Tasmanian Times

The individual has always had to struggle to keep from being overwhelmed by the tribe. If you try it, you will be lonely often, and sometimes frightened. No price is too high for the privilege of owning yourself. ~ Friedrich Nietzsche

The individual has always had to struggle to keep from being overwhelmed by the tribe. If you try it, you will be lonely often, and sometimes frightened. No price is too high for the privilege of owning yourself. ~ Friedrich Nietzsche

Economy

Is a door flying open on Geelong Star … ?

*Pics: The damage … and the culprit? Geelong Star, before its renaming. And below, Basslink cable damage, including the gouge …

image

image

I was going to pose this question in comments to see if any of the fishing folk interested could answer. However, my own inquires have given the the answer.

I have now dismissed any electrical-type effect as the cause of the cable failure. Thanks to those putting cases for and against electrical failure.

I have no found no reason to change my mind that external mechanical trauma was the logical cause.

Exactly what type of object did impinge on the cable?

Could the same type of object – or multiples thereof – be responsible for both types of damage illustrated by the two photographs.

The lower component of the seine fishing nets towing system are the weights. I always thought these to be selected scrap iron … something cheap (no expensive environmentally unfriendly lead these days).

Scrap iron is not uniform and could resemble other types of objects that ‘could’, for some obscure reason, be dragged along the sea bed.

To my great surprise the fishing industry has long had a low cost solution to the problems above. It also solves problems of net-fluid-flow under tow.

Flat steel plates … resembling a door off its hinges. The are often referred to as Flying Doors.

These are drilled in one corner and shackled via short hawsers to the lower tow line and lower mouth; they effectively flutter under tow. This provides a constant drag pattern and, being symmetrical in design, each one has a predictable effect on the whole net stability profile. So adjustment for correct net performance can readily be gauged by removing or adding plates.

If the net is out of adjustment and dives into the seafloor these plates evidently can gouge deeply like a plough … and as someone in comments ( HERE ) pointed out such an event can cause considerable damage to the net.

Not only that, the corners being right angles, are extremely vicious and extremely damaging when coming into contact with another object.

Such action and corner profile would be more than capable of inflicting puncture damage matching that exhibited in the first photograph (above) of the damaged section of the Basslink cable.

Also if the cable was pulled up momentarily by one door (weight) catching the cable lifting it slightly then another adjacent door (weight) could swipe the cable on the flat.

This would account for the superficial damage on the upper part of the main conductor in the second photograph.

I believe this logical mechanical trail leads to the conclusion that a towing fishing vessel damaged Basslink.

If so which fishing vessel?

The spacing between the puncture and the surface damage on the cable could indicate the size of net involved. It does seem some symmetry in weight distribution is needed to keep net dynamics in balance. The spacing between nets is likely to be different on the huge net of Geelong Star against the much smaller nets of the local fishing vessels.

As it seems all seine net type trawlers use this type of flying door technology they are big enough to have to carry AIS (Auto Identification System) and satellite.

I believe past AIS records are available?

The Geelong Star is the only ship to be operating without AIS.

There can only be very few fishing vessels, if any, in the area, at the time of cable failure with the capability of damaging Basslink in this way.

Then by a process of elimination there is a real possibility of narrowing down and eliminating the other vessels.

I have not heard back yet from Basslink concerning the status of the brochure sent to me by Clive Stott ( Comment 27 HERE ). This brochure indicates it is voluntary for fishing boats to notify authorities in the event of accidentally striking the cable – and they have no liability.

The question of testing nets with open gates in Bass Strait where fishing trawling is evidently banned is still not fully researched.

This starts a whole series of other questions concerning the saga. Including Bryan Greens document being censored for poltical purposes? ( HERE: Hydro document censored for political purposes )

Also ultimately … In whose interest?

*Bio of Kelvin Jones: Technically trained and qualified in the UK by a major electrical engineering manufacturing company in Power Engineering with Switch and Protection specialisation, moving on to defence electronics, commissioning RADAR and development of underwater weapons. TV transmission, field work and commissioning work on industrial electronics and HVAC carrier protection. Research in cellular and fibre optics communications. Field work on scientific, bio, and medical instrumentation with extensive work on Medical Imaging particularly CT scanners and Nuclear imaging. Mature age universty studies in computer science and Technology with emphasis on the viability of renewable energy technology on legacy power grids.

EARLIER on Tasmanian Times …

Likely cause of Basslink failure is the Geelong Star

Mercury: Basslink II an energy sequel Tasmania would be best to avoid

ABC: Matthew Groom to use energy meeting to make case for second Bass Strait cable

• Pete Godfrey in Comments: Hi Kelvin, there is historical ships position data available but unfortunately we have to pay to get it. It seems that data stored on computers costs heaps to supply. If we want data on who owns a company, we can look up ASIC records and pay to see the information. Now we can look up data on ships on sites such as AIS Vessel Tracking but again we have to pay. John Hawkins said in your previous article that Basslink have left the off cuts of the cable on the ocean floor. I would have thought that with the price of scrap copper these days that they would have recovered it, even if it was to buy a few years’ grog supply for the shipmates.

Bryan Green: Groom bets it all on a second Bass Strait cable

Rosalie Woodruff: Second Basslink rationale back to front

news.com.au: Tas push agenda at national energy meeting

• Pete Godfrey in Comments: This is a bit of a stab in the dark. I am wondering if the rush to get a second Basslink cable has more sinister reasons. The possibilities are endless but lets look at a couple. First Tasmania is almost totally reliant on Hydro Power. The Dams have a finite lifespan. Already Lake Rowallan Dam has needed extensive repairs to prevent failure. What if the Government know more than they are letting on. Wouldn’t that be novel …

ABC: Concerns Hydro Tasmania’s revised target for dam water storages will raise power prices

• Kelvin Jones in Comments: … A friend of mine in UK has been reading Tas Times … he is an ex-academic and lived for a number of years in Australia. He has quite a sardonic turn of phrase … here is a sample of his comments about Tasmania: “I followed the latest comments on the BassLink saga in the Tasmanian Times. Quite a multi-faceted debate is it not? Enough of you ‘stirrers’ exist to suggest the Geelong Star is culpable. From this part of the world, the State Government’s avoidance behaviour and disingenuousness seems absurd. Tassie is a relatively small place. The truth will out eventually. Better to face it now. I note that the Tassie Times considers itself a “cheeky, irreverent” alternative to mainstream media. It certainly appears to be that. Reading it as an outsider the impression created is of an island populated by seething malcontents, venal local councillors, devious soothsayers, single-agenda activists, and anti-government anarchists for whom any form of “rule” is the stuff of nightmares. Makes for a fun read though …

Author Credits: [show_post_categories parent="no" parentcategory="writers" show = "category" hyperlink="yes"]
40 Comments

40 Comments

  1. Kelvin Jones

    October 24, 2016 at 4:19 pm

    #39 Your comments on induction turbine correspond with my thinking. I will be commenting further at the next opportunity.

  2. Second Opinion

    October 24, 2016 at 1:38 pm

    Simon, Lets go with your pedestal fan example. Plug it in to the grid at the requisite voltage and frequency: it will operate as a motor. Of course it will; and it will spin at whatever speed balances out excitation against friction, windage etc. It will not rotate at the synchronous speed. The difference is called it’s slip.
    Insert your finger between the fan blades (better you than me), and turn the fan in the opposite direction. If you manage (!) to turn it fast enough, it will indeed generate and return power to the grid. Again, there is slip involved. It is an asynchronous generator.
    The Grid determines everything.
    In the absence of “the Grid”, an induction generator is nothing but a liability. In the South Australian case, fluctuations in the Grid caused protections to operate to protect the turbines, and the Grid went down. There was no going back. At least the birds were safe from the 320Km/hour blade tip speeds. PMA turbines have a black start capability. Induction turbines do not.

  3. Simon Warriner

    October 22, 2016 at 10:24 pm

    re 36,

    I suggest Second return to 23 and 25 and focus on this: “My main point was that a large wind turbine that has an induction generator, relies on “slip” to function. In the absence of wind, such a generator will consume energy from the Grid. ” A motor with a fan attached in other words.

    and this: “Jon, Under no-wind conditions, a wind turbine that I speak of will effectively be a motor.” Again, with a fan attached.

    Being pedantic, sorry but what I said about pedestal fans is exactly what you are asserting, not once but twice.

  4. Second Opinion

    October 22, 2016 at 1:58 pm

    Here is an overview of the doubly-wound wind turbine. I think the Tasmanian installed Vestas systems are of this type.

    http://cdn.intechopen.com/pdfs/12519.pdf

  5. Second Opinion

    October 11, 2016 at 4:10 pm

    To Simon at #33,

    I made no such assertion Simon.
    Any wind turbine which loses it’s Grid excitation faces an existential identity crisis. Is it a generator, or is it a motor? It is neither. It is feathered and lifeless.
    There are some Siemens direct-drive turbines at Snowtown2 which would have the capability.
    There is a suggestion that the Basslink fault was internal. [today’s Mercury]
    Is you have viewed the online video of the mamufacture of the Basslink HVDC cable, by Pirelli, you will see that the steel armouring is overlaid by a plastic roving which identifies the cable. If there had been a sudden fault to earth by way of physical damage, or by a standing wave: the roving would have shown a degree of melting from arcing. QED
    There is a video on Vimeo about a cable-laying ship called “Stemat Spirit” Very dramatic, but interesting.

  6. Simon Warriner

    October 9, 2016 at 6:38 pm

    re 34, I feel your pain.

  7. Pete Godfrey

    October 9, 2016 at 4:42 pm

    #33 Simon, if the rotor was wound only it would be a fairly simple matter to just short the slip rings once the machine was over sychronous speed.
    If we ever run into each other we can discuss schrage motors. One of them was the bane of my winding days. 3 months work and some idiot hooked the chain of a gantry onto the end of the shaft and dropped it on the floor. Leading to me having to do the whole thing again. ARRRRRRGGGG.

  8. Simon Warriner

    October 9, 2016 at 1:20 pm

    Pete, the unit I was looking at was wound rotor only, no squirrel cage. It would be interesting to see one, and where the squirrel cage sat relative to the winding, and what speed it was designed for.

    Not sure your schrage analogy is correct, but that is a technical argument that would be better had over a beer ;-).

    I vaguely remember something about there being a frequency applied to the rotor via an inverter but not in any detail I would state as factual.

    Back to the main point, the idea that when the wind stops the grid might be designed so that the windmills turn into giant pedestal fans is hilarious. That is what is being claimed.

  9. Pete Godfrey

    October 9, 2016 at 10:51 am

    #31 Second Opinion, exactly what I have described to you. As Simon Warriner points out too, no engineer would make a generator that was permanently connected to the grid, and also drew power when the generator was stationary.
    Think of this, how would anyone be able to work on such a machine to do maintenance if there were no way to disconnect the windings from the grid.
    I am sure you will find that as the speed of the generators vary that they are connected to the grid via large 3 phase inverters that operate in much the same way as modern small petrol inverter generators.
    The generators would only draw power if there were a fault in their electronic control circuitry.
    If they were connected without such failsafes , they would act as AC induction motors and the blades would spin all the time when the wind dropped below their charging speed.
    I think the newspaper people had little understanding of what they were reporting on, just as the politicians have little understanding of anything unrelated to bickering.

  10. Second Opibion

    October 9, 2016 at 12:14 am

    For now you might like to chew over this.

    https://en.wikipedia.org/wiki/Induction_generator

    I’m trying to determine the turbine types in use in South Australia, but the IPad says No most of the time.

  11. Pete Godfrey

    October 8, 2016 at 5:58 pm

    #29 Simon from what i have read the sliprings feed power to a winding on the rotor so that the generator can produce useful power at sub synchronous speeds. Above synchronous speeds the normal squirrel cage rotor winding begins producing power so takes over.
    It makes the generators useful at lower wind speeds .
    Apparently they are connected to the grid via three phase inverters so the only way that they would draw power when stationary is if there was a failure in the electronics.
    They are known as double wound induction generators. Similar to the old Schrage motors used for variable speed drives before electronics took over.

  12. Simon Warriner

    October 8, 2016 at 2:31 pm

    Limited example, but the Woolnorth wind turbine alternators were not simple induction generators.

    They had wound rotors with sliprings and a complex suite of electronics to control output and frequency. From my memory of a conversation I had with Vestas’s engineers while discussing a quotation to rewind the machine it was stated that the output was controlled by adjusting the rotor supply, I do not recall exactly what was being adjusted. Inductance, resistance and frequency are possibilities. Rotor speed was adjustable by pitch control on the turbine blades.

    Having started my electrical career in the power generation industry, and spent a lot of it in the company of electrical engineers, I find the concept that a state electricity network would allow the connection of generation equipment capable of becoming a load on the system every time the wind speed dropped more than a tad gobsmacking, totally unrealistic, and an insult to the many degree qualified professionals involved in designing any electricity network. But that is just my opinion. Perhaps “second opinion” might like to address that issue?

  13. Jon Sumby

    October 8, 2016 at 11:36 am

    #25, Yes I know of the newspaper article you mention, it was The Australian and in their haste to demonise wind energy they got it hopelessly wrong by a factor of 500 times more than the actual value, which was 0.09 MWh.

    The price spikes you mention are nothing to do with wind power. South Australia routinely has price spikes, even before wind and solar, as they mainly run gas power stations and the gas price is set on the market. This is why SA moved into wind and solar, and since that sector turned on pricing has been more stable and less volatile; but spikes still do happen in relation to the cost of gas. But most people didn’t hear about that because The Australian thinks coal is good, wind is bad.

    ‘According to the AER, one of the principal reasons that gas prices shot higher was that most major coal plants – and one big gas plant – had units unavailable in the first week of July.

    Here’s the list from the AER: Stanwell 2 (off since 25 June), Torrens Island B3 (since 29 June), Liddell 2 (since 30 June), Yallourn 4 (since 1 July), Eraring 3 (since 3 July), Gladstone 3 (since 4 July), Loy Yang A1 & A2 (since 6 July – due to coal issues), Hazelwood (units 1 & 2 since 1 July and unit 5 since 5 July).

    That’s a total of around 3,200MW of coal fired capacity not available, plus the gas outage.

    As the AER noted, that wasn’t the only problem. Gas demand surged to $36.65/gigajoule in Victoria, mostly due to heating needs, and was also high in Sydney, where the price reached a record $28/gigajoule. Records were set in Adelaide too. Gas supply was also tight because so much was needed for the export market, and because of supply constraints in Queensland.

    And, on top of that, gas customers were being hit by transportation “penalty charges” related to higher than normal pipeline use.

    That’s the sort of monopolistic pricing behaviour that the South Australian government is trying to force out. Building more wind and solar farms, and providing more interconnectors, will go a long way to solving that, as will the change in market rules that the generators are fighting so hard to stop.’

    http://reneweconomy.com.au/2016/why-gas-prices-jumped-to-record-levels-and-3200mw-of-coal-went-offline-78687

  14. Pete Godfrey

    October 8, 2016 at 10:22 am

    #23 Second opinion.
    Slip is a function of induction motors that creates torque. If an induction motor were to run at synchronous speed it would produce no torque. The slip speed is the difference between the synchronous speed and the actual shaft speed. Typically around 60 rpm.
    An induction generator will not start generating until it is driven at above synchronous speed.
    For a 50 hz machine the synchronous speed for a 2 pole machine is 3000 rpm, and for a 4 pole 1500rpm.
    If there were no mechanism for disconnecting the stator windings from the grid then anytime the generator was turning lower than synchronous speed the windings would be drawing power from the grid.
    This would be a stupid way to run a wind generator.
    There has to be some control over this, in the old days such as in a car the windings were disconnected by the regulator which had a large set of contacts that only closed once the speed was high enough to charge the battery. In a massive wind turbine with a Megawatt rating I would imagine thyristors would be used that would disconnect the supply until the stator began to generate usable power.
    What you are saying sounds like a political myth.

  15. Clive Stott

    October 7, 2016 at 11:48 pm

    Kelvin, here is a short video of the Basslink repair:

    http://www.dailytelegraph.com.au/news/national/basslink-says-1355m-of-new-cable-laid-on-the-bass-strait-seabed/news-story/2cee1a6223fff463a341f9403ed1fd02?nk=9c2aa85055f4cf920ef0c0d599e40eef-1475921262

    #25: Under no-wind conditions what will the ‘motor’ be doing? Nothing will be turning I take it?
    Zilch generated, zilch consumed?

  16. Second Opinion

    October 7, 2016 at 9:45 pm

    Jon at #24
    Jon, Under no-wind conditions, a wind turbine that I speak of will effectively be a motor. I did not include auxiliaries .The fact remains that under those conditions, any potential benefit from the wind by way of capacity is lost. I am not interested in the ideology; just the facts.
    My comment about their performance during the doldrums in June was taken from a newspaper piece at the time. The point being made was that at a time when South Australia was experiencing power price spikes, wind was on standby and was of no use at all. To change that would require every turbine to be individually equipped with black start capability.
    I see the Magnus effect is getting some attention. Ideal for cyclonic conditions.

  17. Jon Sumby

    October 7, 2016 at 6:56 pm

    #23, just to clarify, it is a myth about wind generators consuming power when said in the way you have with no factual basis, thus implying that they are a burden on the system.

    It is fact that they do use some power because when wind farms are not generating they need power to run lights, computers, ancillary equipment, just as coal fired power stations need to do if they are not generating. The ratio of power generated to power consumed is more than 1000:1, so it is a furphy to imply that wind generators consume more than they produce.

    It is also true that, “Auxiliary load is an electricity load used within a power station as part of the electricity generation process – that is, it is an electricity load used in the making of electricity”. A wind generator is about 0.1% auxiliary load, a typical conventional power station auxiliary load is between 2% and 15%. For example, the Tamar Valley Power Station uses 3% of it’s generated electricity to run the power station itself.

    http://www.infigenenergy.com/comparing-wind-turbine-power-consumption-to-coal-and-gas/

  18. Second Opinion

    October 7, 2016 at 2:06 pm

    To Russell #16,
    Thanks Russell, I do not know what redundancy is built into the SA grid; it might take only the felling of one transmission tower to disable the entire grid in the existing configuration.
    My main point was that a large wind turbine that has an induction generator, relies on “slip” to function. In the absence of wind, such a generator will consume energy from the Grid. Such was the case in June 2016?; a period of low wind speeds, when wind power was consuming more power than it generated.
    Unlike a Permanent Magnet Alternator (PMA), which can itself deliver the excitation needed for operation, an induction generator under loss of Grid excitation, is rendered impotent. That is why the simplicity of the induction turbine, not withstanding the need for an up-gearing gearbox, does have consequences.
    There do exist large PMA turbines, which each require about 250kg. of neodymium and can work as a direct-drive
    generator.
    There is some video of the Basslink cable being manufactured and laid. It was Pirelli Cables, and Siemens, which manufactured and laid Basslink. Pirelli is now called Prysmian Cables. A local VK7 radio amateur has close-up photographs of the cable on his weblog but I can’t find it.

  19. Clive Stott

    October 6, 2016 at 8:53 pm

    #5 Neil, you were asking what the cores are made of.
    They are made of copper, see Jon’s cross section link in #20.

    Thanks for that Jon.
    Yes the armouring would be steel such as is used on many power cables of varying sizes.
    (Try cutting that armouring off with a mini hacksaw up the Snowy, or on Hydro dragline cables here in Tassie, in the middle of Winter).

    Basslink #2 has been raised. Check this 2012 Tas Times article by Chris Harries.
    http://oldtt.pixelkey.biz/index.php?/weblog/article/king-island-wind-power-and-basslink-mark-2/

  20. Pete Godfrey

    October 6, 2016 at 6:45 pm

    #19 nice link Clive. Yes I too hope that this is a piece of redundant cable. Either way after being treated like that it would have to be discarded.
    I would have thought that there would be a slightly gentler way of bringing the cable to the surface.

  21. Jon Sumby

    October 6, 2016 at 5:37 pm

    #19, Clive, you are correct. I was imprecise with my language. If you have a look at this cross section of the cable, I was meaning to refer to the armour layer around the power cables. As far as I know this is steel cabling.

    http://www.climatetasmania.org/wp-content/uploads/2016/03/Basslink.jpg

  22. Clive Stott

    October 6, 2016 at 4:14 pm

    Basslink’s 3 individual cables are bundled together with polypropylene rope.

    Then there is this which looks delicate and interesting 😉
    Hope that is a redundant piece of cable in the photograph.

    http://subseaworldnews.com/2016/01/27/pharos-subsea-hydraulic-cable-grab-helps-repair-basslink/

  23. Clive Stott

    October 6, 2016 at 3:59 pm

    John #13: You say, “Basslink is three cables bundled within a steel wire protective sheath. One is the fibre optic cable, the other two are the copper power cables.”

    Not true.
    Basslink is three separate cables. One is the big HVDC supply cable, one is the smaller MV(I think) return cable. The 3rd is the data cable.

    They are not bundled within a steel wire protective sheath, they are just tied together externally at intervals as the cable is laid.
    Photo here: http://www.abc.net.au/news/2016-08-04/basslink-refuses-to-attend-energy-crisis-inquiry/7688066

  24. Mick Kenny

    October 6, 2016 at 2:36 pm

    The many millions of losses incurred through the failure of Basslink are currently the subject of ongoing legal debate, as I understand things. This dispute would obviously seek to identify the cause and apportion liability and compensation, putting aside the seemingly reckless draining of hydro capacity that created the crisis once failure occurred. I suspect the evidence is out there somewhere but it is clear that the public are still in the dark, despite the power being back on again.

  25. Russell

    October 6, 2016 at 1:51 pm

    Re #11
    I worked in Email Relays Division (Melbourne) as an electrical fitter building, testing and installing the control equipment for the major Australian power stations back in the 1980s.

    If the power loss was due to instability, a gas or coal-fired power station connection would shut down just the same as a wind or solar generator to protect it’s infrastructure?

    If the power being generated can’t go anywhwere because of an external transmission line failure, I would think the result would be exactly the same without any renewables incorporated in the mix. That’s what happens during smaller blackouts isn’t it?

    It’s just that this time the weather event was massive, including two tornados being generated. The problem was entirely of a meteorologically caused nature.

  26. Russell

    October 6, 2016 at 1:38 pm

    “If the net is out of adjustment and dives into the seafloor these plates evidently can gouge deeply like a plough…” not to mention anything of the reef and marine habitat systems these things rip up, which are the nurseries of much of our marine life (ie: our food as well as theirs) and take years to build naturally.

    Why do you think the northern prawn fishing fields and their catch are getting smaller and smaller?

    Maybe a question for Nigel Scullion MP (advocate and former representative of the northern fishing industry)?

  27. Kelvin Jones

    October 6, 2016 at 1:04 pm

    Interesting piece of lateral thinking Pete……. Not implausible, it sends a shiver down my spine if it were so. Lateral thinking is what is needed to get behind the State Government’s “paucity” of information on Basslink.

    A friend of mine in UK has been reading Tas Times he is an ex academic and lived for a number of years in Australia and has quite a sardonic turn of phrase, here is a sample of his comments he made about Tasmania:….

    I followed the latest comments on the BassLink saga in the Tasmanian Times. Quite a multi-faceted debate is it not. Enough of you ‘stirrers’ exist to suggest the Geelong Star is culpable. From this part of the world, the state government’s avoidance behaviour and disingenuous seems absurd. Tassie is a relatively small place. The truth will out eventually. Better to face it now.

    I note that the Tassie Times considers itself a “cheeky, irreverent” alternative to mainstream media.. It certainly appears to be that. Reading it as an outsider the impression created is of an island populated by seething malcontents, venal local councillors,devious soothsayers, single agenda activists, and anti-government anarchists for whom any form of “rule” is the stuff of nightmares.

    Makes for a fun read though. Bit like reports on the annual Labour Party conference here in UK …………..!!!!

    If any one agree’s just say “I” those who don’t no doubt will write screeds decrying the comments…

    Thanks to “second opinion” on SA blackout which is an analysis based on sound electrical engineering principles. When electrical reports like the interim AEMO forSA are viewed according to the electrical laws they take on a different meaning to those perceived by an ordinary person (I am not being condescending). There is a major debate on the Gird network under “Turnbulls lunatic attack on renewable energy”.

    Decentralisation of energy is a very wonderful comment and worth of a whole thread itself and I have no doubt that the editor would love the commentator to start one off. I would love to contribute.

    Although I am the one who digressed from Basslink on this thread I am thinking like Pete Stott laterally on Basslink and the broader issues relating to government.

    I think the issue of the type of fault Basslink sustained is well and truly in the external mechanical trauma basket and narrowed down to a fishing vessel. We have got rid of electrical type myths as the cause of failure.

    It would not be unreasonable to expect formal investigation to access navigational data of the very few vessels meeting the physical criteria to determinate the actual one.

    That is as long as an offence was committed which has not yet been determined and this is an area which needs to researched. If it turns out that such an investigation should have/be taking place then the Government has a lot of questions to answer. We are not talking about the latest guided missile but a vital public utility.

    My reading of the Federal reports on Basslink was that it was not in favour for the reasons so rudely found out the hard way. It hardly seems enthusiastic now on Basslink2, and it is no doubt a topic in the current meeting of energy ministers.

    When discussing the relationship with people and technology always ask the question “in whose interest”. Invariably this means money and power but occasionally there altruistic reasons??????

  28. Jon Sumby

    October 6, 2016 at 11:36 am

    Basslink is three cables bundled within a steel wire protective sheath. One is the fibre optic cable, the other two are the copper power cables. The cable weighs 60 kilograms per metre in air.

    Kelvin, I don’t understand what you are describing; if you can provide a link I would be grateful.

    What I think you are talking about are otter trawl doors, or otter boards (I have never heard the term ‘flying doors’). Perhaps you are meaning the sumwing trawl gear? The only other thing I can think of is a clump weight which is used in pair trawls.

    Otter boards are used in bottom (demersal) trawling and in midwater (pelagic) trawling.

    In bottom trawling they keep the net mouth open and the otter boards drag along the bottom like a plough. The only thing about this is that in the Commonwealth Trawl Sector 2014-2016 bycatch and discards workplan, Bass Strait is closed to bottom trawling under their ‘threatened, endangered and protected’ (TEP) species rules.

    The Geelong Star is trawling for pelagic fish and is geared for midwater trawling and purse seining. It is undesirable and unlikely that the ship’s net would ever touch bottom. If it did the fishing master would have some serious questions to answer.

    The two methods are pictured and described at the bottom of this page:
    http://fish.gov.au/fishing_methods/Pages/nets.aspx

    There is also the Code of Conduct for Fishing and Anchoring with Basslink. The company supplies free electronic data sets for the many chart plotters on the market and this data gives the location of the cable.

    It is unlikely that the Geelong Star would get it’s gear wet anywhere near the cable, particularly with AFMA observers onboard.

    You can read the Code here:
    http://www.basslink.com.au/wp-content/uploads/2014/09/Code_of_Conduct.pdf

    The Code mentions demersal otter trawling, scallop dredging, and anchoring. Since bottom trawling is closed in Bass Strait this leaves scallop dredging and anchoring as possible causes of physical damage, if that is the cause as you say.

    The dredge used in the fishery is constructed of a heavy steel frame covered with steel mesh but open on the front side which is towed and is used to lift scallops out of the sand and mud. Along the lower steel bar at the front is an attached ‘toothbar’ that is made of pointed steel plate that drags along in the sediment and lifts scallops from the sea floor.

    I would suggest that if physical damage is the cause it would be far more likely to be from a scallop dredge, or an anchor drop.

  29. Factfinder

    October 6, 2016 at 4:35 am

    What is decentralised energy?

    Decentralised energy, as the name suggests, is produced close to where it will be used, rather than at a large plant elsewhere and sent through the national grid.

    This local generation reduces transmission losses and lowers carbon emissions. Security of supply is increased nationally as customers don’t have to share a supply or rely on relatively few, large and remote power stations.

    There can be economic benefits too. Long term decentralised energy can offer more competitive prices than traditional energy. While initial installation costs may be higher, a special decentralised energy tariff creates more stable pricing.

    For house builders, developers and PFI consortia, decentralised energy is the cost-effective route to achieving carbon targets. This approach to low carbon energy provision gives you the opportunity to promote a locally provided, sustainable, competitive and smarter energy choice.
    Source: https://www.eonenergy.com/for-your-business/large-energy-users/manage-energy/energy-efficiency/decentralised-energy-experts/What-is-decentralised-energy

    AND
    http://igrid.net.au/resources/downloads/project4/Australian_Decentralised Energy_Roadmap_December_2011.pdf

  30. Second Opinion

    October 6, 2016 at 3:33 am

    While it was a weather event that brought down the power transmission towers in SA, the widespread loss of power was due to an intrinsic characteristic of induction wind turbines in that, despite their combined contribution of 1000 MW. at the time, without a grid supplied constant voltage and frequency excitation, they become useless.
    Just as grid-connect solar PV has Anti-Islanding safe-guards which isolate your system upon loss of the grid, wind power is equally fragile.
    The South Australian situation was a case of When, not If….
    Wikipedia has an article on “Black Start”

  31. Clive Stott

    October 6, 2016 at 2:59 am

    Pete #9, not real sure about energy security from under sea cables that are prone to failure?

    And it is not only problems with the cable itself when we talk about Basslink and our energy security here in Tasmania.
    https://www.aemo.com.au/Electricity/National-Electricity-Market-NEM/Market-notices-and-events/-/media/D39B494D2EDB491D83CD1C48676A441D.ashx

    If what you put forward has some basis then we should have no problem configuring the valves on the interconnector so they only allow power to be imported into Tasmania.

    There would be no exporting until we get our energy in order here in Tasmania, and we don’t need a 2nd Basslink at a billion dollars to do that.

    Speaking of sinister, has it ever crossed your mind Pete that our last big power crisis could have been ‘engineered’ so as to bolster the case for a 2nd Basslink interconnector?

  32. Pete Godfrey

    October 5, 2016 at 8:44 pm

    This is a bit of a stab in the dark.
    I am wondering if the rush to get a second Basslink cable has more sinister reasons.
    The possibilities are endless but lets look at a couple.
    First Tasmania is almost totally reliant on Hydro Power. The Dams have a finite lifespan. Already Lake Rowallan Dam has needed extensive repairs to prevent failure.
    What if the Government know more than they are letting on. Wouldn’t that be novel.
    What if the infrastructure in Tasmania is ageing and in need of massive amounts of maintenance and rebuilding.
    Where would the power come from if we were to have to replace say, The Gordon Dam?
    If it was out of action we would lose 432 MegaWatts of generating capacity. Basslink would have to run flat out to keep up with the demand.
    Or say the pipelines from Great Lake needed replacing that would take out 393 MegaWatts, including Trevallyn power station.
    The Anthony/Pieman scheme puts out 472 Megawatts so taking it out for repairs is a big deal.
    Tasmania uses around 1100 MegaWatts of capacity in Summer and up to 1900MegaWatts in winter.
    That means that if one of these major systems went out for repairs Basslink would be stretched.
    Maybe the second Basslink idea has nothing to do with supplying power to the Big Island but everything to do with energy security here.

  33. phill Parsons

    October 5, 2016 at 2:30 pm

    #7 That the asynchronous can be made synchronous with an investment points to the failure of the piecemeal approach to renewables.

  34. Clive Stott

    October 5, 2016 at 8:39 am

    “While in Geelong, the team unloaded more than 84 tonnes of damaged cable…”

    http://www.basslink.com.au/wp-content/uploads/2016/04/Media-Statement-15-April-FINAL.pdf

    The only thing we don’t know is what caused this one-off event (comment #25) and it is time we did! Time for people to come clean.

    How did Basslink know to start looking for the cable fault at the Tasmanian end?

    When a protection operation on the Basslink Interconnector occurs, the line circuit breaker at the converter station that initiates the protection operation is opened.

    Re South Australia being blamed for renewable targets:

    Increasing non-synchronous loads from renewables can easily be overcome using synchronous condensers. These machines have a synchronised spinning mass (increases the synchronous inertia of a power system) but only consume a small amount of power.

    Mathew Groom seems to be putting the cart before the horse asking for federal money at COAG’s emergency Energy Council on Friday to lay a 2nd Basslink interconnector, when we haven’t been told what caused the damage to the first cable.

    You don’t go out and buy a 2nd new car because the 1st one you bought failed in service.

    Tasmania has bigger problems needing federal money than a 2nd Basslink cable!

    eg, Health, education, aged care, sewage and water….

  35. Clive Stott

    October 5, 2016 at 8:37 am

    I think the following answers what happened to the faulty section of cable mentioned in the previous thread:

    “Basslink has successfully pinpointed the fault location on the interconnector and removed it from the cable on Easter Sunday.

    The fault point was identified at 90.467km from the Tasmanian coastline. The cause of the fault is yet to be determined, subject to forensic testing.”

    http://www.basslink.com.au/wp-content/uploads/2016/03/Media-Statement-29-March.pdf

    “The faulty section of the Basslink power cable was removed in March.

    Basslink is awaiting a report from independent experts tests on the faulty section.”
    http://www.abc.net.au/news/2016-05-20/basslink-repair-ship-sets-sail-after-three-week-delay/7430306

    cont …

  36. Neil Smith

    October 4, 2016 at 11:45 pm

    Pete, I may be wrong but I doubt that the conductors in Basslink (both ways) are made of copper. That would have been cost prohibitive in the first place.

    More likely an aluminium alloy, which while not such a good conductor is much cheaper. As well as having a higher tensile strength making it safer to lay.

    Anyone who actually knows, please tell us.

    Neil

  37. Pete Godfrey

    October 4, 2016 at 8:36 pm

    #2 Hi Tim unfortunately with phone cables by the time they take the insulation off and strip them back to bare copper there would not be much left.
    I am sure over the whole country the weight would add up, the problem is getting the plastic off.
    In the bad old days people just burnt it off, but that is not so environmentally friendly.
    The basslink cable is another story, I read somewhere that it weighs around 80kg per metre.
    Loads of mula there.

  38. john hayward

    October 4, 2016 at 8:13 pm

    The evidence could stack up higher than Mt Ossa, but, with the bench and jury box filled with Liberals still counting a six figure donation from the fishing industry, my money is on the G Star copping something no worse than a hung jury.

    John Hayward

  39. Tim Thorne

    October 4, 2016 at 12:05 pm

    Pete (#1), your comment about the price of copper reminded me that I have never been able to get an answer to the question of what is going to happen to the thousands of kilometres of copper wire that have become redundant because of the NBN.

    I have asked several Telstra employees ever since we were among the lucky few to get fibre to the home, but the nearest thing to an answer I got was, “I think Telstra wants to sell it to the Chinese.”

    Meanwhile about twenty metres of it still attaches our house to a pole across the road.

  40. Pete Godfrey

    October 4, 2016 at 10:39 am

    Hi Kelvin, there is historical ships position data available but unfortunately we have to pay to get it.
    It seems that data stored on computers costs heaps to supply.
    If we want data on who owns a company, we can look up ASIC records and pay to see the information.
    Now we can look up data on ships on sites such as AIS Vessel Tracking but again we have to pay.
    John Hawkins said in your previous article that Basslink have left the off cuts of the cable on the ocean floor. I would have thought that with the price of scrap copper these days that they would have recovered it, even if it was to buy a few years grog supply for the shipmates.

Leave a Reply

Your email address will not be published. Required fields are marked *

To Top