Co2 Batteries That Store Grid Energy Take Off Globally
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The rise of CO2 batteries is sparking interest globally as a potentially game-changing grid energy storage solution, with claims of being 30% cheaper than lithium-ion batteries. As commenters dig into the details, a round-trip efficiency of around 75-77% emerges, sparking debate about its viability compared to lithium-ion's 82% efficiency. While some point out lithium supply limitations as a motivation for alternatives, others counter that lithium reserves will expand with growing demand and that sodium batteries are already emerging as a viable alternative. The discussion highlights the complex trade-offs between cost, efficiency, and resource availability in the quest for sustainable energy storage.
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Great if it can continue to be cheaper, of course. Fingers crossed that they can make it work at scale.
That's not terrible.
These things would probably pair well with district heating and cooling.
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.
A few percent here of there is not that important if the input energy is cheap enough.
And if you want an alternative, sodium batteries are already coming online.
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.
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...
It's the exact reason LFPs are taking off, especially in grid storage scenarios.
The high cycle life combined with the fact that all the materials are easy to acquire and dirt cheap.
LFP cells have long since taken off. Tesla has been making vehicles with LFP battery packs for half a decade now.
There are plenty more, but they're explored only when there's a price hike.
What I'm somewhat surprised about is that we've not seen synergies with desalination and ocean mineral extraction. IDK why the brine from a desalination plant isn't seen as a prime first step in extraction lithium, magnesium, and other precious minerals from ocean water.
But once summer electricity becomes cheap enough due to solar production increasing to handle winter heating loads with the (worse) winter sun, we can afford a lot of electrowinning of "ore" which can be pretty much sea salt or generic rock at that point.
Form Energy is working on grid scale iron air batteries which use the same chemistry as would be used for (excess/spare) solar powered iron ore to iron metal refining.
AFAIK the coal powered traditional iron refining ovens are the largest individual machines humanity operates. (Because if you try to compare to large (ore/oil) ships, it's not very fair to count their passive cargo volume; and if comparing to offshore oil rigs, and including their ancillary appliances and crew berthing, you'd have to include a lot of surrounding infrastructure to the blast furnace itself.)
It will take coal becoming expensive for it's CO2 before we really stop coal fired iron blast furnaces. And before then it's hard to compete even at zero cost electricity when accounting for the duty cycle limitations of only taking curtailed summer peaks.
Billions of dollars in cost, run 24/7 with virtually no downtime during regular operations, in underground tunnels with circumferences in the tens of miles, and all throughout is actively-coordinated super conductors and beam collimation in a high-vacuum tube attached to absurdly complex, ultra-sensitive, massively-scaled instrumentation (not to mention the whole on-site data processing and storage facilities). Certainly open to bring convinced otherwise, but aside from ISS in pure cost, so far it's my understanding that those are the pinnacle of large-scale machines.
I think these guys are basically using desalination tech to make lithium extraction cheaper: https://energyx.com/lithium/#direct-lithium-extraction
As I understand it (which is far from perfectly) it's still not using ocean water, because you can get so much higher lithium concentration in water from other sources. But it's a more environmentally friendly, and they argue cheaper, way to extract the lithium from water than just using the traditional giant evaporation pools.
"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
All of that vs lithium/sodium batteries where you can incrementally install batteries and let it operate without much concern. Maybe some heaters if they are installed in especially cold climates.
Sodium batteries can operate down to -40C. There are very few places on Earth where they would need a heater.
But initial claim was “fraction of the cost, tomorrow” which is super incorrect.
What I'm opposing is flippantly relegating a new technology with real benfits, that the largest manufacturer of lithium ion batteries is significantly betting on, to the 0.01% of the market.
You say 0.01%, largest manufacturer of lithium batteries says 50%. If you meet half way it's still about 25% which is significant.
https://undecidedmf.com/why-the-biggest-battery-company-is-b...
Yes, eventually it might be 50%, but right now you can't even get _specs_ from CATL while LFPs are traded like commodity.
https://www.catl.com/en/news/6401.html
Are you sure you aren't the one blinded by hype?
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.
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.
That's a significant difference.
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.
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.
Well at least people are being honest about committing economic suicide now.
I sometimes wonder if renewables aren't a push by the secret services of Indonesia, Kenya and Colombia for the global north to deintustrialize itself so they can be finally left alone.
And foreseeable future they provide such huge value for grid stability that it wouldn’t make sense economically either.
Battery recycling still hasn't really left the "we can do it in a lab" stage.
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.
How much energy us used to purify and maintain the CO2?
[1] https://en.wikipedia.org/wiki/Carbon_capture_and_storage
> 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.
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?
> 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.
As far as the storage vessel, CO2 has much lower pressure demands than something like, say, hydrogen. On something like a paintball marker the burst disc (i.e. emergency blow off valve) for a CO2 tank is in the range of of 1500-1800PSI [0].
A compressed air tank that has a 62cubic inch, 3000PSI capacity, will have a circumference of 29cm and a length close to 32.7cm, compared to a 20oz CO2 tank that has a circumfrence of 25.5cm and a length of around 26.5cm [1]. The 20oz tank also weighs about as much 'filled' as the Compressed air tank does empty (although compressed air doesn't weigh much, just being through here).
And FWIW, that 62/3000 compressed air vs 20oz CO2 comparison... the 20oz of CO2 will almost certainly give you more 'work' for a full tank. When I was in the sport you needed more like a 68/4500 tank to get the same amount of use between fills.
Due to CO2's lower pressures and overall behavior, it's way cheaper and easier to handle parts of this; I'm willing to bet the blowoff valve setup could in fact even direct back to the 'bag' in this case, since the bag can be designed pessimistically for the pressure of CO2 under the thermal conditions. [2]
I think the biggest 'losses' will be in the energy around re-liquifying the CO2, but if the system is closed loop that's not gonna be that bad IMO. CO2's honestly a relatively easy and as long as working in open area or with a fume hood relatively safe gas to work with, so long as you understand thermal rules around liquid state [also 2] and use proper safety equipment (i.e. BOVs/burst discs/etc.)
[0] - I know there are 3k PSI burst discs out there but I've never seen one that high on a paintball CO2 tank...
[1] - I used the chart on this page as a reference: https://www.hkarmy.com/products/20oz-aluminum-co2-paintball-...
[2] - Liquid CO2 does not like rapid thermal changes or sustained extreme heat; This is when burst discs tend to go off. But it also does not work nearly as well in cold weather, especially below freezing. Where this becomes an issue is when for one reason or another liquid CO2 gets into the system. This can be handled in an industrial scenario with proper design I think tho.
I remember wondering about using natural gas or propane for this a long time ago. Not burning the gas but using it as a compressed gas battery. It liquifies easier than air, etc., but would be a big fire risk if there were leaks while this is not.
Seems neat.
With compressed air, you just release the air back to the atmosphere.
The issue with compressed air is that you have to build more of the system to handle higher pressures and/or have a more robust regulator design, plus the pressures required to compress CO2 back to liquid are typically lower than what you'd need to store a useful final volume compressed air...
Also, As far as having an 'open loop' (i.e. venting to atmosphere), that's typically got it's own problems, mostly that when you need new air you have to make sure it's 'pure', not just things like dust but even whether there's water vapor.
It’ll be interesting to see how the economics of these various solutions play out.
Batteries or direct mechanical storage (compressed gas, pumped hydro, etc.) are both a lot more efficient.
This would make sense if solar gets so cheap that it's something to do with the surplus, and it would be a way to electrify things like long haul aviation where batteries are too heavy. We are flying LNG rockets, so LNG planes are totally possible, or you could upgrade methane to butane or propane which are quite easy to compress to liquid form. Jet engines run great on light weight fuels like that.
FWIW Back in the day, Ammonia was used for refrigeration because it had the right properties for that process; I mention that one because while it's not a fire risk it's definitely a health risk, also it's a bit more reactive (i.e. leaks are more likely to happen)
> Seems neat.
Agreed!
>cm
>oz
Trees are literally CO2 based solar batteries: they take CO2 + solar energy and store it as hydrocarbons and carbohydrates for later use. Every time you're sitting by a campfire you're feeling heat from solar energy. How much better does it get that free energy storage combined with CO2 scrubbing from the atmosphere!
When you look at the ocean, it's able to absorb 20-30% of all human caused CO2 emissions all with no effort on our behalf.
Unfortunately, these two solution are, apparently, "too good to be true" because we're increasingly reducing the ability of both to remove carbon. Parts of the Amazon are not net emitters of CO2 [0] and the ocean has limits to how much CO2 it can absorb before it starts reach its limit and become dangerously too acidic for ocean life.
0. https://www.theguardian.com/environment/2021/jul/14/amazon-r...
The 75% round-trip efficiency (for shorter time periods) quoted in other threads here is surprisingly high though.
It’d be interesting to see if there’s any loss of efficiency with increasing storage duration too (relating to boil-off of the cryogenic side of the storage ?) because this would impact the economics of charging too.
I just get the feeling lithium/sodium ion for electricity and big piles of sand/dirt for heat are going to more-or-less win the energy storage race.
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."
Compare the thermal efficiency of marine diesel engines to their automotive equivalents, for instance.
That enclosure has a huge volume - area the size of several football fields, and at least 15 stories high. The article says it holds 20k tons of co2, which is ~10k 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
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.
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.
This requires the people running this facility, and all the facilities based on it built by unrelated organizations in the future, to not cut engineering corners on the envelope. I don't take this for granted anymore. But as long as you don't get a big rip, then yeah, it'll be hard to build up a dangerous amount. I wonder if a legally mandatory cut and repair trial on the envelope would reduce risk significantly.
Speaking of wind, I also worry about whoever is downwind if there's a big release. I bet 70m is not quite far enough if it's in the wrong direction.
It would not be good, but it wouldn't be Bhopal. And there are still plenty of factories making pesticides.
Also that statement of 70 meters seem very off, looking at the size of the building. What leads to suffocation is the inability to remove co2 from your body rather than lack of oxygen, and thus can be life threatening even at 4% concentration. It should impact a much much larger area.
I don't know the safety limits for this quantity, I hope the "70 meters" claim was by someone who modelled it carefully rather than a gut check.
Also a 'puncture' is very different from the gasbag mysteriously vanishing from existence; My only other thought is that in cold regions (I saw wisconsin mentioned in the article) CO2 does not diffuse quite as fast and sometimes visibly so...
How did they calculate that evacuation distance? CO2 is heavy. That little house about 15m from the bubble needs to be acquired.
The topography matters. If the installation is in a valley, a dome rip could make air unbreathable, because the CO2 will settle at the bottom. People have been killed by CO2 fire extinguishing systems. It takes a reasonably high concentration, a few percent, but that can happen. They need alarms and handy oxygen masks.
Installations like this probably will be in valleys, because they will be attached to wind farms. The wind turbines go in the high spots and the energy storage goes in the low spots.
If it were, say, argon, it would be much more likely to suffocate people, because you don't notice hypoxia the way you do hypercapnia. It can pool in basements and kill everyone who enters.
That being said it is an enormous volume of CO2, so the hypercapnic response in this case may not be sufficient if there's nowhere to flee to, as sadly happened in the Lake Nyos disaster you cited.
Natural gas is naturally odorless and colorless. Therefore, by default, it can accumulate to dangerous levels without anyone noticing until too late. We make natural gas safer by making stink, and we make it stink by adding trace amounts of "odorizers" like thiophane to it.
I wonder whether we could something similar for CO2 working fluid this facility uses --- make it visible and/or "smell-able" so that if a leak does happen, it's easier to react immediately and before the threshold of suffocation is reached.
> putting houses around gas holders was discontinued in the UK.
Easy to build infra and other stuff that far away, especially in locations where this is meant to be used.
There are many aspects of safety
1. If the puncture is due to hurricanes, etc, the danger is non existent. The hurricane will blow away the co2 in no time.
2. If the puncture is due to wear and tear, then the leak will be concentrated and localized. It could naturally diffuse.
CO2 meters can be installed around the unit for indication.
Oxygen masks can be placed around the facility for emergency use.
The dangers are very much mitigatable.
Not a carbon sequestration thing, but will likely fool some people into thinking it is.
[0] https://energydome.com/co2-battery/
> Energy Dome expects its LDES solution to be 30 percent cheaper than lithium-ion.
30% cheaper than batteries from when? today? two years ago?
huge difference, 30% cheaper than lithium batteries feels like a pitch deck number from years ago to me
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.
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.
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.
Pumped-storage hydroelectricity - where it is feasible - is the only kind of energy storage close to "months".
Wait a minute...
There are far more technologies going for the hours scale storage market than will survive. Sure, explore them. But expect most to fail to compete.
Grid level batteries have another very important metric. The actual possibility of buying a particular types of batteries from friendly nations. Simpler technologies like this CO2 battery have a huge advantage here.
[1] https://en.wikipedia.org/wiki/List_of_battery_types
To steelman the point you're making: perhaps the short term storage niche will fracture into smaller niches, in which different technologies could coexist. This also happens in ecology. For example, in one simple experiment with bacteria, it was found two species coexisted, but on closer examination it was found one species persisted in the top of the flasks, the other in the bottom.
For example, for the market niche "getting people from one location to another" there are quite many technologies, like walking, bicycles, scooters, cars, trains, ships, airplanes, helicopters etc., none of them evolved as a clear winner that displaced the others.
You might say, that's a whole market, not just a market niche, but it's also a niche of the larger transportation market.
When we look at something like grid-scale energy storage, how do we know if it's a winner-takes-all niche? Maybe constraints such as availability of space, availability of funding, weather, climate, grid demands etc. create sub-niches with their own winners. Or maybe not, but how can we known?
https://blog.gridstatus.io/caiso-solar-storage-spring-2025/
This site finds optimal combinations of solar, wind, batteries, and a long term storage (in this case, hydrogen), using historical weather data, to provide "synthetic baseload". It's a simplified model, but it provides important insights.
Go there, and (for various locations) try it with and without the hydrogen. You'll find that in a place at highish lattitude, like (say) Germany, omitting hydrogen doubles the cost. That's because to either smooth over seasonal variation in solar, or over long period drop out of wind, you need to either greatly overprovision those, or greatly overprovision batteries. Just a little hydrogen reduces the needed overprovisioning of those other things, even with hydrogen's lousy round trip efficiency.
You can also tweak the model to allow a little natural gas, limiting it to some fixed percentage (say, 5%) of total electrical output. This also gets around the problem. But we utimately want to totally get off of natural gas.
Actually, having expandable, highly re-usable tech like this is much better when the capacities are in terms of hours.
This storage, combined with say 2.5x solar panel installation, could essentially provide power at 1x day and night.
This system can run for decades.
This is the paper that claims 10,000 cycles under optimal conditions.
But if you read it, they measure Equivalent Full Cycles, and it seems that implies 10000 cycles at partial discharge, not full discharge.
The paper calculates everything at nominal discharge upto 80%. Meaning, the installed capacity has to be 25% more than paper value, leading to increased costs.
Add to that, batteries are complex to manufacture, degrade, lose capacity, etc. You need high level of quality control to actually ensure you are getting good batteries. This means, the cost of QA and expertise increases. They are costly to replace, even at an avg of 3000 cycles (roughly 10 years). Bad cells in one batch accelerate degradation and are difficult to trace out. Batteries operate best at low temperatures, so the numbers may vary based on installed location and climatic conditions.
A turbine and co2 compressor system is dead simple to manufacture, control and maintain. A simple PLC system and some automation can make them run quite well. Manufacturing complexity is low, as there are tried and tested tech. Basically piping, valves, turbines and generators. These things can be reliably run for 30 to 40 years. Meaning, the economics and cost efficiency is wildly different.
With such simplicity, they can be deployed across the world, especially in places like Africa, middle east, etc.
On the whole, batteries are not explicitly superior as such. There are pros and cons on both sides.
In evaluating the importance of this, you need to consider not only the time value of money, but also what one might call the "time value of technology". Does it make sense to make the technology long lived when it's improving so quickly? Or do you just replace it in a decade when things are much cheaper?
When evaluating these technologies, you have to look at not just what they cost now, but how rapidly the cost is improving. Batteries are likely improving more quickly than turbines and heat exchangers.
This is one place where I think by 2030 a clear no of options will be established.
This sounds better in every way.
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