COMETA (Peninsula–Mallorca)

Mallorca’s electricity used to stop at the shoreline. On 14 August 2012 Red Eléctrica brought into service the first cable to connect the Balearic Islands to mainland Spain; until then Mallorca and Menorca had run as an isolated system. The project was called Rómulo by Red Eléctrica and is also known as COMETA, and it was Spain’s first high-voltage direct-current link under the sea.

It starts at the Morvedre substation near Sagunto, north of Valencia, and ends at Santa Ponsa, south-west of Palma de Mallorca. The sea crossing is about 237 km. At its deepest the cable lies 1,485 metres down, which Red Eléctrica described at the time as the second-greatest depth in the world for a power cable of its kind. SAPEI, off Sardinia, was deeper.

The contracts were signed in the autumn of 2007: with Nexans and Prysmian on 26 September for the cables, and with Siemens on 9 October for the converter stations. Laying began on 13 January 2011 for the first cable and on 27 January for the second, using the ships Giulio Verne and Nexans Skagerrak. The link began carrying power at reduced capacity early in 2012 and reached full capacity that August, according to the Wikipedia article on COMETA.

The total cost was €375 million: €275 million for the cable and €50 million for each of the two converter stations, according to Red Eléctrica. Wikipedia cites savings of about €25 million in the first quarter of operation.

The link is a bipole of two 200 MW cables, for 400 MW, at 250 kV. That makes it modest next to newer Mediterranean projects such as the Tyrrhenian Link, but for a system the size of Mallorca’s it was a large step. Sources disagree on the year: Wikipedia’s list of HVDC projects gives 2011, its article on the link gives 2012.

The Balearic network has grown since, with AC links planned from Mallorca to Ibiza and Formentera; Wikipedia mentions a 115 km cable at 132 kV. The larger question of how islands join continental grids is covered in the guide to energy islands.