The energy of the future is in rocks

The energy of the future is in rocks

Building a completely sustainable thermal energy storage system that can accelerate the energy transition and foster Italy’s energy independence: that’s our goal with Thermal Energy Storage (TES). The project, which we carried out in collaboration with Israeli startup Brenmiller Energy, was inaugurated on November 4 at the Santa Barbara plant in the province of Arezzo. It’s an innovative system that for the first time allows the plant to store energy on an industrial scale.                                

Four years of work have turned a simple yet visionary idea into reality, leveraging a very common material: rocks. Brenmiller Energy developed the necessary technology in Israel and supplied the storage system, which was later integrated in our Santa Barbara plant in Cavriglia, which helped to test its performance in the field, at scale and under operational conditions.

“With this project, once again, we’re bringing excellent people, ideas and investments to Italy,” stated Luca Solfaroli Camillocci, Head of Enel Green Power and Thermal Generation Italia. “It’s not by chance that all of this takes place in Tuscany, where we’re present throughout the energy value chain and where we’re now taking a step forward, with a new solution to accelerate the energy transition.”

“This experimentation,” added Salvatore Bernabei, CEO of Enel Green Power and Head of Thermal Generation, “allows us to test a family of innovative and sustainable technologies in the area of long-term storage, which will enable ever-increasing integration of renewable sources in the grid.”

Indeed, TES can lead to shorter startup times for the Santa Barbara thermal plant and allow for faster load variations, which are required to increase the penetration of renewables. Decarbonization entails a need to guarantee systems’ flexibility and adequacy, and storage solutions will take on an increasingly central role as we progress along this path.


The technology 

The technology behind TES is an example of excellence because of its easy-to-find material and for its linear process, which is made up of a charge phase and a discharge phase to supply thermal energy. The system is composed of structures that contain rocks, assembled one next to the other and connected mechanically with a hydraulic pipeline. During the charge phase, the heat generated by the Santa Barbara plant runs through tubes immersed in crushed rocks in the form of steam, warming them up; during the discharge phase, the heat accumulated by the rocks is released to warm up pressurized water and generate steam to turn a turbine to produce electricity. The TES system is capable of storing up to 24 MWh of clean heat at a temperature of 550°C for at least 5 hours, guaranteeing the plant’s resiliency and flexibility.       

“This type of storage is an exercise in Italy’s freedom and independence,” said Ernesto Ciorra, Chief Innovability® Officer, “because it can be set up using rocks that are available everywhere on the planet, making it scalable in a sustainable way, anywhere.”

“It’s a simple technology,” explained Nicola Rossi, Head of Innovation at Enel Green Power and Thermal Generation. “It won’t age with time, it has no moving parts, it’s not flammable, it doesn’t contain reactive materials and – unlike batteries – it doesn’t use rare earth elements that can be sourced only from certain countries.”


Sustainable collaborations for the local territory 

The partnership between our Group and Brenmiller began as part of an Italian-Israeli protocol for collaboration designed to intensify the relationships between Israeli companies and major Italian industries. According to Avi Brenmiller, President and CEO of Brenmiller Energy, “this project’s success reflects the kind of innovative collaborations required for the global economy to shift from a context of strong, if decreasing, dependency on fossil fuels to the creation of grids that can distribute 100% clean energy.”

In their remarks during the inauguration, the President of Regione Toscana Eugenio Giani and the mayor of Cavriglia Leonardo Degl’Innocenti O Sanni were pleased to welcome the TES system, viewing it as another step forward in the enhancement of the value of the Santa Barbara area. The history of this 1,500-hectare area revolves around two centuries of mining, with energy generation activities starting in the early 1900s and contributing to the development of Italy and Tuscany – a region that is home to the oldest geothermal complex in the world, which also inspires and fuels a remarkable sustainable tourism business.

This new project reinforces the bond with the territory that has been part of our DNA since our foundation in 1962, and which we express every day in our commitment to Italy’s freedom, growth and energy independence.