Lithium-ion batteries are falling in cost so rapidly that any new process being ramped up is risky business. Form is way further along than this landing page and yet has a long way to go:
What about from an environmental standpoint if we think about that these Lithium--Ion batteries will have to be replaced and recycled every (as the article says, not sure if true) <12 years. We have a history of not pricing in negative externalities, did we do that this time?
> environmental standpoint if we think about that these Lithium--Ion batteries will have to be replaced and recycled every
I am very interested in this question, but those who raise it never have answers about the negative impacts of mining lithium.
For example, the amount of lithium needed for an EV is an order of magnitude less than the amount of steel needed. What is so bad about lithium mining that it's 10x worse than iron mining, pound for pound?
Nobody has ever answered my request for environmental concerns with a concrete environmental lithium mining concern, such as acidification that can sometimes happen with iron mining.
I've researched and researched, found nothing, which leaves me thinking that the worst case scenario for lithium is no worse than the worst case for iron.
Meanwhile, we have such immense documented harms from fossil fuel extraction that nobody ever questions again, or with the same intensity that's reserved for supposedly toxic lithium batteries.
The apparent benefit is massive, so any delay seems to cause massive harm to the environment.
I think we need to flip the question: where is the proof that coal/oil/iron is better for the environment than mining and recycling batteries? (BTW, it's at least 20 years now for grid batteries, with lifetime going up all the time...)
Any analysis of EVs vs ICE cars I've seen put EVs at 1.5-2x the carbon footprint to produce, but win out in the long run. My default assumption has always been it comes from the battery pack - I'm not sure what else could cause such a difference.
My understanding (bowing to ChatGPT) is that you can get 1 pound of iron from <2 pounds of iron ore. But to get 1 pound of lithium, you need around 500 pounds of lithium ore.
So if an electric car requires 2000 pounds of iron and 50 pounds of lithium, that works out to 4000 pounds of iron ore that needs to be mined and refined, vs 25,000 pounds of lithium ore.
Interesting, but tailings never seem to enter much into environmental analyses that I have seen, unless you count coal ash as "tailings" which would be a pretty broad interpretation of the idea.
Lithium is also extracted via brine, as opposed to hard rock. Most of the environmental reporting has been on the brine approaches, which currently are in high elevations of South American mountains, and the problem appears to be mostly the use of land and taking that land out of the ecosystem for economic use as drying pools. But the same problem occurs with mining, too!
You shouldn't post AI slop here. Until a few years ago, no lithium was mined from ore. Now roughly half of it is, mostly spodumene, LiAl(SiO3)2, which you can easily calculate (with units(1)) is 3.7% lithium, 18 times higher than the 0.2% you're claiming. 50 pounds of lithium thus comes, on average, from 25 pounds of brine-derived lithium and 670 pounds of spodumene.
While the rest of what you say is right, you will not find anywhere on Earth a mine with compact spodumene.
Spodumene is dispersed among other minerals into rocks and it only forms a few percent at most of those rocks, if not only fractions of a percent.
The rocks must be crushed and spodumene must be separated from the other much more abundant minerals, by flotation or similar mineral concentration techniques, before going further to chemical processing.
So your 670 pounds must be multiplied by a factor like 100, varying from mine to mine.
Some multiplication factor must also be used for the iron ore, which is also mixed with undesirable silicates, but iron oxide may reach up to a few tens of percent of the rock, so the multiplication factor is much smaller.
Hmm, I thought the Australian deposits were mostly spodumene. I appreciate the correction, although it's embarrassing; I'd rather be embarrassed than wrong.
>So if an electric car requires 2000 pounds of iron and 50 pounds of lithium, that works out to 4000 pounds of iron ore that needs to be mined and refined, vs 25,000 pounds of lithium ore.
means recycling of lithium batteries will be a thriving business. (i.e. big difference from recycling of say tires or plastic bottles, more like, pretty successful, recycling of aluminum, and even better than it)
Lithium cells are still disposable (eg vapes). The difference is that a single EV contains hundreds of kilograms are we are not used to just chucking old cars in the gutter.
I used to drive a Toyota Yaris Hybrid and I really liked it, I moved to a different country and couldn't take the car with me and now I drive a scooter, but if I'll ever buy a car again, it'll most likely be a hybrid, I really like the range.
What do you think the negative externalities actually are? Off of the top of my head: mining, landfill. Same as other metals.
If the processes to extract Lithium from recycling become cheap enough to compete with the prices of mined Lithium, then that happens.
Processes still need to be invented/scaled for that to happen: the only real way to deal with damaged or charged cells that I know of is to deep freeze them, shred them, and then defrost them slowly.
But in either case: Lithium is going to end up as waste. Making it cheaper to make cars affordable and the grid more stable means that disposable batteries will be even cheaper.
I don’t know how modern batteries fare in landfills: Most modern solar panels, for example, are relatively clean (mostly aluminum, silicon, copper, wee bits of lead). But not a waste management expert.
They've been working hard at recycling, and the biggest challenge at the moment is actually getting old batteries for the process. There's not many in-service batteries reaching end of life yet, so they mostly deal with production scrap.
I think 12 years is an underestimate. Lithium-ion batteries will degrade, but they still have usable capacity. There are Tesla Roadsters still going strong, 15 years in. And the battery cell chemistry has since shifted to LFP, which has longer cycle life.
Furthermore, I would expect that an industrial battery is treated better than an EV. Optimal cooling/charging/discharge rates likely have a large impact on longevity.
Some LFP batteries now get rated for 5000 or more cycles or more. Even if you cycle them fully every day, that's 14 years. And that's unlikely to be needed or happening. These might last decades. At which point, battery tech might be massively better. Also, even better batteries might be on the way. E.g. Sodium Ion would be a bit less energy dense and have a similarly long life. It doesn't contain any lithium and could be cheap to manufacture in a few years. The biggest driver here would be cost and other properties (like how quickly can it deliver the power and at what capacity).
It's irrelevant how long they last unless is starts to substantially exceed human lifespans though. 10 years or 20, eventually every product you put out there is replaced and you enter the steadystate waste phase of X tons per year.
Personally of course, I don't think this matters at all: old lithium batteries degrade into salt and don't contain harmful chemicals. There's no real indication we'd ever have a problem dealing with them, even if it was just throwing them all into a big hole till the hole looks enough like a natural lithium source to mine again.
Lithium batteries last as long as one battery out of thousands decides to thermal runaway, and then you have to replace all of them (as well as the facility they were all housed in).
In short no. LFP is very safe. People have done tests involving shotguns, flamethrowers, hammers/nails, etc. And while that destroys the battery, they don't tend to explode, combust, burn uncontrollably, etc. These are nice party tricks with predictable outcome if you understand the chemistry (it's inherently safe).
Humanity's. We've only got one Earth, and if my factory can just dump toxic waste down the drain which flows right to the bay and kills all the fish, for free, why would I pay for it when I could be spending that money on a yacht?
What is the negative externality of recycling batteries? That is way better than having to mine minerals out of the ground, eventually there won't need to be any significant mining and all the battery minerals will be in a constant cycle of being used then recycled
I know very little of chemistry and how batteries are produced, so from that level I'm imagining that once a battery is deemed to have reached end-of-life, it will have to get shipped somewhere, be recycled/refurbished for which presumably we will need some new material which needs to be mined, shipped, etc. All that requires water, produces waste that may or may not be toxic, the metals may come from places lacking human rights, and takes energy which may or may not be clean [1]. So all this could in the end have a considerable amount of negative externality somewhere.
What I like that I'm hearing about this CO2 battery, whether true will have to be seen, is that it might rely on off the shelf components, that's great, means the supply chain can be simple, and has longer life in the first place. And that while potentially even cheaper?
This is cool, but one thing to consider is that you're not going to be getting that CO2 from the atmosphere, but from captured emissions. When that plant is decomissioned, the path of least resistance is to just vent it.
If you've already got pure CO2 in a tank, sequestering it is a much easier problem. The hard part is capturing it out of smokestack emissions or (especially) directly from the atmosphere as it's much more diffuse.
Except that the recycling ... cycle is not perfect. Far from it. I'd reckon maybe half of all lithium ends up in recycling. Other half probably ends up in the landfill. For instance, I picked up a broken ebike from the trash not long ago (Amsterdam). Battery still in it. Same goes for lots of smaller electronics.
That's true, but seems unlikely to be an issue for EV batteries. Cars are large and valuable enough that there are established businesses that deal with scrapping them.
You will not get back 100 % of the raw material in any economically feasible process though.
If your process gets 90% of the lithium out of the battery, after 7 cycles more than half of the lithium is gone. Therefore Mining can’t stop even when the market doesn’t grow anymore.
Current BESS are rated to last 10-15 years. Battery makers are already moving to lithium-free sodium chemistries. It's hard to imagine what we'll be using at the end of seven full cycles (70-105 years from now.) Sodium? Tiny fusion reactors? Firewood and charcoal? Yes, we should care about this and try to leave our descendants with good solutions. No, we should not think about it so much that we leave our descendants with a devastatingly acidified ocean and uninhabitable equatorial regions in the process of worrying about it.
The process of battery manufacturing is always improving, getting more storage with less lithium. So when a battery is recycled, it will actually produce more battery than the original battery, even with lithium losses.
We don't know how long that process will go on, but in any case the amount of lithium needed will be a steady state, assuming constant need for batteries. But much more likely we will see ever increasing demand for batteries, just as we do for steel or copper or whatever minerals power our current economy.
Though they are also poised to get iron ore refining to work. That alone could be worth a bunch (numbers assuming 20y amortization and 30% average duty cycle (using only summer surplus) suggest around 10ct/kg iron metal capex plus 3 kWh/kg iron metal electricity).
I have not seen much data on these designs, but conceptually they should be cheap. Require holding tanks and iron. No high pressures or other exotic requirements.
Round trip efficiency is way worse than lithium, but that might not be meaningful for grid batteries. You just want something that cheaply scales.
Yeah, they have very little information. They say "20MW" once, but it's not clear what part of it is 20MW. They imply it can be scaled up or down but don't say much.
A gas-based design seems like it would be better at a small scale - e.g. the facility in the link has a reservoir the better part of a mile away from the turbines, and has a max output of 600 MW or so.
CO2 may actually be a good working fluid for the purpose - cheap, non-toxic except for suffocation hazard, and liquid at room temperature at semi-reasonable pressures. I'm not an expert on that sort of thing, though.
- Round trip efficiency: how much electricity comes out from electricity going in
- $/kWH capacity: lower is better, how does the battery cost scale as additional energy capacity is added?
- $/kW capacity: lower is better, how does the battery cost scale as additional power capacity is added?
- power to energy ratio: higher is better, to a certain point, but not usually at the expense of $/kWh capacity. If your ratio is 1:100, then you're in range of 4 days duration, which means at most 90 full discharges in a year, which highly limits the amounts of revenue possible.
- Leakage of energy per hour, when charged: does a charged battery hold for hours? Days? Weeks?
These all add up to the $/kWh delivered back to the grid, which determines the ultimate economic potential of the battery tech.
Lithium ion is doing really great on all of these, and is getting cheaper at a tremendous rate, so to compete a new tech has to already be beating it on at least one metric, and have the hope of keeping up as lithium ion advances.
Some tech has notably separate $/kW and $/kWh pricing.
Such as for example the awfully-often mentioned seasonal Europe setup of green summer hydrogen injected into former methane caverns, to be fed to gas turbines in winter.
Though I guess it's hard to measure $/kWh due to usage of natural formations.
Then there's the up-and-coming opportunity for green iron refining (ore to metal), which becomes financially practical when fed with curtailed summer surplus from integrated PV/battery deployments who's entire AC and grid side is undersized vs. PV generation capacity, using day/night shifting with local storage and peak shaving into iron electrolyzers (which would use some of the day/night shifting battery's capacity to increase over-the-year duty cycle of the iron electrolyzers).
For reference we're looking at capex for the electrolyzers (assuming 30% duty cycle average over a year, and zero discount rate over 20 years expected lifespan) around 0.1$/kg iron (metal) and electricity usage around 3 kWh/kg iron (metal).
TFA says 75% round trip efficiency, compared to 85% for batteries.
While there is no leakage as such, the storage vessels might require continuous cooling, unless they are buried deep in the ground and they are very well insulated.
For great enough capacities, so that the costs of the turbo-generator and of the compressor become relatively small, the cost per stored kWh should become significantly lower than for batteries, especially when considering the far longer lifetime.
For small capacities, batteries are certainly preferable, but for very large capacities this should be a very good solution.
I keep seeing comments that Li-ion is getting cheaper at an amazing rate but somehow the 18650 cells I seem to see online keep getting more expensive. Anyone have a source?
Might be the form factor. I think most of the big companies have moved away from 18650 cells. The cheapest full packs (not cells) in the US are $800 for 5kwh. Search “Server Rack Battery” on eBay, amazon or alibaba. These things are way cheaper than they were 12 months ago. The raw cells can be had even cheaper, but they require more specialized knowledge and equipment to use.
Abundant doesn't mean available in location. It can be concentrated in one spot and more economic to mine there and ship where needed.
Australia also exports a billion tons of iron ore to China. Iron ore is everywhere, but easier to mine good ore in Australia and ship it. Shipping is really efficient.
my response was from the security of access angle.
sure, lithium is more abundant than gold or silver but lithium access is not secure. Given that the largest lithium processing facilities by far are in one country (Chile), the supply of lithium is far from secure.
None of those are either rare earth metals or especially rare, graphite isn't a metal at all, and lithium iron phosphate batteries contain neither nickel nor manganese.
That is a rather large amount of land, which more concerningly to me means a huge amount of equipment to get to that 200MWh, which would hint at very very high cost. I wonder how cheap they can get it.
At first, I thought this was an elaborate joke because fossil fuels are effectively "CO2 batteries."
Instead, it's compressed gas. Which is fine and possibly the best solution in certain contexts. But, it isn't exactly revolutionary or necessarily preferable to Li-ion most of the time.
Energy is extracted like from compressed gas, but the advantage of CO2 is that it can be liquefied at a relatively low pressure, so it can be stored at a relatively low volume in vessels that have to resist only to modest pressures.
So it is much easier to store a high amount of energy than it would be to store that energy in compressed air.
Can somebody versed in thermodynamics explain me how can it work?
They say that they keep CO2 in liquid form at room temperature, then turn it into gas, and grab the energy so released.
* Isn't the gas be very cold on expansion from a high-pressure, room-temp liquid? It could grab some thermal energy from the environment, of course, even in winter, but isn't the efficiency going to depend on ambient temperature significantly?
- To turn the gas into the liquid, they need to compress it; this will produce large amounts of heat. It will need large radiators to dissipate (and lose), or some kind of storage to be reused when expanding the gas. What could that be?
- How can the whole thing have a 75% round-trip efficiency, if they use turbines that only have about 40% efficiency in thermal power plants? They must be using something else, not bound by the confines of the Carnot cycle. What might that be?
They store the heat from compression and use it during expansion.
You can see it in the little animation on their website. It's marked TES (thermal energy storage).
It looks like their RTE is based on a 10 hour storage time. The RTE is going to drop after their sweet spot, but if they're just looking to store excess energy from solar farm for when the sun isn't shining that's probably not a huge problem.
Storing the heat is the key part, I suppose, even though they are focusing on storing CO2.
I wonder if something like the paraffin phase transition could be used to limit the temperature of the heat reservoir, and thus the losses during storage.
My hunch is that they're doing this for three reasons.
1. Decompressing the gas can be used to do work, like turning a turbine or something. It's not particularly efficient, as you mention, but it can store some energy for a while. Also the tech to do this is practically off-the-shelf right now, and doesn't rely on a ton of R&D to ramp up. Well, maybe the large storage tanks do, but that should be all. So it _does_ function and nobody else is doing it this way so perhaps all that's seen as a competitive edge of sorts.
2. The storage tech has viable side-products, so the bottom-line could be diversified as to not be completely reliant on electricity generation. The compressed gas itself can be sold. Processed a little further, it can be sold as dry ice. Or maybe the facility can be dual-purposed for refrigeration of goods.
3. IMO, they're using CO2 as a working fluid is an attempt to sound carbon-sequestration-adjacent. Basically, doubling-down on environmentally-sound keywords to attract investment. Yes, I'm saying they're greenwashing what should otherwise be a sand battery or something else that moves _heat_ around more efficiently.
This is more of a compressed-air battery than a sand battery, except that the "air" is CO2 and it's "compressed" enough to cause a phase change.
Heat-based energy storage is always going to be inefficient, since it's limited by the Carnot efficiency of turning heat back into electricity. It's always better to store energy mechanically (pumping water, lifting weights, compressing gas), since these are already low-entropy forms of energy, and aren't limited by Carnot's theorem.
I don't know much about this CO2 battery, but I'm guessing the liquid-gas transition occurs under favorable conditions (reasonable temperatures and pressures). The goal is to minimize the amount of heat involved in the process, since all heat is loss (even if they can re-capture it to some extent).
I suppose that liquid CO2 just requires much less volume to store, while keeping the pressure within reason (several dozen atm). For it to work though, the liquid should stay below 31°C (88°F), else it will turn into gas anyway.
So, in a hot climate, they need to store it deep enough underground, and cool the liquid somehow below ambient temperature.
> they're using CO2 as a working fluid is an attempt to sound carbon-sequestration-adjacent
Um no, that's unfair. CO2 is an easy engineering choice here. It's easy to compress and decompress, easy to contain, non-flamable, non-corrosive, non-toxic and cheap. It's used in many applications for these reasons.
While CO2 is now a great evil among the laptop class, it has been a miracle substance in engineering for roughly 200 years now.
Looking at the diagram on the web page, seems the key is the water. When expanding, use heat stored in the water to heat the gas. Likewise when compressing CO2 into liquid, use the water to store the excess heat generated?
There are papers that do thermodynamic analysis of similar systems finding something like ~65% efficiency. So 75% might be a bit fluffed up, but not outrageously so.
E.g. if they can use the waste heat for district heating and count that as useful work.
> They say that they keep CO2 in liquid form at room temperature, then turn it into gas, and grab the energy so released.
To evaporate something, you need to give it energy (heat). The energy flux through the dome walls is not huge, so CO2 boils away slowly.
> - To turn the gas into the liquid, they need to compress it; this will produce large amounts of heat. It will need large radiators to dissipate (and lose), or some kind of storage to be reused when expanding the gas. What could that be?
Well, you have this giant heatsink called "the atmosphere".
> - How can the whole thing have a 75% round-trip efficiency, if they use turbines that only have about 40% efficiency in thermal power plants?
A quirk of thermodynamics. CO2 is not the _hot_ part, it's the _cold_ part of the cycle.
To explain a bit more, if you confine CO2 and let it boil at room temperature, it will get up to around 70 atmospheres of pressure. You then allow it to expand through a turbine. This will actually _cool_ it to below the room temperature, I don't have exact calculations, but it looks like the outlet temperature will be at subzero temperatures.
This "bonus cold" can be re-used to improve the efficiency of storage or for other purposes.
This is a fairly elegant idea. But it's definitely not "long term storage" as they claim it to be. A long-term storage solution that only holds energy for 8 hours is quite useless. Also, a long-term storage solution needs to be proportionally less expensive than a short term one in order to be equally profitable. For example, if you charge-discharge a lithium battery on a daily basis, and you use any long term solution to charge-discharge every 100 days, then the second needs to be 100 times cheaper if you want to get the same profit, because you sell the electricity only once vs 100 times for the battery. But this solution claims to be only slightly less expensive than lithium batteries, certainly not by a factor of 100. Not even by a factor of 2.
I'm guessing the diagram is missing a bit on the heat exchanger side; they're going to need to dump plenty of (environmental) heat into the expansion thingy to keep the liquid CO2 boiling off indefinitely at the pressure they want.
If this is intended for small-scale to medium-scale on-premise storage then the evaporating CO2 could also serve as the cold side of a building-size AC system for extra efficiency during the high demand portion of the duck curve.
I think there may be quite a market for maintaining hot and cold (and pressurized/liquified) sinks throughout the day/night cycle in highrises or entire cities.
This is potentially promising because it puts pressure on batteries, which gives us more options and reduces the dependence on specific minerals. Also may be cheap enough to be worth putting right next to a solar farm when batteries don't make sense.
What are the drawbacks of this battery compared to a Lithium-Ion battery? I would assume practicality (sizing, installation, etc...) but I would be interested to hear others thoughts on this. This site does a great job marketing the battery but not defining the drawbacks, hence why I am asking.
Worse efficiency, much higher (mechanical!) complexity, much more bespoke and slower to get installed.
I honestly don't see this really taking off, batteries are too cheap already, people just haven't really realized yet.
You can just order 1kWh of storage as a prismatic LiFePO cell for about $60 and have it delivered in the same week. Battery management and inverters are a solved problem, too, and don't have moving parts either.
The efficiency concerns here are valid. For comparison, modern lithium power stations are hitting 90%+ round-trip efficiency pretty consistently now.
The mechanical complexity is what worries me most - CO2 phase changes, compression/decompression cycles, heat exchangers...that's a lot of potential failure points compared to solid-state lithium cells. When researching portable power stations (I used gearscouts to compare $/Wh across different capacities), even budget lithium units are getting surprisingly cost-effective. We're seeing <$0.30/Wh for some models now.
That said, if Energy Dome can achieve reasonable $/kWh at grid scale without the lithium supply chain constraints, the efficiency trade-off might be worth it. The real question is whether the mechanical complexity translates to higher maintenance costs that eat into any capex savings.
With the energy source (presumably solar/wind) being "free," efficiency isn't the most important thing. But the whole thing sounds sort of "Rube Goldberg" even if it works, batteries or supercapacitors or something like that are probably going to be a lot more reliable.
It's sort of like arguing for going back to steam engines because we've got a new way to boil water.
The biggest drawback that this web page acknowledges is lower round trip efficiency (75% for the CO2 battery, 85% for the lithium battery). If that is really the only deficiency, this device is great.
I'd mostly be wary of what the actual costs and operational experience are. This device has moving parts that a battery doesn't. Looking at their news page, I see announcements of projects and partnerships but I don't think that they have any completed projects running yet. I suspect that their CAPEX comparison, where they show lithium ion batteries as 70% more expensive, may be aspirational rather than demonstrated. There are several companies that have already installed megawatt-scale lithium ion grid storage today: Samsung, BYD, Tesla, Fluence, LG Chem... and many of these projects have published costs and operational experience already.
They built a small plant in Sardinia, but I can't find any information on what it cost to build or operate.[1]
I'm skeptical of their cost claims. Turbines aren't cheap and compared to batteries, they require significant maintenance. And while you can increase energy storage by increasing the size/number of CO2 tanks, the only way to increase power output (or "charging" speed) is to add more/bigger compressors and turbines.
There's also the issue of volumetric energy density. Wikipedia says that compressed CO2 storage has an energy density of 66.7 watt-hours per liter, though it's unclear if that's before or after turbine inefficiencies.[2] And that's the density in a compressed tank. It doesn't count the volume of the low pressure dome, which is many times larger. For comparison, lithium batteries are 250–700Wh per liter depending on the chemistry. Specific energy (energy per unit mass) is better than lithium ion, but since these are fixed installations, mass isn't a major concern.
Considering their claims are for a theoretical full scale plant, and that the numbers are already worse than batteries (75% efficiency, lower volumetric energy density, $200/kWh), I'm not optimistic. This technology might have niche uses, but I don't see it competing with most lithium battery installations.
That said, I hope I'm wrong. The more energy storage solutions we have, the better our future will be.
I think the biggest issue is perhaps the danger aspect of it. You are making wild pressure swings on some critical storage structures with some pretty wild temp swings. Making sure that doesn't ultimately destroy the CO2 canister or collapse the CO2 dome will be a challenge.
It also has to be pretty big, which doesn't matter too much other than a critical failure would be more impressive.
They say no leaks, but I'm sure there will be SOME CO2 leakage. Hard to make something like this with gases that doesn't leak at least a little. You could offset that with some CO2 capture via atmospheric distillation.
To store CO2 as a liquid you either need to chill it or you need to increase the pressure until it becomes a liquid. It takes around 75psi to turn CO2 into a liquid at room temperature.
There are historical examples of entire villages around lakes suffocating during a limnic erruption.
I can't exactly find what sort of specs an installation of a large co2 battery might have, so it may be small beans relatively speaking, but that is still a lot of co2 in a very small area, and I certainly hope that both the engineers and regulators know what they're doing with it.
brilliant!, WOW!, how the fuck did everybody else miss this till now!
this could be easily cobbled together useing junkyard salvage!
zero exotic anything! -37°c, I've lived in colder places.
it will scale down to house or smaller sizes, or all the way up to primary grid power.
far north areas with abandoned mines into the permafrost will benifit from this.
very tickled by this
edit: there are a number of hazards and failure modes that are unique to this , but in no way as a dangerous as most other current power generation and handling of chemical storage and transport, and most of the danger to the public can be eliminated by sufficient set backs, ie:in a breach
the CO² would dissapate below lethal levels quickly.
tl;dr: it's a gas compression/decompression energy storage mechanism. It's nothing new and I have never seen one being being financially viable so far.
https://www.latitudemedia.com/news/form-energy-brings-in-mor...
The scale of investment required makes it quite hard for new companies to compete on cost:
https://www.theinformation.com/articles/battery-industry-sca...
I am very interested in this question, but those who raise it never have answers about the negative impacts of mining lithium.
For example, the amount of lithium needed for an EV is an order of magnitude less than the amount of steel needed. What is so bad about lithium mining that it's 10x worse than iron mining, pound for pound?
Nobody has ever answered my request for environmental concerns with a concrete environmental lithium mining concern, such as acidification that can sometimes happen with iron mining.
I've researched and researched, found nothing, which leaves me thinking that the worst case scenario for lithium is no worse than the worst case for iron.
Meanwhile, we have such immense documented harms from fossil fuel extraction that nobody ever questions again, or with the same intensity that's reserved for supposedly toxic lithium batteries.
The apparent benefit is massive, so any delay seems to cause massive harm to the environment.
I think we need to flip the question: where is the proof that coal/oil/iron is better for the environment than mining and recycling batteries? (BTW, it's at least 20 years now for grid batteries, with lifetime going up all the time...)
https://youtu.be/6RhtiPefVzM?si=ITsJsHAKjYtMNZEc
So if an electric car requires 2000 pounds of iron and 50 pounds of lithium, that works out to 4000 pounds of iron ore that needs to be mined and refined, vs 25,000 pounds of lithium ore.
Lithium is also extracted via brine, as opposed to hard rock. Most of the environmental reporting has been on the brine approaches, which currently are in high elevations of South American mountains, and the problem appears to be mostly the use of land and taking that land out of the ecosystem for economic use as drying pools. But the same problem occurs with mining, too!
Spodumene is dispersed among other minerals into rocks and it only forms a few percent at most of those rocks, if not only fractions of a percent.
The rocks must be crushed and spodumene must be separated from the other much more abundant minerals, by flotation or similar mineral concentration techniques, before going further to chemical processing.
So your 670 pounds must be multiplied by a factor like 100, varying from mine to mine.
Some multiplication factor must also be used for the iron ore, which is also mixed with undesirable silicates, but iron oxide may reach up to a few tens of percent of the rock, so the multiplication factor is much smaller.
means recycling of lithium batteries will be a thriving business. (i.e. big difference from recycling of say tires or plastic bottles, more like, pretty successful, recycling of aluminum, and even better than it)
No one made fortune in Li-ion recycling in all those years. Li-ion cells remained disposable.
If the processes to extract Lithium from recycling become cheap enough to compete with the prices of mined Lithium, then that happens.
Processes still need to be invented/scaled for that to happen: the only real way to deal with damaged or charged cells that I know of is to deep freeze them, shred them, and then defrost them slowly.
But in either case: Lithium is going to end up as waste. Making it cheaper to make cars affordable and the grid more stable means that disposable batteries will be even cheaper.
I don’t know how modern batteries fare in landfills: Most modern solar panels, for example, are relatively clean (mostly aluminum, silicon, copper, wee bits of lead). But not a waste management expert.
https://www.redwoodmaterials.com/news/responding-recovering-...
They've been working hard at recycling, and the biggest challenge at the moment is actually getting old batteries for the process. There's not many in-service batteries reaching end of life yet, so they mostly deal with production scrap.
Personally of course, I don't think this matters at all: old lithium batteries degrade into salt and don't contain harmful chemicals. There's no real indication we'd ever have a problem dealing with them, even if it was just throwing them all into a big hole till the hole looks enough like a natural lithium source to mine again.
I worry the answering that question requires answering this question: whose negative externalities?
What I like that I'm hearing about this CO2 battery, whether true will have to be seen, is that it might rely on off the shelf components, that's great, means the supply chain can be simple, and has longer life in the first place. And that while potentially even cheaper?
[1] https://www.youtube.com/watch?v=GSzh8D8Of0k
If your process gets 90% of the lithium out of the battery, after 7 cycles more than half of the lithium is gone. Therefore Mining can’t stop even when the market doesn’t grow anymore.
We don't know how long that process will go on, but in any case the amount of lithium needed will be a steady state, assuming constant need for batteries. But much more likely we will see ever increasing demand for batteries, just as we do for steel or copper or whatever minerals power our current economy.
Round trip efficiency is way worse than lithium, but that might not be meaningful for grid batteries. You just want something that cheaply scales.
- What's the energy areal and volumetric density kWh/m2 & kWh/m3 of this storage?
- How did they derive their CapEx savings figures?
- What's the peak charge/discharge rate of an installation?
- Can this storage be up/down-scaled in capacity and rate and by what limiting factors?
A gas-based design seems like it would be better at a small scale - e.g. the facility in the link has a reservoir the better part of a mile away from the turbines, and has a max output of 600 MW or so.
CO2 may actually be a good working fluid for the purpose - cheap, non-toxic except for suffocation hazard, and liquid at room temperature at semi-reasonable pressures. I'm not an expert on that sort of thing, though.
The major advantage over pumped hydro would be you do not need very specific geography to make it happen (90 - 300+m change in elevation)
- Round trip efficiency: how much electricity comes out from electricity going in
- $/kWH capacity: lower is better, how does the battery cost scale as additional energy capacity is added?
- $/kW capacity: lower is better, how does the battery cost scale as additional power capacity is added?
- power to energy ratio: higher is better, to a certain point, but not usually at the expense of $/kWh capacity. If your ratio is 1:100, then you're in range of 4 days duration, which means at most 90 full discharges in a year, which highly limits the amounts of revenue possible.
- Leakage of energy per hour, when charged: does a charged battery hold for hours? Days? Weeks?
These all add up to the $/kWh delivered back to the grid, which determines the ultimate economic potential of the battery tech.
Lithium ion is doing really great on all of these, and is getting cheaper at a tremendous rate, so to compete a new tech has to already be beating it on at least one metric, and have the hope of keeping up as lithium ion advances.
Such as for example the awfully-often mentioned seasonal Europe setup of green summer hydrogen injected into former methane caverns, to be fed to gas turbines in winter.
Though I guess it's hard to measure $/kWh due to usage of natural formations.
Then there's the up-and-coming opportunity for green iron refining (ore to metal), which becomes financially practical when fed with curtailed summer surplus from integrated PV/battery deployments who's entire AC and grid side is undersized vs. PV generation capacity, using day/night shifting with local storage and peak shaving into iron electrolyzers (which would use some of the day/night shifting battery's capacity to increase over-the-year duty cycle of the iron electrolyzers).
For reference we're looking at capex for the electrolyzers (assuming 30% duty cycle average over a year, and zero discount rate over 20 years expected lifespan) around 0.1$/kg iron (metal) and electricity usage around 3 kWh/kg iron (metal).
While there is no leakage as such, the storage vessels might require continuous cooling, unless they are buried deep in the ground and they are very well insulated.
For great enough capacities, so that the costs of the turbo-generator and of the compressor become relatively small, the cost per stored kWh should become significantly lower than for batteries, especially when considering the far longer lifetime.
For small capacities, batteries are certainly preferable, but for very large capacities this should be a very good solution.
For buying LFP cells, I would start here: https://diysolarforum.com/
The largest exporter is Australia and the largest importer is China. Were lithium abundant, why does China import most of its lithium?
Australia also exports a billion tons of iron ore to China. Iron ore is everywhere, but easier to mine good ore in Australia and ship it. Shipping is really efficient.
sure, lithium is more abundant than gold or silver but lithium access is not secure. Given that the largest lithium processing facilities by far are in one country (Chile), the supply of lithium is far from secure.
"LFP contains neither nickel[35] nor cobalt, both of which are supply-constrained and expensive. "
[35] pdf https://nickelinstitute.org/media/1987/nickel_battery_infogr...
One of the few numbers I could find on their site was:
> Our standard frame 200MWh battery requires about 5 he (12 acres) of land to be built.
They also refer to it as a "20MW/200MWh" plant.
Instead, it's compressed gas. Which is fine and possibly the best solution in certain contexts. But, it isn't exactly revolutionary or necessarily preferable to Li-ion most of the time.
So it is much easier to store a high amount of energy than it would be to store that energy in compressed air.
They say that they keep CO2 in liquid form at room temperature, then turn it into gas, and grab the energy so released.
* Isn't the gas be very cold on expansion from a high-pressure, room-temp liquid? It could grab some thermal energy from the environment, of course, even in winter, but isn't the efficiency going to depend on ambient temperature significantly?
- To turn the gas into the liquid, they need to compress it; this will produce large amounts of heat. It will need large radiators to dissipate (and lose), or some kind of storage to be reused when expanding the gas. What could that be?
- How can the whole thing have a 75% round-trip efficiency, if they use turbines that only have about 40% efficiency in thermal power plants? They must be using something else, not bound by the confines of the Carnot cycle. What might that be?
You can see it in the little animation on their website. It's marked TES (thermal energy storage).
It looks like their RTE is based on a 10 hour storage time. The RTE is going to drop after their sweet spot, but if they're just looking to store excess energy from solar farm for when the sun isn't shining that's probably not a huge problem.
I wonder if something like the paraffin phase transition could be used to limit the temperature of the heat reservoir, and thus the losses during storage.
1. Decompressing the gas can be used to do work, like turning a turbine or something. It's not particularly efficient, as you mention, but it can store some energy for a while. Also the tech to do this is practically off-the-shelf right now, and doesn't rely on a ton of R&D to ramp up. Well, maybe the large storage tanks do, but that should be all. So it _does_ function and nobody else is doing it this way so perhaps all that's seen as a competitive edge of sorts.
2. The storage tech has viable side-products, so the bottom-line could be diversified as to not be completely reliant on electricity generation. The compressed gas itself can be sold. Processed a little further, it can be sold as dry ice. Or maybe the facility can be dual-purposed for refrigeration of goods.
3. IMO, they're using CO2 as a working fluid is an attempt to sound carbon-sequestration-adjacent. Basically, doubling-down on environmentally-sound keywords to attract investment. Yes, I'm saying they're greenwashing what should otherwise be a sand battery or something else that moves _heat_ around more efficiently.
Heat-based energy storage is always going to be inefficient, since it's limited by the Carnot efficiency of turning heat back into electricity. It's always better to store energy mechanically (pumping water, lifting weights, compressing gas), since these are already low-entropy forms of energy, and aren't limited by Carnot's theorem.
I don't know much about this CO2 battery, but I'm guessing the liquid-gas transition occurs under favorable conditions (reasonable temperatures and pressures). The goal is to minimize the amount of heat involved in the process, since all heat is loss (even if they can re-capture it to some extent).
So, in a hot climate, they need to store it deep enough underground, and cool the liquid somehow below ambient temperature.
Um no, that's unfair. CO2 is an easy engineering choice here. It's easy to compress and decompress, easy to contain, non-flamable, non-corrosive, non-toxic and cheap. It's used in many applications for these reasons.
While CO2 is now a great evil among the laptop class, it has been a miracle substance in engineering for roughly 200 years now.
I am _very_ suspicious the efficiency is anywhere close to 75%.
E.g. if they can use the waste heat for district heating and count that as useful work.
To evaporate something, you need to give it energy (heat). The energy flux through the dome walls is not huge, so CO2 boils away slowly.
> - To turn the gas into the liquid, they need to compress it; this will produce large amounts of heat. It will need large radiators to dissipate (and lose), or some kind of storage to be reused when expanding the gas. What could that be?
Well, you have this giant heatsink called "the atmosphere".
> - How can the whole thing have a 75% round-trip efficiency, if they use turbines that only have about 40% efficiency in thermal power plants?
A quirk of thermodynamics. CO2 is not the _hot_ part, it's the _cold_ part of the cycle.
To explain a bit more, if you confine CO2 and let it boil at room temperature, it will get up to around 70 atmospheres of pressure. You then allow it to expand through a turbine. This will actually _cool_ it to below the room temperature, I don't have exact calculations, but it looks like the outlet temperature will be at subzero temperatures.
This "bonus cold" can be re-used to improve the efficiency of storage or for other purposes.
I wonder if they design in flow channels for the heavier CO2 to flow down to safe, unpopulated areas.
Is there an advantage to the domes? IIRC some CAES system are put into old mines, that sort of thing.
Not sure if there's more scattered around the site, but that's on the front page.
If this is intended for small-scale to medium-scale on-premise storage then the evaporating CO2 could also serve as the cold side of a building-size AC system for extra efficiency during the high demand portion of the duck curve.
I think there may be quite a market for maintaining hot and cold (and pressurized/liquified) sinks throughout the day/night cycle in highrises or entire cities.
I honestly don't see this really taking off, batteries are too cheap already, people just haven't really realized yet.
You can just order 1kWh of storage as a prismatic LiFePO cell for about $60 and have it delivered in the same week. Battery management and inverters are a solved problem, too, and don't have moving parts either.
The mechanical complexity is what worries me most - CO2 phase changes, compression/decompression cycles, heat exchangers...that's a lot of potential failure points compared to solid-state lithium cells. When researching portable power stations (I used gearscouts to compare $/Wh across different capacities), even budget lithium units are getting surprisingly cost-effective. We're seeing <$0.30/Wh for some models now.
That said, if Energy Dome can achieve reasonable $/kWh at grid scale without the lithium supply chain constraints, the efficiency trade-off might be worth it. The real question is whether the mechanical complexity translates to higher maintenance costs that eat into any capex savings.
https://gearscouts.com/power-stations
It's sort of like arguing for going back to steam engines because we've got a new way to boil water.
A large portion of power comes from new and exciting ways to boil water that turns a turbine ;)
Most fossil fuel plants are water boilers as are all nuclear plants.
There's even some solar power plants that are effectively just water boilers.
I'd mostly be wary of what the actual costs and operational experience are. This device has moving parts that a battery doesn't. Looking at their news page, I see announcements of projects and partnerships but I don't think that they have any completed projects running yet. I suspect that their CAPEX comparison, where they show lithium ion batteries as 70% more expensive, may be aspirational rather than demonstrated. There are several companies that have already installed megawatt-scale lithium ion grid storage today: Samsung, BYD, Tesla, Fluence, LG Chem... and many of these projects have published costs and operational experience already.
I'm skeptical of their cost claims. Turbines aren't cheap and compared to batteries, they require significant maintenance. And while you can increase energy storage by increasing the size/number of CO2 tanks, the only way to increase power output (or "charging" speed) is to add more/bigger compressors and turbines.
There's also the issue of volumetric energy density. Wikipedia says that compressed CO2 storage has an energy density of 66.7 watt-hours per liter, though it's unclear if that's before or after turbine inefficiencies.[2] And that's the density in a compressed tank. It doesn't count the volume of the low pressure dome, which is many times larger. For comparison, lithium batteries are 250–700Wh per liter depending on the chemistry. Specific energy (energy per unit mass) is better than lithium ion, but since these are fixed installations, mass isn't a major concern.
Considering their claims are for a theoretical full scale plant, and that the numbers are already worse than batteries (75% efficiency, lower volumetric energy density, $200/kWh), I'm not optimistic. This technology might have niche uses, but I don't see it competing with most lithium battery installations.
That said, I hope I'm wrong. The more energy storage solutions we have, the better our future will be.
1. https://www.energy-storage.news/energy-dome-launches-4mwh-de...
2. https://en.wikipedia.org/wiki/Compressed_carbon_dioxide_ener...
It also has to be pretty big, which doesn't matter too much other than a critical failure would be more impressive.
They say no leaks, but I'm sure there will be SOME CO2 leakage. Hard to make something like this with gases that doesn't leak at least a little. You could offset that with some CO2 capture via atmospheric distillation.
I can't exactly find what sort of specs an installation of a large co2 battery might have, so it may be small beans relatively speaking, but that is still a lot of co2 in a very small area, and I certainly hope that both the engineers and regulators know what they're doing with it.
https://en.wikipedia.org/wiki/Limnic_eruption