335 km
of subsea HVDC cables
1,200 meters
water depth
Partnership
Ariadne Interconnection S.P.S.A
Market
Subsea interconnection
Location
Greece
Context
In 2020, Nexans has been awarded a significant contract to design, manufacture, and install a 335km subsea high voltage direct current (HVDC) cable system for Ariadne Interconnection S.P.S.A, a subsidiary of IPTO, Greece’s state grid operator. The Crete-Attica interconnection aims to link the electricity network on mainland Greece to Crete, facilitating the transition from fossil fuel generation to renewable wind and solar energy resources. Crete, with a population of around 700,000 people and attracting over 4 million visitors annually, currently relies predominantly on outdated fossil fuel generation. The submarine cable interconnection promises a reliable power supply crucial for Crete’s future prosperity, while also reducing emissions and making the island more attractive to tourists. Additionally, it enables the development of Crete’s own renewable energy resources by facilitating the export of excess generation to the mainland.
Challenges
One of the primary challenges of this project lies in the complexity of installing a subsea HVDC cable spanning 335 km, from the Attica region on the Greek mainland to the Herakleion area in Crete, especially considering water depths reaching up to 1,200 meters. Additionally, the need to ensure the cable’s resilience against environmental factors and potential damages during installation poses a significant challenge. Furthermore, coordinating the manufacturing, transportation, and installation processes within the designated timeframe presents logistical hurdles.
335 km
of subsea HVDC cables
1,200 meters
water depth
Nexans implication
Over a 35-month project, the Group played a crucial role throughout the project lifecycle. We provided one 500 megawatt (MW) HVDC subsea cable system to form half of the total 1,000 MW bipolar interconnection.
The Nexans cable, rated at 500,000 Volt, is based on its well-proven mass impregnated nondraining (MIND) design for HVDC cable systems and will integrate fiber optic elements for sensor applications. The near-shore sections of the cable, installed at water depths down to 100 meters, feature an aluminum conductor core with a cross-section of 1,800 mm². The deeper sections of the cable, installed at depths down to 1,200 meters, feature a 1,500 mm² cross-section aluminum conductor. The HVDC cable was manufactured in the Nexans plant in Halden, Norway.
In terms of installation, Nexans deployed one of its dedicated cable vessels, Nexans Aurora, to lay the cable along the designated route. To project the cable and ensure its secure positioning down to 600 meters water depth, we deployed the Nexans Capjet water jetting system, specialized trenching equipment.
