By Macy Dennon
Once workers clear a mine of all things valuable or desired, the next step often involves shutting down the site. In a new IIASA-led study, published on Jan. 11, researchers and scientists discovered a way to turn those mines into energy generators, using an apparatus called a gravity battery.
A gravity battery is a type of energy storage system that uses gravitational force to store and release energy. It typically consists of a large weight, such as a concrete block, suspended by cables or ropes. The weight is raised to a certain height using electricity, and when energy is needed, the mechanism allows the weight to fall, turning a generator to produce electricity. A pulley system then lifts the weight to a higher elevation, storing potential energy so the process can repeat. There has not been much use of this technology, which is still in its infancy.
Gravity batteries are simple and have few moving parts, which makes them durable and low-maintenance. The recent proposal suggests using old abandoned mines, as they have enough space for the battery to comfortably operate. Researchers proposed a different type of gravity battery generating system called Underground Gravity Energy Storage System (UGES).
New Atlas, a science and technology news website, explains the new system, noting, “The basic idea was that the elevators in high-rise buildings would use regenerative braking systems to generate electricity while lowering weighted payloads from higher to lower floors. Autonomous trailer robots would pull the loads in and out of the elevators, as needed.” The issue with this idea is that sand would end up pilling up at the bottom of the mines, causing them to fill up. Utilizing the excess energy would allow buckets of sand to be lifted back up to the surface.
A study published online in the journal Energies estimates that the “UGES could have a global energy storage potential of 7 to 70 TWh (terawatt hours), with most of the plants being located in countries where there are already a lot of abandoned mines, such as China, India, Russia and the US.”
Julian Hunt, a researcher in the IIASA Energy, Climate, and Environment Program and the lead author of the study, said, “when a mine closes, it lays off thousands of workers. This devastates communities that rely only on the mine for their economic output. UGES would create a few vacancies as the mine would provide energy storage services after it stops operations,”he continued, “mines already have the basic infrastructure and are connected to the power grid, which significantly reduces the cost and facilitates the implementation of UGES plants.”
Though this is just a proposal, the advancement could lead to a prosperous future. Behnam Zakeri, study co-author and a researcher in the IIASA Program, concluded, “To decarbonize the economy, we need to rethink the energy system based on innovative solutions using existing resources. Turning abandoned mines into energy storage is one example of many solutions that exist around us, and we only need to change the way we deploy them.”
(Sources: IIASA, MDPI, New Atlas, Interesting Engineering)