First Stage of Plan to Improve Security of Electricity Supply Between Saaremaa and Hiiumaa Starts

On Thursday, Empower AS began the installation of the new 110 kV undersea cable in the Great Strait on Elering’s order, having started the first stage of the plan to improve the security of electricity supply in Saaremaa and Hiiumaa.

“At the moment, five old 35-kV undersea cables supply the islands of western Estonia, but they are unreliable and do not meet modern requirements. By the end of this decade, Elering is planning on installing another 110-kV undersea cable between the mainland and Muhu island as well as another cable connection next to the overhead line between Muhu and Saaremaa,” explained Elering’s Chairman of the Board, Taavi Veskimägi. At present, consumers in Saaremaa and Hiiumaa are supplied by two overhead lines supported by pylons on the causeway of the Small Strait. If a pylon were to break due to weather conditions or other reasons, this could result in electricity outages for dozens of hours in Saaremaa and Hiiumaa. To increase the security of supply, Elering is also planning to install an undersea cable between Saaremaa and Muhu.

At the moment, Elering is undergoing procurement for the renewal of the Leisi 110-kV substation in northern Saaremaa. Reconstruction of the substation is an important step for Elering’s transmission network’s possible expansion to Hiiumaa. In addition, Elering is considering making changes that would increase the network’s security of supply in the Muhumaa section of the transmission network.

The installation of the Virtsu-Võiküla cable between the mainland and Muhu island started on Thursday near Muhu, where the cable was laid into the water from a cable ship and then 800 metres of the cable was pulled onto land. The cable will be connected to the 110-kV substation at Võiküla.

In the next few days, the rest of the cable will be laid on the seabed and the other end of the cable will be pulled onto land in Virtsu and connected to the substation of Virtsu via a short overhead line.

The Virtsu-Võiküla cable will be installed in one piece and will be approximately eight kilometres long. The entire length of the cable will be placed in soil to avoid possible damage.

According to the plan, the new Virtsu-Võiküla undersea cable installation project will be finished this autumn. According to the public procurement, the cost of construction work is 9.4 million euros without purchase tax.

The new cable is more powerful than the combined capacity of the 35 kV cables that have been used until now. The new cable is also more environmentally friendly due to its use of polyethylene insulation (XLPE) instead of oil-impregnated paper. This will be the first 110 kV undersea cable in Estonia’s domestic electricity network. The expected lifespan of the undersea cable is 40 years.

Cable installation works in the Great Strait. Photographer: Ain Köster.