Inverters can easily replace physical inertia, it just requires technology developed within the past 30 years, and most grid folks haven't thought about new technology for far longer than that.
As more and more intermittent renewables get pushed onto grids, they become more reliable. Most outages are from single points of failure from large generators or transmission. Dealing with highly distributed renewables means that grid ops get used to acting fast, and there's greater redundancy instead of so many SPOF. Kind of how cloud services got reliable by expecting there to be failure and designing it into the system.
Storage is advancing super quickly, is super fast to deploy, and can replace a lot of more expensive things like transmission upgrades.
We have all the tech to replace fossil fuels on the grid with the above. The only question is the final cost. It's likely to be far far lower than using existing "hard" energy, because by the time we can deploy 50 TWhs of storage, it will have gotten so cheap. We don't know when costs will stabilize, but they have a loooong distance to fall.
And we have all sorts of other technologies that will make all this far cheaper: enhanced geothermal, enhanced geothermal with temporal storage based on injection pressure and release, iron air batteries, flow batteries, thermal storage for industrial process heat, etc. etc. etc.
For every area of the energy economy, there are two to three solutions that look promising. Fusion and fission look promising for none. That's not to say that they can't have some serious innovation and start dropping their costs, but nobody currently operating in the field has demonstrated a path. Yet.
> As more and more intermittent renewables get pushed onto grids, they become more reliable
This is called grid firming, and it’s massively expensive.
I don't think that's the same thing, but what expenses are you thinking of specifically? The German grid for example got much more reliable with additional solar.
Grids were designed to operate in tight tolerances. Cycling power levels up and down a lot, while handling the frequency variation lots of renewables inputs bring, wears down the grid without protective measures. Those measures are called firming [1].
Not sure what Germany did (or plans to do—you can run an unfirmed grid until stuff starts failing for several years).
[1] https://www.gevernova.com/gas-power/applications/grid-firmin...
"Capacity firming" will be carried out by legacy gas turbines as they run less and less, and eventually by batteries.
Batteries are also much better than gas at frequency regulation, and even at the prices a decade ago, completely took over the market for frequency regulation in the PJM market in the US. But frequency regulation is very very tiny in terms of power needs, it only takes a very small number of grid batteries to completely solve that problem.
The amount of batteries waiting in the interconnection queue completely dwarfs gas. There will be no "firming" coming from new gas turbines, unless old-school corrupt utilities are able to sneak it by PUCs by creating some sort of crisis and tricking them.
> "Capacity firming" will be carried out by legacy gas turbines as they run less and less, and eventually by batteries
At least among the American TSOs, there are zero I know of that plan to do this. Do you have a source for one that does?
Trillions have already been spent on gas. That infrastructure will need to earn its return through the 2040s at the very least, and that precludes running them exclusively for firming. To the extent retrofits are being discussed, it’s as an add-on amidst full peaked functionality.
> Batteries are also much better than gas at frequency regulation
Limiting solar and wind by utility-scale battery capacity means scaling back EV adoption or solar and wind deployment. The math simply doesn’t work. (Again, in America. Without significantly raising rates. Not sure elsewhere.)
> it only takes a very small number of grid batteries to completely solve that problem
Frequency regulation is one component of firming. Batteries are good at some components, marginal at others. (As a system. Technologically, they're fine.)
Apart from de-industrialised grids, a batteries-only approach has been practically abandoned through the 2030s. It's why we're building so many turbines and abandoning nukes.
If every (second) house would have a powerwall, wouldn't that make the grid stable?
> every (second) house would have a powerwall, wouldn't that make the grid stable?
At 131mm American households [1] and $11.5k per PoweWall [2] that’s over $750bn at 50% loading.
[1] https://www.statista.com/statistics/183635/number-of-househo...
[2] https://www.thisoldhouse.com/solar-alternative-energy/review...
China is starting to mass produce NaCl batteries. They will be cheaper.
And also only Powerwalls produced in this quantity would have way lower prices. My point was batteries are getting cheaper every day.
It could be less stable, if each and every powerwall is slightly out of phase.
But this is something, one can avoid by only allowing well tuned batteries to the grid? Or is this a serious problem to get right?
A powerwall is $12k installed.
That's about 5 years worth of power bills for most people.
What new technology changes things to not require spinning turbines?
Integrated circuits, basically. The term if "grid forming inverter" and the standards are somewhat new. I'm not an expert, but here is one standard, I don't know if it has been adopted or if others are preferred:
https://www.energy.gov/sites/default/files/2023-09/Specs%20f...
And they have been used where? Everything I can find suggests they are theoretical, not in use even on micro grids yet, and many have huge concerns about them being able to support a grid on their own.
Also the technology required has been around for decades it’s not new and no one’s done it yet.
So again what’s changed because it seems like for now there is no “I have a grid and need something now” solution it’s a “maybe one day”
Massive improvements to battery technology.
That’s a non answer - what improvement
It is an answer, in that batteries were used for frequency regulation far before they were used for energy arbitrage.
But the real innovation is communication networks and IC control of the inverter. It's completely possible to create a waveform that modulates and responds to variation in frequency in the same way a large spinning mass would. And if reactive power is for some reason not enough, synchronous condensers are very old technology to solve that.