Project overview
The route in Italy
In Italy, the siting of the infrastructure focuses on municipalities surrounding the Terna Suvereto substation, designated by the national transmission system operator as the grid connection point. This choice is based on the Suvereto hub’s capacity to host the interconnection, its proximity to major electricity demand centres, and the need to avoid overloading central and southern Italy’s grids, already congested due to the high concentration of renewable generation.
The Italian route of the infrastructure, currently under consultation with the relevant local authorities, includes a landfall point in the Gulf of Follonica area, underground cables along existing infrastructure corridors to a new converter station, and a marine electrode designed to ensure the safety and reliability of the interconnection.
Preliminary siting options for the submarine cable landfall, converter station, and electrode have undergone initial assessments that excluded the presence of significant landscape, archaeological, and hydrogeological constraints. These options have been preliminarily reviewed by the relevant national, regional, and local authorities, and subsequently updated through a Participatory Design process. They will be subject to a Public consultation, the formal citizen participation tool by current legislation as part of the permitting process before the Ministry of Environment and Energy Security (MASE).
For further information on the proposed locations, please consult the interactive map or the Non-Technical Summary.
The marine route
From the coastline to approximately 1,000 metres depth, the submarine cables will be buried beneath the seabed at varying burial depths, depending on geological and environmental conditions. This approach is designed to balance protection against potential human interference with permitted fishing activities. At depths beyond 1,000 metres, where bottom trawling and anchoring activities are minimal, the cables will be laid directly on the seabed without burial requirements.
To minimise environmental impact on the marine ecosystem, installation techniques such as jetting will be used in sandy seabeds, while mechanical trenching or rock dumping will be applied in rocky or irregular seabed conditions. At the landfall points, the connection between submarine and onshore cables will be carried out using HDD (Horizontal Directional Drilling), a trenchless technique that avoids open-cut trenching, both offshore and onshore.
The cables will be manufactured using advanced insulating materials such as mass impregnated paper or cross-linked polyethylene (XLPE), selected according to the characteristics of each section to ensure safety, reliability, and environmental compatibility. The infrastructure is designed for a minimum operational lifetime of 40 years. The interconnection may be developed in progressive phases, starting with an initial installed capacity and subsequent increases up to the planned 2 GW capacity.
The route in Tunisia
The project is designed around the development of a large-scale integrated renewable energy hub in Tunisia’s desert regions, leveraging some of the world’s highest solar irradiation and strongest wind resources.
The energy mix combines utility-scale solar PV, onshore wind generation, and Battery Energy Storage Systems (BESS), targeting an overall installed capacity of at least 5 GW. This hybrid configuration is intended to optimize resource complementarity and deliver a more balanced and reliable generation profile.
Renewable electricity generated by the plants will be transmitted to the Tunisian coast through dedicated high-voltage transmission infrastructure, developed by Zhero in close cooperation with STEG. The transmission corridor will also include intermediate connection points to support integration with the local Tunisian grid. From the coast, power will be exported across the Mediterranean through High-Voltage Direct Current (HVDC) submarine interconnectors, enabling efficient long-distance transmission while minimizing electrical losses.
The integration of large-scale BESS technology will allow the system to achieve a semi-baseload renewable generation profile — a capability that is difficult to replicate in Italy and across most of Europe. This will make it possible to supply low-carbon electricity even during traditionally hard-to-abate periods, supporting deeper decarbonization of the power sector. As with the interconnection infrastructure, the renewable generation platform can also be implemented in phases, allowing capacity to be commissioned progressively over time.
Project timeline
The timeline is indicative and subject to change based on the progress of the permitting process.