arrow-right angle-down-sx angle-down-dx menu-hamburger search
test
test
test
test
test
test
test
test
test
test
test
test

Laying the backbone of the world

Milestone submarine cable projects


With over 140 years of experience, Prysmian has a long history marked by many major milestones projects that have consolidated its reputation as a pioneer in the cable industry. The history of Prysmian Group submarine cable installations has its roots back in Pirelli Group.
In the 19th century, the production of cables proved to be the main driver of Pirelli Group, resulting in the formal establishment of its cable division in 1879 and the first manufacturing of insulated wiring and cables for electric and telegraphic application. 
Towards the close of the century, Pirelli achieved worldwide technology leadership in submarine telegraphic cables. To support the market growth, Pirelli opened a plant in La Spezia specifically dedicated to the production of submarine telegraphic cables. In 1885, to cover the fast and increasing demand for submarine cables, Pirelli built a cable-laying steamship, the Città di Milano, a 77-metres-long vessel able to transport up to 450 kilometres of submarine telegraphic cables. The Città di Milano operated in many regions, from Italy to Spain, from the Red Sea to the Indian Ocean, to then sink in 1919 off to the Aeolian Islands in Sicily. She was replaced with the Città di Milano II, a military vessel that was already used by the Italian Navy and that Pirelli refitted for commercial purposes related to submarine cable laying. After 8 September 1943, date that marked the armistice of Italy with the Allies, the crew basically sank the vessel in order not to give it to Germany.
1890_The Città di Milano entering the port of Taranto
By the 1960s, the Italian economy was booming, technology was advancing quickly, and several plants were opening to meet the changing needs of the industry. During these years, Pirelli production of submarine cables moved from La Spezia to Pozzuoli (Naples), in a factory which became what Prysmian now considers a centre of excellence for the production of submarine cables.

 

SA.CO.I is a submarine 200 kV HVDC interconnection for power transmission between Sardinia, Corsica and the Italian mainland. Laid in 1965 and completed in 1967, the submarine interconnection was a historical milestone in terms of installed length (it is about 120 kilometres long, of which 103 kilometres between Tuscany and Corsica, and the rest across the Strait of Bonifacio), electrical transmission capacity (300 MW) and sea depth reached (450 metres). Moreover, the interconnection has been in operation for longer than any other subsea power cable in the world, testifying to the reliability, efficiency and effectiveness of the technology. In 2017, the Group celebrated the 50th anniversary of the taking over of the SA.CO.I interconnection, which marks a world record for the operation of a HVDC submarine cable link.

The 1980s

In the 1980s, two major subsea cable projects were launched on different sides of the globe. The submarine power cables across Messina Strait — linking Sicily to the Italian peninsula, in Calabria — were laid in 1981 and commissioned in 1983. With a total transmission capacity of 1,000 MW, they formed two circuits at 380 kV AC. This project was a milestone in terms of the technological features used in an environment that was extremely challenging due to the strong marine currents of the strait.
In 2016, Prysmian implemented a second subsea power cable project with a total transmission capacity of 1,200 MW between Calabria and Sicily, in the Tyrrhenian Sea North of Messina Strait, using Giulio Verne cable laying vessel.
 Again in the early 1980s, the Group installed one HVAC circuit, with single-phase cables (520 kV – 1,200 MW) across Georgia Strait, the passage between the mainland coast of British Columbia, Canada, and Vancouver Island. This project was a major challenge because of the logistical difficulties derived by the location — which was so remote at that time — and a sea depth in the range of 400 meters, as well as the fact that the project involved coordinating various international partners. 

Moreover, in the mid-1980s, the Company was one of the two cable suppliers for the Cross-Channel project, a 270 kV HVDC submarine interconnection under the English Channel between the UK and France. The 2,000 MW Cross-Channel link was completed in 1986.
The 1980s
Cableship Giulio Verne in operation

“This project was also significant for another reason. One of the two selected installation operators, ITM Offshore Ltd, used its own purpose-built cable-laying vessel, the ITM Venturer. In 1988, the ship was bought and entered into the Pirelli Group fleet, being renamed Giulio Verne. Today, after more than 30 years of service this cable-laying vessel is still a vital part of Prysmian fleet.”

Array

Sebastiano Aleo

Director of Submarine Systems Installation Department

 

In 1990, the Company implemented the first of various cable-laying projects in the USA. Working with the New York Power Authority (NYPA), a high voltage submarine cable system (345 kV AC) was installed to increase the transmission capacity in the New York State, between the mainland and Long Island. To this purpose, a refitting of the vessel was required: a 25 m external diameter carousel, able to load 7,000-tons of cable, was added to the Giulio Verne and state-of-the-art technologies were implemented. 
In those years, the Company was committed to installing also two main optical submarine cable infrastructures: one in Italy, where around 4,000 kilometres of cable festoons were installed along the Tyrrhenian coast, linking also Sardinia and Sicily to the Italian peninsula, and one around the Malaysian coast for about 1,600 kilometres.

The 2000s

With the Italy-Greece submarine 400 kV DC interconnection transmitting 500 MW of power, a further important milestone was achieved: the Company laid a submarine power cable at an impressive record water depth of 1,000 meters across the South Adriatic Sea. To this purpose, a new cable laying machine, a 6 meters diameter capstan able to withstand a mechanical force of 50 tons, was installed on-board of the Giulio Verne. 
Another important project implemented in 2004-2005 was the Basslink, a 500 MW - 450 kV DC submarine cable system of 370 kilometres (of which almost 300 km at sea) linking the state of Victoria and Tasmania in Australia. The project presented special challenges associated with the very rough sea conditions often found in the Bass Strait and the logistical difficulties due to the long distance from Italy. Also for this project the installation was performed by the Giulio Verne, specifically configured to lay for the first time three submarine cables in bundle (HV, return and optical cables).


In July 2005, Prysmian was founded through the acquisition of the energy and telecom cables and systems activities of Pirelli. More information available here.


In 2008-2010, the SA.PE.I. project, a submarine 500 kV HVDC interconnection with a total transmission capacity of 1,000 MW, required the laying of two poles connecting Sardinia and the Italian mainland in Lazio, whose installation operations were performed by the Giulio Verne. The system, developed on a submarine route of 420 kilometres (and 20 km of land route), with a maximum sea depth of 1,600 meters, still remains a worldwide record in terms of the water depth ever reached during installation of a power cable

The 2000s
The Giulio Verne during SA.PE.I deep-water installation operation

 

In 2011-2012, Prysmian implemented a strategic underground and submarine 345 kV HVAC interconnection to transfer 660 MW between New York City and the New Jersey transmission grid, most of which ran under the Hudson River.

Starting from 2014, the Western Link project was installed allowing HVDC power transmission from renewable sources in Scotland to supply consumption centres in England. The contract set records in terms of voltage (600 KV) and unmatched transmission capacity for long-haul systems of 2,200 MW over distances in excess of 400 km. The link included land sections in Scotland, England and Wales, while the poles in the 380 km long submarine section in the Irish Sea were connected thanks to the Giulio Verne and wholly protected along the route.

In this decade, the Group has strengthened its market position also in offshore wind farm connections, with the implementation of major projects developed mainly in Germany, such as BorWin2BorWin3HelWin1HelWin2SylWin1, and DolWin3 (all HVDC projects between 250 – 320 kV) in the North Sea and the West of Adlergrund offshore wind farm cluster (3 core 220 kV AC) in the Baltic Sea.

Under a “one-stop-shop-solution provider” approach, the installation activities have been made possible thanks to the use of Prysmian’s entire vessel fleet — composed by the Giulio Verne, the Cable Enterprise and the Ulisse — and its state-of-the art burial equipment – first of all Hydroplow, Heavy Duty Plough, and Sea Mole PLIB jetting machine -, in addition to its cable manufacturing centres of excellence of Arco Felice-Pozzuoli in Italy and Pikkala in Finland (discover more about our installation capabilities here).
Prysmian vessels are able to cover the full range of installation operations, from very shallow to very deep water, working on soft or hard soils, to lay single and bundled cables. They provide to the Group the experience and assets necessary for catering to all aspects of cable installation.