10 ms·

CO2 batteries that store grid energy take off globally

370 points by rbanffy 11mo ago

AndrewDucker 11mo ago
No mention of round-trip efficiencies, and claims are that it's 30% cheaper than Li-Ion. Which might give it an advantage for a while, but as Li-Ion has become 80% cheaper in the last decade that's not something which will necessarily continue. Great if it can continue to be cheaper, of course. Fingers crossed that they can make it work at scale.
- cogman10 11mo ago
  I'm seeing round trip efficiencies around 75%. That's not terrible. These things would probably pair well with district heating and cooling.
  - 3eb7988a1663 11mo ago
    That is shockingly good. EIA reports existing grid scale battery round trip is like 82% which do not have moving parts. ...in 2019, the U.S. utility-scale battery fleet operated with an average monthly round-trip efficiency of 82%, and pumped-storage facilities operated with an average monthly round-trip efficiency of 79%.... https://www.eia.gov/todayinenergy/detail.php?id=46756 https://www.eia.gov/todayinenergy/detail.php?id=46756
    - pbmonster 11mo ago
      > existing grid scale battery round trip is like 82% which do not have moving parts. This is incorrect for a lot of containerized lithium systems. They have a lot of moving parts in their AC systems - the compressors, the fans, the cooling water pumps. Lithium cells really don't like to be hot. If you put them next to solar farms in the sun belt or if you discharge them moderately quickly, you'll have to cool them. This cooling system also eats into the overall efficiency, but what's even worse is that its the majority of the maintenance budget.
  - lambdaone 11mo ago
    A theoretical study shows 77%, which is in the same ballpark: https://www.sciencedirect.com/science/article/pii/S1364032123011036 https://www.sciencedirect.com/science/article/pii/S136403212... A few percent here of there is not that important if the input energy is cheap enough.
  - hawk_ 11mo ago
    "I am seeing" as in do you use CO2 batteries at home or something?
- Gys 11mo ago
  Lithium supply is limited. So an alternative based on abundant materials is interesting for that reason I guess?
  - _aavaa_ 11mo ago
    Lithium is not that limited, current reserves are based on current exploration. More sources will be found and exploited as demand grows. And if you want an alternative, sodium batteries are already coming online.
    - standeven 11mo ago
      It's also very recyclable, so big batteries that reach end of life can contribute back to the lithium supply.
    - cogman10 11mo ago
      In fact, the limiting element for Li chemistries is generally the Nickel. Pretty much everything else that goes into these chemistries is highly available. Even something like Cobalt which is touted as unavailable is only that way because the industrial uses of cobalt is basically only li batteries. It's mined by hand not because that's the best way to get it, but because that's the cheapest way to get the small amount that's needed for batteries. Sodium iron phosphate batteries, if Li prices don't continue to fall, will be some of the cheapest batteries out there. If they can be made solid state then you are looking at batteries that will dominate things like grid and home power storage.
      - to11mtm 11mo ago
        > Even something like Cobalt which is touted as unavailable is only that way because the industrial uses of cobalt is basically only li batteries. AFAIR Cobalt is also kinda toxic which is a concern. But as far as that and > In fact, the limiting element for Li chemistries is generally the Nickel Isn't that part of why LiFePO was supposed to take off tho? Sure the energy density is a bit lower but theoretically they are cheaper to produce per kWh and don't have any of the toxicity/rarity issues of other lithium designs...
- scotty79 11mo ago
  Also sodium batteries are coming to the market at a fraction of the cost. "We’re matching the performance of [lithium iron phosphate batteries] at roughly 30% lower total cost of ownership for the system." Mukesh Chatter, cofounder and CEO, Alsym Energy
  - lambdaone 11mo ago
    I see this as complementary to other energy storage systems, including sodium ion batteries; each will have its own strengths and weaknesses. I expect energy storage density cost will be the critical parameter here, as this looks best suited to do diurnal storage for solar power systems near out-of-town predictable power consumers like data centers.
    - 3eb7988a1663 11mo ago
      Maintenance of the system is my biggest question. Lot of mechanical complexity with ensuring your gas containment, compressors, turbines, etc are all up to spec. This also seems like a system where you want to install the biggest capacity containment you can afford at the onset. All of that vs lithium/sodium where you can incrementally install batteries and let it operate without much concern. Maybe some heaters if they are installed in especially cold climates.
      - namibj 11mo ago
        Don't even really need notable heaters if you regulate your thermal vents enough.
      - ycui1986 11mo ago
        from the picture, the compressor and generator located inside the dome. the dome is filled with CO2. maintenance people have to carry oxygen tank, or they die.
        RobertoG 11mo ago
        they just do the maintenance when is empty?
- Herring 11mo ago
  Efficiency isn't that important if the input cost is low enough. Basically the utility is throwing it away (curtailment) so you probably can too. CAPEX is really the most important part of this.
- TrainedMonkey 11mo ago
  AFAIK cost here counts only the manufacturing side. While your conclusion that in the long run economies of scale will prevail, the lifetime costs are probably more than 30%. For example I expect recycling costs to be significantly worse for the Li-Ion.
  - namibj 11mo ago
    Grid scale LFP with once daily cycling lasts 30 years before the cells are degraded enough to think about recycling. And those are very low maintenance over that time. You're probably mostly going to swap voltage regulators and their fans, perhaps bypass the occasional bad cell by turning the current to zero, unscrewing the links from the adjacent cells to the bad cell, and screwing in a fresh link with the connect length to bridge across.
    - bickfordb 11mo ago
      Also: From what I understand the LFP battery degradation is essentially corrosion that is removed by recycling and you can retrieve 99% of the essential LFP elements and make it into a new battery. So economically we only need to extract the LFP related materials for each human user almost once, instead of oil over and over again.
  - gpm 11mo ago
    > For example I expect recycling costs to be significantly worse for the Li-Ion. I think there's a good argument for the opposite. Recycling costs for Li-Ion once we are doing it at scale should be significantly negative. There are valuable materials you get to extract, they aren't in that complex a blend to extract them from, and there's a lot of basically the same blend. The biggest risk in this claim is, I think, the implicit claim that we won't figure out how to extract the same materials from the earth much cheaper in the meantime cratering the end of life value of batteries - but in that event the CO2 battery technology is underwater anyways and the chemical batteries win on not wasting R&D costs. By contrast while there's some value in the steel that goes into building tanks and pumps and so on, the material cost if a much lower fraction of the cost of the device. Most of the cost went into shaping it into those complex shapes. I don't know for sure what the cost breakdown of the CO2 plant looks like but if a lot of the cost is something else it's probably something like concrete or white paint that actually costs money to dispose of.
- GeekyBear 11mo ago
  It's cheaper, doesn't involve the use of scarce resources, and is expected to have an operational lifetime that is three times longer than lithium ion storage facility. That's a significant difference.
  - namibj 11mo ago
    2021 total world energy production of approximately 172 PWh would require 27.5 billion metric tons of lithium metal at typical 0.16g/Wh of a modern LFP cell; meanwhile, we have approximately 230 billion metric tons of lithium for taking (e.g. as part of desalination plants producing many other elements at the same time from the pre-consecrated brine) from the oceans. Note that we require only a fraction of a year's worth of energy to be stored, I think less than 5% if we accept energy intensive industry in high latitude to take winter breaks, or even more with further tactics like higher overproduction or larger interconnected grid areas. And that's all without even the sodium batteries that do seem to be viable already.
    - cossatot 11mo ago
      Do you think desalinating 10% of the world's ocean water is feasible? What are the energy resources necessary to do that?
      - defrost 11mo ago
        Think of those numbers as one kind of in extreme case argument. Another reality is that most of the global grid scale energy usage is not transport via mobile batteries that benefits most from high energy density lithium batteries that pack maximal energy from least weight. Battery farms don't move, they can use other battery chemistries that are cheaper in resources and weigh a lot more per energy unit than lithium while still powering cities, smelters, processing plants, etc. As for desalination in general, yes, there will be a lot more of that in coming years, fresh potable water supplies are stretched from a global PoV.
    - deleted 11mo ago
      [deleted]
- dzhiurgis 11mo ago
  Batteries aren’t really suited for seasonal storage - they decay when fully charged. And foreseeable future they provide such huge value for grid stability that it wouldn’t make sense economically either.
  - PunchyHamster 11mo ago
    lithium yearly discharge is in single digit %, what a nonsense argument.
    - usrusr 11mo ago
      GP wasn't talking about discharge, losing a little energy, they were talking about wear and tear, as in the batteries aging fast while in a highly charged state. Battery recycling still hasn't really left the "we can do it in a lab" stage.
      - adrianN 11mo ago
        The supply side for battery recycling hasn’t really taken off yet. Wait another ten or twenty years until large numbers of electric cars reach eol.
      - PunchyHamster 11mo ago
        It's more coz digging new lithium is still cheaper.
- SwtCyber 11mo ago
  I agree with you: the real test isn't whether it's 30% cheaper today, but whether it holds its economics over 20–30 years at scale
- yohannparis 11mo ago
  Different solutions for different needs. It's good for engineers and planners to have multiple solutions available that provide better fit to their prerogatives and needs. We don't need one solution to do it all. We need plural ones.
readthenotes1 11mo ago
Does pure-ish CO2 have advantages over regular air or the freon-like substance used in air conditioning? How much energy us used to purify and maintain the CO2?
- cogman10 11mo ago
  It's pretty cheap to acquire a boatload of and, assuming you don't get it directly from burning fossil fuels, there's really no environmental harms of it leaking into the atmosphere. [1] [1] https://en.wikipedia.org/wiki/Carbon_capture_and_storage https://en.wikipedia.org/wiki/Carbon_capture_and_storage
  - zahlman 11mo ago
    > CCS could have a critical but limited role in reducing greenhouse gas emissions.[6] However, other emission-reduction options such as solar and wind energy, electrification, and public transit are less expensive than CCS and are much more effective at reducing air pollution. Given its cost and limitations, CCS is envisioned to be most useful in specific niches. These niches include heavy industry and plant retrofits.[8]: 21–24 > The cost of CCS varies greatly by CO2 source. If the facility produces a gas mixture with a high concentration of CO2, as is the case for natural gas processing, it can be captured and compressed for USD 15–25/tonne.[66] Power plants, cement plants, and iron and steel plants produce more dilute gas streams, for which the cost of capture and compression is USD 40–120/tonne CO2.[66] ... And then for this usage, presumably you'd have to separate the CO2 from the rest of the gas.
- analog31 11mo ago
  It's easy to liquefy, so it has a density advantage over air, and would be bad if released but not super bad.
  - 3eb7988a1663 11mo ago
    Suffocation seems like the most relevant concern in the event of a catastrophic leak.
deleted 11mo ago
[deleted]
lambdaone 11mo ago
This seems almost too good to be true, and the equipment is so simple that it would seem that this is a panacea. Where are the gotchas with this technology? 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; are there any numbers publicly available for either?
- zahlman 11mo ago
  Well, it isn't going to sink enough CO2 to move the needle: > If the worst happens and the dome is punctured, 2,000 tonnes of CO2 will enter the atmosphere. That’s equivalent to the emissions of about 15 round-trip flights between New York and London on a Boeing 777. “It’s negligible compared to the emissions of a coal plant,” Spadacini says. People will also need to stay back 70 meters or more until the air clears, he says. So it's really just about enabling solar etc.
  - api 11mo ago
    It’s a battery not a sequestration technology.
  - dmd 11mo ago
    It has nothing whatsoever to do with sinking CO2.
    - zahlman 11mo ago
      I understand this, but it coincidentally uses CO2 and it's hard for me to understand why the technology would sound "too good to be true" without imagining such a purpose.
      - andruby 11mo ago
        It's a one-time "use" though, it's not consuming CO2, so it's not going to move any needle
- 11mo ago
scotty79 11mo ago
"First, a compressor pressurizes the gas from 1 bar (100,000 pascals) to about 55 bar (5,500,000 pa). Next, a thermal-energy-storage system cools the CO2 to an ambient temperature. Then a condenser reduces it into a liquid that is stored in a few dozen pressure vessels, each about the size of a school bus. The whole process takes about 10 hours, and at the end of it, the battery is considered charged. To discharge the battery, the process reverses. The liquid CO2 is evaporated and heated. It then enters a gas-expander turbine, which is like a medium-pressure steam turbine. This drives a synchronous generator, which converts mechanical energy into electrical energy for the grid. After that, the gas is exhausted at ambient pressure back into the dome, filling it up to await the next charging phase."
- vaylian 11mo ago
  And I suppose the whole thing is a closed system? Which means, none of the CO2 would be released to the outside?
  - stubish 11mo ago
    Yes. If the CO2 was just released you would have to pay the energy cost to extract it from the atmosphere again.
  - scotty79 11mo ago
    Not intentionally during normal operation. I'm sure those things are gonna leak like hell, but still, it's just CO2 so it's not as bad.
alexchamberlain 11mo ago
Would this be effective at smaller volumes? Could it get down to say the size of a washing machine for use at home?
- lambdaone 11mo ago
  Very unlikely. All the technologies involved work best at scale; for example, the area-to-volume ratio of the liquid gas storage vessel is a critical parameter to keep energy losses low.
  - rgmerk 11mo ago
    Also, parasitic losses in engines tend to be proportionally lower as the engines get bigger. Compare the thermal efficiency of marine diesel engines to their automotive equivalents, for instance.
- kumarvvr 11mo ago
  The turbines would have to spin at very high speeds at those sizes to be efficient.
standardUser 11mo ago
I've been waiting for large-scale molten salt/rock batteries to take off. They've existed at utility scale for years but are still niche. They're not especially responsive and I imagine a facility to handle a mass amount of molten salt is not the easiest/cheapest thing to build. This sounds better in every way.
creativeSlumber 11mo ago
what happens if that large enclosure fails and the CO2 freely flows outside? That enclosure has a huge volume - area the size of several football fields, and at least 15 stories high. The article says it holds 2k tons of co2, which is ~1,000,000 cubic meters in volume. CO2 is denser than air will pool closer to the ground, and will suffocate anyone in the area. See https://en.wikipedia.org/wiki/Lake_Nyos_disaster https://en.wikipedia.org/wiki/Lake_Nyos_disaster Edit: It holds 2k tons, not 20K tons.
- tonfa 11mo ago
  > People will also need to stay back 70 meters or more until the air clears, he says.
  - SoftTalker 11mo ago
    Good luck running 70m in a CO2 dense atmosphere. And CO2 hugs the ground it does not float away. It will persist in low areas for quite a while. Anyone in the local vicinity would need to carry emergency oxygen at all times to be able to get to a safe distance in case of rupture. Otherwise it's a death sentence, and not a particularly pleasant one as CO2 is the signal that triggers the feeling of suffocation.
    - cycomanic 11mo ago
      It's unlikely that the thing will burst and disperse all CO2 immediately. It's just slightly higher pressure than the outside (that's the whole principle). So you have a slow leak of CO2 to the outside. You don't have to run that fast (or run at all). The way I understood the quote, the safety distance is when they have to do an emergency deflate (e.g. due to wind). The way they calculate the 70 m is probably based on the volume and how large of a area you cover until the height is low enough that you can still breath. Generally, because it's leaking to the outside, where there is going to be wind it will not stick around for long time I suspect.
      - andrewflnr 11mo ago
buckle8017 11mo ago
So it's a compressed air facility but it's using dry CO2 because it makes the process easier and CO2 is cheap. Not a carbon sequestration thing, but will likely fool some people into thinking it is. So the question is, how much does it cost? The article is completely silent on this, as expected.
- to11mtm 11mo ago
  > So the question is, how much does it cost? The article is completely silent on this, as expected. Honestly considering the design overall, I feel like one could make a single use science project version of this on a desk (i.e. aside from the CO2 recharging part) for under 200 bucks. 12oz CO2 tank, some sort of generator and whatever you need to spin it that is sealed, tubing, and a reclamation bag for the used CO2. And IMO using CO2 makes the rest of the design cheaper; Blow off valves are relatively cheap for this scenario, especially because CO2 gas system pressures are fairly low, and there's plenty of existing infrastructure around the safety margin. And I think even with blow off valves this could be a 'closed' system with minimal losses (although that would admittedly add to the cost...) I guess I'm saying is the main unknown is how expensive this regeneration system is for the quoted efficiency gains.
- thescriptkiddie 11mo ago
  The tanks to hold liquid CO2 will likely be a lot cheaper than compressed air tanks because the required pressure is much lower. But they are going to loose a lot of energy to cooling the gas and reheating the liquid. I would be surprised if the round-trip efficiency is higher than 25%.
  - alwa 11mo ago
    They claim 75% efficiency AC-AC [0], and they point out that there’s no degradation with time. What estimates are you using to arrive at the 25% figure? [0] https://energydome.com/co2-battery/ https://energydome.com/co2-battery/
    - thescriptkiddie 11mo ago
laurencerowe 11mo ago
> Energy Dome expects its LDES solution to be 30 percent cheaper than lithium-ion. Can see how this could scale up for longer storage fairly cheaply but on current trends batteries will have caught up in cost in 2-3 years.
- Smoosh 11mo ago
  Aren’t CATL already producing sodium-ion batteries for about 60% the cost of lithium-ion for equivalent capacity?
  - laurencerowe 11mo ago
    Yeah. Maybe this tech will have a place for week-long storage and be a good buffer for wind power but I hard to see the economics working for daily cycling.
nanomonkey 11mo ago
I'm curious if this method could be used along with super critical CO2 turbine generators. In other words after extracting the energy stored in compressed CO2, if you could then run it through a heat exchanger to bring it up to super critical temps and pressure and then utilize it as the working fluid in a turbine.
- pjc50 11mo ago
  It looks from the diagram that a turbine is the energy extraction mechanism? As you'd expect.
  - nanomonkey 11mo ago
    Correct, going from cold compressed liquid co2 though. For supercritical CO2 one would then heat up the gas and use it as a working fluid to turn the turbines further. If you could reuse the same turbine, one could store excess solar/wind energy in the compressed gas form, and then fire up a natural gas or biomass gasification reactor and then feed the heat into the system to produce more electricity on demand.
pfdietz 11mo ago
We don't need another few-hours storage technology. Batteries are going to clobber that. What we need is a storage technology with a duration of months. That would be truly complementary to these short term storage technologies.
- newyankee 11mo ago
  Had heard a lot about flow batteries few years back. I am guessing they are slowly taking off as well, the trial and error that explains their feasibility , need and ability to pay for themselves in a market like ERCOT is the key. This is one place where I think by 2030 a clear no of options will be established.
- 2thumbsup 11mo ago
  A few hours are sometimes enough to start generators when renewable energy supply decreases. Obviously, the more capacity the better, but costs will increase linearly with capacity in most cases. Pumped-storage hydroelectricity - where it is feasible - is the only kind of energy storage close to "months".
  - pfdietz 11mo ago
    The point is that's already a well-served market. These competitors are like alternative semiconductors going up against silicon.
  - ifwinterco 11mo ago
    You can store energy for months pretty easily as chemical energy. Just get some hydrogen, then join it to something else, maybe carbon, in the right proportion so it's a liquid at room temperature making it nice and easy to both store and transport. Wait a minute...
  - pfdietz 11mo ago
    Oh: pumped hydro is not a "months" storage technology. The capex per unit of storage capacity is far too high.
- perlgeek 11mo ago
kogasa240p 11mo ago
Been hearing about this project for years, nice to see that it's gaining traction! Only question is that if they use captured Co2 initially or if they have to produce it.
mark-r 11mo ago
They never mention what advantage CO2 has over any other gas, like plain air?
- oneiric 11mo ago
  The fluid in high pressure storage is a liquid, making the storage much cheaper. Liquid N2 (most of air) would require over 40 times more pressure or cold temperatures. Purifying out CO2 or any gas is generally a negligible cost.
klustregrif 11mo ago
> And in 2026, replicas of this plant will start popping up across the globe. > We mean that literally. It takes just half a day to inflate the bubble. The rest of the facility takes less than two years to build and can be done just about anywhere there’s 5 hectares of flat land. Gotta love the authors comitment to the bit. Wow, only half a day you say? And then just between 1 to 2 years more? Crazy.
- pjc50 11mo ago
  After the five years of planning approvals and grid connection approvals, of course.
nayuki 11mo ago
> The tried-and-true grid-scale storage option—pumped hydro [--> https://spectrum.ieee.org/a-big-hydro-project-in-big-sky-country https://spectrum.ieee.org/a-big-hydro-project-in-big-sky-cou... ], in which water is pumped between reservoirs at different elevations—lasts for decades and can store thousands of megawatts for days. > Media reports show renderings of domes but give widely varying storage capacities [--> https://www.bloominglobal.com/media/detail/worlds-largest-compressed-carbon-dioxide-energy-storage-project-tops-out https://www.bloominglobal.com/media/detail/worlds-largest-co... ]—including 100 MW and 1,000 MW. It looks like the article text is using the wrong unit for energy capacity in these contexts. I think it should be megawatt-hours, not megawatts. If this is true, this is a big yikes for something coming out of the Institute of Electrical and Electronics Engineers.
- B1FF_PSUVM 11mo ago
  > big yikes for something coming out of the Institute of Electrical and Electronics Engineers. Besides the unit flub, there's an unpleasant smell of sales flyer to the whole piece. Hard data spread all over, but couldn't find efficiency figures. Casual smears such as "even the best new grid-scale storage systems on the market—mainly lithium-ion batteries—provide only about 4 to 8 hours of storage" (huh, what, why?). I could also have used an explanation of why CO2, instead of nitrogen.
  - hkt 11mo ago
    I'm sat here thinking: why not compressed or liquefied air?
    - ted_dunning 11mo ago
      The basic issue is that they need a phase change at a reasonable temperature. Liquifying air requires much lower temperatures than CO2.
  - ycui1986 11mo ago
    i think it had something to do with CO2 can be made into supercritical state relatively easily, not for nitrogen or other common gases.
belviewreview 11mo ago
I seem to recall from an article I read about this technology a few years ago that it's efficient partly because when the gas is compressed, they are able to store the heat that is produced, and then later use the stored heat for expanding the gas.
- andrewflnr 11mo ago
  That seems important. I wish we knew how. I found an article that did mention the heat was "stored", with no further detail. The animation down on this page suggests it's stored in water somehow: https://energydome.com/co2-battery/ https://energydome.com/co2-battery/
ursAxZA 11mo ago
It might function as a kind of cogeneration-style buffer, but CO₂ still gets emitted in manufacturing and maintenance — and I’m not sure the volumetric efficiency is all that compelling. Still, if we ever end up with rows of these giant “balloons,” the landscape might look unexpectedly futuristic.
jmward01 11mo ago
As always, diversity in the energy ecosystem is a huge plus. Time and time again we see that 'one size fits all' is simply not true so I'm a fan of alternative approaches that use completely different principles. This enables the energy ecosystem to keep exploring the space of possibilities efficiently. I hope this continues to be developed.
- hn_throwaway_99 11mo ago
  > Time and time again we see that 'one size fits all' is simply not true Do we though? It feels like we're still in the stage where we're just trying to figure out what the best solution is for grid-scale storage, but once we do figure it out, the most efficient solution will win out over all the others. Yes, there may be some regional variation (e.g. TFA mentions how pumped hydro is great but only makes sense where geography supports it), but overall it feels like the world will eventually narrow things down to a very small number of solutions.
  - jmward01 11mo ago
    The point I was making isn't that we are or aren't actually narrowing down our options, it is that diversity of options is important. We have artificially limited diversity in our energy ecosystem and the rapid adoption of solar/wind/etc shows that. We could have been here decades ago if we actually encouraged diversity and exploration of alternate energy instead of actively discouraging it. Now that it is impossible to hold wind/solar back they are dominating. We should learn from that and encourage exploring diverse options in storage. Luckily I don't think storage has nearly the pushback that generation has had so I think it will be easier for many options to enter and find their niche.
mannyv 11mo ago
I have two solar panels that can generate around 960w/hr. Both panels cost around $400 ($200x2). Cheap. Storing that energy is quite expensive. an Anker Solix 3800, which is around 3.8kwh, costs $2400 USD. To store 10kwh would cost $7200 USD (which gets us more than 10kwh). If that cost asymmetry can come down then it becomes feasible to use solar power to provide cheap/local electricity in poor countries at a house scale.
- cornstalks 11mo ago
  There are way cheaper options than the Anker Solix 3800. Here are some options, in no particular order: - $3,300: 10 kWh with 2x EG4 WallMount Indoor 100Ah. - $3,110: 14 kWh with 1x WallMount Indoor 280Ah. - $2,690: 10 kWh with 1x Deye RW F10.2 B - Will Prowse's YouTube channel has reviewed several battery builds that are >10 kWh and near $2,000, but they're DIY assembly.
  - thradgt 11mo ago
    Batteryhookup has batteries for $40/kWh :) just put together a off grid setup for a friend and 8kwh cost $400 in parts!
    - mannyv 11mo ago
      I'll check that out. The goal is to get to something that runs all night (or almost all night) with around 1kwh output using as little space as possible. I've just started poking around, but this'll help. In the third world there's plenty of sunlight, but you don't need the power during the day necessarily. That price'll get to $400 for storage, $400 for panels, which is ballpark.
  - coryrc 11mo ago
    And still much more than the cost of the solar panels, which was GP's point.
    - cornstalks 11mo ago
ycui1986 11mo ago
no mentioning of storage overhead? how much energy being wasted for each charging and discharging cycle?
- chickenbig 11mo ago
  https://energydome.com/co2-battery/ https://energydome.com/co2-battery/ states 75% efficient.
idiotsecant 11mo ago
We desperately need mass energy storage. Everyone gets excited about renewable generation, but it is counterproductive without investing 5x-10x what we spend on generation in improved transmission and storage. It would be better to build 1/10th the amount of solar we do and pair it with appropriate energy storage than it is to just build solar panels. This is a crisis that almost nobody seems to talk about but is blindingly obvious when you look at socal energy price maps. The physics simply doesn't work without storage!!
calmbonsai 11mo ago
I ain't got time for this. Give me a paper, some numbers, and a plant flow diagram.
nashashmi 11mo ago
A better understanding of the science in the system: https://newatlas.com/energy/energy-dome-co2-sardinia/ https://newatlas.com/energy/energy-dome-co2-sardinia/ Similar discussion: https://news.ycombinator.com/item?id=44685067 https://news.ycombinator.com/item?id=44685067 (162p/153c)
unsigner 11mo ago
Peacetime technology from people who ignore the shooting war next door. Do you really want to build your energy system on huge soft targets? This looks much more vulnerable than solar arrays or battery installations to small-to-medium warheads (i.e anything from $500 FPV drones with an RPG round to $100k middle strike drones with 100 kg of payload).
- ehnto 11mo ago
  No reason this couldn't be put underground, except cost.
- lambdaone 11mo ago
  It could be made much less vulnerable by dividing the gas storage balloon structures into a set of multiple smaller structures, ideally with some further internal partitioning so a single punctured surface does not release all the gas in that structure. Everything else is as 'hard' or 'soft' as any other piece of industrial plant, and can be hardened further by putting it inside a reinforced building or set of buildings, internal redundancy etc.
- pmontra 11mo ago
  Customers will evaluate the risks. Thermal power plants are an easy target too, and oil and gas pipelines. And the oil tankers, according to the news of the last weeks. By the way, nobody cares about oil spills anymore. I guess all those ships were sailing empty /s
  - unsigner 11mo ago
    Of course they care about oil spills - this is why all the oil tankers in the last weeks were attacked when empty.
Jean-Papoulos 11mo ago
>The company uses pure, purpose-made CO2 instead of sourcing it from emissions or the air, because those sources come with impurities and moisture that degrade the steel in the machinery. So no environmental advantages. It's supposedly 30% cheaper than lithium-ion, but BYD cars have sodium-based based batteries on the road right now which CATL says will end up being 10-20$/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.
- PunchyHamster 11mo ago
  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
  - nazgul17 11mo ago
    AFAIU, pumped storage can only be built in very few locations around the globe.
    - 3D30497420 11mo ago
      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.
  - audunw 11mo ago
    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.
fulafel 11mo ago
There's remarkably little about the costs, given that's the main claim going for it vs the estabilished alternatives.
reader9274 11mo ago
Thunderf00t!! Get in here!
usrusr 11mo ago
I wonder how much Google is factoring in the implicit cooling cycle? Because any pressurized gas energy storage is either including some advanced heat storage or is just venting the heat created during compression (the ancient Huntorf facility in Germany is infamous for that, super wasteful) Usually you want to keep the heat and put it back into the compression medium during decompression and hope that losses from the heat storage aren't too big, but when you have a cooling use case nearby, you can use that low intensity heat to compensate heat storage losses, or even overcompensate. When you consider how much of the power input of a datacenter is typically used for cooling, compressed gas storage could be useful even if there was zero electric recovery (just time-shifting the power consumption for cooling to a time with better energy availability)
- SwtCyber 11mo ago
  If Google is colocating these with data centers, even low-grade heat that would otherwise be a loss could still be useful, or at least reduce how much active cooling the DC needs
- nirvael 11mo ago
  I'm sort of thinking out loud here but could you have two batteries running simultaneously but on opposite cycles, so while one is cooling the other is heating? Obviously it wouldn't be 100% efficient but it might reduce some wasted energy.
  - wongarsu 11mo ago
    The heat and cold are created by the compressing or decompressing the CO2 (our any other gas). If one battery is heating while the other needs heat that would imply that one is charging while the other discharges, which is rarely useful in normal operation
    - nirvael 11mo ago
      Yeah you're right I didn't think that through, why would you charge a battery while discharging another, just use the energy directly.
SwtCyber 11mo ago
The real question for me isn't the physics so much as ops over 20–30 years: maintenance, leakage, real-world efficiency after thousands of cycles
mapt 11mo ago
> The problem is that even the best new grid-scale storage systems on the market—mainly lithium-ion batteries—provide only about 4 to 8 hours of storage. This isn't the first time I've seen this sort of claim this week about batteries. If you're a journalist writing these words, stop doing that, and consider your life choices. Ask your boss for tuition assistance to put you through a 7th grade summer-school science class on matter and energy. If you're a journalist writing these words in an ostensibly technical engineering journal? Christ. I don't even know where to begin.
seydor 11mo ago
More blowing up than taking off
slfnflctd 11mo ago
People have been experimenting with compressed gas energy storage for a long time. This one may finally have legs. First thing I thought of was a startup from years ago, mildly surprised no one has mentioned it: https://en.wikipedia.org/wiki/LightSail_Energy https://en.wikipedia.org/wiki/LightSail_Energy I was really excited about them and was disappointed to see the project fail. It seems using pure CO2 and scaling up to a massive size are significant boosts to this type of technology (in addition to the heat mitigation along the way).
cramcgrab 11mo ago
I just plant trees. Have a ton of land in NY, just doing my part.
rbanffy 11mo ago
I have one concern: what if the container bursts? CO2 is heavier than air, and a sudden pressure decrease will cool it down further, so it'll hug the ground. What would be a safe distance for the people around the plant to live without the risk of being asphixiated in an accident?
- ragebol 11mo ago
  The article mentions > If the worst happens and the dome is punctured, 2,000 tonnes of CO2 will enter the atmosphere. That’s equivalent to the emissions of about 15 round-trip flights between New York and London on a Boeing 777. “It’s negligible compared to the emissions of a coal plant,” Spadacini says. People will also need to stay back 70 meters or more until the air clears, he says. So: 70 meters
  - gosub100 11mo ago
    > or more I guess it just depends on how much oxygen you really need.
pkphilip 11mo ago
Wasn't there a plan to use concrete blocks as energy storage medium by pulling them up a little bit at a time when there is surplus power?
- jvanderbot 11mo ago
  Sure, some people have proposed that, but if you calculate how much has to be lifted to get 20 MW stored (or so), it gets pretty ridiculous pretty quickly. Like "Lift the largest aircraft carrier 20 meters" silly. You have some pretty severe size/mass issues. It makes more sense to use water + a dam, but then again, we like to use water for things besides energy storage, and we're talking about a _lot_ of water. This gas bag is effectively the same as water+dam, except the pressure is from the tanks and the compressor creates it, vs pumping uphill to create pressure.
LikeBeans 11mo ago
I wonder how does it compare to hoisting a concrete (or something heavy) block up a pulley system as an energy store? When you need the energy you let it slide down pulling some steel cable that turns a generator, or multiple cables into multiple generators. Or even a cascade of concrete blocks at different heights as a space saver.
- sowbug 11mo ago
  The article does address that. ...and even dangling heavy objects in the air and dropping them. (The creativity devoted to LDES is impressive.) But geologic constraints, economic viability, efficiency, and scalability have hindered the commercialization of these strategies.
- cenamus 11mo ago
  Probably extremely poorly, as that's basically pumped hydro on _tiny_ scale. The amount of mass/water that fits into storage lakes is insane
  - LikeBeans 11mo ago
    Good point. I was thinking more about areas without much water and a large field of poles each hoisting several blocks. Sort of wind turbines but without the blades.
thallium205 11mo ago
Trees?
yoan9224 11mo ago
The round-trip efficiency comparison (60-75% vs lithium-ion's ~90%) is interesting but somewhat misleading without context. For grid-scale storage, the relevant question isn't efficiency in isolation - it's lifecycle economics including capex, degradation, and replacement cycles. Lithium-ion has superior efficiency but degrades significantly after 5,000-7,000 cycles, typically reaching 80% capacity in 7-10 years. If CO2 batteries can maintain performance for 20+ years with minimal degradation (which the article suggests), the lower efficiency becomes less relevant. You're trading 15-25% energy loss for potentially 2-3x longer operational life and no lithium supply chain dependencies. The real breakthrough is duration-flexible storage. Lithium-ion economics break down beyond 4-hour discharge rates because you're paying for both energy capacity and power capacity. CO2 systems decouple these - the turbine size determines power output, the storage tank size determines duration. That makes them ideal for seasonal storage patterns where you might charge for days during high renewable production and discharge slowly over weeks during winter lulls. What's missing from the article: what's the round-trip efficiency at different discharge rates? Does efficiency drop significantly when discharging over 12 hours vs 4 hours? That would determine whether these make sense for daily solar smoothing vs weekly wind intermittency vs seasonal storage.
- nine_k 11mo ago
  The system actually sort of uses the atmosphere as an ambient heat sink (when compressing) or heat source (when expanding). I wonder if that heat could be stored in a more sensible way, e.g. as heated water in a tank near the bubble. This could improve the efficiency figures at short repeating patterns (charding at high noon, discharging through the night).
  - anotherpaul 11mo ago
    As far as I understand they do try to keep the heat around for the next decompression. As of course they need it. But I could not find what type of heat storage they use. Ultimately they "only" seem to need to store it for 12h, right?
- whimsicalism 11mo ago
  I think it is generally polite to flag when you are using an LLM to write your comment, some people tire of reading the same style of writing over and over - even if the content of your comment is interesting!
javier_e06 11mo ago
So much potential! Get my CocaCola on the line! Heck give me Heineken too!
openasocket 11mo ago
I don’t know much about chemistry, but is there a reason why they are using CO2 as the gas medium instead of something else? I was thinking ambient air would be readily available, and you don’t have to worry about suffocating people if it ruptures. Is CO2 particularly efficient to compress?
- GoToRO 11mo ago
  Air is no good because it has moisture in it. When you decompress it, it becomes ice, blocking and breaking pipes.
euroderf 11mo ago
Had to wade thru miles of marketing muck to get to the tech talk.
Ayanonymous 11mo ago
I’m new to the idea of grid‑scale energy storage technologies, but this was a really clear and interesting introduction to how CO₂ batteries could help with long‑duration renewable energy storage. It’s exciting to see new approaches that might make solar and wind power more reliable and affordable. Thanks for sharing!

370 points by rbanffy 11mo ago

No mention of round-trip efficiencies, and claims are that it's 30% cheaper than Li-Ion. Which might give it an advantage for a while, but as Li-Ion has become 80% cheaper in the last decade that's not something which will necessarily continue. Great if it can continue to be cheaper, of course. Fingers crossed that they can make it work at scale.

cogman10 11mo ago
I'm seeing round trip efficiencies around 75%. That's not terrible. These things would probably pair well with district heating and cooling.
- 3eb7988a1663 11mo ago
  That is shockingly good. EIA reports existing grid scale battery round trip is like 82% which do not have moving parts. ...in 2019, the U.S. utility-scale battery fleet operated with an average monthly round-trip efficiency of 82%, and pumped-storage facilities operated with an average monthly round-trip efficiency of 79%.... https://www.eia.gov/todayinenergy/detail.php?id=46756 https://www.eia.gov/todayinenergy/detail.php?id=46756
  - pbmonster 11mo ago
    > existing grid scale battery round trip is like 82% which do not have moving parts. This is incorrect for a lot of containerized lithium systems. They have a lot of moving parts in their AC systems - the compressors, the fans, the cooling water pumps. Lithium cells really don't like to be hot. If you put them next to solar farms in the sun belt or if you discharge them moderately quickly, you'll have to cool them. This cooling system also eats into the overall efficiency, but what's even worse is that its the majority of the maintenance budget.
- lambdaone 11mo ago
  A theoretical study shows 77%, which is in the same ballpark: https://www.sciencedirect.com/science/article/pii/S1364032123011036 https://www.sciencedirect.com/science/article/pii/S136403212... A few percent here of there is not that important if the input energy is cheap enough.
- hawk_ 11mo ago
  "I am seeing" as in do you use CO2 batteries at home or something?
Gys 11mo ago
Lithium supply is limited. So an alternative based on abundant materials is interesting for that reason I guess?
- _aavaa_ 11mo ago
  Lithium is not that limited, current reserves are based on current exploration. More sources will be found and exploited as demand grows. And if you want an alternative, sodium batteries are already coming online.
  - standeven 11mo ago
    It's also very recyclable, so big batteries that reach end of life can contribute back to the lithium supply.
  - cogman10 11mo ago
    In fact, the limiting element for Li chemistries is generally the Nickel. Pretty much everything else that goes into these chemistries is highly available. Even something like Cobalt which is touted as unavailable is only that way because the industrial uses of cobalt is basically only li batteries. It's mined by hand not because that's the best way to get it, but because that's the cheapest way to get the small amount that's needed for batteries. Sodium iron phosphate batteries, if Li prices don't continue to fall, will be some of the cheapest batteries out there. If they can be made solid state then you are looking at batteries that will dominate things like grid and home power storage.
    - to11mtm 11mo ago
      > Even something like Cobalt which is touted as unavailable is only that way because the industrial uses of cobalt is basically only li batteries. AFAIR Cobalt is also kinda toxic which is a concern. But as far as that and > In fact, the limiting element for Li chemistries is generally the Nickel Isn't that part of why LiFePO was supposed to take off tho? Sure the energy density is a bit lower but theoretically they are cheaper to produce per kWh and don't have any of the toxicity/rarity issues of other lithium designs...
scotty79 11mo ago
Also sodium batteries are coming to the market at a fraction of the cost. "We’re matching the performance of [lithium iron phosphate batteries] at roughly 30% lower total cost of ownership for the system." Mukesh Chatter, cofounder and CEO, Alsym Energy
- lambdaone 11mo ago
  I see this as complementary to other energy storage systems, including sodium ion batteries; each will have its own strengths and weaknesses. I expect energy storage density cost will be the critical parameter here, as this looks best suited to do diurnal storage for solar power systems near out-of-town predictable power consumers like data centers.
  - 3eb7988a1663 11mo ago
    Maintenance of the system is my biggest question. Lot of mechanical complexity with ensuring your gas containment, compressors, turbines, etc are all up to spec. This also seems like a system where you want to install the biggest capacity containment you can afford at the onset. All of that vs lithium/sodium where you can incrementally install batteries and let it operate without much concern. Maybe some heaters if they are installed in especially cold climates.
    - namibj 11mo ago
      Don't even really need notable heaters if you regulate your thermal vents enough.
    - ycui1986 11mo ago
      from the picture, the compressor and generator located inside the dome. the dome is filled with CO2. maintenance people have to carry oxygen tank, or they die.
      - RobertoG 11mo ago
        they just do the maintenance when is empty?
Herring 11mo ago
Efficiency isn't that important if the input cost is low enough. Basically the utility is throwing it away (curtailment) so you probably can too. CAPEX is really the most important part of this.
TrainedMonkey 11mo ago
AFAIK cost here counts only the manufacturing side. While your conclusion that in the long run economies of scale will prevail, the lifetime costs are probably more than 30%. For example I expect recycling costs to be significantly worse for the Li-Ion.
- namibj 11mo ago
  Grid scale LFP with once daily cycling lasts 30 years before the cells are degraded enough to think about recycling. And those are very low maintenance over that time. You're probably mostly going to swap voltage regulators and their fans, perhaps bypass the occasional bad cell by turning the current to zero, unscrewing the links from the adjacent cells to the bad cell, and screwing in a fresh link with the connect length to bridge across.
  - bickfordb 11mo ago
    Also: From what I understand the LFP battery degradation is essentially corrosion that is removed by recycling and you can retrieve 99% of the essential LFP elements and make it into a new battery. So economically we only need to extract the LFP related materials for each human user almost once, instead of oil over and over again.
- gpm 11mo ago
  > For example I expect recycling costs to be significantly worse for the Li-Ion. I think there's a good argument for the opposite. Recycling costs for Li-Ion once we are doing it at scale should be significantly negative. There are valuable materials you get to extract, they aren't in that complex a blend to extract them from, and there's a lot of basically the same blend. The biggest risk in this claim is, I think, the implicit claim that we won't figure out how to extract the same materials from the earth much cheaper in the meantime cratering the end of life value of batteries - but in that event the CO2 battery technology is underwater anyways and the chemical batteries win on not wasting R&D costs. By contrast while there's some value in the steel that goes into building tanks and pumps and so on, the material cost if a much lower fraction of the cost of the device. Most of the cost went into shaping it into those complex shapes. I don't know for sure what the cost breakdown of the CO2 plant looks like but if a lot of the cost is something else it's probably something like concrete or white paint that actually costs money to dispose of.
GeekyBear 11mo ago
It's cheaper, doesn't involve the use of scarce resources, and is expected to have an operational lifetime that is three times longer than lithium ion storage facility. That's a significant difference.
- namibj 11mo ago
  2021 total world energy production of approximately 172 PWh would require 27.5 billion metric tons of lithium metal at typical 0.16g/Wh of a modern LFP cell; meanwhile, we have approximately 230 billion metric tons of lithium for taking (e.g. as part of desalination plants producing many other elements at the same time from the pre-consecrated brine) from the oceans. Note that we require only a fraction of a year's worth of energy to be stored, I think less than 5% if we accept energy intensive industry in high latitude to take winter breaks, or even more with further tactics like higher overproduction or larger interconnected grid areas. And that's all without even the sodium batteries that do seem to be viable already.
  - cossatot 11mo ago
    Do you think desalinating 10% of the world's ocean water is feasible? What are the energy resources necessary to do that?
    - defrost 11mo ago
      Think of those numbers as one kind of in extreme case argument. Another reality is that most of the global grid scale energy usage is not transport via mobile batteries that benefits most from high energy density lithium batteries that pack maximal energy from least weight. Battery farms don't move, they can use other battery chemistries that are cheaper in resources and weigh a lot more per energy unit than lithium while still powering cities, smelters, processing plants, etc. As for desalination in general, yes, there will be a lot more of that in coming years, fresh potable water supplies are stretched from a global PoV.
  - deleted 11mo ago
    [deleted]
dzhiurgis 11mo ago
Batteries aren’t really suited for seasonal storage - they decay when fully charged. And foreseeable future they provide such huge value for grid stability that it wouldn’t make sense economically either.
- PunchyHamster 11mo ago
  lithium yearly discharge is in single digit %, what a nonsense argument.
  - usrusr 11mo ago
    GP wasn't talking about discharge, losing a little energy, they were talking about wear and tear, as in the batteries aging fast while in a highly charged state. Battery recycling still hasn't really left the "we can do it in a lab" stage.
    - adrianN 11mo ago
      The supply side for battery recycling hasn’t really taken off yet. Wait another ten or twenty years until large numbers of electric cars reach eol.
    - PunchyHamster 11mo ago
      It's more coz digging new lithium is still cheaper.
SwtCyber 11mo ago
I agree with you: the real test isn't whether it's 30% cheaper today, but whether it holds its economics over 20–30 years at scale
yohannparis 11mo ago
Different solutions for different needs. It's good for engineers and planners to have multiple solutions available that provide better fit to their prerogatives and needs. We don't need one solution to do it all. We need plural ones.

readthenotes1 11mo ago

Does pure-ish CO2 have advantages over regular air or the freon-like substance used in air conditioning? How much energy us used to purify and maintain the CO2?

cogman10 11mo ago
It's pretty cheap to acquire a boatload of and, assuming you don't get it directly from burning fossil fuels, there's really no environmental harms of it leaking into the atmosphere. [1] [1] https://en.wikipedia.org/wiki/Carbon_capture_and_storage https://en.wikipedia.org/wiki/Carbon_capture_and_storage
- zahlman 11mo ago
  > CCS could have a critical but limited role in reducing greenhouse gas emissions.[6] However, other emission-reduction options such as solar and wind energy, electrification, and public transit are less expensive than CCS and are much more effective at reducing air pollution. Given its cost and limitations, CCS is envisioned to be most useful in specific niches. These niches include heavy industry and plant retrofits.[8]: 21–24 > The cost of CCS varies greatly by CO2 source. If the facility produces a gas mixture with a high concentration of CO2, as is the case for natural gas processing, it can be captured and compressed for USD 15–25/tonne.[66] Power plants, cement plants, and iron and steel plants produce more dilute gas streams, for which the cost of capture and compression is USD 40–120/tonne CO2.[66] ... And then for this usage, presumably you'd have to separate the CO2 from the rest of the gas.
analog31 11mo ago
It's easy to liquefy, so it has a density advantage over air, and would be bad if released but not super bad.
- 3eb7988a1663 11mo ago
  Suffocation seems like the most relevant concern in the event of a catastrophic leak.

deleted 11mo ago

[deleted]

lambdaone 11mo ago

This seems almost too good to be true, and the equipment is so simple that it would seem that this is a panacea. Where are the gotchas with this technology? 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; are there any numbers publicly available for either?

zahlman 11mo ago
Well, it isn't going to sink enough CO2 to move the needle: > If the worst happens and the dome is punctured, 2,000 tonnes of CO2 will enter the atmosphere. That’s equivalent to the emissions of about 15 round-trip flights between New York and London on a Boeing 777. “It’s negligible compared to the emissions of a coal plant,” Spadacini says. People will also need to stay back 70 meters or more until the air clears, he says. So it's really just about enabling solar etc.
- api 11mo ago
  It’s a battery not a sequestration technology.
- dmd 11mo ago
  It has nothing whatsoever to do with sinking CO2.
  - zahlman 11mo ago
    I understand this, but it coincidentally uses CO2 and it's hard for me to understand why the technology would sound "too good to be true" without imagining such a purpose.
    - andruby 11mo ago
      It's a one-time "use" though, it's not consuming CO2, so it's not going to move any needle
11mo ago

scotty79 11mo ago

"First, a compressor pressurizes the gas from 1 bar (100,000 pascals) to about 55 bar (5,500,000 pa). Next, a thermal-energy-storage system cools the CO2 to an ambient temperature. Then a condenser reduces it into a liquid that is stored in a few dozen pressure vessels, each about the size of a school bus. The whole process takes about 10 hours, and at the end of it, the battery is considered charged. To discharge the battery, the process reverses. The liquid CO2 is evaporated and heated. It then enters a gas-expander turbine, which is like a medium-pressure steam turbine. This drives a synchronous generator, which converts mechanical energy into electrical energy for the grid. After that, the gas is exhausted at ambient pressure back into the dome, filling it up to await the next charging phase."

vaylian 11mo ago
And I suppose the whole thing is a closed system? Which means, none of the CO2 would be released to the outside?
- stubish 11mo ago
  Yes. If the CO2 was just released you would have to pay the energy cost to extract it from the atmosphere again.
- scotty79 11mo ago
  Not intentionally during normal operation. I'm sure those things are gonna leak like hell, but still, it's just CO2 so it's not as bad.

alexchamberlain 11mo ago

Would this be effective at smaller volumes? Could it get down to say the size of a washing machine for use at home?

lambdaone 11mo ago
Very unlikely. All the technologies involved work best at scale; for example, the area-to-volume ratio of the liquid gas storage vessel is a critical parameter to keep energy losses low.
- rgmerk 11mo ago
  Also, parasitic losses in engines tend to be proportionally lower as the engines get bigger. Compare the thermal efficiency of marine diesel engines to their automotive equivalents, for instance.
kumarvvr 11mo ago
The turbines would have to spin at very high speeds at those sizes to be efficient.

standardUser 11mo ago

I've been waiting for large-scale molten salt/rock batteries to take off. They've existed at utility scale for years but are still niche. They're not especially responsive and I imagine a facility to handle a mass amount of molten salt is not the easiest/cheapest thing to build. This sounds better in every way.

creativeSlumber 11mo ago

what happens if that large enclosure fails and the CO2 freely flows outside? That enclosure has a huge volume - area the size of several football fields, and at least 15 stories high. The article says it holds 2k tons of co2, which is ~1,000,000 cubic meters in volume. CO2 is denser than air will pool closer to the ground, and will suffocate anyone in the area. See https://en.wikipedia.org/wiki/Lake_Nyos_disaster https://en.wikipedia.org/wiki/Lake_Nyos_disaster Edit: It holds 2k tons, not 20K tons.

tonfa 11mo ago
> People will also need to stay back 70 meters or more until the air clears, he says.
- SoftTalker 11mo ago
  Good luck running 70m in a CO2 dense atmosphere. And CO2 hugs the ground it does not float away. It will persist in low areas for quite a while. Anyone in the local vicinity would need to carry emergency oxygen at all times to be able to get to a safe distance in case of rupture. Otherwise it's a death sentence, and not a particularly pleasant one as CO2 is the signal that triggers the feeling of suffocation.
  - cycomanic 11mo ago
    It's unlikely that the thing will burst and disperse all CO2 immediately. It's just slightly higher pressure than the outside (that's the whole principle). So you have a slow leak of CO2 to the outside. You don't have to run that fast (or run at all). The way I understood the quote, the safety distance is when they have to do an emergency deflate (e.g. due to wind). The way they calculate the 70 m is probably based on the volume and how large of a area you cover until the height is low enough that you can still breath. Generally, because it's leaking to the outside, where there is going to be wind it will not stick around for long time I suspect.
    - andrewflnr 11mo ago

buckle8017 11mo ago

So it's a compressed air facility but it's using dry CO2 because it makes the process easier and CO2 is cheap. Not a carbon sequestration thing, but will likely fool some people into thinking it is. So the question is, how much does it cost? The article is completely silent on this, as expected.

to11mtm 11mo ago
> So the question is, how much does it cost? The article is completely silent on this, as expected. Honestly considering the design overall, I feel like one could make a single use science project version of this on a desk (i.e. aside from the CO2 recharging part) for under 200 bucks. 12oz CO2 tank, some sort of generator and whatever you need to spin it that is sealed, tubing, and a reclamation bag for the used CO2. And IMO using CO2 makes the rest of the design cheaper; Blow off valves are relatively cheap for this scenario, especially because CO2 gas system pressures are fairly low, and there's plenty of existing infrastructure around the safety margin. And I think even with blow off valves this could be a 'closed' system with minimal losses (although that would admittedly add to the cost...) I guess I'm saying is the main unknown is how expensive this regeneration system is for the quoted efficiency gains.
thescriptkiddie 11mo ago
The tanks to hold liquid CO2 will likely be a lot cheaper than compressed air tanks because the required pressure is much lower. But they are going to loose a lot of energy to cooling the gas and reheating the liquid. I would be surprised if the round-trip efficiency is higher than 25%.
- alwa 11mo ago
  They claim 75% efficiency AC-AC [0], and they point out that there’s no degradation with time. What estimates are you using to arrive at the 25% figure? [0] https://energydome.com/co2-battery/ https://energydome.com/co2-battery/
  - thescriptkiddie 11mo ago

laurencerowe 11mo ago

> Energy Dome expects its LDES solution to be 30 percent cheaper than lithium-ion. Can see how this could scale up for longer storage fairly cheaply but on current trends batteries will have caught up in cost in 2-3 years.

Smoosh 11mo ago
Aren’t CATL already producing sodium-ion batteries for about 60% the cost of lithium-ion for equivalent capacity?
- laurencerowe 11mo ago
  Yeah. Maybe this tech will have a place for week-long storage and be a good buffer for wind power but I hard to see the economics working for daily cycling.

nanomonkey 11mo ago

I'm curious if this method could be used along with super critical CO2 turbine generators. In other words after extracting the energy stored in compressed CO2, if you could then run it through a heat exchanger to bring it up to super critical temps and pressure and then utilize it as the working fluid in a turbine.

pjc50 11mo ago
It looks from the diagram that a turbine is the energy extraction mechanism? As you'd expect.
- nanomonkey 11mo ago
  Correct, going from cold compressed liquid co2 though. For supercritical CO2 one would then heat up the gas and use it as a working fluid to turn the turbines further. If you could reuse the same turbine, one could store excess solar/wind energy in the compressed gas form, and then fire up a natural gas or biomass gasification reactor and then feed the heat into the system to produce more electricity on demand.

pfdietz 11mo ago

We don't need another few-hours storage technology. Batteries are going to clobber that. What we need is a storage technology with a duration of months. That would be truly complementary to these short term storage technologies.

newyankee 11mo ago
Had heard a lot about flow batteries few years back. I am guessing they are slowly taking off as well, the trial and error that explains their feasibility , need and ability to pay for themselves in a market like ERCOT is the key. This is one place where I think by 2030 a clear no of options will be established.
2thumbsup 11mo ago
A few hours are sometimes enough to start generators when renewable energy supply decreases. Obviously, the more capacity the better, but costs will increase linearly with capacity in most cases. Pumped-storage hydroelectricity - where it is feasible - is the only kind of energy storage close to "months".
- pfdietz 11mo ago
  The point is that's already a well-served market. These competitors are like alternative semiconductors going up against silicon.
- ifwinterco 11mo ago
  You can store energy for months pretty easily as chemical energy. Just get some hydrogen, then join it to something else, maybe carbon, in the right proportion so it's a liquid at room temperature making it nice and easy to both store and transport. Wait a minute...
- pfdietz 11mo ago
  Oh: pumped hydro is not a "months" storage technology. The capex per unit of storage capacity is far too high.
perlgeek 11mo ago

kogasa240p 11mo ago

Been hearing about this project for years, nice to see that it's gaining traction! Only question is that if they use captured Co2 initially or if they have to produce it.

mark-r 11mo ago

They never mention what advantage CO2 has over any other gas, like plain air?

oneiric 11mo ago
The fluid in high pressure storage is a liquid, making the storage much cheaper. Liquid N2 (most of air) would require over 40 times more pressure or cold temperatures. Purifying out CO2 or any gas is generally a negligible cost.

klustregrif 11mo ago

> And in 2026, replicas of this plant will start popping up across the globe. > We mean that literally. It takes just half a day to inflate the bubble. The rest of the facility takes less than two years to build and can be done just about anywhere there’s 5 hectares of flat land. Gotta love the authors comitment to the bit. Wow, only half a day you say? And then just between 1 to 2 years more? Crazy.

pjc50 11mo ago
After the five years of planning approvals and grid connection approvals, of course.

nayuki 11mo ago

> The tried-and-true grid-scale storage option—pumped hydro [--> https://spectrum.ieee.org/a-big-hydro-project-in-big-sky-country https://spectrum.ieee.org/a-big-hydro-project-in-big-sky-cou... ], in which water is pumped between reservoirs at different elevations—lasts for decades and can store thousands of megawatts for days. > Media reports show renderings of domes but give widely varying storage capacities [--> https://www.bloominglobal.com/media/detail/worlds-largest-compressed-carbon-dioxide-energy-storage-project-tops-out https://www.bloominglobal.com/media/detail/worlds-largest-co... ]—including 100 MW and 1,000 MW. It looks like the article text is using the wrong unit for energy capacity in these contexts. I think it should be megawatt-hours, not megawatts. If this is true, this is a big yikes for something coming out of the Institute of Electrical and Electronics Engineers.

B1FF_PSUVM 11mo ago
> big yikes for something coming out of the Institute of Electrical and Electronics Engineers. Besides the unit flub, there's an unpleasant smell of sales flyer to the whole piece. Hard data spread all over, but couldn't find efficiency figures. Casual smears such as "even the best new grid-scale storage systems on the market—mainly lithium-ion batteries—provide only about 4 to 8 hours of storage" (huh, what, why?). I could also have used an explanation of why CO2, instead of nitrogen.
- hkt 11mo ago
  I'm sat here thinking: why not compressed or liquefied air?
  - ted_dunning 11mo ago
    The basic issue is that they need a phase change at a reasonable temperature. Liquifying air requires much lower temperatures than CO2.
- ycui1986 11mo ago
  i think it had something to do with CO2 can be made into supercritical state relatively easily, not for nitrogen or other common gases.

belviewreview 11mo ago

I seem to recall from an article I read about this technology a few years ago that it's efficient partly because when the gas is compressed, they are able to store the heat that is produced, and then later use the stored heat for expanding the gas.

andrewflnr 11mo ago
That seems important. I wish we knew how. I found an article that did mention the heat was "stored", with no further detail. The animation down on this page suggests it's stored in water somehow: https://energydome.com/co2-battery/ https://energydome.com/co2-battery/

ursAxZA 11mo ago

It might function as a kind of cogeneration-style buffer, but CO₂ still gets emitted in manufacturing and maintenance — and I’m not sure the volumetric efficiency is all that compelling. Still, if we ever end up with rows of these giant “balloons,” the landscape might look unexpectedly futuristic.

jmward01 11mo ago

As always, diversity in the energy ecosystem is a huge plus. Time and time again we see that 'one size fits all' is simply not true so I'm a fan of alternative approaches that use completely different principles. This enables the energy ecosystem to keep exploring the space of possibilities efficiently. I hope this continues to be developed.

hn_throwaway_99 11mo ago
> Time and time again we see that 'one size fits all' is simply not true Do we though? It feels like we're still in the stage where we're just trying to figure out what the best solution is for grid-scale storage, but once we do figure it out, the most efficient solution will win out over all the others. Yes, there may be some regional variation (e.g. TFA mentions how pumped hydro is great but only makes sense where geography supports it), but overall it feels like the world will eventually narrow things down to a very small number of solutions.
- jmward01 11mo ago
  The point I was making isn't that we are or aren't actually narrowing down our options, it is that diversity of options is important. We have artificially limited diversity in our energy ecosystem and the rapid adoption of solar/wind/etc shows that. We could have been here decades ago if we actually encouraged diversity and exploration of alternate energy instead of actively discouraging it. Now that it is impossible to hold wind/solar back they are dominating. We should learn from that and encourage exploring diverse options in storage. Luckily I don't think storage has nearly the pushback that generation has had so I think it will be easier for many options to enter and find their niche.

mannyv 11mo ago

I have two solar panels that can generate around 960w/hr. Both panels cost around $400 ($200x2). Cheap. Storing that energy is quite expensive. an Anker Solix 3800, which is around 3.8kwh, costs $2400 USD. To store 10kwh would cost $7200 USD (which gets us more than 10kwh). If that cost asymmetry can come down then it becomes feasible to use solar power to provide cheap/local electricity in poor countries at a house scale.

cornstalks 11mo ago
There are way cheaper options than the Anker Solix 3800. Here are some options, in no particular order: - $3,300: 10 kWh with 2x EG4 WallMount Indoor 100Ah. - $3,110: 14 kWh with 1x WallMount Indoor 280Ah. - $2,690: 10 kWh with 1x Deye RW F10.2 B - Will Prowse's YouTube channel has reviewed several battery builds that are >10 kWh and near $2,000, but they're DIY assembly.
- thradgt 11mo ago
  Batteryhookup has batteries for $40/kWh :) just put together a off grid setup for a friend and 8kwh cost $400 in parts!
  - mannyv 11mo ago
    I'll check that out. The goal is to get to something that runs all night (or almost all night) with around 1kwh output using as little space as possible. I've just started poking around, but this'll help. In the third world there's plenty of sunlight, but you don't need the power during the day necessarily. That price'll get to $400 for storage, $400 for panels, which is ballpark.
- coryrc 11mo ago
  And still much more than the cost of the solar panels, which was GP's point.
  - cornstalks 11mo ago

ycui1986 11mo ago

no mentioning of storage overhead? how much energy being wasted for each charging and discharging cycle?

chickenbig 11mo ago
https://energydome.com/co2-battery/ https://energydome.com/co2-battery/ states 75% efficient.

idiotsecant 11mo ago

We desperately need mass energy storage. Everyone gets excited about renewable generation, but it is counterproductive without investing 5x-10x what we spend on generation in improved transmission and storage. It would be better to build 1/10th the amount of solar we do and pair it with appropriate energy storage than it is to just build solar panels. This is a crisis that almost nobody seems to talk about but is blindingly obvious when you look at socal energy price maps. The physics simply doesn't work without storage!!

calmbonsai 11mo ago

I ain't got time for this. Give me a paper, some numbers, and a plant flow diagram.

nashashmi 11mo ago

A better understanding of the science in the system: https://newatlas.com/energy/energy-dome-co2-sardinia/ https://newatlas.com/energy/energy-dome-co2-sardinia/ Similar discussion: https://news.ycombinator.com/item?id=44685067 https://news.ycombinator.com/item?id=44685067 (162p/153c)

unsigner 11mo ago

Peacetime technology from people who ignore the shooting war next door. Do you really want to build your energy system on huge soft targets? This looks much more vulnerable than solar arrays or battery installations to small-to-medium warheads (i.e anything from $500 FPV drones with an RPG round to $100k middle strike drones with 100 kg of payload).

ehnto 11mo ago
No reason this couldn't be put underground, except cost.
lambdaone 11mo ago
It could be made much less vulnerable by dividing the gas storage balloon structures into a set of multiple smaller structures, ideally with some further internal partitioning so a single punctured surface does not release all the gas in that structure. Everything else is as 'hard' or 'soft' as any other piece of industrial plant, and can be hardened further by putting it inside a reinforced building or set of buildings, internal redundancy etc.
pmontra 11mo ago
Customers will evaluate the risks. Thermal power plants are an easy target too, and oil and gas pipelines. And the oil tankers, according to the news of the last weeks. By the way, nobody cares about oil spills anymore. I guess all those ships were sailing empty /s
- unsigner 11mo ago
  Of course they care about oil spills - this is why all the oil tankers in the last weeks were attacked when empty.

Jean-Papoulos 11mo 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.

PunchyHamster 11mo ago
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
- nazgul17 11mo ago
  AFAIU, pumped storage can only be built in very few locations around the globe.
  - 3D30497420 11mo ago
    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.
- audunw 11mo ago
  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.

fulafel 11mo ago

There's remarkably little about the costs, given that's the main claim going for it vs the estabilished alternatives.

reader9274 11mo ago

Thunderf00t!! Get in here!

usrusr 11mo ago

I wonder how much Google is factoring in the implicit cooling cycle? Because any pressurized gas energy storage is either including some advanced heat storage or is just venting the heat created during compression (the ancient Huntorf facility in Germany is infamous for that, super wasteful) Usually you want to keep the heat and put it back into the compression medium during decompression and hope that losses from the heat storage aren't too big, but when you have a cooling use case nearby, you can use that low intensity heat to compensate heat storage losses, or even overcompensate. When you consider how much of the power input of a datacenter is typically used for cooling, compressed gas storage could be useful even if there was zero electric recovery (just time-shifting the power consumption for cooling to a time with better energy availability)

SwtCyber 11mo ago
If Google is colocating these with data centers, even low-grade heat that would otherwise be a loss could still be useful, or at least reduce how much active cooling the DC needs
nirvael 11mo ago
I'm sort of thinking out loud here but could you have two batteries running simultaneously but on opposite cycles, so while one is cooling the other is heating? Obviously it wouldn't be 100% efficient but it might reduce some wasted energy.
- wongarsu 11mo ago
  The heat and cold are created by the compressing or decompressing the CO2 (our any other gas). If one battery is heating while the other needs heat that would imply that one is charging while the other discharges, which is rarely useful in normal operation
  - nirvael 11mo ago
    Yeah you're right I didn't think that through, why would you charge a battery while discharging another, just use the energy directly.

SwtCyber 11mo ago

The real question for me isn't the physics so much as ops over 20–30 years: maintenance, leakage, real-world efficiency after thousands of cycles

mapt 11mo ago

> The problem is that even the best new grid-scale storage systems on the market—mainly lithium-ion batteries—provide only about 4 to 8 hours of storage. This isn't the first time I've seen this sort of claim this week about batteries. If you're a journalist writing these words, stop doing that, and consider your life choices. Ask your boss for tuition assistance to put you through a 7th grade summer-school science class on matter and energy. If you're a journalist writing these words in an ostensibly technical engineering journal? Christ. I don't even know where to begin.

seydor 11mo ago

More blowing up than taking off

slfnflctd 11mo ago

People have been experimenting with compressed gas energy storage for a long time. This one may finally have legs. First thing I thought of was a startup from years ago, mildly surprised no one has mentioned it: https://en.wikipedia.org/wiki/LightSail_Energy https://en.wikipedia.org/wiki/LightSail_Energy I was really excited about them and was disappointed to see the project fail. It seems using pure CO2 and scaling up to a massive size are significant boosts to this type of technology (in addition to the heat mitigation along the way).

cramcgrab 11mo ago

I just plant trees. Have a ton of land in NY, just doing my part.

rbanffy 11mo ago

I have one concern: what if the container bursts? CO2 is heavier than air, and a sudden pressure decrease will cool it down further, so it'll hug the ground. What would be a safe distance for the people around the plant to live without the risk of being asphixiated in an accident?

ragebol 11mo ago
The article mentions > If the worst happens and the dome is punctured, 2,000 tonnes of CO2 will enter the atmosphere. That’s equivalent to the emissions of about 15 round-trip flights between New York and London on a Boeing 777. “It’s negligible compared to the emissions of a coal plant,” Spadacini says. People will also need to stay back 70 meters or more until the air clears, he says. So: 70 meters
- gosub100 11mo ago
  > or more I guess it just depends on how much oxygen you really need.

pkphilip 11mo ago

Wasn't there a plan to use concrete blocks as energy storage medium by pulling them up a little bit at a time when there is surplus power?

jvanderbot 11mo ago
Sure, some people have proposed that, but if you calculate how much has to be lifted to get 20 MW stored (or so), it gets pretty ridiculous pretty quickly. Like "Lift the largest aircraft carrier 20 meters" silly. You have some pretty severe size/mass issues. It makes more sense to use water + a dam, but then again, we like to use water for things besides energy storage, and we're talking about a _lot_ of water. This gas bag is effectively the same as water+dam, except the pressure is from the tanks and the compressor creates it, vs pumping uphill to create pressure.

LikeBeans 11mo ago

I wonder how does it compare to hoisting a concrete (or something heavy) block up a pulley system as an energy store? When you need the energy you let it slide down pulling some steel cable that turns a generator, or multiple cables into multiple generators. Or even a cascade of concrete blocks at different heights as a space saver.

sowbug 11mo ago
The article does address that. ...and even dangling heavy objects in the air and dropping them. (The creativity devoted to LDES is impressive.) But geologic constraints, economic viability, efficiency, and scalability have hindered the commercialization of these strategies.
cenamus 11mo ago
Probably extremely poorly, as that's basically pumped hydro on _tiny_ scale. The amount of mass/water that fits into storage lakes is insane
- LikeBeans 11mo ago
  Good point. I was thinking more about areas without much water and a large field of poles each hoisting several blocks. Sort of wind turbines but without the blades.

thallium205 11mo ago

Trees?

yoan9224 11mo ago

The round-trip efficiency comparison (60-75% vs lithium-ion's ~90%) is interesting but somewhat misleading without context. For grid-scale storage, the relevant question isn't efficiency in isolation - it's lifecycle economics including capex, degradation, and replacement cycles. Lithium-ion has superior efficiency but degrades significantly after 5,000-7,000 cycles, typically reaching 80% capacity in 7-10 years. If CO2 batteries can maintain performance for 20+ years with minimal degradation (which the article suggests), the lower efficiency becomes less relevant. You're trading 15-25% energy loss for potentially 2-3x longer operational life and no lithium supply chain dependencies. The real breakthrough is duration-flexible storage. Lithium-ion economics break down beyond 4-hour discharge rates because you're paying for both energy capacity and power capacity. CO2 systems decouple these - the turbine size determines power output, the storage tank size determines duration. That makes them ideal for seasonal storage patterns where you might charge for days during high renewable production and discharge slowly over weeks during winter lulls. What's missing from the article: what's the round-trip efficiency at different discharge rates? Does efficiency drop significantly when discharging over 12 hours vs 4 hours? That would determine whether these make sense for daily solar smoothing vs weekly wind intermittency vs seasonal storage.

nine_k 11mo ago
The system actually sort of uses the atmosphere as an ambient heat sink (when compressing) or heat source (when expanding). I wonder if that heat could be stored in a more sensible way, e.g. as heated water in a tank near the bubble. This could improve the efficiency figures at short repeating patterns (charding at high noon, discharging through the night).
- anotherpaul 11mo ago
  As far as I understand they do try to keep the heat around for the next decompression. As of course they need it. But I could not find what type of heat storage they use. Ultimately they "only" seem to need to store it for 12h, right?
whimsicalism 11mo ago
I think it is generally polite to flag when you are using an LLM to write your comment, some people tire of reading the same style of writing over and over - even if the content of your comment is interesting!

javier_e06 11mo ago

So much potential! Get my CocaCola on the line! Heck give me Heineken too!

openasocket 11mo ago

I don’t know much about chemistry, but is there a reason why they are using CO2 as the gas medium instead of something else? I was thinking ambient air would be readily available, and you don’t have to worry about suffocating people if it ruptures. Is CO2 particularly efficient to compress?

GoToRO 11mo ago
Air is no good because it has moisture in it. When you decompress it, it becomes ice, blocking and breaking pipes.

euroderf 11mo ago

Had to wade thru miles of marketing muck to get to the tech talk.

Ayanonymous 11mo ago

I’m new to the idea of grid‑scale energy storage technologies, but this was a really clear and interesting introduction to how CO₂ batteries could help with long‑duration renewable energy storage. It’s exciting to see new approaches that might make solar and wind power more reliable and affordable. Thanks for sharing!