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England and Scotland are presently debating the terms
of a referendum in 2014 that could see Scotland leave the United
Kingdom. Two years after that vote, however, Scottish and English energy
networks will become significantly better connected.
The Western
HVDC Link is a unique project establishing many firsts for
interconnectors around the world. Costing around £1 billion to install,
it will be the first grid interconnector below the sea ever to use high
voltage direct current. It will become the longest 2,200MW capacity HVDC
cable in the world and will be the first to operate at 600kV.
This
project is set to break boundaries in several regards as it seeks to
meet a significant need for greater grid capacity across the UK. With
large scale development of renewable energy capacity in Scotland, the
challenge is to grow transmission capacity between Scotland and England,
where large population centres consume much of the energy produced.
This challenge is pressing as the two existing overhead lines that cross
the border are running at capacity already.
This project will help
to meet that need, but must also face the problem of significant
transmission loss that can occur over a 420km cable. The 600kV voltage
level is designed to help bring the loss down to just three percent. The
more conventional 400kV A.C level used in connectors would risk losing
three times that level.
There are also projected cost benefits to
raising the voltage level from the previous highest example of 500kV to
600kV. This can enable the cable to handle a greater electrical capacity
without the need for a wider diameter of copper, saving on the cost of
an expensive raw material.
National Grid Electricity Transmission
and Scottish Power Transmission have commissioned the order and aim to
see cable installation along the route and construction of converter
stations in Hunterston in Ayrshire and Connah’s Quay in ten north of
Wales. However, with Flintshire County Council rejecting the planning
application for Connah’s Quay on 8 February, it remains to be seen how
proposals for the southern converter station will adjust.
The cable
itself will run under the Irish Sea through the area designated by the
Crown Estate as zone nine. Zone nine is part of round three of the
off-shore wind programme and rights to the area were granted to Centrica
Energy Renewable Investments Limited.
Western HVDC in numbers
- €1.1 billion – the contract awarded for establishing the link
- 2,200MW – the capacity of the new HVDC cable
- 600,000 – the voltage level of the new interconnector
- 420km – the length of cable between converter stations
- 3% - transmission losses, including cable and converter losses
- 32GW – off-shore capacity in phase three
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