Scientists estimate that there are millions of abandoned mines worldwide that can be utilized to create energy storage systems. Abandoned mines are those that have been left behind after extraction, and they can be safely and effectively used for energy storage.
Once a mine has been depleted of ore, it is essentially rendered useless. It becomes merely a hole left in the ground. However, recent studies suggest that the shafts of these mines could serve as the basis for gravity battery systems to store energy.
A coal mine in western Virginia, USA – (Photo: THE ATLANTA – JOURNAL CONSTITUTION).
The stored electricity could be used during periods of high electricity demand. At times of surplus energy in the grid, the gravity battery system would pull back the excess energy for storage, intended for use when necessary.
One of the most popular types of technology is called the pumped hydro storage system. Water flows from a high elevation, generating electricity by turning turbines as it descends. When there is surplus energy, that water is pumped back to the starting point.
In 2022, scientists from the International Institute for Applied Systems Analysis (IIASA) in Austria proposed a different kind of gravity battery.
The basic idea is that elevators in high-rise buildings would use regenerative braking systems to generate electricity while lowering loads from higher floors to lower ones. Automated towing robots would move loads in and out of the elevators as needed.
Recently, researchers from IIASA announced the Underground Gravity Energy Storage (UGES) system based on mines.
This system would also utilize elevators. However, these elevators would be located in abandoned mines, lifting and lowering containers filled with sand.
A series of generator motors on both sides of the shaft would move each elevator up and down, generating electricity through regenerative braking on the way.
Scientists estimate that UGES could have a global energy storage potential ranging from 7 to 70 TWh (terawatt-hours).
“When a mine closes, thousands of workers are laid off. UGES will rehire some positions to support the energy storage facility,” said Julian Hunt from IIASA, the lead author of the study published in the journal Energies.
Abandoned mines have existing infrastructure and connections to the grid, significantly reducing costs. At the same time, they facilitate the deployment of UGES plants.
