United Kingdom

United Kingdom

Undersea cable viable says expert -- A nod for HVDC

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A subsea cable down the east coast of Britain linking power from wind farms from as far north as the Shetlands and Orkney islands to centres of demand -- such as south-east England -- would be technically and economically feasible. This is the conclusion of a report commissioned by the owner of most of the UK seabed, the Crown Estate.

The report, East Coast Transmission Network: Technical Feasibility Study, was conducted by consultancy Econnect. It was commissioned by the Crown Estate a year ago to examine the technological feasibility and the capital costs of a high capacity offshore cable taking electricity from the far north of Scotland, coming ashore at Norfolk in the east of England and continuing to London.

Econnect concludes that an offshore network would be feasible using high voltage direct current (HVDC) cables with new voltage source converter (VSC) technology. VSC has a smaller conductor size making cable laying easier and it offers more flexibility in connecting to the network: it can join the grid at weak points on the mainland alternating current system. It also brings operational and system support benefits to system operators, such as instantly controllable power flow.

An initial core design, connecting already identified new onshore and offshore generation, would cost around £1.6 billion to £1.7 billion. A longer term 2020 scenario network, building on the core design and connecting future developments, such as offshore wind projects from a third round of government leases, and interconnections with the Netherlands and Norway as part of a European "supergrid," would cost a total £4.8 billion.

Econnect argues that these costs need to be seen in the context of the strategic development of the UK's onshore and offshore renewable energy resource, the difficulties in gaining planning consent for new transmission routes onshore as well as the avoided costs of climate change. The costs of the HVDC links outlined in the study, it adds, compare favourably with the cost of onshore AC reinforcements outlined in the 2003 Renewable Energy Transmission study.

"This report confirms that an undersea cable down the east coast is technologically and economically viable and we have now commissioned more detailed studies, says the Crown Estate's Rob Hastings. "The prospect of taking green energy right down the east coast to heavily populated areas in the south -- and potentially to the rest of Europe -- is incredibly exciting."

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