Abandoned mines could find new use as gravity batteries | The scientists behind a new study estimate that, worldwide, there are likely millions of disused mines suitable for energy storage
https://newatlas.com/energy/old-mine-shafts-gravity-batteries/
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From the article: Just because a mine has been exhausted of its ore, that doesn’t necessarily mean it has no value. A 2023 study suggests that the shafts of such abandoned mines could serve as energy-storing gravity batteries.
First of all, just what is a gravity battery?
Well, in a nutshell, it’s a system in which electricity is generated by releasing a heavy load, allowing it to drop. That electricity can then be used at times when demands on the municipal grid are high. At other times, when there’s excess energy in the grid, the gravity battery system uses some of that energy to pull the load back up, effectively storing the energy for later use.
One of the most common types of the technology is what’s known as a pumped-storage hydroelectric system. In this setup, water is released from a high elevation, generating electricity by spinning up turbines as it flows downhill. When excess energy is available, that water is pumped back up to the starting point.
In 2022, scientists from Austria’s International Institute of Applied Systems Analysis (IIASA) proposed a different type of gravity battery. The basic idea was that the elevators in high-rise buildings would use regenerative braking systems to generate electricity while lowering weighted payloads from higher to lower floors. Autonomous trailer robots would pull the loads in and out of the elevators, as needed.
That brings us to the mine-based Underground Gravity Energy Storage (UGES) system, proposed by the same researchers. It would likewise utilize elevators, but these ones would be in existing disused mine shafts, and they’d be raising and lowering containers full of sand.
As I understand it, the problem with mines is that they’re inherently unstable. These mine shafts aren’t suited for this purpose without some serious overhauling and shoring up to make safe and reliable. You would effectively have to drill, build, and maintain, a larger hole around the shaft, and at that point, it’s probably easier to just drill a new, fresh hole.
Gravity batteries are a nice idea, but water batteries are infinitely easier to create out of old reservoirs.
Isn’t this one of those “*sounds nice but not actually practical*” ideas like the one that was going to use cranes to stack blocks?
Compared to pumped hydro which can store [millions of tonnes of water](https://en.wikipedia.org/wiki/Marchlyn_Mawr), you’re going to struggle to get anywhere close to those moving weights up & down.
But mines aren’t generally located where we need the power most. So there’s a lot of cost running transmission lines to remote mountain areas.