A method to store excess renewable energy, reuse abandoned mines and create jobs.
Because it matters: Gravity batteries are a potential candidate for storing excess renewable energy, but finding places to install them is quite a challenge. Researchers have proposed that abandoned mines around the world could be a cost-effective solution that could also create jobs.
A study by the International Institute for Applied Systems Analysis (IIASA) suggests reuse abandoned mines to install gravity batteries. Upgrading old mines could provide enough energy to match the daily electricity consumption of the entire planet.
Gravity batteries try to solve one of the main problems of renewable energies, such as wind and solar: store excess energy. Wind and solar often generate more energy than a grid can immediately use, so power companies must store the excess, usually in batteries.
Methods like the IIASA experiment use this extra energy to lift heavy objects. When power is needed again, weight is released, which spins a turbine and converts kinetic energy into gravity.
In theory, gravity batteries can be anything with a lot of weight, like water or solid objects. In the IIASA study, sand was lowered and lifted in abandoned mine shafts, moving it back and forth between the upper and lower chambers based on energy requirements.
Another advantage of the process is that although the batteries tend to self-discharge over time, gradually losing the stored energy, the gravitational method stores energy in sand (or anything lifted to take advantage of gravity), which does not self-discharge.
IIASA proposes to use abandoned mines because it is likely that there are already millions around the planet that could be converted relatively inexpensively for this purpose. Most have basic infrastructure and are connected to the electricity grid.
Researchers believe that after a investment cost of about $1-10 per kilowatt hour and a cost of $2,000 per kilowatt of electrical capacityhis method could have a worldwide potential of 7 to 70 terawatt hours.
According to the International Energy Association, global energy consumption in 2020, the last year on record, was 24,901.4 terawatt hours, which is equivalent to about 68 terawatt hours per day.
In addition, the operation of gravity batteries in abandoned mines could restore or preserve some of the jobs lost with the closure of these mines.