“It’s not easy being green” – Why we’re upgrading the transmission network in the north of Scotland

Hopefully you had a chance to watch Power to the People on BBC4. One of the issues the second of three documentaries on SSE dealt with was the challenges we faced during the construction of the replacement Beauly-Denny overhead line.

The project, a replacement of the 220km transmission line between Beauly in the north of Scotland and Denny, near Stirling is being delivered jointly with Scottish Power Transmission and is an enormous undertaking for everyone involved. The documentary did a great job of covering the final tower construction and the fantastic effort the team has put in, but there was no way it could have  captured the true scale of the project. These are just a few of the statistics for our section of the new line and I’m sure you’ll agree that they are simply staggering:

  • Over 20,000 tonnes of steel– the equivalent weight of two large ferries;
  • At its peak a team of more than 1,500 people worked on the design and build of the 539 steel towers;
  • 2,600km of aluminium conductor – enough to run from Perth to Rome;
  • 67,000 cubic meters of concrete – enough to fill 27 Olympic swimming pools;
  • More than four million nuts and bolts – a million more than the number of rivets on the Eiffel Tower;
  • Installation and removal of 250km of access tracks – equivalent of three times the length of the M8 motorway; and
  • The construction of the transmission tower with the highest elevation in the UK, built at 2526ft above sea level on the Corrieyairack Pass.

The need for the Beauly-Denny project was identified over 10 years ago when it was recognised that the old 132kV line between Beauly and Denny was the weakest circuit on the transmission network and was therefore a limiting factor in the transfer of electricity. Rebuilding this circuit with the replacement, higher capacity line was therefore the logical and economic decision to release capacity across the transmission system.

Full energisation of the Beauly-Denny line is anticipated by the end of 2015. With simultaneous reinforcement of the network between Beauly and Aberdeenshire, the investment has directly enabled the connection of 80 additional renewable generation developments which are expected to have a combined installed capacity of over 1,460MW by the end of December 2015. As a result, the total level of generation either connected to the transmission system or currently under construction is over 4GW which is already far greater than could have been accommodated on the network if the Beauly-Denny line had not been upgraded.

Looking to the future, there is a further 8GW of renewable generation contracted to connect to the Scottish Hydro Electric Transmission (SHE Transmission) network. Even if only a fraction of this materialises, and over 3GW has already been granted consent, further reinforcement of our network beyond Beauly-Denny is needed. That’s why we’ve invested around £2 billion in our transmission network since 2008.

One such investment is the reinforcement of the transmission network between Caithness in the very north of Scotland and Moray in the northeast. With an investment of over £1.1 billion Caithness-Moray is the largest capital investment that SSE has ever undertaken. In addition to upgrading onshore infrastructure, the new HVDC subsea cable will be capable of carrying up to 1,200MW. As well as being the first HVDC infrastructure on our network this projects represents the largest investment in the north of Scotland electricity transmission network since the hydro development era of the 1950s.

In addition to these massive infrastructure projects we have also been strengthening the existing network with projects such as replacing the wires along the 157km overhead line between Beauly via Blackhillock, near Keith to Kintore in Aberdeenshire and upgrading the network between Beauly and Mossford, near Garve.

The investment we are making in the north of Scotland electricity transmission network not only facilitates the connection of renewable energy, it strengthens the network and helps keep the lights on. As you’ll have seen in the documentary we have a talented and dedicated workforce which is proud to work in some of the country’s most challenging conditions.

About the author

Dave Gardner Director of Transmission

David joined what was the North of Scotland Hydro Electric Board in 1986 and has held various development and construction positions mainly in the generation side of the business including hydro, wind, CHP and CCGT. In 2007 Dave became SSE's Head of Ventures where he led a team responsible for delivering over £120m of investments in various cleantech businesses. In 2010 Dave became Director of Onshore Renewables and was responsible for the development of SSE's onshore renewable energy projects in the UK and Ireland. This includes the construction of over 1000MW of onshore wind farm capacity including Hadyard Hill, Clyde, Griffin and Gordonbush. Then in late 2012 Dave took over the position of Director of Transmission or SHE Transmission where he is now responsible for the delivery of the £5bn transmission portfolio which will facilitate the connection of the North of Scotland future renewable energy generation projects.

Read more articles by Dave Gardner