This is how abandoned mines become energy stores

Researchers from Austria have developed a concept whereby the shaft of an abandoned mine can be transformed into a gravity battery. Such a system could both generate and store electricity.

With the energy transition we are facing new challenges. Because the sun is shining and the wind doesn’t always blow. At the same time, we need a solid level of security of supply. Otherwise, in the worst case, a local oversupply or undersupply could become reality. But how can sustainable forms of energy be sensibly stored?

Many researchers have already developed some interesting proposals. In addition to storage in classic batteries, there is even a battery that stores energy in CO2. Scientists from the Austrian International Institute for Applied Systems Analysis (IIASA) have now presented another approach.

Gravity Battery uses abandoned mining infrastructure

This in turn is based on a previous proposal to use elevators as battery storage. If there is an excess of energy, a normal elevator transports weights upwards. If we need electricity, the weights fall down again. The new approach works in a similar way, taking advantage of the abandoned mine infrastructure.

Because when mines are exhausted and all metals or rare earths are mined, the structures become orphaned. However, the mine shafts can be used as gravity batteries. If there is a surplus of energy, the shafts transport sand and soil to the surface. When power is needed, elevators bring the “charged dirt” back down.

Mines have enormous storage potential

This has several advantages. Some jobs could be retained in the mines to control the largely autonomous process. This requires automated conveyor belts and vehicles that are loaded and unloaded with soil, among other things.

According to the researchers, abandoned mines could already store seven to 70 terawatt hours of energy. Most gravity batteries, meanwhile, are located in China, India, Russia and the United States. But there is also great potential in opencast mining in western Germany, for example.

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