[HN Gopher] CO2 Battery
___________________________________________________________________
CO2 Battery
Author : xnx
Score : 156 points
Date : 2025-07-25 16:32 UTC (1 days ago)
(HTM) web link (energydome.com)
(TXT) w3m dump (energydome.com)
| ricciardo wrote:
| 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.
| SoftTalker wrote:
| Mechanical complexity.
| nine_k wrote:
| Say, lower round-trip efficiency, and maybe lower peak power.
| Also likely a larger area is required: can't make a powerwall
| out of it.
| salynchnew wrote:
| Square footage and durability of the form factor?
| cogman10 wrote:
| 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.
| datadrivenangel wrote:
| The storage of CO2 as a liquid means less pressure then a
| high pressure gas.
| cogman10 wrote:
| 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.
| RandallBrown wrote:
| 75 psi seems very low. Numbers I'm seeing online say more
| like 800-900 PSI.
| cogman10 wrote:
| Ah, you're correct I was turning bar into psi on the
| charts I was looking at.
| tzs wrote:
| They are storing it at 70 bar, which is a little over
| 1000 psi.
| jabl wrote:
| I would say the big issue would be the size and cost of the gas
| dome. For storing a substantial amount of gaseous CO2 that will
| be humongous.
| randallsquared wrote:
| The main drawback appears to be short storage time.
| philipkglass wrote:
| 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.
| ggreer wrote:
| 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.
|
| 1. https://www.energy-storage.news/energy-dome-launches-4mwh-
| de...
|
| 2. https://en.wikipedia.org/wiki/Compressed_carbon_dioxide_en
| er...
| myrmidon wrote:
| 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.
| SoftTalker wrote:
| 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.
| cogman10 wrote:
| > 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.
| ethan_smith wrote:
| 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.
|
| https://gearscouts.com/power-stations
| SoftTalker wrote:
| Not a battery in the chemical sense. Energy storage through phase
| change of a gas coupled with a mechanical generator to make
| electricity.
| datameta wrote:
| A thermal sand battery and gravity-water battery are both non-
| chemical so the term battery extends beyond "vessel with redox
| reaction".
| datadrivenangel wrote:
| 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.
| nine_k wrote:
| 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?
| jabl wrote:
| 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?
| pragma_x wrote:
| 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.
| s_tec wrote:
| 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).
| nine_k wrote:
| 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 31degC (88degF), 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.
| topspin wrote:
| > 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.
| klunger wrote:
| Yes, it is not clear why they have chosen CO2 beyond PR.
| There are other gas mixtures that would likely have better
| yields.
| Aloisius wrote:
| 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.
| nine_k wrote:
| 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.
| Aloisius wrote:
| According to one of their patents, they're just using an
| insulated container with some incoherent solid to store
| heat like gravel or ceramic granules.
| schainks wrote:
| Marketing. They have marketing.
|
| I am _very_ suspicious the efficiency is anywhere close to 75%.
| cyberax wrote:
| 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.
| cyberax wrote:
| > 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.
| bee_rider wrote:
| How does it compare to CAES? (Compressed air)
|
| Is there an advantage to the domes? IIRC some CAES system are put
| into old mines, that sort of thing.
| RandallBrown wrote:
| > No cryogenic temperatures and high costs that are typically
| associated with compressed air energy storage
|
| Not sure if there's more scattered around the site, but that's
| on the front page.
| conradev wrote:
| 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:
|
| 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...
| barbazoo wrote:
| 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?
| ysofunny wrote:
| > We have a history of not pricing in negative externalities,
| did we do that this time?
|
| I worry the answering that question requires answering this
| question: whose negative externalities?
| fragmede wrote:
| 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?
| brandonagr2 wrote:
| 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
| barbazoo wrote:
| 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?
|
| [1] https://www.youtube.com/watch?v=GSzh8D8Of0k
| tehjoker wrote:
| 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.
| SoftTalker wrote:
| 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.
| slow_typist wrote:
| 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.
| matthewdgreen wrote:
| 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.
| epistasis wrote:
| 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.
| slow_typist wrote:
| There is a chemical limit though to the storage/lithium
| ratio.
| timschmidt wrote:
| No worries, we have a solution worked out already:
| https://en.wikipedia.org/wiki/Ford_Nucleon
|
| /s
| throwaway3b03 wrote:
| 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.
| cogman10 wrote:
| That changes rapidly as EVs and grid storage take off.
| 99+% of those will be recycled and those will make up the
| bulk of lithium battery consumption.
| nicoburns wrote:
| 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.
| ziga wrote:
| 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.
| 0cf8612b2e1e wrote:
| 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.
| jillesvangurp wrote:
| 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).
| XorNot wrote:
| 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.
| leptons wrote:
| 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).
| pabs3 wrote:
| Does that happen with LFP? It is supposed to be safer.
| jillesvangurp wrote:
| 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).
| epistasis wrote:
| > 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...)
| smithkl42 wrote:
| 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.
| epistasis wrote:
| 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!
| trhway wrote:
| >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)
| numpad0 wrote:
| Li-ion batteries are older than you think. First volume
| production of NMC cells happened 1991. LFP in 1997.
| Google was founded 1998.
|
| No one made fortune in Li-ion recycling in all those
| years. Li-ion cells remained disposable.
| HeadsUpHigh wrote:
| The volume of batteries wasn't there, neither did we
| really have the network to sell scrap batteries like we
| do with used cars.
| adrianN wrote:
| 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.
| kragen wrote:
| 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.
| adrian_b wrote:
| 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.
| kragen wrote:
| Hmm, I thought the Australian deposits were mostly
| spodumene. I appreciate the correction, although it's
| embarrassing; I'd rather be embarrassed than wrong.
| nandomrumber wrote:
| _At the mine 's current size, it can fulfil a third of
| the worldwide demand for lithium spodumene
| concentrate,[1] which is used to produce lithium
| hydroxide, a component of lithium-ion batteries._
|
| https://en.wikipedia.org/wiki/Greenbushes_mine
| 01HNNWZ0MV43FF wrote:
| That's why hybrids are great, hedges your bets between iron
| and lithium
| eptcyka wrote:
| Non-plugin hybrids typically do not use lithium
| batteries.
| UncleOxidant wrote:
| Is this _still_ the case? Haven 't most of the
| manufacturers switched over from NiMH?
| senectus1 wrote:
| my 2023 Rav 4 is still NiMH
| eptcyka wrote:
| They are better suited for the usecase, as they can
| sustain far more charge cycles without degradation. Which
| you end up doing a lot.
| dzhiurgis wrote:
| Terrible cars tho. Nobody likes their hybrids compared to
| pure EV.
| LoveMortuus wrote:
| 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.
| spauldo wrote:
| I like my Honda just fine. Granted, I've never owned an
| EV, but considering I travel a lot and gas stations are
| plentiful and fast, it's a better fit for me than an EV
| would be.
|
| I do think a plug-in hybrid would be better for when I'm
| not traveling, but I bought this car specifically for
| travel.
| bcrosby95 wrote:
| 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.
| cr125rider wrote:
| And the cross over point is surprisingly fast:
|
| https://youtu.be/6RhtiPefVzM?si=ITsJsHAKjYtMNZEc
| epistasis wrote:
| People don't realize the massive amount of emissions from
| using their car because they don't see the massive amount
| of material they put into their car every time they fuel
| up.
|
| A 20 gallon tank produces 400 pounds of CO2 for every
| fill up.
|
| Even manually filling a tank by lifting a series of five
| gallon containers would seriously reorient the average
| person's conception of their fuel usage.
| bcrosby95 wrote:
| Yeah, and the most deceptive thing is that burning 1 lb
| of gasoline produces about 3 lbs of CO2.
| conradev wrote:
| 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.
| epistasis wrote:
| That's very interesting about the freezing. I wonder if
| Redwood Materials does that?
|
| 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.
| bodyfour wrote:
| The one exception I'd make to this is Sodium-ion which does
| seem to have some chance of reaching manufacturing scale:
| https://www.batterytechonline.com/materials/5-key-takeaways-...
| namibj wrote:
| 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).
| hnaccount_rng wrote:
| How do these numbers compare with traditional methods?
| 0cf8612b2e1e wrote:
| 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.
| physarum_salad wrote:
| Lithium is a geopolitical metal and catches fire. Obviously
| what you are saying is true but there are always risks.
| dzhiurgis wrote:
| AFAIK lithium isn't used for long duration storage
| pockettanyas wrote:
| Right now that's true, but it's a price limitation, not a
| technical limitation.
| dzhiurgis wrote:
| I'm not too sure about it. Dendrites form when you charge
| to 100% and leave it for days and weeks. In some sense it
| wouldn't matter if cells costs 100x less than now.
| epistasis wrote:
| Some key parameters for new grid storage tech:
|
| - 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.
| metalliqaz wrote:
| There is also security of access to rare earth metals needed
| for those batteries.
| epistasis wrote:
| This is not an issue. Lithium, iron, and phosphate are all
| abundant.
| eldaisfish wrote:
| If lithium was as abundant as you claim, why is the Lithium
| Triangle a thing?
|
| The largest exporter is Australia and the largest importer
| is China. Were lithium abundant, why does China import most
| of its lithium?
| 7thaccount wrote:
| I think because we weren't doing a whole lot of looking
| until recently. I think a bunch of lithium has been
| recently discovered in Arkansas.
| ianburrell wrote:
| 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.
| eldaisfish wrote:
| 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.
| fragmede wrote:
| Because processing it is a value added service, and China
| doesn't have an incentive to build lithium processing
| plants in Australia.
| metalliqaz wrote:
| ... cobalt, nickel, manganese, graphite...
| ziga wrote:
| Grid-scale storage (and increasingly EVs) use lithium-
| iron-phosphate battery cells, which don't require
| cobalt/nickel/manganese.
| kragen wrote:
| 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.
| kragen wrote:
| This should say, "neither cobalt nor manganese". They do
| contain nickel.
| epistasis wrote:
| I don't think there's any nickel, and Wikipedia agrees,
| but I always love a correction:
|
| "LFP contains neither nickel[35] nor cobalt, both of
| which are supply-constrained and expensive. "
|
| [35] pdf https://nickelinstitute.org/media/1987/nickel_ba
| ttery_infogr...
| kragen wrote:
| I'm an idiot, you're right.
| zekrioca wrote:
| Okay, next periodical table elements...
| kragen wrote:
| No, those batteries do not use rare earth elements. I don't
| know of any battery type that uses rare earth elements. Where
| did you get that idea?
| foobarian wrote:
| 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?
| ziga wrote:
| https://about.bnef.com/insights/commodities/lithium-ion-
| batt...
| deegles wrote:
| I guess they're asking where to actually buy them at these
| prices, not doubting that the price is dropping.
| ziga wrote:
| Ah, those are wholesale prices. And the form factor will
| increasingly be prismatic LFP packs, not cylindrical
| cells.
|
| For buying LFP cells, I would start here:
| https://diysolarforum.com/
| MichaelNolan wrote:
| 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.
| cmrdporcupine wrote:
| Yea and I don't see EV prices dropping either.
| citrin_ru wrote:
| To see if anything is getting cheaper over the time,
| especially long term it's useful to adjust for inflation - if
| everything getting more expensive fast but Li-ion prices rise
| slower than other goods - adjusted for inflation Li-ion
| getting cheaper.
| namibj wrote:
| 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).
| adrian_b wrote:
| 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.
| drmaximus wrote:
| Relevant video: https://youtu.be/GSzh8D8Of0k?si=cTH_k8p2FetVmQro
| dinfinity wrote:
| This answers most of the important questions surrounding this
| specific tech. Much appreciated.
| Peteragain wrote:
| 75%? That would mean a 87.5% efficient compressor/liquifier and a
| 87.5% efficient turbine/generator set? Inconceivable!
| pjdesno wrote:
| It appears to be about as efficient as a pumped storage hydro
| facility (e.g. here's one in Massachusetts, built in 1970 or so -
| https://en.wikipedia.org/wiki/Bear_Swamp_Hydroelectric_Power...)
|
| 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.
| daqnz wrote:
| > A gas-based design seems like it would be better at a small
| scale
|
| 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)
| schainks wrote:
| Maybe I missed something, but what's the cost per kWh?
| darksaints wrote:
| 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.
|
| https://en.wikipedia.org/wiki/Limnic_eruption
| jonplackett wrote:
| You may have the coolest battery tech ever - but your website
| won't scroll down.
| metalman wrote:
| brilliant!, WOW!, how the fuck did everybody else miss this till
| now! this could be easily cobbled together useing junkyard
| salvage! zero exotic anything! -37degc, 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.
| gs17 wrote:
| It's a cool idea, but unfortunately their brochure has no
| details. It's just there to get you to fill out the contact form.
|
| 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.
| epistasis wrote:
| 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.
| benlivengood wrote:
| 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.
| TeeMassive wrote:
| 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.
| calmbonsai wrote:
| I come away with more questions than answers. The website is so
| numerically data-poor it serves as a net detriment to selling
| this solution.
|
| - 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?
| gs17 wrote:
| 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.
| credit_guy wrote:
| 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.
| calrain wrote:
| If that large storage bladder fails, I'm assuming people and
| animals all around it will suffocate?
|
| I wonder if they design in flow channels for the heavier CO2 to
| flow down to safe, unpopulated areas.
| klunger wrote:
| 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.
| adrian_b wrote:
| 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.
| sambeau wrote:
| What is the advantage here over compressed air?
| pwg wrote:
| Likely that CO2 liquefies at a lower pressure than air
| liquefies, making the storage pressure vessels cheaper as a
| result.
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