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Tasmania grid struggles with drought, bushfires, lost connection

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Tasmania’s electricity grid is facing its biggest challenge in years, with its hydro storage about to fall to its lowest levels ever, bushfires forcing the closure of some power facilities, and a faulty cable cutting the connection between the island and the country’s main electricity grid.

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The Apple Isle’s main source of electricity – hydro power – is being challenged by its driest ever spring, pushing reserves down to just 18.9 per cent.

The lowest level ever is 16.5 per cent, reached in 2007, but overall storage levels are predicted to fall to a low of 14 per cent by the end of March – if normal rainfall patterns resume. At current rates, however, some fear they may fall below those levels, although there has been some light rain in recent days.

To make matters worse, the Basslink cable linking the island’s grid to the mainland has been cut by technical problems, and will probably remain closed for another two months, while the raging bushfires have threatened power lines and forced the temporary closure of at least four hydro plants.

“These circumstances are extraordinary and unprecedented,” Premier Will Hodgman and energy minister Matthew Groom said in a joint statement late last week. “It will be tough, but we will get through it.”

To address the issue, the government has had to bring its Tamar Valley gas power generator – scheduled for permanent closure last year – out of mothballs.

That has provided 280MW of added capacity, but the government is now looking to bring another 105MW of gas and diesel power back into the system to hedge against further depletion of its hydro resources.

TEMCO, the operator of the country’s only s manganese alloy smelter, has volunteered to cut its demand in half – down to 30MW – to try to ease the problem, although the government is confident that it will not have to impose power restrictions on other users.

“While the government cannot rule out energy savings measures with major users, based on current projections they are not anticipated to be required,” the government statement said.

“Based on advice, the government has no plans to pursue energy savings measures with the broader community,” it said last week. But on Monday it updated this to: “We continue to remain in close contact with the major industrial users.”

Meanwhile, wholesale power prices have jumped nearly three-fold over the long-term average.

The Tasmanian government says water storage levels fell 1.1 per cent last week despite the restart of Tamar Valley. The Basslink had been used to provide 80GWh a week since September, when hydro levels began to fall dramatically.

Two of the major storages – Great Lake and Lake Gordon – have already hit low levels of 13.7 per cent and 11.8 per cent respectively.

To make matters worse, one of the power stations with a fuller lake – the Fisher facility that draws its water from Lake MacKenzie – has been closed because bushfires, which are threatening Tasmania’s wilderness areas, are threatening transmission lines.

The 42MW Fisher power station is expected to return to service this week. The 51MW Lemonthyne power station, also impact by bush-fires, has returned to service, while the 10.5MW Rowallan Power Station may be offline for several weeks.

Even the state’s biggest power station, the 430MW Gordon power station, had to be closed for much of one day because of the threat of bushfires, although Hydro Tasmania insists there is no threat to the power supply.

Basslink – which operates the second longest subsea HVDC cable in the world – says it has more than 100 people working to fix the interconnector, which went down on December 20 and may be out until March 19. The government has not ruled out further delays.

It says it does not know the exact cause of the fault, although it appears to be located about 100km off the Tasmanian coastline in Bass Strait. A special vessel – Ile De Re – has been routed to Australia, along with three containers of special materials and 16 experts from Italy, where cable operator Prysmian is based.

Hydro Tasmania’s website says the state-owned company has 30 hydro power stations – based in “high rainfall” parts of the state.

It also has three wind farms – the 168MW Musselroe wind farm, the 65MW Bluff Point wind farm and the 75MW Studland Bay wind farm – on the main island. Rooftop solar amounts to around 90MW. Total demand in Tasmania averages from around 900MW to more than 1,100MW.

The shortage of power resources has meant that power prices have surged, and have been averaging more than $100/MWh since the start of the year, more than double other state markets. Average prices have ranged from $30/MWh to $47/MWh over the last six years.

Tasmania is not alone in suffering from the impact of drought on its hydro power facilities. Brazil has been facing actual and potential power cuts because of severe drought, and Snowy Hydro, based in NSW, last year bought another gas-fired power station as back up in the event that drought cuts its ability to provide hydro power.
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  • Jon

    Just goes to show the value of dispatchable generation! It also doesn’t help that Tas Hydro profiteered enormously on the carbon tax and ran their storage very low just before it was repealed. They have also been profiting from the RET by gaming the baseline and then running plant differently to ensure they maximise their LGC return. All this relied on adequate replenishment year on year, unfortunately now it hasn’t come.

    • Barri Mundee

      Just goes to show the value of the inter-state grid connection.

  • Chris Harries

    Just a clarification on the drought issue. Most of the rainfall that falls in Hydro Tas storages comes from the west in frontal rain showers. This rainfall pattern is mostly determined by weather engines that drive our weather in the Southern and Indian oceans.

    When we loosely talk about drought in relation to hydro water inflows we are really taking more about evaporation from soils rather than reduced precipitation. I’m told by those in the science field that about 60 percent of the inflow reduction can be attributed to soils drying out (higher mean ambient temperatures) which results in frontal showers being absorbed into soils rather than running off into dam storages. This happens even when rainfall is not below par.

    This may seem to be fairly irrelevant point, but it is very pertinent to the general impact that global warming is imposing on hydro-electric systems around the world. Here in Tasmania we depend hugely on the hydro-electric system but we depend on it too much. There is a strong argument in there for greater diversification of supply.

    • Barri Mundee

      Tassie arguably does not have enough wind and solar.

      • Chris Harries

        Sorry, Barri, do you mean installed capacity or wind and solar potential?

        With regard wind energy potential, Tas has some of the best wind sites in Australia. In terms of solar we may not be the hottest, sunniest state, but we do have a similar latitude to Germany.

        There is also an advantage in Tasmania in that there is not need to worry at all about the intermittency factor. The hydro-electric system can absorb any amount of surplus and send it out again to match demand.

        • Barri Mundee

          I meant installed capacity Chris, sorry I should have been more clear.
          I agree, Tassie has very good wind sites and also plentiful sunshine to support higher solar generation than now.

          I would have to be concerned though that hydro may in future years be unable to generate as much as in the recent years if relatively low rainfall becomes the new normal?

    • RobS

      Yes in this case we have had both high rates of evaporation AND low inflows. We have had record low rainfalls across most of the state, in some areas the last three months rainfall has been under half of the previous record low.

    • RobS

      Across the west coast we have had rainfall over 300mm below the mean for the october-december period

  • Chris Fraser

    I always thought Tas Hydro doesn’t get LGCs on its pre-1997 dams hydro generation ?

    • Malcolm Scott

      They ran them at greater capacity in the carbon price period (particularly toward the end) than the baseline that was set for old renewable – to the benefit of Tasmanians with greater government revenue.