How abandoned mines can be reused as gravity batteries

A new study proposes that abandoned mines can be reused as gravity batteries and store excess energy from renewable sources.

The study was led by the International Institute for Applied System Analysis (IIASA) and published in the “Energies” journal.

Furthermore, solar and wind power plants experience days where they produce more energy than the grid can use and the proposed solution for this comes through a technology called Underground Gravity Energy Storage (UGES).

UGES works by effectively raising sand containers, when excess energy is produced and thus price is low, and releasing those containers when extra energy is needed. This can be achieved through regenerative braking, which recovers braking energy from a slowing mass, and converts its kinetic energy into a form that can be immediately used or stored.

For this to be achieved, at least 300-meter-deep shafts are needed for the sand containers to fall effectively. Hence, abandoned mines are ideal for this use, as many of them already contain such shafts and are already connected to the power grid.

Also, according to Julian Hunt, lead author of the study and researcher with (IIASA), this technique could remediate the effects of a closing mine to the local community, as some jobs will still remain available in the new power storing facility.

Finally, it is noted that investing costs in UGES vary between 1-10 USD/KWh, while power capacity ones at 2 USD/KW and an estimated 7-70 TWh potential capacity exists worldwide.