Due for replacement sometime after 2015, the existing 33kV undersea cable to the Isles of Scilly from the mainland has been exposed by the 2013/14 winter storms.
The 55km cable installed in 1988 as part of a project to reinforce the supply to the islands, and to interconnect the outer islands, is at the end of its economic life.
The cable has a capacity of 7.5MW (maximum demand is currently approximately 4.5MW on the islands), and can be used to backfeed to the mainland 4MW if required from the 5.7MW primarily from the power station at St Mary’s.
Interestingly, the installation of the cable reduced electricity prices for islanders and allowed the introduction of Economy 7 using electricity from the mainland.
As announced earlier this year, BT is planning to reuse redundant submarine cables to improve connectivity for the Isles of Scilly. It was said that cables running from UK to Ireland and UK to Spain would be reused.
It now emerges that this is thought the redeployment of the out of service Rioja 1 cable which linked Porthcurno to Santander, Spain which has been redundant since 2006.
The cable was cut 15km from shore, and an 85km section recovered from the seabed using cable ship CS Resolute.
The cable was landed at Portcressa beach on the Isles of Scilly on 23rd July 2014 and relaid back to the mainland for reconnection approximately 15km offshore.
Further information in the Kingfisher Bulletin (iss 12, 2014) here.
BT Press release: here.
Kingfisher Bulletins have been produced every two weeks for the past 15 years and are produced to improve the safety of fishing activities in the vicinity of offshore developments, or activities.
They can be found here.
The ferocious winter in the UK which saw the railway line from Penzance back to the UK washed away, also exposed several submarine cables (the five cables below are on the same beach).