Underground Gravity Storage Using Buoyant Cylinders and Pistons
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Solution Overview
Problem
There is a need for large-scale, cost-effective electric energy storage facilities that can be easily constructed at various sites without geographical constraints, such as mines or suitable topography, and can provide medium to long-term energy storage without energy dissipation.
Innovation Solution
A modular cylindrical structure with a vertical orientation, using either a solid mass or buoyant piston, supported in a buoyant, semi-buoyant, or fixed system, which can be constructed at onshore or offshore sites, utilizing steel, concrete, or composite materials, and incorporating pipes and pumps to store and release energy through regenerative loading.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Duration of action of moving object
If chemical batteries are used for short term storage, then energy storage capability is improved, but energy loss increases over time
Solution Approach 1:
The patent replaces chemical battery systems with a mechanical gravity-based energy storage system. A mass is lifted vertically using electrical energy during charging and lowered during discharging to generate electricity through regenerative braking, substituting chemical energy storage with mechanical potential energy storage to eliminate chemical energy dissipation losses
Solution Approach 2:
The system operates through periodic cycles of lifting the mass during energy charging and lowering the mass during energy discharging. This periodic mechanical action allows the system to store energy by raising the mass to a higher elevation and release energy by lowering it, enabling multiple charge-discharge cycles without energy dissipation
2Quantity of substance
If hydro-storage is used for long term storage, then energy storage capacity is improved, but geographical constraints increase
Solution Approach 1:
The patent transitions from horizontal geographical expansion (hydro-storage requiring specific topography and water bodies) to vertical dimension utilization. By lifting and lowering a mass vertically within a confined space, the system achieves large energy storage capacity without being constrained by geographical features, enabling deployment in diverse locations including urban environments
Solution Approach 2:
The system changes the fundamental parameters of energy storage by using gravitational potential energy (mass × height × gravity) instead of water volume and elevation differences. This parameter change allows the system to achieve comparable energy storage capacity to hydro-storage while being adaptable to various site locations without requiring specific geographical conditions
3Speed
If gravity energy storage is implemented, then response time is improved, but storage scale is limited
Solution Approach 1:
The patent employs a nested structure where a large mass is contained within a vertical shaft or building structure. The mass itself can be segmented into multiple components that are stacked or arranged vertically, allowing the system to achieve both rapid response time through direct gravitational action and large storage scale by increasing the mass or height within the nested configuration
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution achieves high energy efficiency (85-90%) and cost-effectiveness by minimizing material demand and friction losses, allowing for uniform and peak electric energy supply to the grid, with scalability from tens to thousands of MW-hr capacity.
Implementation Method 1
The energy stored by raising the mass and then released by lowering the mass is a product of the mass, the height lifted and the gravitational acceleration constant
Implementation Method 2
The cylindrical structure is supported in a buoyant, semi buoyant or fixed system
Data Source
AI summary
Underground facilities built for storing electric energy in the form of gravity and buoyant energy are described herein. In one embodiment, the facility is disposed in a thixotropic fluid beneath the ground surface and houses water to maintain a positive buoyancy and a piston having a bulk density greater than the water. In another embodiment, the underground facility is configured as a buoyant capsule arranged in a cylinder filled with water, where the cylinder is sealed except for openings in a bottom half of the cylinder to allow near unimpeded water flow from a location inside to a location outside of the cylinder. In another embodiment, the underground facility is configured as a negatively buoyant capsule.