How much new renewable energy does Tasmania need? | RenewEconomy

How much new renewable energy does Tasmania need?

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Tasmanian government may soon claim that state’s electricity crisis is behind us. The facts, however, are rather less encouraging from all angles.

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Presuming Basslink is fixed in the next month and rainfall returns to typical levels (a couple of big ifs at this point), the Tasmanian state government will claim that our electricity crisis is behind us. The facts are rather less encouraging from all angles; energy security, economic impact and environmental consequences.

Even if Basslink starts running flat out southwards as soon as it is fixed it can only supply 500 MW, a bit less than half Tasmania’s average consumption of 1100 MW.  The remaining half has to come from hydro or continuing to burn expensive gas at Tamar Valley. (The 200 MW of diesel generators on order are likely only to be used if repairs are delayed or there is no significant rain.) With our dams nearly empty, it is likely that we will be reliant on a fair bit of gas and Victorian coal fired electricity until our dams are back to a safe level.

The core problems is that long term sustainable yield from existing hydro (8700 GWh) and the two existing wind farms (898 GWh in 2014-15) is a bit less[1] than annual consumption (9752 GWh in 2014-15).  In normal operation Basslink makes up any difference, but this makes it very difficult to make a big impact on storage levels and explains why over the long term Basslink imports more than it exports.

The peak energy stored in Hydro dams has gone down every year since the 2012 peak of 62% in October 2012. Storage is currently at 17.3%[2] and is projected to go down to 14%[3] by mid March.  One can argue about the respective contributions of normal weather variability, climate change, the policies of respective state governments, and the rush to earn export cash during the carbon tax period. But the unarguable fact is that we are living beyond our current renewable energy means.


To meet the shortfall described above, and build our dams back up to 62% over 5 years requires an extra 1544 GWh a year[1].  That’s less than the projected output of the abandoned TasWind proposal for King Island. But hopefully we have learnt from the current crisis not to rely on a single source of energy or a technology with a single point of failure.


A plausible diversified portfolio might consist of:

Screen Shot 2016-02-22 at 11.35.30 AM

A variety of sources and locations has many benefits:

  • spreading the economic benefit widely across the state,
  • tapping multiple sources of public and private capital,
  • minimising environmental impact in any one location,
  • increasing resilience to changing economics and circumstances,
  • minimising the need for expensive new transmission infrastructure, and
  • getting started faster.

We need to start rapidly on building this extra infrastructure. Until a substantial section of it is in place we will continue using expensive gas and/or dirty brown coal, our dams will remain low, and our energy security will remain fragile.

The situation will get worse rapidly if:

  • Basslink repairs take longer than anticipated,
  • rainfall does not return to anticipated levels and we have to set a ‘new normal’ as a result of climate change[1], or
  • electricity demand increases.

In the current circumstances, praying for rain is a reasonable impulse, but it is not an alternative to evidence based policy and urgent political action to encourage investment in new renewable energy generation capacity.

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  1. Farmer Dave 4 years ago

    Great discussion, thanks Jack. I really liked the graph. As Chris Harries has pointed out elsewhere, one of the issues is that even if Tasmania’s rainfall returns to “normal”, runoff into dams will be reduced because of the higher temperatures brought on by climate change.

    I completely agree that the local economic benefits of the kind of diversified portfolio you have described would be considerable, and could the issue which attracts the attention of the current government, if they can be persuaded to listen to people other than the usual cartel of industry insiders and advisors. Have you considered the kinds of policy changes that would be needed to encourage such a diversified portfolio?

  2. Malcolm M 4 years ago

    What happens if one of the major loads were to close ? The Bell Bay aluminium smelter has a load of ~100 MW, producing aluminium into a low-priced and over-supplied market. What if it were to close, as appears to be on the cards for the Portland smelter, and has been threatened for the Bluff smelter in New Zealand ?

    The risk of any one of these large loads closing in Tasmania would surely be part of the risk assessment of any new wind capacity in the State.

    • Jack Gilding 4 years ago

      Malcolm: Concern that a major industrial would close has been a preoccupation driving state energy policy for years. It has been used both as a rationale for Basslink 2 (arguing that we wouldn’t be able to use the surplus and would want to export it, requiring more than the capacity of existing Basslink). It is also used as an argument that we don’t need more renewable energy generation. Closure of a major industrial would clearly be a major set-back for Tasmania in terms of jobs. Hopefully the declining Australian dollar has made closures less likely. Medium term, global pursuit of a low carbon economy should give Tasmania a competitive advantage in attracting larger energy consumers (if we build the generation capacity). Under the current circumstances, loss of a major load, would be a problem for loss of jobs but it may not be a problem in terms of energy policy. I am not privy to consumption figures or tariffs for individual large customers but if 4 customers use half our electricity, let’s assume the biggest user uses 15% of total consumption of 9752 GWh = 1463 GWh, that’s less than the 1544 GWh required to meet shortfall and rebuild dams to 62% over 5 years. 1463 GWh/year is also a continuous output of 167 MW so well within capacity of Basslink to export.

    • Chris Harries 4 years ago

      Malcolm, for the record Bell Bay’s commercial contract is for 322MW of electricity. This is constant load, the furnaces not being able to be turned on and off without entailing a huge cost. This is the major component of Tasmania’s overall demand so it’s a critical issue, and one that has been in people’s minds for several decades.

      It should definitely be high up in contingency planning, just because of the consequences – though I expect that the Tas Government would do almost anything to try to prevent a shut down. Owning to economy of scale the smelter would either shut down completely or not at all, its one of the smallest aluminium smelters around and way below optimal economy of scale.

  3. Mike Ives 4 years ago

    Wow Jack that plausible portfolio selection capacity factor works out at a massive 43%. Where are you buying your solar and wind turbines from?

    • Jack Gilding 4 years ago

      Sorry Mike, I don’t understand the question or where you got 43% figure. By capacity factor I mean the percentage actually generated compared with that MW capacity would generate if it was running flat out for the whole year. My figures are from Clean Energy Council for solar – In Tas work on 3.5 hours average sun a day over a year, 3.5/24 = 14.58% – call it 14%. Small run of river hydro 40% based on the existing Humboldt scheme. 35% a conservative figure for good wind locations in Tasmania.

      • Mike Ives 4 years ago


        Firstly an apology. I read your table wrongly sorry Jack and took the 400 MW as the total instead of just for Granville Harbour. I should have said 31.2% as per David’s calc. Thanks David.

        Secondly this is great. Last year I was carrying out a plausible study for Tasmania as I feel we should be trialling the much heralded Australian 100% renewable theory right here in Tasmania before other staes. With Tasmania’s sparse population, renewable resources including hydro (if it decides to rains again) plus even hot rocks, if it works here there may be hope for the rest of Australia doing the same. The notion was to cover Tasmania’s total electricity demand by renewables with the current hydro capacity to fall back on effectively as storage. Any surplus hydro could be shipped off to Victoria (at that time BASSLINK was fully operational but would need a capacity upgrade)

        My concern would be that we head down the 100% renewable trail, assuming we ever get our mitigation act together, only to find we have to keep fossil fuel plants operational just to meet the shortfall. I am sure fossil power shareholders would be only too willing to oblige..

        Much more electrical generation of course would be required to tackle some of Tasmania’s transport issues.

        Now the figures.

        I haven’t found any current info as to how the full blown Humboldt Scheme is fairing. Any suggestions Jack/David?

        Granville Harbour Wind at 35% seems only a theoretical figure mentioned in Pitt & Sherry’s Development Plan. I would be grateful for a link to Woolnorth’s actual performance figure if you have it.

        Household solar CF at 14% seems rather conservative for Tasmania Jack but still have to check our 3kW PV bank performance later this year as a guide..

        Tasmanian’s do have the Roaring Forties but Australia’s average wind farm capacity factors average out at only 29% according to Dr Barry Brook

        The UK’s average wind farm capacity factor is 21.7%…/digest-of-uk-energy-statistics-dukes.

        The 2014 US wind farm capacity factors averaged 34% while solar PV was 25.9% and solar thermal 19.8%. Conventional hydro comes in at 37.3%

        Where is this going? Well if we can agree or agree to disagree I think a plausible 100% renewable Tasmania number crunching exercise would be a very worthwhile application to collaborate on. Anyone?

        • Mark Duffett 4 years ago

          It seems the EIA solar PV capacity factor is for utility scale installations only, which will be concentrated in areas of highest insolation within the US (and probably with tracking mechanisms as well?). It will thus be quite unrepresentative of rooftop performance in areas where most people live (and Tasmania).

          Comparing the numbers in the table above, it’s tempting to say simply build 5 Granville Harbour-sized wind installations instead of 4 and don’t worry about the rest.

          • Mike Ives 4 years ago

            Good comment Mark if only we could confirm the 35% figure

    • David Osmond 4 years ago

      Looks to me that the overall average CF is 31% (1509 GWh from 551.5 MW of generation). Obviously most of the generation is coming from the 4 ~100MW wind farms with an average CF of 35%, which is similar to Musselroe’s capacity factor, but lower than Woolnorth’s. I’d suspect that any new wind farm in Tassie would likely have a CF exceeding ~40%.

      • Mark Duffett 4 years ago

        Is that suspicion is based on turbines of considerably greater height and radius as canvassed at, or are there particular Tasmanian sites capable of achieving CF >40% with current turbines that haven’t yet been utilised?

        • David Osmond 4 years ago

          Just based on current technology turbines. Woolnorth is already getting CF around 40%, with turbines that are many years old. With current technology turbines with larger rotors and higher hub heights it would be getting much higher than 40% CF. Other sites in Tassie may not be quite as windy as Woolnorth, but could easily get 40% CF with current technology turbine technology.

  4. Jack Gilding 4 years ago

    Missing footnotes:
    [1] Sustainable yield+actual wind: 8700+898=9598 GWh. Consumption minus generation: 9752-9598=154 GWh annual shortfall. The shortfall could be significantly bigger if demand returned for example to the 10,400 GWh annual demand peak of 2008.

    [2] As at 15 Feb 2016

    [3] Energy update, Matthew Groom, 12 Feb 2016

    [4] Rebuild dam levels over 5 years + annual shortfall: 6951/5 + 154=1544 GWh

    [5] This would increase the % of houses in Tas with solar from 11% to 22%, still less than the current rate in Qld and SA. See

    [6] Like the existing 560 kW Humboldt scheme

    [7] Similar size to existing Nichols Poultry turbine

    [8] Each of 33 turbines

  5. Smurf1976 4 years ago

    I think some figures have been mixed here.

    The consumption data in the article appears to include centrally dispatched generation only, since it understates total consumption. That is, it excludes power generated from non-scheduled generation (eg hydro plants under 30 MW) which is significant overall in the Tasmanian context. Either that or the data being used is for consumption as metered and does not include network losses.

    Total net input to the grid (total input less exports via Basslink) is around 11,000 GWh per annum. That includes all hydro, wind, gas and Basslink but not small distributed sources (solar, landfill gas etc).

    On the other hand, the 8700 GWh hydro yield figure includes all Hydro Tas generation, scheduled and non-scheduled.

    So the difference between total energy load on the system versus hydro + wind generation is around 1300 GWh per annum.

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