New pumped hydro gravity storage concept to be deployed at coal mine
Energy storage facility will provide power for new technology hub and also help stabilise grid in Italian island of Sardinia
A novel pumped hydro gravity storage system will be installed at what was once Italy’s largest coal mine, with the renewable energy it stores aimed at helping transform the area into a technology hub as it shifts away from the fossil fuel industry.
Energy Vault and coal mining company Carbosulcis, owned by the Sardinia regional government, have unveiled plans for the 20MW gravity-based system to be deployed in the 500-metre-deep mine shaft.
The gravity storage system at the coal mine will be paired with 80MW of lithium-ion batteries, which Energy Vault also specialises in.
The system uses a “unique and low-cost fabric vessel” Energy Vault calls the “Water Tree”.
This “modular pumped hydro” system would see water piped up from these water trees through tubes when there is excess renewable energy. The water would then be stored in other water trees at a greater elevation, ready for release and discharge when power is needed.
Installation of the first modular gravity components at the mine in Sardinia will take place next month, with testing of the underground component of the system expected to be completed next year.
The coal mine is set to be retired by the end of 2026 and the Sardinian regional government wants to convert it into a technology hub with minimum environmental impact.
The storage system is also aimed at stabilising the island’s power grid, dispatching green power to help meet the high demand during peak load hours and encouraging further local use of renewable generation in Sardinia.
“Energy storage is a critical component to better utilising renewable energy around-the-clock on the island of Sardinia,” said Carbosulcis CEO Francesco Lippi.
The partnership with Energy Vault is a “vital step” in developing the technology hub, which he said is intended to promote innovation while “strengthening the concept of ‘smart transition’ to renewable energy” in an area that has been “heavily affected by the exit from fossil fuels, like coal.”
Marco Terruzin, chief commercial and product officer at Energy Vault, said this new use of the developer’s gravity energy storage technology – deploying it underground – could hold “vast potential for future applications.”
“We see a future where our technology helps power the world with renewables,” he said, “Whether it’s on an island in Italy, by a wind farm near Shanghai, China, providing backup power for a town in California, or supporting the grid in Texas.”
Its technology has so far proved particularly popular in China, where it commissioned a “world first” system last year, with a large pipeline of other projects also announced.
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