Comment by Jean-Papoulos
3 days ago
>The company uses pure, purpose-made CO2 instead of sourcing it from emissions or the air, because those sources come with impurities and moisture that degrade the steel in the machinery.
So no environmental advantages. It's supposedly 30% cheaper than lithium-ion, but BYD cars have sodium-based based batteries on the road right now which CATL says will end up being 10-20$/kwh (10x cheaper than current batteries).
So what's the actual advantage of this ? I think it's just lucky to land just at the right time where batteries aren't cheaper enough yet.
To cite and expand on lambdaone below [1]:
> Clearly power capacity cost (scaling compressors/expanders and related kit) and energy storage cost (scaling gasbags and storage vessels) are decoupled from one another in this design
Lambdaone is differentiating between the costs to store energy (measured in kWh or Joules) and the costs to store energy per time (which is power, measured in Watts). If you want to store the whole excess energy that solar panels and wind turbines generate on a sunny, windy day, you need to have a lot of power storage capability (gigawatts of power generated during peak power generation). This can be profitable even if you only have a low energy storage capability, e.g. if you can only store a day worth of excess solar/wind energy, because you can sell this energy in the short term, for example in the next night, when the data centers are still running, but solar panels don't produce power. This is what batteries give you -- high power storage capabilities but low energy storage capacities.
Of course, you can always buy more batteries to increase the energy storage capacities, but they are very expensive per energy (kWh) stored. In contrast, these CO2 "batteries" are very cheap per energy (kWh) stored -- "just" build more high pressure tanks -- but expensive per power (Watts) stored, because to store more power, you need to build more expensive compressors, coolers etc. This ability to scale out the energy storage capability independently of the power storage capability is what Lambdaone was referring to with the decoupling.
For what is this useful? For shifting energy over a larger amount of time. Because energy storage costs of batteries are so high, they are a bad fit for storing excess energy in the summer (lots of solar) and releasing it in the winter (lots of heating). I'm not sure if these "CO2" batteries are good for such long time frames (maybe pressure loss is too high), but the claim most certainly is that they can shift energy over a longer time frame than is possible with batteries in an economically profitable fashion.
[1] https://news.ycombinator.com/item?id=46347251
What an excellent explanation, thanks
Even if sodium-ion really gets to $10–20/kWh, you still have degradation, cycle limits, fire risk, and a practical lifetime that's maybe 10–15 years
If it is barely cheaper than lithium, it's much more expensive than traditional pumped storage.
Yeah, it's expensive to build, but then cheap to run for decades.
It's nice that we explore alternatives but this just seems like investor bait
Pumped hydro is just not a valid comparison. I wish people would understand that already… it’s only good for long term storage in certain key geographical regions. Its use case is very limited.
You don’t want to used pumped hydro for short term storage because the rapid cycling will drive up the maintenance costs. You actually hear about hydro power plants talking about installing batteries to reduce wear.
In these discussions please keep in mind that frequency regulation, short term and long term shortage are different applications with different needs. The costs for pumped hydro are generally reported with their target application in mind. It’s not as applicable to dedicated short term storage and certainly not applicable to frequency regulation.
It's cute you think short cycles are somehow better in gas turbines and compressors and that you will restart the whole thing constantly to fill short term demands
> In these discussions please keep in mind that frequency regulation, short term and long term shortage are different applications with different needs.
The comparison is valid; If you want to fill hour to hour demand or add some frequency regulation, an inverter with a bunch of batteries is far, far better than this
> You don’t want to used pumped hydro for short term storage because the rapid cycling will drive up the maintenance costs. You actually hear about hydro power plants talking about installing batteries to reduce wear.
They are still cycled daily, that's the entire point of them that even worked pre renewables - load up on cheap night energy and unload it with demand. Renewables just flipped that to load in solar peak.
And putting few hours worth of batteries to reduce cycling is beneficial in both of those cases.
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Ireland is lucky enough to have several suitable sites, but just one operational: Turlough Hill, which has been running for over 50 years and is in use daily. It's at least as useful in terms of grid stability and (relatively) rapid dispatch as capacity. Output ~0.7% of total daily (~120GWh), ~5% of daily peak (~6GW), wintertime figures. For comparison electricity usage has increased about 8-fold since it was deployed in 1974.
AFAIU, pumped storage can only be built in very few locations around the globe.
This is mentioned in the article, that you need very specific topography for water pumped storage. Additionally, it can require a lot of space and be quite expensive and time-consuming to build.
Pumped hydro is not viable in most areas of the world. This is.
> So what's the actual advantage of this ?
I would posit that they hope Wright's Law will take hold; the components can be optimised and the deployment standardised. Also it looks as if most of the stuff can be made within the US or EU, dodging tariffs.
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