Researchers have developed a way to utilize abandoned underground mines as gravity based energy storage solutions.
Renewable energy sources are the only energy sources that we can look forward to meet our daily power requirements. Almost everything around us works on some kind of energy. A novel technique called Underground Gravity Energy Storage turns decommissioned mines into long-term energy storage solutions, thereby supporting the sustainable energy transition.
an international team of researchers has developed a novel way to store energy by transporting sand into abandoned underground mines. The new technique, called Underground Gravity Energy Storage (UGES), proposes an effective long-term energy storage solution while also making use of now-defunct mining sites, which likely number in the millions globally.
The UGES system generates electricity when the price is high by lowering sand into an underground mine and converting the potential energy of the sand into electricity via regenerative braking, and then lifting the sand from the mine to an upper reservoir using electric motors to store energy when electricity is cheap. The main components of UGES are the shaft, motor/generator, upper and lower storage sites, and mining equipment. The deeper and broader the mineshaft, the more power can be extracted from the plant, and the larger the mine, the higher the plant’s energy storage capacity.
Unlike other storage systems, which lose energy via self-discharge over long periods, there is no energy lost to self-discharge, enabling ultra-long time energy storage ranging from weeks to several years.
Mines on the other hand already have the basic infrastructure and are connected to the power grid, which significantly reduces the cost and facilitates the implementation of UGES plants. The investment costs of UGES are about 1 to 10 USD/kWh and power capacity costs are about 2 USD/kW. The technology is estimated to have a global potential of 7 to 70 TWh, with most of this potential concentrated in China, India, Russia, and the U.S.
Turning abandoned mines into energy storage is one example of many solutions that exist around us, and can be enabled by changing the way we deploy them.
Reference : Julian David Hunt et al, Underground Gravity Energy Storage: A Solution for Long-Term Energy Storage, Energies (2023). DOI: 10.3390/en16020825