When a mine runs out of its ore, it can no longer be used. It simply becomes an abandoned hole in the ground. But new research suggests that such mine shafts could act as gravitational batteries to store energy.
What is a gravity battery?
In short, it is a system that generates electricity by releasing a heavy load and letting it fall. That power can be used when the demand on the municipal grid is high.at other times, when excess Depending on the energy in the grid, the gravity battery system uses some of that energy to lift the load, effectively storing the energy for later use.
One of the most common types of this technology is what is known as a pumped storage hydroelectric system. In this setup, water is released from a height and spins turbines as it flows downhill to generate electricity. When excess energy becomes available, that water is returned to the starting point.
Last year, scientists at the International Institute for Applied Systems Analysis (IIASA) in Austria proposed a different type of gravity battery. The basic idea was that a tall building elevator would use a regenerative braking system to generate electricity and lower a weighted payload from a higher floor to a lower floor. Autonomous trailer robots move cargo in and out of elevators as needed.
This leads to a mine-based underground gravity energy storage (UGES) system recently proposed by the same researchers. Elevators are used as well, but these are located in existing abandoned mines to raise and lower sand-filled containers.
Hunt et al.
A series of electric motor/generator units on either side of the shaft move each elevator up and down, generating electricity via regenerative braking on descent and using some of that power on ascent.
For maximum efficiency, the elevator can take on a sand load at the ground surface, remove it at the bottom of the shaft, and then return to the empty ground surface. Needless to say, in this scenario, the storage he area at the bottom of the shaft will eventually fill up with sand. Because of this, if there was excess energy in the grid, the elevator had to push some of the sand back to the top surface. A combination of electric belt conveyors and dump trucks is used for loading and unloading.
Scientists estimate that UGES could have a global energy storage potential of 7 to 70 TWh (terawatt hours). Most of the plants are located in countries that already have many abandoned mines, such as China, India and Russia. we.
“Thousands of workers will be laid off when the mines close. […] UGES will create some vacancies as the mine provides energy storage services after it ceases operations,” said IIASA’s Julian Hunt, lead author of a paper on the study. Significantly reduce costs and facilitate the introduction of UGES plants. ”
The paper was recently published in the journal energy.
Source: IIASA
