Decommissioned mines might be used to power gravity batteries, according to a study by the International Institute for Applied Systems Analysis (IIASA). Old mines could be converted to produce enough energy to meet the world’s daily electricity needs.
One of the main issues with renewable energy sources like solar and wind is how to store extra energy. Gravity batteries aim to address this issue. Wind and solar farms often provide more energy than a grid can immediately use, so power companies must store the excess, typically in batteries.
That extra energy can be used to lift heavy objects as shown in the IIASA experiment. The weight is then dropped when the energy is required once more, spinning a turbine and converting the kinetic energy from gravity.
Gravity batteries might theoretically be anything heavy, such as liquid or solid substances. The sand was moved back and forth between upper and lower chambers in abandoned mine shafts as part of the IIASA study based on energy requirements. The fact that the energy is held in the sand (or whatever material is raised to harness gravity) rather than a battery, which tends to self-discharge over time and lose its stored energy, is another benefit of the technique.
Since there are probably millions of abandoned mines on the Earth that might be quite inexpensively adapted for this purpose, the IIASA suggests exploiting them. The majority are already wired into the electricity grid and have the basic infrastructure for the job.
The researchers predict that this technology might produce 7–70 terawatt-hours globally after an initial investment cost of $1–10 per kilowatt-hour and a cost of $2,000 per kilowatt of power capacity. The International Energy Association estimates that the total amount of energy consumed worldwide in 2020, the most recent year for which data is available, was 24,901.4 terawatt-hours, or almost 68 terawatt-hours per day.
Additionally, running gravity batteries in retired mines could bring back or keep some of the jobs that were lost when those mines closed.
