in nearly a twofold savings in the ownership cost of gravity energy storage system over a 20-year operational span with further prospects for enhanced economic benefits.