The use of renewable energy sources such as wind and solar has become increasingly popular in recent years, but one of the major challenges with these energy sources is finding a way to store the excess energy that is generated. Gravity batteries have been proposed as a potential solution to this problem, but finding suitable locations to install them can be a challenge. A new study from the International Institute for Applied Systems Analysis (IIASA) suggests that abandoned mines could be repurposed to operate as gravity batteries, providing a cost-effective solution that may also provide jobs.
Gravity batteries work by using the excess energy generated by wind and solar to lift heavy objects. When the energy is needed again, the weight is dropped, which spins a turbine and converts the kinetic energy from gravity into electricity. Theoretically, gravity batteries can be anything with a lot of weight, such as water or solid objects. The IIASA study used sand in abandoned mine shafts, moving it back and forth between upper and lower chambers based on energy needs.
One of the major advantages of the gravity battery method is that it does not suffer from self-discharge over time, unlike traditional batteries. The energy is stored in the sand (or whatever else is lifted to harness gravity) which does not lose its stored energy over time. This means that gravity batteries have the potential to be a more efficient and long-lasting solution than traditional batteries.
Abandoned mines were chosen as the location for these gravity batteries because there are already millions of them across the planet that could be relatively cheaply converted for this purpose. Most contain the basic infrastructure for the job and are already connected to the power grid. The researchers estimate that after a roughly $1-10 per kilowatt-hour investment cost and a $2,000 per kilowatt power capacity cost, their method could have a global potential of 7-70 terawatt-hours. According to the International Energy Association, global energy consumption for 2020 – the most recent year on record – totaled 24,901.4 terawatt-hours, which divides into about 68 terawatt-hours per day.
Furthermore, operating gravity batteries in abandoned mines could restore or preserve some of the jobs lost when those mines closed. This not only provides employment opportunities for people in areas where mines have closed, but also helps to revitalize these communities.
Overall, the study from IIASA suggests that abandoned mines could be a viable solution for storing excess renewable energy, and could have a significant impact on the global energy supply. The use of gravity batteries in abandoned mines may not only provide a sustainable energy solution but also provide jobs and help revitalize communities.