Laurence Alexander - Chief Marketing Officer, Energy Vault
September 25th, 2024
On August 5, 2024, Energy Vault announced a 100MW Hybrid Gravity Energy Storage Project to Accelerate Carbon Free Technology Hub at Carbosulcis the Italy’s Largest Former Coal Mining Site in Sardinia.
Carbosulcis SpA is a company fully owned by the Autonomous Region of Sardinia. Since 2014 the company has been active in the Closure Plan for coal extraction activities. Nevertheless, the company inherited impressive infrastructures that were used to support the original mining activity. Such as, industrial assets and buildings for a volume of more than 200,000 m3, distributed on an area of above 200 hectares between the Seruci and the Nuraxi Figus sites, in addition to a network of underground tunnels for about 15 km at a depth that varies between 350 and 500 m below ground. These can be accessed through 4 vertical mine shafts with a depth up to 500 m and also through an inclined shaft, designed as a vehicle tunnel consisting of three sections of over 1 km each.
The 100MW energy storage system, preceded by a prototype already under construction, will be realized in successive phases and owned by Energy Vault, and if put in place, it could be of fundamental importance to increase the local use of renewable energy while accelerating the formation of the Renewable Energy Technology Hub.
Our EV0 solution has been designed for underground mines, pairing our modular gravity storage and batteries. This unique energy storage solution will be deployed within the 500-meter-deep mine shafts, along with the VaultOS™ proprietary energy management software.
Today I visited the Nuraxi Figus site with Mauro Pedretti, Luca Manzella, Gionatan Cattaneo, Gianmarco Zorloni, Greg Daily and Giovanni Frondoni to meet the Carbosulcis management and project team.
Both teams’ passion for the system was inspirational and motivational. I saw and felt what can be achieved through talented people coming together, thinking differently and driving innovation to effect real change, making a difference to communities and changing people’s lives.
This innovation and passion for change is what Energy Vault was founded upon, I do see examples of this every day, and this is why I joined Energy Vault at the start of its journey.
Today for me was a real inflection point, which has made me more focused to drive success.
Why changing people’s lives?
The Nuraxi Figus mine took 23 years to build at a cost of circa 1 billion Euros and at full production employed over 1000 people. In 2018 when the mine closed employment was reduced to 500 people, and today about 100 people are left.
In addition, the Hybrid Energy Storage System could contribute to stabilize the island’s power grid, with plans to dispatch renewable energy to help meet the high demand during peak load hours while encouraging further local use of renewable generation in Sardinia.
Thanks to the close collaboration and hospitality of Carbosulcis, with this industrial prototype, it is now possible to experiment directly within a mining infrastructure. The optimal conditions of the mine, the professionalism of Carbosulcis employees, the only ones capable of managing the work at -400 m under sea level, combined with our knowledge will soon lead to the installation of the prototype and its commissioning.
Project Progress
We are currently in the stage 1 of the project, installing the first full scale EV0 water trees, the modular water tanks designed, developed and tested by the Swiss team.
EV0 is based on the same principle of pumped hydro. Pumping water up to the higher tanks consumes electricity whereas letting the water flow down to the lower tanks spins the turbine which generates electricity. Our innovation lays in the idea to standardize pumped hydro designs decreasing the need of a perfect topography, geology and environment to contain water but to use cheap tanks instead. The use of cheap tanks, which moves the water in a closed loop, removes most of the problems which current pumped hydro deployments are facing. Additionally, the innovative tank systems can also enable deployment of pumped hydro systems in locations where traditional systems are not optimally fitting the topography and geology.
To validate our design and testing conducted in Switzerland, in collaboration with Carbosulcis, we will install two full scale tanks entirely manufactured in Italy. Each tank will have a capacity of 560 cubic meters and a diameter of approximately 11 meters. In this initial phase, we will replicate 30 years of operation by subjecting the membrane and ropes to rigorous stress testing. This will involve filling one of the tanks to capacity and using a pump to continuously circulate the water between the reservoir, simulating real-world conditions.
Following the successful completion of Phase 1, which includes also the full realization of a complete EV0 system, connecting the above ground tanks with the first underground one, via a penstock and a small scale power turbine , after receiving the relevant authorizations, we will expand the system to include an additional 38 tanks and the full scale power system. These 40 tanks will be located near pit number 2 of the mine and connected to the mine tunnels via a penstock. Large tensile-structure tanks will also be positioned within the tunnels.
In conjunction with the expanded tank system, we will implement an 80 MW short-duration storage battery. This battery will optimize the interconnection capabilities available at the mine site.
Global Innovation Importance
The system we have designed, and building is intended to become a show case to show the world what can be achieved. Our first chance to show this is to an international delegation of Interreg Europe on the 13th of November, and we are working with the government to organize minister meetings and showcase what we are buildin.g.
Our system has also caught the imagination of the Sardinian University. Luca & Gianmarco met with them today as they would like to partner with us asap on the project.
I want to personally thank everyone that has been involved in this project – you have excited and motivated me through your inspirational dedication and problem solver abilities to “Enable a Renewable World”.