In 2004, Italy consumed 45 billion kWh of electricity more than it generated. Much of this shortfall is imported from neighboring Switzerland, France and Austria, but crisis threatens whenever the demand for heating or air conditioning surges during the winter and summer peak periods.

With the public demanding a secure supply of power but unwilling to support large infrastructure projects like new power plants, Terna is facing a difficult challenge. Part of the solution lies in Sardinia.

Unlike the rest of Italy, Sardinia produces more electricity than it consumes. The problem is that it is an island more than 400 km from the mainland. ABB’s High Voltage Direct Current (HVDC) technology will help the surplus be transferred across the Mediterranean Sea to the national grid.

HVDC is an ABB technology for delivering large volumes of power across long distances via high-capacity overhead lines or undersea cables with considerably lower transmission losses and less environmental impact than alternative technologies.

This particular solution will enable Terna to transfer 1000 MW of surplus electricity from Sardinia – enough to power one million homes – via a 420-km cable and at a depth of up to 1600 meters to a key substation near Rome, where it will be fed into the mainland grid.

“The link significantly increases Terna’s flexibility and options to manage the grid,” says Matteo Marini, global head of front end sales for ABB’s Power Systems division. “It will boost supply to the mainland by the equivalent of two or more generating units without incurring the huge expense and social impact of building a new power plant.”


ABB was awarded the contract for meeting the demanding specifications, which include exceptionally low transmission losses and noise levels at the converter stations, and for its previous track record in supplying Italy’s two existing HVDC links between Sardinia and Tuscany (commissioned in 1967) and Italy and Greece (2001).

With a length of 420 km, the interconnection will be the second longest undersea power link in the world, some 160 km shorter than the NorNed link which ABB is supplying to interconnect the power grids of the Netherlands and Norway.

The contract calls for ABB to design and deliver two converter stations for existing 400 kV substations at Fiume Santo in Sardinia and Latina on the mainland. The stations include converter transformers and air-insulated and gas-insulated switchgear.