CO2 batteries that store grid energy take off globally
spectrum.ieee.org
spectrum.ieee.org
> Media reports show renderings of domes but give widely varying storage capacities [--> 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.
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.
You can liquefy CO2 at a higher temperature than N2
Or it's just so obvious - to them! that it doesn't need to be mentioned, which then doesn't make it an ad.
Lithium ion battery systems are expensive as shit, and not that big for how much they cost.
Because the most efficient way to make money with a lithium ion battery (or rather the marginal opportunity after the higher return ones like putting it in a car are taken) is to charge it in the few hours of when electricity is cheapest and discharge it when it is most expensive, every single day, and those windows generally aren't more than 8 hours long...
Once the early opportunities are taken lower value ones will be where you store more energy and charge and discharge at a lower margin or less frequently will be, but we aren't there yet.
Advertising that your new technology doesn't do this is taking a drawback (it requires a huge amount of scale in one place to be cost competitive) and pretending it's an advantage. The actual advantage, if there is one, is just that at sufficient scale it's cheaper (a claim I'm not willing to argue either way).
The bigger you build it, the less it costs per MWh of storage.
Grid scale lithium is dropping in cost about 10-20% per year, so with a construction time of 2 years per the article lithium will be cheaper by the time the next plant is completed
The fact that pumps, turbines, rotating generators don’t fail linearly doesn’t mean they are not subject to wear and eventual failure.
There are a number of new methods for reconditioning lithium instead of recycling.
Biodegradable batteries would be great for many applications.
You can recycle batteries at big box stores; find the battery recycling box at Lowes and Home Depot in the US.
Grid energy storage: https://en.wikipedia.org/wiki/Grid_energy_storage
Why can’t battery capacity be described in joules? And then charge and discharge being a function of voltage and current, could be represented in joules per unit time. Instead its watt-hours for capacity, watts for flow rate.
Watt-hours… that’s joules / seconds * hours? This is cursed.
That camel's nose was already in the tent with the mAh thing in phone/etc batteries, now with electric vehicles we're firmly in kWh land.
Not to mention that's what the power utilities used all along ...
A watt is a joule of energy divided by a second of time, this is a rate, joule per second is also a valid name similar to nautical mile per hour and knot being the same unit.
Multiplication vs division, quantity vs rate, see the relationship? Units may have different names but are equivalent, both the proper name and compound name are acceptable.
A watt hour is 3600 joules, it’s more convenient to use and matches more closely with how electrical energy is typically consumed. Kilowatt hour is again more directly relatable than 3.6 megajoules.
Newton meter and Coulomb volt are other names for the joule. In pure base units it is a kilogram-meter squared per second squared.
The energy unit meter is distance moved, while the force unit meter is the length of the moment arm.
This is confusing even though valid, so the energy unit version is rarely used.
You can exert newton meters of force while using no energy, say by standing on a lug nut wrench allowing gravity to exert the force indefinitely unless the nut breaks loose.
The UK is metric except for distance and beer.
So the disgusting ‘miles-per-litre’ is presumably needed too.
One, a beer gallon, the other a wine gallon. The US still also has 'dry gallons' for things like pints of blueberries.
Arguably, we should probably use kg-of-fuel (or mol) instead of litres-of-fuel anyway.
Now, Kg is a measure of mass (or weight, depending on who you are asking), which throws density into the equation, which is proportional to the temperature, which will vary according to where and when the driving takes place. But since the time and place, and hence the temperature is (allegedly) defined when the fuel consumption was tested, the density is a constant, and as such you can leave it out from the relation.
Mass = V*ρ
(I know, I am being pedantic² :)
It's the other way round: chemically how much energy you get from burning your fuel is almost completely a function of mass, not of volume. (And in fact, you aren't burning liquid fuel either, in many engines the fuel gets vaporised before you burn it, thus expanding greatly in volume but keeping the same mass.)
> [...] which throws density into the equation, which is proportional to the temperature [...]
For an ideal gas, sure. But not for liquid fuels.
> "litres-of-fuel per km-driven" (Volume/Distance) is still fully reductible to an area: litres is still a volume (1 cubic decimeter) and km is still a distance (1x10⁴ dm) Maybe you meant that the other way around? Distance/Volume (as in Miles/gallon) is an Area⁻¹ (Distance⁻²), which is more difficult to imagine in space.
I don't think that the reciprocal is a problem. No, what I mean is that you can't cancel fuel with driving. Litres-of-fuel is a different unit than distance-driven ^ 3. Similar to how torque and energy are different physical quantities that you can't cancel willy-nilly, despite their units looking similar.
You might find a physical interpretation for an adventurous cancelling, and that's fine. But that's because you are looking behind the raw unadorned units at the physics, and basing your decision on that.
Units are a very stripped down look at physics. So units working out are necessary for cancelling to make sense, but not sufficient.
The first time I saw it:
>There are 10 kinds of people in the world, those who understand binary and those who don't.
The joke is that 10 is how you express 2 in base 2.
I think there is another layer to the joke, though; often in mathematics, computer science, algorithms, and software engineering, things get divided into sets, sets get broken down into two sets according to whether some property about the elements is true or false, and this joke echoes that.
It's just meant to be silly.
Watt hours is saying, how long will my personal battery pack last me that powers my 60 W laptop? Which is also fine in that context.
What makes kW less useful is really just that most EVs don't advertise their capacity very prominently. But if you knew you had an 80 kWh battery and the car uses 20 kW at freeway speeds, then it's easy to see that it'll drive for 4 hours.
Which is definitely less intuitive because it hasn't been introduced to the public, but is interchangeable in the same quirky way we already compare MPG (Distance/Volume) with lt/100KM (Volume/Distance)
But on the other hand we also use hours for measuring time instead of kiloseconds...
Oh, and 1Ms weeks, consisting of 7 working days and 3 off days sound nice too.
One can dream! :-)
Oh, we should switch our standard counting system to dozenal a well.
Watts = volts * amps and the people working with batteries are already thinking in terms of voltage and amperage. It'd be painful to introduce a totally new unit and remember 1 watt for an hour is 3.6kj instead of... 1 watt-hour.
It is not more cursed than km/h (1 m/s = 3600 m/h = 3.6 km/h)
Both those units are more convenient than their SI equivalent and their "cursedness" come from the hour/minute/second time division.
If we had decimal time, as it was initially proposed with the metric system, we wouldn't have this problem, but we weren't ready to let go of hours/minute/second.
Imagine if the distance between you and I was 438 kiloflerp-hours. And to get to you in one hour I have to drive at a speed of 438 kiloflerps. It works, it kinda makes sense. It just feels inconsistent with all the other units I work with.
Another place where the cursed unit of hour crops up is describing the amount of electric charge that you can pull out of a battery (especially rechargeable ones) in terms of millamp-hours (mA⋅h). Note that in actual SI, 1 mA⋅h = 3.6 C (coulombs). Even more cursed is high-capacity lithium-ion USB power banks that are advertised like 10,000 mAh (or even "10K mAh"), which should at least be simplified to 10 A⋅h (ampere-hours). But mA⋅h isn't a good way to describe batteries because you also need to multiply by voltage (3.7 V for Li-ion, I think 1.2 V for NiMH) to figure out the energy (usually expressed in W⋅h).
One more fun fact - photographic flash units are advertised in watt-seconds (W⋅s) for the maximum amount of energy delivered in a flash pulse of light. But that just simplifies to joules, which is a shorter and less confusing unit name. People really need to stop multiplying watts with time and use joules as designed in the SI.
It is analogous to the Joule, but it doesn't mean the same thing. "This car has a 250 million ft.lb battery and 0.1 Wh of torque" passes dimensional analysis.
But also, the second paragraph already describes the 100 MWh vs MW nuance.
All users (states) were given an allotment which, when it was set, was more than what would ever be the yearly supply.
From the outset it was essentially a free for all. Everyone was happy, they kinda got what they asked. It's just that they were all living in a paper reality
> pumped hydro [...] can store thousands of megawatts for days.
You can't "store" a megawatt – because you can only store energy, not power.
But another interpretation is, if you actually store thousands of megawatts (i.e. gigawatts) for days, then at the very least, 1 GW × 1 day = 24 GW⋅h. If we take "a few" to mean 3, then 3 GW × 3 day = 216 GW⋅h. I'm not sure there exists a large enough pumped hydro plant in the world that stores 216 GW⋅h of energy. So I think the article meant to say, "store a few gigawatt-hours to be released over a period of a few days".
> Media reports show renderings of domes but give widely varying storage capacities—including 100 MW and 1,000 MW.
Once again, you can't store megawatts of power, full stop. You can store megawatt-hours of energy. The linked article at Bloomberg said that a project in China is building 600 MW of wind power, 400 MW of solar power, and 1 GW⋅h of energy storage – which is the correct unit.
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.
...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%....
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 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.
Who in their right mind would pay 40% more to pick a dangerous and fussy product just because it's a bit smaller and lighter for their home?
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 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.
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.
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.
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).
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)
So far so good, just the old thermodynamics. It gets interesting when you have a cooling use case anyways: then you can skip on some of the decompression recovery and use the "cold" from decompression directly, to cool down something that needs cooling, without going the extra way of converting back to electricity and then sending the electricity recovered into a compressor setup for "creating cold". Bonus points if you also have a use case for the heat you did not use in reconversion to electricity, but chances are between losses during storage and heating some the gas back some amount beyond neutral you won't have much spare heat anyways.
a thermal-energy-storage system cools the CO2 to an ambient temperature
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.
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
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.
> In these discussions please keep in mind that frequency regulation, short term and long term shortage are different applications with different needs.
The comparison is valid; If you want to fill hour to hour demand or add some frequency regulation, an inverter with a bunch of batteries is far, far better than this
> You don’t want to used pumped hydro for short term storage because the rapid cycling will drive up the maintenance costs. You actually hear about hydro power plants talking about installing batteries to reduce wear.
They are still cycled daily, that's the entire point of them that even worked pre renewables - load up on cheap night energy and unload it with demand. Renewables just flipped that to load in solar peak.
And putting few hours worth of batteries to reduce cycling is beneficial in both of those cases.
Don't do that here.
But it's sad that you get triggered by snark and not... ignorance and/or lying
> Clearly power capacity cost (scaling compressors/expanders and related kit) and energy storage cost (scaling gasbags and storage vessels) are decoupled from one another in this design
Lambdaone is differentiating between the costs to store energy (measured in kWh or Joules) and the costs to store energy per time (which is power, measured in Watts). If you want to store the whole excess energy that solar panels and wind turbines generate on a sunny, windy day, you need to have a lot of power storage capability (gigawatts of power generated during peak power generation). This can be profitable even if you only have a low energy storage capability, e.g. if you can only store a day worth of excess solar/wind energy, because you can sell this energy in the short term, for example in the next night, when the data centers are still running, but solar panels don't produce power. This is what batteries give you -- high power storage capabilities but low energy storage capacities.
Of course, you can always buy more batteries to increase the energy storage capacities, but they are very expensive per energy (kWh) stored. In contrast, these CO2 "batteries" are very cheap per energy (kWh) stored -- "just" build more high pressure tanks -- but expensive per power (Watts) stored, because to store more power, you need to build more expensive compressors, coolers etc. This ability to scale out the energy storage capability independently of the power storage capability is what Lambdaone was referring to with the decoupling.
For what is this useful? For shifting energy over a larger amount of time. Because energy storage costs of batteries are so high, they are a bad fit for storing excess energy in the summer (lots of solar) and releasing it in the winter (lots of heating). I'm not sure if these "CO2" batteries are good for such long time frames (maybe pressure loss is too high), but the claim most certainly is that they can shift energy over a longer time frame than is possible with batteries in an economically profitable fashion.
I would posit that they hope Wright's Law will take hold; the components can be optimised and the deployment standardised. Also it looks as if most of the stuff can be made within the US or EU, dodging tariffs.
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.
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!
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.
>cm
>oz
The 75% round-trip efficiency (for shorter time periods) quoted in other threads here is surprisingly high though.
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...
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.
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
Edit: It holds 2k tons, not 20K tons.
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 do 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. Odorizers are also dirt cheap. Natural gas industry goes through tons of the stuff.
> 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.
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."
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.
- $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.
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.
But sure, I agree it would help if battery prices came down.
Obviously more panels are better.
The goal is to be able to run a small window AC unit and various small appliances at night. That's a tremendous quality-of-life upgrade for a huge number of people. $1000 USD would make it somewhat affordable, in the window for a viable small business/NGO opportunity. There's obviously a whole lot more (installation, labor, maintenance, etc), but material cost needs to be low for it to work.
> which is around 3.8kwh, costs $2400 USD. To store 10kwh would cost $7200 USD (which gets us more than 10kwh).
84kwh / 3.8 kwh is about 22. 22 * 2400 is ~53k.
https://www.mobile-solarpower.com
Like the other commenter said, batteries are a lot cheaper if you are willing to shop around. His top recommended budget battery today is a 4x your Anker Solix's capacity, and around 1/4th the price. You can find many 5kWh server rack batteries for under $1000 now.
We are starting to see Chinese options pop up but not sure if I would install them yet.
https://www.docanpower.com/eu-stock/zz-48kwh-50kwh-51-2v-942...
51.2v 314ah cells (15kwh battery) 16x 580-590w solar panel
Installed for 310k PHP = $5,275
I've also specced out 15-16kwh batteries using the Yxiang design for around the price of your Solix. The problem in the US is regulatory and a particularly predatory tradesman market at the moment.
(yes, I'm leaving it open if regulation makes a difference or not - for all we know it could even make a negative difference, helping companies that are better at regulation than at safety. But if I had to bet, I know where my money would be)
This is one place where I think by 2030 a clear no of options will be established.
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.
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?
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.
Batteries are still extremely important here, for short duration smoothing. Most stored energy is still going through batteries, so their capex and efficiency is important.
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.
I suspect thermal storage will beat out hydrogen, if Standard Thermal's "hot dirt" approach pans out.
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.
"LFP chemistry offers a considerably longer cycle life than other lithium-ion chemistries. Under most conditions, it supports more than 3,000 cycles; under optimal conditions, more than 10,000 cycles."
https://en.wikipedia.org/wiki/Lithium_iron_phosphate_battery...
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? Was "this PC will last 20 years!" ever a selling point?
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.
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
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).
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.
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.
> 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
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.
Similar discussion: https://news.ycombinator.com/item?id=44685067 (162p/153c)
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.
This sounds better in every way.
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.
Edited to add: https://en.wikipedia.org/wiki/Kigali_Amendment has some information on this.
...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.
So: 70 meters
I guess it just depends on how much oxygen you really need.
Compare the thermal efficiency of marine diesel engines to their automotive equivalents, for instance.
Still, if we ever end up with rows of these giant “balloons,” the landscape might look unexpectedly futuristic.
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.
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.
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.
> 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.