Experimental project underway in preparation for Italy’s subsea power cable connection

Italy’s transmission system operator (TSO) Terna has embarked on the experimental transplanting of a native aquatic plant from the Mediterranean Sea, as part of the environmental offsets associated with the construction of a 970 km, 1,000 MW direct current (DC) double submarine cable link between Campania, Sicily, and Sardinia.

The TSO explains that these Cymodocea nodosa plant repositioning operations in the Fiumetorto landing site fall within the wider project that will enable it to connect Sicily to Sardinia and the Italian peninsula via a double submarine cable – the Tyrrhenian Link, a strategic infrastructure for the Italian electricity system concerning the energy transition targets set by the National Energy and Climate Plan (INECP).

As part of the experimental transplanting activity, the Italian player highlights that around 20,000 plants are set to be replaced in three areas, covering 1,200 m2 at a depth of 10 meters, employing experimental techniques in line with the environmental sustainability standards.

These activities entail two phases: an initial transplanting covering 800 m2 and a second transplanting on another 400 m2 two years later that will benefit from the experience gained through the reuse of the experimental factors that will have achieved the best results in previous years.

The Cymodocea nodosa plant, described as playing an essential role in the marine ecosystem which enabled it to be safeguarded by the European Union (EU), is said to protect the coastline from erosion, preserve biodiversity, and capture CO2.

Terna intends to pour around €3.7 billion into the Tyrrhenian Link’s infrastructure. Prysmian and Nexans are among the players hired to supply the cables for the project, which is scheduled to be fully operational in 2028.

Upon completion, the power line, for which a deal for the final tranche of the €1.9 billion financing was signed with the European Investment Bank (EIB) a few months ago, is expected to upgrade the electricity exchange capacity, facilitate the development of renewable energy sources, and improve the grid reliability.

According to Terna, every step of the plant repositioning project, deemed “purely experimental as it has never been tried before with this species, on such a large scale and in the open sea,” was overseen by its personnel in collaboration with Consorzio Nazionale Interuniversitario per le Scienze del Mare (CoNSIMa) and Sistemi avanzati per l’Ambiente (ECON), and shared with Direzione Generale Tutela della Biodiversità e del Mare (MASE) thanks to the support of Istituto Superiore per la Protezione e la Ricerca Ambientale (ISPRA).

The TSO emphasizes two combinations of three experimental factors, which will be employed, entailing the type of pegs used to secure phanerogams to the seabed (biodegradable plastic or galvanized steel), the length of the single phanerogam segments to be replanted (long or short) and their layout on the seabed (linear and parallel to the bathymetry or curved or ring-shaped).

After transplanting activities have been completed, a five-year environmental monitoring plan is scheduled to start to detect the success of the operations over time through an appropriate sampling protocol. The six-year intervention is expected to lay the foundations for new developments concerning the environmental restoration of marine phanerogams.

Earlier this year, Italy’s Ministry of Environment and Energy Security gave its blessing for the Adriatic Link submarine power line, which is also set to facilitate the integration of renewable sources and support energy transition goals in Italy. Terna and Steg recently welcomed the grant agreement for the Elmed electrical interconnection between Italy and Tunisia.

A tender for the manufacture and installation of onshore cables destined for the second Malta to Italy interconnector was launched in February 2024. Meanwhile, the European Commission (EC) greenlighted a €570 million Italian scheme to incentivize ships to use shore-side electricity at berth in maritime ports, boosting the shipping sector’s decarbonization.