Repurposed underground mines could store enough energy to power “the whole earth” for a day, new research suggests.
During the good weather conditions, wind and solar often generate more energy than a grid can use. So where can we store this excess energy?
According to scientists at the International Institute for Applied Systems Analysis (IIASA), abandoned mines could provide a solution.
They claim that the breakthrough has been deactivated mines in vast “gravity batteries” they could provide up to 70 terawatts of energy storage. This is enough to satisfy the whole world daily electricity consumption.
“To decarbonise the economy, we need to rethink the energy system based on innovative solutions that use existing resources,” urges Behnam Zakeri, study co-author and IIASA program researcher on energy, climate and the environment.
“Coming back abandoned mines in energy storage is one example of the many solutions that exist all around us and we just need to change the way we implement them.”
How do gravitational batteries work?
Most of the batteries we use in everyday life store energy through electrochemical processes. It will release a particular chemical reaction powerwhich can then be used.
Gravity batteries, on the other hand, are mechanical gizmos.
There are many different versions of this type of battery. The simplest – and oldest – is a form of grandfather clock powered by gravity.
The most common type in use today is pumped storage hydroelectricity. This is where water is pumped to higher elevations to store energy and released through turbines to generate electricity. Pump storage is very common, with a total installed storage rating of 1.6 terawatt hours.
The proposed gravity system in the mines has a global energy capacity potential of seven to 70 TWh, say the IAASA researchers in the paper, published in Energies.
How would a gravity battery work in a mine?
The Underground Gravity Energy Storage (UGES) model proposed by IIASA researchers uses existing elevators to raise and lower sand-filled containers.
Mines are suitable for this batteries. This is because they already have deep shafts that could be used to drop a weight. Gravity batteries require at least 300 meters of drop clearance to function properly.
Building these projects could help generate income in impoverished conditions mining communities even, say the researchers.
“When a mine closes, it lays off thousands of workers. This devastates communities that depend only on the mine for their economic output. UGES would create some vacancies as the mine would supply energy storage services after disruption of operations,” says Julian Hunt, IIASA program researcher for energy, climate and the environment and lead author of the study.
“The mines already have the basic infrastructure and are connected to the electricity grid, which significantly reduces costs and facilitates the implementation of UGES plants.”