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Heli-saw to ‘transform’ electricity sector

13 May 2024

New Zealand’s electricity sector could be transformed by a radical new approach to keeping trees off power lines, says a King Country-based energy distributor.

The Lines Company (TLC), based in Te Kūiti, has undertaken its first successful trial of the heli-saw – a specialised tree-trimming saw hanging from a helicopter. The heli-saw, owned by Lakeview Helicopters in Taupō, was trialled by TLC in a forestry block in Kuratau near Taupō last month.

In just over an hour the heli-saw successfully trimmed 950 metres of radiata pine along a corridor housing a 33kV network line. Material was left at the base of the trees, leaving two blocks of trees – 9 years and 14 years – undamaged.

TLC’s vegetation manager Jason Gaukrodger said the trial was “sensational”, saving the company weeks and weeks of work and thousands of dollars. It proved the heli-saw technology had incredible potential, he said.

“I had high expectations, but this blew me out of the water in terms of how efficient it was. It was much faster than I anticipated, and the pilots had incredible control. This technology has the potential to be transformational for electricity distribution companies like ours, as well as for the forestry sector.”

TLC chief executive Mike Fox said for customers the potential benefits could be huge. TLC services 24,000 connections across some of New Zealand’s most challenging geographical terrain. Around 10 per cent of its network – approximately 150,000 hectares – is covered in forestry blocks, some poorly maintained. The company had 269km of power lines running through forestry blocks as well as 106km of line through Department of Conservation (DoC) land.

It was an ongoing battle to keep trees clear of power lines, making the network vulnerable to storms and weather events.

“Cyclone Gabrielle is a good example of what can happen. Across our network we sustained around $1.65 million in damage just from that one event, and the vast majority of that cost was from trees falling into lines,” Fox said.

“In a normal year, we’d invest around $1.6 million in vegetation management but in the future, we will need to invest more because of increasingly volatile weather patterns and the increase in commercial forestry. Over the next 10 years, we’ve budgeted a further $200,000 to $600,000 per annum to keep trees away from power lines and in some cases, reroute some lines away from trees completely.”

“Those costs are huge, and at TLC we don’t have a big customer base to spread them across. The financial impact is significant, costing each customer on average $60 to $90 per year.”

TLC will continue to trial the heli-saw technology later this month in a plantation forest south of Piopio in the King Country. A 2.6km corridor through a commercial forest will be trimmed, with support from the forestry owners. Gaukrodger said the forestry sector was invited to see the heli-saw in action at Kuratau and left impressed. TLC would continue to work alongside foresters, he said.

“This technology helps both TLC and forestry owners manage the risk from trees and does so cost-effectively, especially in steep or hard-to-access terrain. The other option is felling the trees completely, but removing edge trees opens up forestry blocks to wind. We can send arborists in to trim trees but we are literally looking at weeks and weeks of work. With this technology, weather permitting, we’re talking hours.”

Gaukrodger said when considering the heli-saw, safety was TLC’s primary concern. Heli-saws from Lakeview Helicopters are approved by the Civil Aviation Authority (CAA) for use under H125 B3E and AS350 B2 helicopters.

“We began looking at this technology a few years ago so have had time to think about every facet of safety. We’ve put a huge amount of time into health and safety documentation and into developing a helicopter guide for use on our network. The trial itself also involved a site-specific health and safety management plan,” he said.

He is optimistic the upcoming trial at the end of this month will again showcase what can be achieved.

“This is a tool desperately needed by our industry and none of us want it to fail. It has the potential to transform the way we manage vegetation and that’s important for TLC because across our network, more and more land is now going into commercial forest. It also allows us to reduce safety risk because we’re not having arborists up trees for extended periods of time, sometimes in challenging terrain.”

Heli-saws have the potential to help distribution companies better manage faults, he said.

“If a tree brings a line down and if weather permits, we could trim the whole corridor, doing the job once and doing it properly. We have to get ahead of the game and used appropriately, this could be a game-changer for us and the wider sector.”

Fox said TLC was keen to share its learnings and experience of the technology with other parts of the sector.

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