Specialist anchor cages slash wind turbine installation time

Allthread Industry anchor cage pieces are craned into position at Murra Warra Wind Farm (anchor cages)
Allthread Industry anchor cage pieces are craned into position at Murra Warra Wind Farm

A recent innovation by Australian company Allthread Industry dramatically reduces the time, labour and safety challenges involved with installing wind turbine anchor cages, writes Megan Holbeck of Stride Renewables.

Allthread Industry supplied 38 anchor cages for Stage 2 of the Murra Warra Wind Farm, cutting the time taken for each installation from the standard one-and-a-half days to around 90 minutes, with labour requirements shrinking from fouor to six people to just two. 

Anchor cages are enormous masses of concrete and steel. When installed, their weight keeps the turbine tower stable even under the huge forces generated by wind. Designs vary, but the basic concept is that a thick steel baseplate with hundreds of huge bolts attached (each up to 4m long and 50kg) is put in a pit, then buried in deep concrete, with the protruding bolts then attached to the turbine’s base. 

Related article: Major Project: Murra Warra Wind Farm

Imported anchor cages are supplied as flat packs and assembled onsite, but Allthread took a different approach. They manufactured and assembled the Murra Warra anchor cages in the safe, controlled environment of their Sydney factory, delivering preassembled cages to site, ready to be craned into position. The installation process was quick and seamless, taking around 90 minutes to build each anchor cage and check positional accuracy after the cage was unloaded from the truck. There were phenomenal time savings across the 38 cages, with installation completed two weeks ahead of schedule, despite the project commencing two weeks late due to unrelated issues. 

Nick Canto, principal consultant at local engineering consulting firm icubed said, “In my entire time working with wind farms and cages, I have never seen a project finish on time, much less early, until this one.”

Allthread Industry anchor cage

Allthread’s method was not only quicker but safer, with preassembled cages delivered to site. In contrast, to assemble a flat-pack cage involves workers installing 176 bolts per anchor onsite, on uneven ground and in the elements. According to Allthread group general manager Simon Preston, manual handling is always the biggest cause of injury onsite, but with the installation of the 38 Murra Warra anchor cages there were no reported safety incidents. 

Allthread was not only competitive on innovation, speed and safety but also on price: when the cost of installation and labour were included, their anchor cages were approximately $200,000 cheaper than the imported alternative—approximately 5 per cent of anchor cage costs. Local manufacturing also allowed faster delivery, with the first cage delivered to site only seven weeks after the contract was signed, without the uncertainty of shipping (the imported version would have taken around three months).

According to Preston, Allthread Industry is an Australian company that is serious about reducing environmental impact, supporting local steel manufacturers and local jobs. As part of this commitment, all steel and 97 per cent of the total content used in the Murra Warra cages was Australian, and 50 per cent of the material was also recycled. Plastic components were even sourced from a supplier in Orange who recycles COVID-19 vaccination syringes. The increased recycled content and lower travel miles of Allthread cages dramatically reduces their embedded carbon. 

Other innovations also reduced landfill. The grout pocket trench at the top of each anchor is usually formed using single-use, non-recyclable, imported foam ingots, resulting in 15 tonnes of landfill across each project. 

Related article: Top performing solar and wind assets of 2021

Preston says, “The environmental impacts just weren’t right, particularly for a renewable energy project, so we developed a method using reusable metal rings. This eradicated the environmental impact and also allowed us to assemble the anchor cages in our factory and truck them to the site.”

Feedback has been fantastic. Zenviron project manager Brendan Jenkinson said, ‘”As far as I’m concerned, there’s no other way to do anchor cages. I don’t ever want to do it any other way.”

Allthread are national leaders in the production of anchor cages for wind turbines, already supplying more than 1100 in Australia. As Preston says, “If this is what the steel-manufacturing industry in Australia can do for anchor cages, just imagine what we could do for towers.”  

Previous articleWoodside to withdraw from Myanmar joint venture
Next articleAustralia could step up as Putin cuts gas supplies to Europe