Energy Solutions — Gravity Batteries?

Abandoned mines could be a solution to the world's growing energy storage needs. Gravity batteries, also known as pumped hydroelectric energy storage (PHES), use the Earth's gravity to store energy. When there is excess energy, such as from solar or wind power, water is pumped uphill into a reservoir. When there is a demand for energy, the water is released downhill, spinning turbines to generate electricity.

PHES is a proven technology that has been used for decades. There are currently over 200 PHES facilities in the world, with a total capacity of over 200 gigawatts (GW). However, PHES facilities are typically located in remote areas, away from the centres of energy demand.

Abandoned mines could provide a solution to this problem. Mines are already located in areas with high energy demand, and they have the infrastructure in place to store large amounts of water. In addition, mines are already well-connected to the grid.

A study by the International Institute for Applied Systems Analysis (IIASA) found that using abandoned mines for PHES could provide up to 70 terawatts (TWh) of energy storage capacity. This is enough to meet the world's daily electricity demand for several days.

The use of abandoned mines for PHES would have a number of benefits. It would help to reduce the amount of energy that is lost when excess renewable…