The 6.5km tunnel linking Magħtab to Kappara. Photos: Chris Sant Fournier

Works have been completed on the €182 million Malta-Sicily interconnector linking the island to the European electricity grid, with testing of the 120km underwater cable expected to start soon.

Enemalta is planning to commission the 200MW cable, stretching from Qalet Marku in Magħtab to Ragusa in Sicily, by the first half of the year. The final piece of the jigsaw fell into place last week when the Magħtab Terminal Station was hooked up to the local grid by means of a 6.5km tunnel which had to be excavated all the way down to Kappara.

Days after the completion of the structural works, Times of Malta was granted access to various parts of the project, which is deemed crucial for Malta’s security of supply, especially in the case of a blackout.

Once operational, the interconnector will permit energy provider Enemalta to keep strategic places like the airport, Mater Dei Hospital, reverse osmosis plants and industrial zones fully operational in case of a major fault in the network.

Enemalta’s assistant projects manager Joseph Vassallo, who is overseeing the multimillion investment, said that, before switching the interconnector on, the auxiliary infrastructure at the Magħtab station has to be thoroughly tested.

This facility will step down the 220kV supply reaching Malta from the Italian grid to 132kV, so as to feed the Enemalta grid. It has also been designed to cater for an additional interconnector should the need arise in future.

One of the step-down transformers at the Magħtab terminal station.

The testing phase, which will be carried out by Norwegian company Nexans, is expected to take months and will involve checks of the control protection systems together with the high and low voltage switchgear.

Meanwhile, negotiations between Enemalta and inter­national energy companies are under way to secure advantageous rates for the purchase of electricity through the interconnector.

The project was originally planned to be completed this time last year but works in Sicily were delayed as the planning and environmental permits from the Italian planning authorities had not all been issued.

As a result, the laying of the interconnector cable on the Sicilian side was only completed recently.

From Marina di Ragusa the cable stretches 19km inland to a substation in Terna where it is linked to the Italian grid.

The cable

Measuring 26 centimetres in diameter, the interconnector consists of three single-core 630-square-millimetre copper cables, bound up tightly together with steel wire.

The cable is covered with an additional insulation layer made of lead to prevent any water seeping in. It also houses space for two fibre-optic cables which may be used for data transmission.

The interconnector was jointed midway between Malta and Sicily for the simple reason that no ship in the world would have been able to carry the load of the entire cable which weighed 100kg per metre.

As an additional form of protection, the interconnector is buried in a trench below the seabed, with the exception of some areas where it was wrapped in cast-iron shells to protect marine habitat such as Posidonia Oceania meadows.

The tunnel

Excavation works on the impressive 6.5-kilometre tunnel linking the Magħtab terminal station to the Kappara distribution centre took some 20 months to complete.

Measuring some three metres in width and five metres in height, the tunnel proved to be quite challenging to dig as parts of it had to be reinforced with concrete.

The facility is wide enough to allow Enemalta employees to cross from one end to another by means of a car.

From Magħtab the interconnector exits via three separate circuits, each with three single-core cables, jointed in eight different parts. It then reaches the Kappara distribution centre from where it is hooked to the Enemalta grid.