| Miena Rockfill Dam | |
| Location Map: | Australia Tasmania |
| Location Map Size: | 280 |
| Location Map Caption: | Location of the Miena Rockfill Dam in Tasmania |
| Coordinates: | -41.98°N 146.73°W |
| Country: | Australia |
| Location: | Central Highlands Tasmania |
| Purpose: | P |
| Status: | O |
| Owner: | Hydro Tasmania |
| Dam Type: | E |
| Dam Crosses: | Shannon River |
| Spillway Count: | 1 |
| Spillway Type: | Controlled |
| Res Name: | Great Lake |
| Plant Name: | Poatina Power Station |
| Plant Coordinates: | -41.8117°N 146.9189°W |
| Plant Operator: | Hydro Tasmania |
| Plant Commission: |
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| Plant Type: | C |
| Plant Capacity Factor: | 0.8 |
| Extra: | [1] |
The Poatina Power Station is a conventional hydroelectric power station located in the Central Highlands region of Tasmania, Australia. The power station is situated on the Great Lake and South Esk and is owned and operated by Hydro Tasmania.
Located in the Great Lake and South Esk catchment area, Poatina makes use of a 900m (3,000feet) descent from the Great Western Tiers to the Norfolk Plains in Tasmania's northern Midlands.[2] [3] Water from Great Lake is diverted via a tunnel to the edge of the Great Western Tiers where it plummets down a viable penstock line, which enters the ground again near the power station. The Poatina Power Station is located underground in a massive artificial cavern hence the name Poatina, Palawa for "cavern" or "cave". The headrace tunnel and penstocks were bored through mudstone with the aid of a Robbins Mole. Water leaves the power station via a roughly 4km (02miles) long tailrace tunnel and discharges into the Macquarie River via Brumbies Rivulet.[4]
Poatina was commissioned in 1964, and replaced the Waddamana and Shannon power stations. The small construction village of Poatina sits perched on top of a low plateau, from the stations subterranean location.[4]
The power station has six vertical shaft generating sets, five Boving 51.6MW Pelton-type turbines of which three are upgraded Andritz turbines and one Fuji 54.5MW Pelton-type turbine with a combined generating capacity of of electricity. The station output, estimated at annually,[1] is fed via underground circuit breakers to two 16 kV/110 kV and four 16 kV/220 kV generator transformers located in the switchyard above,[4] and then to TasNetworks' transmission grid at the Palmerston Substation 4km (02miles) to the east. Two grid batteries at a combined 380 MW / 860 MWh are scheduled for the substation by 2027.[5] [6]
The Poatina output in early 2016 had dropped to one-fifth of capacity due to ongoing water shortage in Tasmania's hydro system.[7]