The opportunity

EnergyConnect is the 900-kilometre electricity interconnector (transmission line), which will run from Wagga Wagga in NSW to Robertstown in SA, with a connection to Red Cliffs in VIC. This backbone infrastructure will connect customers with more renewable energy enabling a further 4950MW of generation capacity. Transgrid’s construction delivery partner in NSW, SecureEnergy led by Elecnor Australia, has set numerous sustainability targets and is the first project of its kind in Australia to undertake ISC’s IS Design and As-built ratings.

Objectives

SecureEnergy was particularly focused on applying innovative solutions reducing the whole-of-life carbon footprint, minimising the use of energy, water, and materials, reducing waste, and ensuring resilience against forecast climate impacts. One innovation is an Australian first, the use of guyed steel towers for a 330kV double circuit transmission line.

Unlike conventional self-supporting towers, which stand on four legs, guyed steel towers comprise a central mast held in place by four steel cables. Guyed towers are used extensively in the US, South America, Africa and Europe in locations where the topography is flat. Australia’s grid is often in hilly and rocky areas, so this will be the first use of double circuit guyed towers in Australia, with EnergyConnect using a blend of guyed and self-supporting towers.

“Guyed towers let us clear less space in environmentally sensitive areas. While the permanent footprint is slightly larger, guyed tower construction is significantly less invasive on the landscape and results in an overall better economic outcome for energy consumers,” Yousseph Ters, Transgrid Project Integration Manager said.​

A different approach

• Innovative guyed towers – these require approximately 15 per cent less steel and 25 per cent less concrete in construction compared with self-supporting conventional towers which have four legs, achieving a reduced carbon footprint.​
• Reducing carbon footprint through using sustainable concrete mixes – SecureEnergy is using SCM in place of Portland cement and recycled aggregate has been implemented, reducing the projects greenhouse gas emissions. This involved early engagement with concrete suppliers to understand the current market in regional NSW and VIC and what was achievable. The project team found that concrete manufacturers in rural Australia, typically use 100% Portland cement and naturally occurring sand in their BAU concrete mixes. The concrete supply contract requires a minimum 35% SCM content and recycled aggregate (manufactured sand), which has been adopted. ​
• Minimising the impact on carbon sequestration through reduced land and vegetation clearance – SecureEnergy identified refinements to the clearing model presented in the EIS and BDAR to align with the vegetation clearance requirements detailed in Transgrid’s Transmission Line Construction Manual. These refinements are being implemented across the project. The accepted deviations have led to approximately 35% reduction in vegetation clearance on the Western Section (SA Border to Buronga) and 11% reduction in vegetation clearance on the Eastern Section (Buronga to Wagga Wagga).​

Key learnings

Outcomes are not perfect e.g. some guy ropes came a bit loose because of the heat expansion of the ropes but we should always be learning and improving.

Knowledge sharing is key to duplication – Transgrid will deliver internal knowledge share workshops for their other key transmission projects using the lessons learnt on EnergyConnect.