Building power line resilience
Forestry and Land Scotland (FLS) is working with SSE’s network businesses – SSEN Transmission and SSEN Distribution - to increase power line resilience before winter weather sets in.
Thousands of homes were left without power last winter when unprecedented storms flattened swathes of forestry and caused a major failure of power supplies.
Despite a Herculean effort to clear windblown trees and restore the power network, some homes were without electricity for a week or more. It will take us several more years to fully clear the vast amount of storm damaged trees across our forests.
In a joint effort across the north of Scotland, FLS, SSEN Transmission and SSEN Distribution are working together to reduce the likelihood of such power cuts in future.
David Leven, East Region Manager for FLS said;
“Everyone will remember the severity of last year’s storms and while the power network has been restored, the damage to our forests is still evident in many places.
“One of the hidden impacts of this damage is that there are some trees in some locations that are now unstable and more vulnerable to being blown down by weaker winds than we saw last year.
“In addition to clearing trees that have been blown down, we are also working with SSEN to identify where trees have been destabilised along wayleaves so that we can fell those trees and remove the risk of them causing more damage.
“At the moment it’s important to deal with the most immediate risks and our regional teams are working locally with SSEN to prioritise these areas. However, we are also looking, over the longer term, to reduce the risk further by redesigning wayleave edges to reduce tree height – and taking opportunities at the same time to enhance biodiversity.”
Forests are designed in such a way that these wayleave edges are largely protected from wind damage. However, catastrophic failure in the face of exceptional storm winds is both difficult to predict and to avoid.
Wayleaves vary in width and some are bordered by trees that exceed 30m in height which presents a risk should they be affected by extreme winds. We are looking at ways to design the forest to minimise this risk. One option is planting smaller native trees in these border edges.
Where we are able to do this, it will have the additional advantage of increasing the variety of habitat for wildlife along with improving both biodiversity and landscape in our forests.
John Sharpe, SSEN Distribution’s Tree-cutting Operations Manager, said:
“Last winter, Storms Arwen, Malik and Corrie presented unprecedented challenges for the North of Scotland, with significant disruption experienced due to fallen trees and windborne debris striking overhead power lines.
“This year, we’re investing above and beyond the committed £100m investment in our regions to boost the resilience of our network, with £2m of additional, targeted investment in tree cutting, inspecting around 2,000km of network and clearing trees and vegetation from approximately 600km of power line between now and Spring 2023.
“Working closely with Forestry and Land Scotland to complete this essential resilience investment is critical, with our 35-tonne live line harvester allowing many tree feeling projects to be carried out safely without the need to temporarily turn off power supplies to our customers.”
Martin Sangster, SSEN Transmission Vegetation Management Operations Manager, said:
“As part of our ongoing maintenance of our electricity network, we undertake extensive tree cutting resilience activities to reduce the risks of tree related faults. As part of this year’s resilience programme we have been working with Forestry and Land Scotland to address a one kilometre section of our network which crosses through their woodland areas in the north east of Scotland, one of the hardest hit areas during last year’s storms.
“Commercial conifer species can create significant risks to overhead network infrastructure so we are pleased to work with Forestry and Land Scotland to address these risks. We are also committed to working with Forestry Land Scotland to deliver its objectives to redesign suitable clearance corridors for overhead network infrastructure by utilising alternative woodland species to also encourage the benefits of biodiversity.
“We remain committed to ensuring our transmission network remains as safe and reliable as possible, transporting electricity to homes and businesses in the communities we serve across the north of Scotland.”
Resilience felling has been ongoing since the winter storms of ‘21/’22, with a substantial amount taking place in Countesswells forest.
This has included work along 1000m of powerline - two high voltage lines and some lower level distribution lines - that, following discussion with SSEN, required a number of shutdowns in order for it to be carried out safely.
SSEN has also been carrying out additional work to improve network resilience in the wider northeast area.
Notes to editors
Forestry and Land Scotland (FLS) manages forests and land owned by Scottish Ministers in a way that supports and enables economically sustainable forestry; conserves and enhances the environment; delivers benefits for people and nature; and supports Scottish Ministers in their stewardship of Scotland's national forests and land.