The upgrade of Lemonthyme brings Hydro Tasmania one step closer to upgrading every power station in the Mersey-Forth, ensuring it is ready for a new era of hydropower. 

The Mersey-Forth Scheme has a generating capacity of 290 MW with Lemonthyme contributing up to 54 MW. The Scheme produces enough power to supply about 10% of state’s energy needs.

It is the first time the power station has had a full upgrade since it was commissioned in 1969, and the works will add a further 30 years to its working life.

The single-turbine station will get a new turbine runner, main inlet valve, distributor, a refurbished turbine relief valve and full electrical upgrade, making the power station more efficient and reliable.

Hydro Tasmania Executive General Manager Assets and Infrastructure Jesse Clark said Lemonthyme Power Station was an important part of the Mersey-Forth Scheme.

“Lemonthyme is an essential power station in the Mersey-Forth, connecting the Mersey River to the River Forth via a 6.5-kilometre tunnel and 1.6-kilometre penstock,” said Mr Clark.

“That vital link between the two rivers makes it a critical asset in our portfolio.”

Hydro Tasmania’s Cambridge Workshop has played a key role in the upgrade of the station, refurbishing the turbine relief valve and machining technical parts to reduce any defects or errors.

“The level of accuracy required for these parts to work in our turbines is down to hundredths of a millimetre. In the design phase, we added some additional material to the parts we ordered to ensure we could get the fit just right,” said Mr Clark.

“The team at Cambridge has done a fantastic job inspecting, measuring and machining the parts to ensure they are the perfect fit for the turbine.”

Around 13 local specialist contractors have also been involved in the upgrade, providing services like steel works, designing platforms, transport frames and jigs and fixtures.

The Lemonthyme Power Station upgrade is expected to be completed by the end of 2026 with the upgrade of the final power station, Fisher, due to start in 2027. 

Upgrades at Paloona, Devils Gate, Wilmot, Cethana and Rowallan power stations have already been completed.