The Rómulo project represented an electricity interconnection challenge that proved to be successful in paving the way to eliminating the electrical isolation of the Balearic Islands and enabled the integration of renewable generation from the mainland into the archipelago. Today marks the seventh anniversary of the commissioning of this pioneering project.

On 14 August 2012, Red Eléctrica brought into service the submarine interconnection that linked the electricity systems of Majorca and Menorca with that of the Iberian Peninsula. Thanks to this infrastructure, sometimes up to 40% of the Balearic Islands’ electricity demand has been covered by energy coming from the Peninsula, ending decades of electrical isolation and increasing the guarantee of supply and the integration of renewable generation.

20.4% of the demand on the Balearic Islands in 2018 was covered by electricity coming from the Peninsula via this link, which contributed to increasing to 12% the share of renewable technologies used to cover the demand of the Balearic Islands. Of the total energy demanded by the Islands in 2018, 15% was generated by technologies that produce zero CO2 emissions.

With an investment of 420 million euros, the electricity interconnection between the Balearic Islands and the Peninsula was the first effort made in Spain to reduce the isolation of insular systems and increase their security of supply, pursuant to European recommendations. This project, known as Rómulo, has also led to an average annual saving of 50 million euros as the higher costs incurred by having to generate electricity in the Balearic Islands’ themselves have been reduced.

This submarine interconnection, a pioneering infrastructure in its day as it was the longest underwater link in direct current, favours a greater integration of renewable energy into the Balearic Islands and reduces dependence on generation that uses fossil fuels, such as coal, gas and diesel.

Rómulo is comprised of three cables (one of them a return cable) in direct current that is 237 km in length and that run along the seabed between Sagunto (Valencia) and Santa Ponsa (Majorca) reaching a maximum depth of 1,485 metres.

The project involved the installation of a high-voltage submarine interconnection of ±250 kV, carried out by means of a 400 MW bipolar link with a return conductor, which enables the circuit to be closed off if either of the two main cables need to be worked on. That is to say, it is an interconnection which comprises of two power cables in addition to a third return cable to increase the availability of the electricity supply.

Due to the distances involved and the power capacity required for this dual link, the interconnection was designed to use direct current technology, which allows energy losses in transmission to be reduced, controls the bidirectional power flows and increases the power transmission capacity three-fold with respect to a cable using alternating current.

Find out more about the Rómulo project here