Nuclear is great but it is a terrible baseload for renewables because nuclear cannot just spin up and spin down like hydro or natural gas can.
I'm not.
>which have already demonstrated their viability in southern Australia.
They didn't. They replaced natural gas in one specific use-case, namely to provide grid stability. Those batteries (no batteries) are capable of bridging renewable variability.
When the wind is blowing. If the wind isn't blowing, you're not getting any power and you're going to have to fire up those coal/natural gas plants.
>when their new synchronous capacitor projects are completed they won't need stand by gas power plants.
How much power can these 'synchronous capacitors' store, and for how long? Can they even store enough to power a small city (~250k) for more than few mins? Let me spoil something for you, there is no battery technology that can scale to run a modern economy and hard industry. Not now, and not upcoming. If you have favorable geography, you may be able to do pumped storage, but that's about the best you can do.
Keep in mind that EVEN if you miraculously had something to store grid-scale power over a long-term, you need to greatly overprovision renewables because those 'batteries' need to be charged (with lots of energy loss) during peaks enough to bridge daily, seasonal and inter-year variability. And of course, land-use requirements for renewables is MASSIVE (from mining to deployment to decommissioning) - so renewables are very heavy on the environment. They aren't going to work.
There's a reason why no developed region relies on renewables without either fossil fuel backup (or if geography allows, geothermal or hydro). There's a reason why Germany is spending billions to build pipelines to ship natural gas from Russia for decades to come. What do they know about renewables, that you don't?