A Gravity-Based Energy Storage System Using Buoyancy-Assisted Mass Repositioning

Abstract

Gravity-based energy storage systems store energy by elevating a mass and releasing it to generate power. A key limitation of such systems is the energy required to reset the mass to its elevated position after discharge. This paper proposes a novel canal-lift-assisted gravity battery that employs buoyancy and gravity-driven water transfer, inspired by ship canal lock mechanisms, to reduce the effective energy required for mass lifting. The system utilizes a two-chamber configuration in which a buoyant block is lifted by controlled water filling rather than direct mechanical hoisting. Water is transferred between chambers using gravity-fed channels and valves, while the mass drop phase generates electricity through a turbine. Analytical reasoning shows that although the system does not eliminate energy input, it significantly reduces peak mechanical lifting power and improves operational flexibility.

Introduction

The growing reliance on renewable energy sources like solar and wind has increased the need for efficient, scalable energy storage systems. Traditional electrochemical batteries face limitations in cost, degradation, and environmental impact, while gravity-based energy storage—storing energy by elevating a mass and releasing it to drive a generator—offers long lifetimes and minimal material wear. However, conventional gravity batteries require high-power mechanical lifting to reset the mass, resulting in peak energy demand, mechanical complexity, and operational inefficiency.

This work proposes a canal-lift-assisted gravity battery, which combines buoyancy-assisted lifting, gravity-driven water transfer, and controlled descent to reduce the effective energy required for mass resetting. Inspired by ship canal locks, the system lifts a buoyant mass using water-level manipulation rather than direct mechanical lifting, while energy generation occurs via controlled gravitational descent through a rope–pulley–gearbox–generator assembly. A jib crane is used only for low-energy lateral positioning at the water surface, not for vertical lifting.

Key Components and Design:

• Gravity Mass: Single block with ballast and passive buoyancy, constrained to vertical motion by guide rails.

• Water Column: Sealed chamber for buoyancy-assisted lifting; controlled water filling/draining is only needed for reset or maintenance.

• Mechanical PTO Assembly: Converts descent motion to electrical energy via a gearbox and generator with clutch and braking system for controlled operation.

• Crane: Auxiliary, low-energy positioning device at the water surface.

• Safety Measures: Braking, controlled clutch engagement, and mechanical guidance ensure smooth, safe, and repeatable cycles.

Working Principle:

1. Buoyancy-Assisted Lifting: Mass rises in the water column without mechanical actuation.

2. Surface Positioning: Crane laterally aligns the mass for connection to the PTO system.

3. Engagement and Holding: Mass is connected to the generator system; braking/clutch prevents shock loads.

4. Controlled Descent: Mass descends under gravity, generating electricity via the generator; speed is regulated.

5. Stop and Reset: Braking stops the mass at the bottom; the cycle is ready to repeat without emptying the water column.

Advantages:

• Reduces peak mechanical power demand.

• Minimizes mechanical stress and complexity.

• Provides safe, repeatable, and energy-efficient operation.

• Integrates principles from gravity batteries, buoyancy-assisted lifting, and canal-lock mechanisms.

Conclusion

This study presented a conceptual design and analytical assessment of a canal-lift assisted gravity battery that combines controlled gravitational descent with buoyancy-assisted mass repositioning. The proposed system employs a single gravity mass, a permanently filled water column, and a mechanically controlled power take-off assembly to store and release energy in a safe and regulated manner. Unlike conventional gravity-based storage systems that rely on direct mechanical lifting, the proposed approach reduces auxiliary energy input by utilizing buoyant forces to assist mass lifting during the reset phase. The inclusion of controlled engagement mechanisms, fail-safe braking, and guide rails ensures stable operation, predictable power output, and mechanical safety throughout repeated operating cycles. Importantly, the system adheres strictly to energy conservation principles and does not depend on cyclic emptying of the water column or pumped-hydro behavior. Analytical evaluation demonstrates that the energy output of the system is governed by the gravitational potential energy of the mass, while auxiliary energy consumption is minimized through buoyancy-assisted handling and limited crane usage at the water surface. Although the system exhibits lower energy density compared to electrochemical storage technologies, it offers advantages in terms of durability, scalability, mechanical simplicity, and long service life. Overall, the proposed canal-lift assisted gravity battery represents a mechanically robust and conceptually sound approach to large-scale energy storage, particularly suited for industrial and grid-support applications where long-term reliability and safety are critical considerations.

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Copyright

Copyright © 2026 Aakash Sandhanshiv, Pratik Suralkar, Akshaya Dani. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.