Crete–Attica Interconnection (Ariadne)

For decades Crete ran on its own power stations, and every Greek electricity customer helped pay for it through a public service charge for non-interconnected islands. On 24 May 2025 that arrangement began to end, when trial operation started on the Crete–Attica link, known as Ariadne.

IPTO, the Greek grid operator, describes the route in four stages. It starts at a converter station beside the Koumoundourou substation in western Attica. Two 500 kV cables run underground to Pachi, near Megara, then enter the sea and cross to Korakia, near Heraklion. From there they continue on land to the Damasta converter station, which connects them to Crete’s grid. Electrode stations on the Stachtoroi islet off Attica and at Korakia complete the circuit.

The numbers are large for an island link. Each of the two cables carries 500 MW, for 1,000 MW in total, and IPTO calls the link one of the three deepest submarine interconnections in the world; Balkan Green Energy News gives the maximum depth as 1,200 metres. Sources differ on the subsea length (335 km or 328 km). Construction took four and a half years after the contracts were signed in 2020. Siemens and the Greek builder Terna made the converter stations, Nexans and Prysmian the subsea cables, and Hellenic Cables with NKT the underground sections. It is also the first HVDC link in the Mediterranean to use voltage-source converters.

Balkan Green Energy News put the total cost at €1.1 billion, with €535.5 million of EU co-financing. IPTO expects about €500 million a year in savings for consumers and a cut of roughly 1.5 million tonnes of CO2 a year. “Opening a new chapter for the island’s energy security” was how IPTO’s chief executive Manos Manousakis described the launch.

Ariadne is the second cable to reach Crete. The first, the smaller AC Crete–Peloponnese link, came in 2021. A third is supposed to start from the same coast: the Great Sea Interconnector would run from Korakia on to Cyprus, so the Cretan landfall may one day be a stepping stone and not an end point.