One of Australia’s oldest wind farms could nearly double capacity by “repowering” with bigger turbines

Plans to “repower” an ageing wind farm in north-western Tasmania, almost doubling its energy generating capacity in the process, are seeking the all-clear from the federal environment minister, paving the way for what would be a significant first for Australia’s wind industry.

An application to repower the Woolnorth wind farm joined the queue for assessment under the EPBC Act on Monday, seeking a green tick to replace the project’s nearly 20-year old wind turbines with new and much more powerful models.

The 140MW Woolnorth wind farm is made up of two smaller, adjacent projects – the 75MW Studland Bay and 63MW Bluff Point wind farms mounted on the cliffs on the north coast of the island.

They are owned by a joint venture between the Tasmania government-owned Hydro Tasmania (25%) and China-owned Shenhua Clean Energy Holdings (75%).

According to the referral documents, the Woolnorth repowering project would replace the 62 existing turbines across the two wind farms – some of which have been in place since 2002 – with 48 new models, cutting its total turbine count by 14 while boosting its total combined capacity to 240MW.

According to the EPBC documents, the new turbines would have roughly 120 metre tall towers, with 90 metre blades, taking them to a maximum tip height 210 metres – compared to around 130 metres tip height of the current turbines.

And while the turbines are expected to be in “generally similar locations” to the existing layout, each new turbine would require construction of a new below-ground foundation, as well as a laydown area of around 50m x 50m.

The wind farm’s supporting transmission system would also need to be upgraded to accommodate the higher output of the turbines, the documents say.

The power of repowering

Repowering – as RenewEconomy has reported – is when old turbines are upgraded, as opposed to decommissioned, which is when they are completely removed and a site is returned to its previous state and use.

While as-yet untested in Australia, European data has shown that wind farm repowering can, on average, triple an existing project’s capacity while reducing the number of turbines by a quarter.

Australian research, published last month, has estimated that about 1,700 megawatts (MW) of ageing wind generation in Australia could be repowered to deliver 6000 MW, using just a third of the turbines.

But, of course, it is not as straightforward as it sounds. Hurdles exist in the form of costs, renegotiating new connection agreements and regaining landowner and community buy-in for bigger turbines. Another problem for Australia is that the state and federal approvals process is uncharted territory.

In a submission to the Tasmania parliament in February, Hydro Tasmania said studies for repowering its wind sites, including the approvals required, were underway, with a commissioning target for the repowered Woolnorth of around 2030, by which time some of the original turbines will be nearly 30 years old.

The plan

Woolnorth’s owners argue it is a perfect candidate to get the ball rolling on repowering in Australia, with its proven wind resource, its position in the recently declared North West Renewable Energy Zone and its potential to feed into the Marinus Link and North West Transmission Development upgrade.

Woolnorth Renewables says now is the time to get the project underway, with the Bluff Point turbines nearing 20 years of age, making it increasingly difficult to source parts and major components for maintenance.

The referral documents also note that ageing wind turbine generators (WTGs) have “a more limited capacity to handle ‘network’ events,” or to conform to operating standards set by the network and the Australian Energy Market Operator (AEMO) and react to operational directives.

“Repowering with modern WTGs will increase reliability, meaning that [Woolnorth wind farm] can improve compliance with regulatory requirements,” the documents say.

Finally, the project’s owners point to the benefits of increasing the project’s generating output, which they say will help address climate change and meet the Tasmanian government’s target of 200% renewables by 2040.

The referral documents say potential impacts to the environment from the construction of new turbines include vegetation clearing, earthworks and construction noise, while during operation the primary potential impact would be bird and bat collision with turbine blades.

Woolnorth Renewables says that two migratory species have been recorded in bird collision surveys on the existing wind farms – the short-tailed shearwater and white-throated needletail.