Ann: South Erregulla Peaking Power Plant, page-69

I needed to get my head around size of 85Mw plant so will share this for others.
Exmouth WA has standalone power supplied through gas fed generators. Originally built as 8Mw to supply town of 3000 residents and commercial plus substantial tourist influx, note no grid connectivity with rest of WA.
85 Mw I guess would go close to supplying entire city of Geraldton (30k plus population), so it's a substantial generator and would become a critical part of the network.

As compared to equiv battery back up at an estimated $600k/ Mwh x 85Mw = $51m investment for 1hr of supply ( correct me if I'm wrong), then it is fully discharged.

Where as gas generated will have extended supply ability, gas in ground is the battery. Battery systems do have their place but supplying huge volumes for a city over long periods isn't it.