The invention of “gravity” technology to turn mines into giant energy batteries

In recent years, energy storage has gained interest among energy industry players. It effectively makes it possible to secure the frequency of the power grid by balancing consumption and generation. It is also a means of compensating for the variability of solar power and pinwheel. For these reasons, many storage solutions are being studied. International researchers recently published their research results on the invention ofa new storage method for exploiting abandoned mine shafts. These sites, which researchers say number in the millions worldwide, actually have an interesting storage potential that deserves to be explored. They also estimate that the global potential is 7 to 70 TWh. Your system is called “Underground Gravity Storage” or UGES, meaning “Gravity Underground Storage”.

A regenerative braking system

UGES is a type of gravity storage. Basically, this system consists of releasing a heavy load. It falls by gravity and generates electricity as it falls. UGES is based on this technology. The idea is to use elevators to move sand through the mine shafts. Researchers apply a regenerative braking system to it to generate electricity. As a matter of fact, Kinetic energy that is lost when braking can be converted into electricity, which is deployed during peak network usage. Some of the electricity generated is then used to run the elevators up the shaft.

An optimized system

In order to optimize energy production, the cabins are filled with sand when leaving. Arriving at the bottom of the well, they are unloaded so that they can be brought up as easily as possible. When deflated, the elevators require less energy to regain altitude. This results in cavities at the bottom of the indentations storage for sand.

Gravity storage is a technology that uses gravity to store electrical energy. For this purpose, masses that can be raised and lowered are used to store mechanical energy, which can then be converted into electricity if required. Photo credit: Hunt et al.

Obviously storage areas are likely to fill up over time. To avoid this, the elevators still transport sand to the top, but only at certain times and thanks to the current of the net. This scenario is carried out in times of overproduction of electricity, where prices are lowest. Underground trucks drive to the bottom of the shafts to load and unload the elevators.

Gravity energy storage is an efficient way to store electrical energy on a large scale, but it requires expensive equipment and large storage areas.
Gravity energy storage is an efficient way to store electrical energy on a large scale, but it requires expensive equipment and large storage areas. Illustrative photo not contractual. Photo credit: Shutterstock

A more efficient alternative to the lithium-ion battery

the huge batteries are one of the most popular storage solutions today. However, they lose energy over long periods of time through self-discharge. This is an almost nonexistent disadvantage with UGES. Since the sand is the heart of the system, no energy is lost through self-discharge. This means that data can be stored for a very long time, up to several years. Added to this are the investment costs for underground storage are only rated at 1 to 10 USD/kWh the infrastructure is already “ready”. Also, huge batteries like Tesla’s Megapacks cost up to several hundred dollars per kilowatt-hour. More information : dx.doi.org

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