antimongo

Major issue with spinning up turbines over night is the actual gas turbine unit ramp rates. Meaning how quickly they can go from cold and offline to hot and full output. Some units take upwards of 8 hours to get to their full output.

And the peak load of an average grid is right when the sun is setting and everyone is getting home from work, around 5 in the afternoon.

At that time, solar is dropping fast, and you don’t have time to start up your slow units, they’d have to already be online.

So utilities are often forced to leave their gas units online, even when solar is pumping out power, just to have them ready for the peak demand (and also have them for night).

Agreed, energy density isn’t really very relevant from a grid perspective; space is pretty abundant when you’re talking about an entire grid region.

I was definitely hinting at the dispatch-ability of PV in my other comments, but you totally have the idea.

And it’s going to be batteries totally. At the publicly owned power utility I work at, I actually was in the energy storage technology group for a small stint. Whole purpose of the group was just running feasibility analyses on installing utility-scale batteries.

The core issue is batteries at scale are a completely infant technology. We had proposals that were literally straight out of graduate research. That’s great and all for the technology development, but my company only cares about reliability, dispatch-ability, and competitive rates. We’re not interested in prototypes.

I’d keep a close eye on molten salt batteries and flow batteries. I think those are the most developed. Especially flow batteries, companies like Sumitomo are making pretty big progress in Japan, and starting to move over to the US.

But again, issue is scale. A useful battery for a medium-sized utility is something like 50MW at 4 hours duration (equivalent to something like a peaker unit, though not all that useful for nighttime baseload). And this battery would be something in the range of like $250M. And a comparable gas peaker unit, about $80M, and that unit can run 24/7.

So the economics at utility scale are getting there, but we’re not there yet.

I do look forward to a 99% solar and battery grid though. With that 1% filled by emergency natural gas.

Solar can go in more diverse locations, absolutely. Especially advantageous because solar can be installed right on top of the buildings that need electricity. Lowers dependence on already-overloaded transmission lines.

Just from a utility perspective, it’s a lot simpler, easier to buy a plot of industrial zoned land, and stick a combined cycle on it. This is enough to power an entire medium city, 24/7.

Compared to logistically working with a massive number of private property owners to install solar on their property. And the result of all that work is enough to power the same city from 7 in the morning to 7 at night.

From a power-generated-per-area perspective, PV is about 500x less dense than a modern gas-fired combined cycle.