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- Aug 28, 2019 5:48 pm GMTAug 28, 2019 5:44 pm GMT
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This item is part of the Distributed Energy Resources - Special Issue - 09/2019, click here for more
In 1916, there was a virtually total blackout in the state of South Australia, (SA) -https://en.wikipedia.org/wiki/2016_South_Australian_blackout - the which I made a submission to the chief Scientist in Australia, Alan Finkel.
The problem was two fold, firstly SA was subjected to what is now grudgingly accepted to be called a Cold water/SubTropical Cyclone, which by the way, a Tropical cyclone, (Hurricane in the US?) can change into if it gets into colder water, - if it is strong enough, - we see this happening in Far North Queensland where Tropical Cyclones are not uncommon, if they get too far south, (south is colder in Oz).
It seems that the mindset that says Cyclones don’t go into colder water is wrong, although often disproved, hence the SA building standards were/are inadequate for a Sub TC, although as Global Warming progresses they will be more frequent, - there is a constant parade of big Lows just south of Australia.
So, if you read the blackout site link above, in total 23 huge steel pylons collapsed, - one nasty thing about Sub TC’s is that the peripheral winds, up to 200kms away from the centre, are the strongest, - opposite to a Tropical TC, so several interconnectors failed, - causing among other things, some wind turbines, - which have powered 70% of SA’s power system on occasion, and could have certainly this one, - to disconnect due to ‘stringent’ safety requirements, then as more interconnects failed, the East Australia Grid line to SA failed for the same reason the wind turbines failed and the whole house of cards, - including all the main wind turbines in the state, - which were thriving in the strong winds, to also disconnect.
Ignoring the stupid response of the Coal Industry controlled Federal Govt to blame the Wind Turbines, this is a very plausible situation to occur in any electricity network, and also shows the importance of electing flexible people to Govt. positions and looking very carefully at old managerial staff with outdated fantasy attitudes in Govt departments and private companies in the electrical grid network, in any country.. - times are a-changing.
Two things spring to mind to address in this discussion, one (1/-) is the ability of a network to sustain damage and continue functioning, the other (2/-) is the ability of a network or multiple networks to have high renewable energy input and still provide power if the renewable network, driven as it is by nature, finds nature capricious.
So, to consider 1/- what is needed is to separate individual networks in a state, and state to state, (easier as state to state has happened relatively recently in Oz and is often a single line, - eg South Australia. as a working example :)
So, if there is a partial shutdown in one part of the south Australian network, eg. by transmission towers being overset/inoperable, there needs to be a way to isolate that area, and then the areas which still have generation, (eg the wind turbines) allowed to continue, by having a device, (Inverter, powered in such a case by Batteries) that sets the frequency of the network for the area still able to function, - as if it was some sort of micro grid.
Currently the East Australia grid, has it’s frequency set by a specific very reliable turbine in the Snowy mountain network, although even that could have one of these Inverter back-up units.. - I suggest the Inverters produced by the Australian company Selectronics, as they can come in or butt out as the circumstances permit, - an unusually talented range of Inverters on the world market and Australian owned as well, but no doubt many Inverters around the world have that capability now.
So each individual network needs to have some generation capacity or be connected to another area with such, - upon such separation from the whole grid, all non critical loads, - Hot water systems, street lighting or whatever, could be disconnected as happens already with off peak supply.
During this very short period, a battery bank of sufficient size would keep the system functioning, in the Virtual Power Station mode, then that separated area having shed all non vital loads, - unless the Renewable energy available provided enough, - would function until the full extent of its situation could be analysed and any other rapidly available generation brought on line, that analysis would require seconds, if that, then the time to bring on line the available assets. - here a link to an earlier article, note particularly the usage of Hydro as a giant battery,
During that time also domestic and commercial “ home storage’ - if their owners had set up to do such, (and should be handsomely compensated, or lent money to so do) would be drawn on, and then the extra generation should be on line and that “Microgrid” - a city or a region or even a whole state, could be fine until the national connection is re-made.
Fitting in to this situation, is the need for Storage, currently Batteries, Hydro, as I have suggested in other articles, pumped Hydro, and fast start-up gas generators. One may consider Nuclear, but it’s dynamics are unsuitable, it can not ramp up quickly, and is indeed far too expensive to not run at full capacity all the time in any case, but a technology which uses similiar equipment to Nuclear, - ie heat exchangers to convert heat into electricity, is Geothermal, There is no doubt that the virtually pollution and green house free technology of Geothermal could completely replace the coal generated electricity supply in Australia and many countries and indeed, if our sun finally dims out, geothermal energy would allow us to survive for millions, if not billions, of years.
Geothermal is probably only worthy, due to sun, wind and moon provided energy and how incredibly cheap that is becoming, if nuclear was being considered, but as Storage, it is far more attractive, being able to ramp up very quickly.
As it uses the heat which has made it's way up from the centre of the earth one could argue it is not, sustainable, but on a site by site basis I think one can argue it is. - The heat in a particular site is gradually replaced from the surrounding and underlying rocks, heat that will gradually in any case make it's way to the surface of the earth and be lost in space.
Should a geothermal site be used as a back-up to wind and solar, not only will the original heat last longer but the replenishment will start to become a definite factor. Thus of all the baseload technologies it is the one to most benefit by being used less. The technology of the hole drilling is fully available as it is currently used by the oil drilling industry and the heat exchangers by the Nuclear industry, although they are not buying much these days..
Storage is the grease that links all the renewable technologies together, - wind, solar, tidal, (predictable for thousands of years in advance,) wave power, and bio generation, (eg from cities’ waste) as well as what may be yet developed, Geothermal, or long term Hydro used as storage is the long term solution, and the more (now cheap and becoming cheaper) renewable energy, just has to be connected to all each other, as that will supply very close to 100% dispatchable elecricity.
Distributed energy can allow areas of climate disaster, or other, to continue to provide citizens, in it’s area, electricity despite national grid collapse, - with adequate planning - and also add generating capacity to the entire national grid, either when other areas are low in generation or when there is excess generation, for example to allow cheap electricity to be supplied to eg aluminium/iron smelting, concrete/cement production, water de-salinisation fron the ocean, High energy very toxic waste destruction, Launching of space craft, and pumped Hydro, - no doubt you can all think of others.