Energy Vault and Carbosulcis, a coal mining company owned by the local government in Sardinia, have signed an agreement to deploy a project combining gravity energy storage and BESS technology.

The two companies are to develop a 100 MW ‘Hybrid Gravity Energy Storage System’, a solution that Energy Vault has designed for deployment in underground mines. It combines its proprietary gravity energy storage technology and battery energy storage system (BESS) technology, and would be deployed in a large coal mine shaft, named Nuraxi Figus, that Carbosulcis is to retire in 2026.

Carbosulcis is owned by the Autonomous Region of Sardinia, whose government wants to turn the coal mine into a carbon-free Technology Hub to aid the industrial and economic development of an area heavily affected by the phase-out of coal production.

The solution would comprise a form factor of Energy Vault’s gravity technology that is to be combined with a modular pumped hydro application and controlled by the company’s energy management software.

Installation of the first modular gravity components will begin in September 2024 with testing of the underground component of the Hybrid ESS expected to be completed in 2025. The company has commissioned several projects recently, including a BESS in Texas and its first gravity storage project in China.