Big difference between "it adds" and "possibly helps"...... devil in the execution details, I think most of us agree about that

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50+ years ago, we pretty much
only had Big Power Generation - that worked well, when we had govts that were focused on providing reliable low cost power. Big projects got done in a timely fashion, and electricity was relatively affordable. Me, I don't have a problem with that model, but realistically, the genie is out of the bottle, both in terms of free-markets, energy costs, and govts ability to fund major projects.
Add resiliency. A lot has changed in 50 years. Today, you can just stroke a cheque, and have a contractor install a turn-key automatic genset. Or a PV array. Or a PV array, with batteries, and choose to go off-grid when you want, or at least have Island capability when the grid is down. At that is just at home.
In the business/industrial world, co-gen or tri-gen has been in place for a long time, and likely won't be displaced. We have lots of distributed power generation sites connected now, from all sorts of sources. Can we readily support the grid from alternate sources, when a major plant goes down ? The answer obviously depends on many factors, at the time of a specific incident.
IMO, having alternate sources of power is useful, whether just at home, or for a grid system. Storage is a factor, that needs to be improved, it will be interesting to see how things go in Oz.
Ensuring reliability is a challenge for any system. One advantage to smaller generation points is if one (or ten) goes down, the impact can be relatively small, IF the system switching is capable.
So, while I do like the relative simplicity of the old Big Power model, I don't think we'll be going back there. If you described to somebody even 30 years ago sitting in your living room and using a cell phone to turn the light across the room on, they'd have laughed. There's been progress here in the last 20 years with distributed power generation, and I think we are only getting started.....
Rgds, D.