Bornholm Cable

Bornholm Cable
Location of Bornholm Cable
Location
Country	Sweden, Denmark
Coordinates	55°17′49.9″N 14°26′7.1″E / 55.297194°N 14.435306°E / 55.297194; 14.435306
Ownership information
Owner	Energinet
Technical information
Power rating	60 MW
AC voltage	60 kV

The Bornholm Cable is a submarine power cable under the Baltic Sea, connecting the power grid of the Danish island of Bornholm to the Swedish power grid owned by E.on with a capacity of 60 MW.^[1] It is owned by Energinet,^[2] previously by Östkraft.^[3]

There is an agreement between Svenska kraftnät and Energinet about balancing the Bornholm grid.^[2]

The cable sections are:^[4]

• Hasle substation to Bornholm coast: 1.4 km underground, 400 mm² conductors at 60 kV
• Undersea section: 43.5 km, 240 mm² conductors at 60 kV
• Swedish coast to cable terminal: 700 m underground, 400 mm² conductors at 60 kV
• Cable terminal to Borrby substation: 4.2 km overhead line with 127 mm² conductors at 60 kV
• Borrby substation to Tomelilla substation: 132 kV line with two circuits

The undersea section has been repeatedly damaged: in 2004,^[5] in 2010^[6] and in 2013.^[7][8][9] The damage in 2013 cost half a million Danish crowns per day, due to electricity price differences between Bornholm and southern Sweden and the costs of two ships waiting for calm weather to repair the cable.^[7]

Reserve generating capacity for when the cable is out of service is provided by coal power plants on Bornholm and by diesel generators to cover the start-up time of the coal plants.^[6] There is also a project using energy stored in electric vehicles as a backup supply for a period of hours.^[10]

In 2018, the cable was buried deeper in the seabed to prevent damage,^[11] but suffered failure due to a dragging ship anchor in early 2022.^[12]

• Electric power infrastructure on Bornholm
• List of high-voltage transmission links in Denmark