Underground, submarine and superconducting cables

Buried and undersea cables for cities, offshore wind and international links; superconducting pilots.

Transport · Electricity · No. 53

• Transport
• Form: Electricity

When a tanker dragged its anchor across Estlink 2 on Christmas Day 2024, 650 MW vanished for about six months.

Chart: Illustration: Underground, submarine and superconducting cables

Where it comes from

Chart: Map of where it comes from

A power cable swaps air for solid insulation around a thick copper or aluminium core. On land, 400 kV cables sit about 1.2 m deep, with joint bays every 500-1,000 m.

Three things to know

1. Cable failures make up about 80% of offshore wind insurance claims, and fixing an export cable fault takes about 60 days.
2. Superconducting cables lose no power in the conductor but need constant cooling to about minus 200 C; Munich plans a 15 km, 500 MW link.
3. Old lead-sheathed cables hold about 12 kg of lead per metre, which makes deciding whether to remove them tricky.

The journey

1. 1 SubstationConverter stations at each end for DC
2. 2 Copper coreFat conductor, up to 2,500 mm²
3. 3 InsulationXLPE plastic or oil-soaked paper
4. 4 LayingTrench, tunnel or ploughed seabed
5. 5 DeliveryCities, offshore wind and neighbouring countries

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