Energy Vault to Develop 100 MW Hybrid Gravity Energy Storage System at Retired Coal Mine in Italy

Energy Vault Holdings, a developer of sustainable grid-scale energy storage solutions, and Carbosulcis, a coal mining company owned by the Autonomous Region of Sardinia, Italy, plan to develop a 100 MW hybrid gravity energy storage system (GESS) for underground mines, pairing their modular gravity storage and batteries. 

 

The energy storage solution to be deployed within 500-meter-deep mine shafts, along with the VaultOS proprietary energy management software, is essential for the Sardinia Government's target of converting the coal mine to a carbon-free technology hub for new industrial and technological activities.

 

The solution leverages Energy Vault EV0 gravity technology through a water-based, modular pumped hydro application. The proposed system combines pumped hydro energy storage technology with Energy Vault’s gravity energy storage technology to repurpose the site's underground features as a retired coal mine. 

 

“We are very excited about the innovative energy storage combined solution proposed by Energy Vault, including underground gravity energy storage technology, that we are testing together and that can become one of the solutions to support our project to convert our mine into a new Technology Hub. This project will maximize the local use of renewable energy and, at the same time, provide services that will improve the stability of the power grid in Sardinia,” said Francesco Lippi, CEO of Carbosulcis. 

EV0 is part of Energy Vault’s G-VAULT GESS portfolio. This is Energy Vault's second deployment of a hybrid energy storage system after the Calistoga PG&E project in northern California, the green microgrid, which pairs green hydrogen with lithium-ion batteries.

 

The solution is designed to enhance and benefit from the site's specific topology and the 500-meter-deep mine shafts. The companies have executed a land lease agreement. Installation of the first modular gravity components is set to begin in September 2024, and the testing of the underground component of the system is expected to be completed in 2025.

 

The proposed site would be wholly owned and operated by Energy Vault.

 

Carbosulcis’ Nuraxi Figus site, located on the island of Sardinia in Italy, will be retired by the end of 2026. The Sardinia regional Government aims to convert the site into a technology hub with minimal environmental impact. Moreover, the hybrid energy storage system will help stabilize the island’s power grid, with plans to dispatch renewable energy to help meet the high demand during peak load hours and boost local use of renewable generation in Sardinia.