the Spanish peninsula and the Balearic island of Mallorca Riccardo Vailati*, Claudio Pincella**, Giuseppe Stigliano**, David Alvira*** Javier Arèvalo Camacho***, Cristóbal Bermùdez Blanco***, Ramon Grandino*** Alberto Granda*** CIGRE’ 2006 Session 41 Technical Exhibition Exposition Technique Parigi, 27 Agosto 1 Settembre 2006 * CESI RICERCA ** CESI SpA *** RED ELÉCTRICA DE ESPAGNA The Balearic Islands electric system consists of two independent subsystems (Mallorca – Menorca and Ibiza – Formentera) not linked to the Spanish Peninsular system integrated in the UCTE. Several electric transmission links have been planned and are under study to connect these three systems. New transmission developments have been planned by the Spanish regulatory authorities and are expected to: – contribute to supply the demand increase in the Islands, – improve quality and reliability of supply in the Islands, – connect the Islands to the “Iberian Electric Market”, – complement the natural gas pipeline planned between the peninsula and the Islands, as energy infrastructure. The feasibility of the high depth HVDC link between the Peninsula and Mallorca has been assessed for a total rating of around 400 MW. Technological, electrical (network), environmental and economic studies have been conducted to define, evaluate and compare the scenarios and alternatives drawn for the project. The key issue with respect to the cable route has been to optimise submarine cable factors such as length, depth and cable weight, remaining within the limits of the state of the art on cable design and marine depths. This approach minimises technological risk and ensures that the link would be accomplished within a time frame of 3-4 years. The studies, which have been supported by an EC TEN Grant Agreement, have led to a preferred alternative for this interconnector that consists of a Bipolar HVDC link rated 2×200 MW with a metallic emergency return. KEYWORDS Submarine cable – High Voltage Direct Current – Cable Laying and Protection – Feasibility – Environmental Constraints – Cost of Losses – Benefits – Economic Evaluation.