World-beating €1.1bn under-sea cable to connect England and Scotland

The route of the Western HVDC Link

While politicians talk of Scottish independence from England, a world-beating €1.1 billion contract has today been announced to make the two countries even more interconnected.

The Western HVDC Link will be the first submarine grid interconnector ever that uses a high voltage direct current (HVDC), and is to join the Glasgow and Wirral areas along the bed of the Irish Sea. It is planned to be up and running by 2016.

No ordinary wire, this grid connection has two other firsts: it will be the longest 2,200MW capacity HVDC cable in the world, as well as the first to use a voltage level of 600kV (600,000 volts).

This will increase the link’s capacity and provide lower transmission losses.

The highest voltage level used to date has been 500 kV; Siemens says that raising the voltage level in the cable by 20% raises the amount of electrical capacity it can handle by the same amount, while still using the same diameter of copper in the cable, thereby reducing the cost of this expensive material.

Furthermore, the transmission losses over its 420 km will be reduced to below 3% (including cable and converter losses). A conventional 400-kv A.C. connector would lose about three times this amount.

The project has been commissioned by the National Grid Electricity Transmission and its counterpart Scottish Power Transmission from Italian cable company Prysmian and the German company Siemens Energy, to bring renewable energy from Scotland and the Irish Sea to help England meet its 2020 renewable targets.

The order comprises cable installation along the route and construction of converter stations in Hunterston, in Ayrshire, and Connah's Quay on the Wirral peninsula on the Wales-England border.

Ignacio Galán, Chairman of ScottishPower, said that the project should be seen "in the context of a vital upgrading of the UK electricity grid over the coming years, with the electricity grid between Scotland and England already running close to maximum capacity".

He said that ScottishPower expects to invest a total of ￡2.6 billion between 2013-2021 on upgrading its transmission network in the UK.

"Overall, we are projecting investments totalling ￡12 billion in the UK over the course of this decade, including major offshore wind projects around the country,” he added.

Nick Winser, Executive Director at National Grid said: “This link will have a vital role of play in helping to address the problem of climate change.

"We are investing in an innovative solution using the most advanced technology. The benefits for consumers and electricity generators in being able to transport power in the most efficient way, will be felt for years to come.”

Round 3 windfarms

The Western HVDC Link will support the planned expansion of renewables such as offshore wind and marine power at sites that are far away from loads and where the amount of electricity produced can be dependent on weather conditions.

It will therefore help to meet the consequent challenge of balancing power generation and consumption within the grid.

Underground or submarine cables lengths of 80 km or more are only possible with HVDC transmission technology because when A.C. lines reach this length the cable’s insulation serves as a capacitor and becomes charged, thereby absorbing most of the electricity.

Future wind farms will be far offshore due to the higher yield and because the near-coastal regions were already contracted out in rounds 1 and 2.

For round 3, with 32 GW of wind power, areas have been identified for wind farms that are between 40 and 200 km off the coast.

In the Irish Sea, the area is 'Zone 9', located between the Isle of Man and Anglesey.

"This order underscores our technological leadership in the HVDC field," said Udo Niehage, CEO of the Power Transmission Division of Siemens Energy.

“It will be the first subsea interconnector with a transmission capacity of 2200 megawatts – this equals the power output of two large-scale power plants,” he added.

The project was conceived in 2009 following an Electricity Network Strategy Group survey which identified a number of transmission reinforcements needed to enable renewable energy to be connected and secure the UK’s energy supplies.

Its report said the HVDC subsea link would be the most appropriate way to ensure that the additional energy generated in Scotland could be transmitted to the rest of Britain, because HVDC becomes more economic at longer distances.

Udo Niehage said that he foresees an expanding need for HVDC. “By 2020, I’m expecting to see new HVDC transmission lines with a total capacity of 250 gigawatts. That is a dramatic increase. In the last 40 years, we’ve only installed 100 gigawatts worth of HVDC transmission lines.

“Additional HVDC transmission projects will be awarded in Germany and Europe during this year.”

China, India, and Brazil in particular are also utilising the technology more and more, because their energy demand is growing rapidly and large distances must be bridged to ensure a supply of electricity from renewables projects.

The $1bn contract to connect North Sea windfarms

What is possibly the world's largest ever order - at $1bn - for grid connection technology for offshore wind farms has been signed, an indicator of the coming huge expansion in wind capacity in Europe.

Dutch-German transmission grid operator TenneT has commissioned ABB, a power and automation technology group, to supply a power link connecting offshore North Sea wind farms to the German mainland grid.

The initiative will form part of Germany's plans to meet its carbon reduction targets while phasing out its nuclear power plants.

When completed, it will be the world’s largest offshore HVDC (high-voltage direct current) system - rated at over 900 megawatts (MW) - and will be capable of supplying over 1.5 million households with wind-generated electricity.

It will utilise ABB's HVDC (high voltage direct current) Light technology. This means that by transmitting the power at high voltage in direct current (DC), rather than alternating current (AC), electrical losses over distance can be kept to below 1% per converter station.

The technology is well proven and ten years old - ABB has previously used it to connect the BorWin1 windfarm and last year won a contract to connect the 800MW Dolwin1 windfarm, both also in the North Sea.

The cables can transmit power underground and underwater over long distances with the other advantages of having neutral electromagnetic fields, oil-free cables and compact converter stations.

The company claims that it is economically feasible to expand transmission capacity using this system, to minimise the visual and environmental impact of the grid and improve the quality of the power supply.

The expense and visual intrusion of overland grid-connection cables has become a focus for opposition to the expansion of wind power in the UK , particularly in Scotland.

The planned connector will link the 400 MW Gode Wind II and other wind farms in the North Sea, sending DC electricity at 320 kilovolts to a converter station at Dörpen on the German coast, via another station offshore, along 135 kilometers of underwater and underground cables. It will then feed AC electricity into the mainland grid.

It should be completed by 2015, so that by 2020 Germany will have more than doubled its offshore wind electricity generation, from its present 8% of total supply (a capacity of over 27 gigawatts).

Britain and Germany are both competitors and partners in the race to establish windfarms in the North Sea. Wind energy is expected to more than triple its power output by 2020 in the EU.

Energy and Climate Change Minister Chris Huhne, on a visit yesterday to the Vestas wind turbine facility in the Isle of Wight, spoke enthusiastically of the UK leading the world in the area, with some 1.5GW of wind capacity installed.

"Last week’s new European Wind Energy Association numbers found almost all turbines installed in the first half of this year were in the UK: 101 off the UK, compared to just 7 in the rest of Europe," he said.

Justin Wilkes, Policy Director of the European Wind Energy Association (EWEA), believes that 194 billion Euros will be invested in European onshore and offshore wind farms in this decade. "This success is mainly driven by a strong EU regulatory framework to 2020, which we need also after 2020," he said, as he launched a new EWEA report on scenarios for onshore and offshore wind power deployment in the EU.

This says that electricity production from wind power is expected to increase from 182 Terawatt hours (TWh) or 5.5% of the total EU demand in 2010, to 581 TWh or 15.7% of the total demand in 2020. At this point it will be equivalent to the combined electricity consumption of all households in France, Germany, Poland, Spain and the United Kingdom.

Chris Huhne would like to see many more of the turbines that are erected around the UK being built in this country, which was a motivation for his visit to the Vestas facility in Newport on the Isle of Wight. This was a turbine-making factory that Vestas closed two years ago despite attempts by the government to dissuade its Danish owner.

Huhne said that he believes "Vestas are one of a number of companies who have announced intentions to open turbine manufacturing plants in the UK. I very much hope to see that intention become reality.”

Despite not making wind turbines, the factory still employs 220 people. It is testimony to efforts by islanders to attain its council's goal of being carbon neutral by 2020.

Huhne saw how the facility now designs and tests wind turbine blades. “Innovative new components, including those likely to be tested and developed here in these very facilities, will play a crucial role in bringing [future wind power] costs down," Huhne said. "As will new, high yield, multi-megawatt turbines of the type Vestas have recently announced."

Council representatives and members of the Eco Island community group then discussed with Chris Huhne proposals to create an ocean energy centre to test tidal and wave technology off the west and south coasts of the island.