But in the past having 700MW of thermal generation 350km distant from the main load in SA was perfectly OK!
The report indicates 438MW of thermal capacity was unavailable and this excludes the 75MW of Pelican Pt steam generation that is only available when the second GT is in operation. Thus 513MW (18%) of installed thermal capacity was unavailable on the day.
The bulk of Vic's thermal base load stations are on the eastern side of Mel +700km away, the Snowy is further as is NSW generation.
The loses from https://en.wikipedia.org/wiki/Electric_power_transmission#Losses
seem to indicate around 2-2.5% per 100km of travel. So about 15%, SA has to pay for that.
While pulling from 350km is also not the best outcome, its half the distance and feeds some of the customers along the way including large industry near by the station.
I read that the steam turbine (ST) runs at slightly less than 50% of capacity when only one gas Turbine (GT) is in operation. As my employer has about 20 x GT's running 8 x ST's, I tend to agree with that. That link posted by other recently also stated the same and specifically mentioned PP. (thats how I read it and open to correction). Running a GT without a ST is incredibly inefficient and expensive and usually only done for peaking purposes and the report stated that PP rarely runs 2 x GT's and the graph demonstrated this.
There is nothing wrong with SA being connected to the Vic grid to help provide a more balanced, efficient and secure load. But the level of dependency is exceeding common sense as demonstrated since Northern went off line.
SA has for reasons only known to them a rag tag number of small generators including the previous Northern that date back decades. Why are they doing this, its not recent decision its generational?
For a load of its SA's size (Nominally 1100MW lowest, 2800MW highest peak) and considering the coal resource it should by my book have 2 x base load generators physically separated to reduce risk. Looking at whats been built elsewhere in Oz (mostly Qld) in last 20 years the standard approach appears to be for a coal fired station is, twin turbine ~800-900MW depending on grade of coal. This should be built again at Port Augusta due to convenience of rail, water and local large demand.
Additionally a twin turbine GT with ST in Adelaide running on gas. Such as Pelican Point which is 160MW x 2 GT + 165MW ST = 485MW. However these are smaller units and I would go larger as combined with coal thats only 1335MW. If they had something around >250MW each or >750MW combined, thats >1600MW which covers probably 40% of the time.
On top of this you have 5 x peaking gas GT's adding another 300MW each for a total of 1500MW or grand total of 3100MW. Again for reliability of supply you would place these in two separate stations. The extra GT allows for 1 turbine to be off load and not connected to the SE qrid and still keep the lights on.
During winter the coal fires station would do its down time for maintenance, allowing 1 off at a time.
The inter tie with the SE grid provides further redundancy and allows the option to pull from Vic rather than use some/all the GT's during peak
This covers all bases all year round and gets SA off the front page of the developing world press as a laughing stock.
Now for RE
- PV roof top Solar, has minimal impact and only a few percent of total load and typically it peaks when demand peaks.
- Wind, wind is a great alt to use peaking supply (not capacity) when its available. Note I said PEAKING. However the push above ~1000 - 1200MW will cause significant harm and cost to the grid. Potentially it can be sold into Vic and NSW during times of excess and even the Base load gas can ramp down somewhat, but the viability of the base load gas power station should not be compromised. The wind energy also no longer needs to be subsidised.
Wind also needs to fund the Peaking gas plants to remain viable when on stand-by as that's winds insurance policy. So the ability for wind to sell into the grid more than say ~500 -750 MW should be limited to them paying for stand-by operation of the peaking stations. ie the owners still make a profit whether they are used or not.