[Smurfs1976]

On 20 December the Basslink power cable (HVDC) which links mainland Australia to the island state of Tasmania failed.

Investigation thus far suggests that the fault is offshore approximately 100km (60 miles) north of Tasmania and is not a fault with on-shore equipment at either end as was initially assumed. The underlying cause is unknown at this stage.

An international team involving experts from Italy and a ship from New Zealand is being assembled to carry out further investigation and repairs. Suggested time at this stage to restore the link is about 2 months (noting that the extent of the damage is presently unknown).

Basslink is the second longest undersea HVDC link in the world and has been in service since 2006. It is the only electrical link between Tasmania and mainland Australia.

All electricity load is at present still being supplied however the failure increases vulnerability on both sides since electricity is normally sent in either direction on an "as needed" basis.

Tasmania can meet its peak demand from local hydro generation but needs supply (generally taken overnight) from the mainland states to avoid overuse of water resources. The loss of the link will thus slowly drain the lakes unless rainfall is above average (recent months have been extremely dry however).

A mothballed gas-fired plant in Tasmania, the only fossil fuel power plant in the state, is being returned to service as soon as possible (estimated to be ready mid-January) which will replace about 45% of the power that was previously coming in via the cable. Depending on the weather, this may or may not be sufficient to stabilise water reserves but it will at least slow the rate of decline.

The mainland states of Victoria and South Australia, including the cities of Melbourne and Adelaide, rely to a modest extent on supply from Tasmania during times of peak demand, noting that demand in those states peaks at a very different time (Summer) when compared to Tasmania (Winter) such that sharing of generating capacity via the link is a practical option. Whether or not any supply problems occur in Victoria and SA will depend on the weather (temperature), reliability of generating plant in those states and the extent of wind generation during any major demand spike.

So overall there's some uncertainty as to the practical effects however loss of the link certainly does increase vulnerability if something else were to go wrong.

[SeaGypsy]

We are already in drought & it will get much worse. El Nino means very low rainfall for most of Oz for the next few years likely. By winter Tassie will be in trouble.

Sent from my HUAWEI Y520-U33 using Tapatalk

[Cog]

Let us not discount the possibility that a giant squid is involved or perhaps Godzilla.

[Shaved Monkey]

They were going to fire up their gas powered power plant this year because of the lack of water for hydro
Its sat dormant for 18 months as they were importing heaps of power via the cable,before it broke.

The dry conditions have led to Hydro importing about 40 per cent of the state's electricity needs via the undersea power cable Basslink, which is connected to the national electricity grid.

http://www.abc.net.au/news/2015-12-16/h ... 16/7034550

[Smurfs1976]

The Basslink cable has now returned to service after an outage which lasted almost 6 months.

The fault was found offshore and repair involved cutting the cable, lifting it to the surface and joining a new section in.

During the time of the outage:

Hydro storage levels in Tasmania reached a low of 12.9% (that's an all time record low) and have since recovered to 27.1% due to recent heavy rains.

6 temporary "power stations" were constructed at existing hydro power station and major sub-station sites and placed into base load operation. The temporary generating plants involved a total of around 150 individual generating units. Most were diesel engines but 3 gas turbines (oil-fired) were also obtained and installed for temporary operation.

All of this went from never having been thought of to actually running in a matter of weeks with equipment obtained from several countries. Quite an effort for all involved. Hauling the diesel was also a considerable operation and all done using road tankers with the fuel itself shipped in via the normal fuel terminals.

The temporary generation was all synchronised to the main grid and mostly operated for base load in order to conserve remaining water in the hydro system.

Also we air-freighted back a gas turbine (natural gas-fired) that was undergoing repairs overseas prior to the cable failure and place that and some other old open cycle GT's into base load production along with the modern CCGT plant at the same site. As a result a new all time natural gas consumption record was set on several occasions during the past 6 months with around 75% of all gas supplied into the state being used for electricity generation.

Of the individual water storages, the massive Lake Gordon (27 times the volume of Sydney Harbour when full) reached a low of 5.85% or 46 meters (151 feet) measured as a straight vertical drop below the full water level. The power station remained in operation during this time, mostly running all machines at full capacity until the diesel generators took up some of the load.

Other lakes also reached very low levels although Lake Gordon was the most extreme of the major storages. My video of Lake King William, another key storage, is here:

https://www.youtube.com/watch?v=YWWB1tLv-uU

As luck would have it, not only has the cable been fixed but the biggest problem we've had here over the past two weeks has been flooding rather than drought. Many of the smaller dams are now full with floods affecting a number of towns including the small city of Launceston. Lives have been lost in the floods unfortunately - the worst floods we've had since 1929 coming after one of the worst droughts on record.