Mass Block Stacking Strategy for Efficiency Enhancement of Gravity Energy Storage Systems

Abstract

INTRODUCTION: Gravity energy storage systems (GESS) have gained increasing attention because they are less constrained by geography and natural resources, offer flexible capacity expansion, and suit large-scale, long-life, and high-safety applications. However, the growing penetration of intermittent renewable energy increases dispatch frequency and start–stop cycles, making the energy consumption of the stacking (mass-block handling) process a critical factor affecting overall efficiency and cost.

OBJECTIVES: This paper aims to reduce the energy consumption of mass-block stacking operations in GESS, thereby improving system efficiency and supporting the integration of high shares of renewable energy in smart grids.

METHODS: A stacking-zone layout for GESS is designed first. Under given charging/discharging conditions, a nearest-neighbor algorithm is developed to minimize the transporter’s energy consumption. For additional (dynamic) charging/discharging conditions, a greedy algorithm with penalty terms is proposed to obtain a low-energy stacking strategy. Case studies are conducted for stacking 100–200 mass blocks (MBs) under given conditions and adding 10–50 MBs under additional conditions of 120 and 150 MBs.

RESULTS: In the simulation cases, compared with the traditional method, the proposed strategy achieves an average energy-saving rate of 25.78% under the given discharge condition. Under additional discharge conditions, the average energy-saving rates are 20.85% (based on 120 MBs) and 16.8% (based on 150 MBs).

CONCLUSION: The proposed stacking-zone design and energy-optimized scheduling strategies effectively reduce stacking energy consumption and enhance the operational efficiency of GESS in grids with intermittent and fluctuating renewable generation, offering a useful reference for future gravity energy storage stacking-system development.