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Interesting concept. At $150,000,000 for 500MwH = $300/KwH of energy storage. Tesla's Megapack solution is $300/KwH also, giving this a good running chance if

Interesting concept. At $150,000,000 for 500MwH = $300/KwH of energy storage. Tesla's Megapack solution is $300/KwH also, giving this a good running chance if they can get costs down with scale. I like that it can potentially run for decades without chemical degradation, and that it is environmentally friendly since most of the parts (compressors, dryers, generators, tanks) can be recycled down the line with minimal environmental impact. Things that seem concerning at first glance: * Maintaining sub -196'C requires a lot of complex refrigeration, monitoring and pressurization equipment, which can be prone to failure (see Hampson–Linde cycle). The expansion factor of liquid air to air is roughly 800x. * Round-trip energy efficiency: I can't see a system taking electrical input to produce liquid air on the way in and similarly to run a turbine generator on the other end without having substantial losses both ways... I believe Tesla is around 88% on their system. * Gasses used in refrigeration continue to be an environmental and health concern even with modern compounds. Hopefully with some cost scaling or proof of longevity it can be a valid solution. 1. https://en.wikipedia.org/wiki/Hampson%E2%80%93Linde_cycle https://en.wikipedia.org/wiki/Hampson%E2%80%93Linde_cycle

Robotbeat 5y ago
I mean… you can recycle batteries, too. And the environmental “issue” with batteries is largely a red herring (steel mining and even recycling would look bad if you had a campaign of misinformation against it like batteries do, cherry-picking dramatic industrial-scale images without comparison with what it is replacing). $300/kWh isn’t anything to really write home about. Not opposed to it, though. While I don’t think it’s a slam-dunk win against batteries by any stretch, it’s good enough not to be a waste of money if someone builds one (which is probably true for that cement-block gravity energy storage thing).
- usrusr 5y ago
  “you can recycle batteries“ It has been done, in a laboratory. Scrap steel is routinely sold at market rate.
  - jeffbee 5y ago
    Scrap batteries are also sold at market rate, because "sold at market rate" is a tautology, true of any subject.
    - jsight 5y ago
      Yeah, and judging by the prices on ebay, the "market rate" for some batteries is pretty high. It might not stay that way when the higher volume electric cars start to age out.
    - usrusr 5y ago
      Only when market rate is a positive number.
  - bane 5y ago
    Nah, it's done every day in places all over Pakistan and India (and a few other places) https://youtu.be/afwO_MZjRjA https://youtu.be/afwO_MZjRjA
  - ClumsyPilot 5y ago
    Car batteries arr recycled st a good price
    - usrusr 5y ago
      Good luck building a BEV empire or grid storage on lead acid batteries.
boringg 5y ago
What do they use for the refrigerant? Refrigerant leaks have some of the highest green house gas potentials of all compounds. Depending on the product > 2000 times global warming potential of CO2.
- asdfasgasdgasdg 5y ago
  I would imagine a facility like this would have much better monitoring for refrigerant pressure drops than a typical consumer-grade system, plus a staff onsite that would be able to close valves and rapidly find and repair leaks.
  - IgorPartola 5y ago
    Not to be too glib, but that’s what we imagined about Chernobyl as well.
    - asdfasgasdgasdg 5y ago
      Despite your disclaimer, I do feel this is too glib. What is the takeaway? Yes, a bad thing happened one time at that facility (and others, at other times). That doesn't have much bearing on what I said. It is still reasonable to suspect that refrigerant leaks will not be a major problem at this facility.
      - IgorPartola 5y ago
        I am saying that in general I would prefer a system that’s safe by design, not by the fact that there are going to be people there who can make very human mistakes and create a problem. It is all relative: is it safer to run a facility like this or to transport a tanker-full of crude oil across waterways? But just saying that well there will be people there to open a valve when bad things happen is naive.
        asdfasgasdgasdg 5y ago
        When comparing the risk of refrigerant leaks in cooling systems in general vs heat exchange systems at a highly technical and actively monitored facility, it is relevant that the facility is actively monitored and probably has much better controls than typical refrigerant-using installations. It's not naïve to observe that most refrigerant leaks are likely from systems that are not monitored (i.e. almost all residential systems and probably most commercial ones).
contravariant 5y ago
* Round-trip energy efficiency: I can't see a system taking electrical input to produce liquid air on the way in and similarly to run a turbine generator on the other end without having substantial losses both ways... I believe Tesla is around 88% on their system. Well you can just power an engine on the temperature gradient. That's going to incur some losses though. This seems to be the downside of storing energy cooling stuff, you have to fight the second law of thermodynamics both ways.
- ncmncm 5y ago
  You get to run both a heat engine, on the temperature difference, and a turbine, on the resulting boiled-off gas. So, you get benefit of thermodynamics both ways. Furthermore, the heat engine uses heat pumped out and saved from liquifying the gases. It is typically a mistake to assume people behind an innovative development, that they are spending $150M on, are idiots.
  - AtlasBarfed 5y ago
    Is that analogous to how turbochargers can get ICE engines to exceed carnot limits?
    - ncmncm 5y ago
      Turbochargers run in open-cycle engines that are not bound by Carnot limits. Diesels run on the Rankine cycle, and gasoline engines run on the (similar) Otto cycle. Both of those take in cold air and exhaust hot air, so can be more efficient than an engine that runs a fixed supply of working fluid around the Carnot cycle. Turbo- and super-charging enables an engine with a given displacement to take in more air, and thus can burn more fuel, than one that must fill cylinders with no more than ambient air pressure; and can thereby deliver more power. It doesn't change the engine's thermodynamic profile.
  - contravariant 5y ago
    In the end you're still powering something by letting something cold grow warm, so I'm not seeing how you could avoid the second law of thermodynamics. I suppose that in theory the cooling step would be where you could recoup your losses a bit by using an efficient heat pump, but getting the coefficient of performance greater than 1 could be pretty difficult for such extreme temperature differences.
kolinko 5y ago
As for the price per kWh, I guess this system scales sublinearly (as opposed to more or less linearly with LiIon). They can probably increase the number of tanks storing oxygen in the future for way less than $300kWh (assuming they keep the same system wattage).
- CydeWeys 5y ago
  I came to precisely the opposite conclusion. Batteries keep getting cheaper every year, while air pressurization technology does not (that is a very mature technology). So if this air pressurization is only the equal of batteries in year one, then it's already lost.
  - hokkos 5y ago
    The point is not about future price evolution, but the marginal price of storing 1h more, if you just need another tank it will be cheaper than having the same energy in a battery, with the same system to store and destore the liquid air. Li-ion is not a good fit for long term storage.
    - CydeWeys 5y ago
      This system is already 500 MWh (that's huge). How much better scaling do you think it's going to get beyond that?
      - ncmncm 5y ago
        The expensive part is the 50MW bits. They can build out storage capacity cheaply, because it is just tankage.
        Retric 5y ago
        But if you’re only inputting and extracting at 50MW then having more than 600MWh of storage means it takes longer than 24h to fully charge and discharge. If anything 500MWh of storage is already well into diminishing returns as daily storage makes money every day but long term storage has less frequent returns.
deleted 5y ago
[deleted]
asdfadsfgfdda 5y ago
The linde cycle is not used industrially, they are using a reverse brayton cycle. This cycle use air as the refrigerant, and is probably the most widely distributed industrial cycle in the world (because liquified gases do not transport easily).
- deleted 5y ago
  [deleted]
- tgtweak 5y ago
  Good find. Looks like state of the art in liquid air energy storage was 96% on storage side and 77% on recovery. ("Thermodynamic analysis of a hybrid energy storage system based on compressed air and liquid air" by Bharath Kantharaj, Seamus Garvey, Andrew Pimm) https://nottingham-repository.worktribe.com/OutputFile/758034 https://nottingham-repository.worktribe.com/OutputFile/75803...
hippich 5y ago
Interestingly, if my calculations are correct, a 1kWh car lead acid battery costs $80+tax retail - https://www.autozone.com/batteries-starting-and-charging/battery/econocraft-battery-h6-e-group-size-48-615-cca/811871_0_0 https://www.autozone.com/batteries-starting-and-charging/bat... Obviously, besides batteries, you need other components to transmit, convert, etc electricity, yet the difference is quite large. I guess question becomes - how much it will cost to maintain such cryogenic storage solution vs replacing lead acid batteries over time. EDIT: while shopping for a used UPS unit for my server rack, with expectation that the unit itself will come without batteries and I will purchase new batteries separately, I was getting about $125-$150 per kWh for everything, including UPS itself and a set of new batteries. I am not proposing to use used tech to build such a storage, just interesting to look at prices.
- AYBABTME 5y ago
  Lead acid has a very poor cycle life and poor round trip efficiency as well. Also, its advertised capacity isn't usually reachable even at very low C rates. biased/sponsored test but still casually informative test of actual lead-acid performance: https://youtu.be/iy3hga_P5YY https://youtu.be/iy3hga_P5YY
- justshowpost 5y ago
  Besides inefficient chemistry remark above, car batteries classified as high-discharge as opposed to deep-cycle. We need the latter for energy storage. If you'd like to assess the cost of lead-acid, check out «marine» batteries instead. PS: lead-acid is very dull at self discharge.
- tgtweak 5y ago
  Using Tesla's own numbers for a turnkey installation such as this. Costs will probably come down another $50-80 per kWh with improvements in battery costs.

Robotbeat 5y ago

I mean… you can recycle batteries, too. And the environmental “issue” with batteries is largely a red herring (steel mining and even recycling would look bad if you had a campaign of misinformation against it like batteries do, cherry-picking dramatic industrial-scale images without comparison with what it is replacing). $300/kWh isn’t anything to really write home about. Not opposed to it, though. While I don’t think it’s a slam-dunk win against batteries by any stretch, it’s good enough not to be a waste of money if someone builds one (which is probably true for that cement-block gravity energy storage thing).

usrusr 5y ago
“you can recycle batteries“ It has been done, in a laboratory. Scrap steel is routinely sold at market rate.
- jeffbee 5y ago
  Scrap batteries are also sold at market rate, because "sold at market rate" is a tautology, true of any subject.
  - jsight 5y ago
    Yeah, and judging by the prices on ebay, the "market rate" for some batteries is pretty high. It might not stay that way when the higher volume electric cars start to age out.
  - usrusr 5y ago
    Only when market rate is a positive number.
- bane 5y ago
  Nah, it's done every day in places all over Pakistan and India (and a few other places) https://youtu.be/afwO_MZjRjA https://youtu.be/afwO_MZjRjA
- ClumsyPilot 5y ago
  Car batteries arr recycled st a good price
  - usrusr 5y ago
    Good luck building a BEV empire or grid storage on lead acid batteries.

boringg 5y ago

What do they use for the refrigerant? Refrigerant leaks have some of the highest green house gas potentials of all compounds. Depending on the product > 2000 times global warming potential of CO2.

asdfasgasdgasdg 5y ago
I would imagine a facility like this would have much better monitoring for refrigerant pressure drops than a typical consumer-grade system, plus a staff onsite that would be able to close valves and rapidly find and repair leaks.
- IgorPartola 5y ago
  Not to be too glib, but that’s what we imagined about Chernobyl as well.
  - asdfasgasdgasdg 5y ago
    Despite your disclaimer, I do feel this is too glib. What is the takeaway? Yes, a bad thing happened one time at that facility (and others, at other times). That doesn't have much bearing on what I said. It is still reasonable to suspect that refrigerant leaks will not be a major problem at this facility.
    - IgorPartola 5y ago
      I am saying that in general I would prefer a system that’s safe by design, not by the fact that there are going to be people there who can make very human mistakes and create a problem. It is all relative: is it safer to run a facility like this or to transport a tanker-full of crude oil across waterways? But just saying that well there will be people there to open a valve when bad things happen is naive.
      - asdfasgasdgasdg 5y ago
        When comparing the risk of refrigerant leaks in cooling systems in general vs heat exchange systems at a highly technical and actively monitored facility, it is relevant that the facility is actively monitored and probably has much better controls than typical refrigerant-using installations. It's not naïve to observe that most refrigerant leaks are likely from systems that are not monitored (i.e. almost all residential systems and probably most commercial ones).

contravariant 5y ago

* Round-trip energy efficiency: I can't see a system taking electrical input to produce liquid air on the way in and similarly to run a turbine generator on the other end without having substantial losses both ways... I believe Tesla is around 88% on their system. Well you can just power an engine on the temperature gradient. That's going to incur some losses though. This seems to be the downside of storing energy cooling stuff, you have to fight the second law of thermodynamics both ways.

ncmncm 5y ago
You get to run both a heat engine, on the temperature difference, and a turbine, on the resulting boiled-off gas. So, you get benefit of thermodynamics both ways. Furthermore, the heat engine uses heat pumped out and saved from liquifying the gases. It is typically a mistake to assume people behind an innovative development, that they are spending $150M on, are idiots.
- AtlasBarfed 5y ago
  Is that analogous to how turbochargers can get ICE engines to exceed carnot limits?
  - ncmncm 5y ago
    Turbochargers run in open-cycle engines that are not bound by Carnot limits. Diesels run on the Rankine cycle, and gasoline engines run on the (similar) Otto cycle. Both of those take in cold air and exhaust hot air, so can be more efficient than an engine that runs a fixed supply of working fluid around the Carnot cycle. Turbo- and super-charging enables an engine with a given displacement to take in more air, and thus can burn more fuel, than one that must fill cylinders with no more than ambient air pressure; and can thereby deliver more power. It doesn't change the engine's thermodynamic profile.
- contravariant 5y ago
  In the end you're still powering something by letting something cold grow warm, so I'm not seeing how you could avoid the second law of thermodynamics. I suppose that in theory the cooling step would be where you could recoup your losses a bit by using an efficient heat pump, but getting the coefficient of performance greater than 1 could be pretty difficult for such extreme temperature differences.

kolinko 5y ago

As for the price per kWh, I guess this system scales sublinearly (as opposed to more or less linearly with LiIon). They can probably increase the number of tanks storing oxygen in the future for way less than $300kWh (assuming they keep the same system wattage).

CydeWeys 5y ago
I came to precisely the opposite conclusion. Batteries keep getting cheaper every year, while air pressurization technology does not (that is a very mature technology). So if this air pressurization is only the equal of batteries in year one, then it's already lost.
- hokkos 5y ago
  The point is not about future price evolution, but the marginal price of storing 1h more, if you just need another tank it will be cheaper than having the same energy in a battery, with the same system to store and destore the liquid air. Li-ion is not a good fit for long term storage.
  - CydeWeys 5y ago
    This system is already 500 MWh (that's huge). How much better scaling do you think it's going to get beyond that?
    - ncmncm 5y ago
      The expensive part is the 50MW bits. They can build out storage capacity cheaply, because it is just tankage.
      - Retric 5y ago
        But if you’re only inputting and extracting at 50MW then having more than 600MWh of storage means it takes longer than 24h to fully charge and discharge. If anything 500MWh of storage is already well into diminishing returns as daily storage makes money every day but long term storage has less frequent returns.

deleted 5y ago

[deleted]

asdfadsfgfdda 5y ago

The linde cycle is not used industrially, they are using a reverse brayton cycle. This cycle use air as the refrigerant, and is probably the most widely distributed industrial cycle in the world (because liquified gases do not transport easily).

deleted 5y ago
[deleted]
tgtweak 5y ago
Good find. Looks like state of the art in liquid air energy storage was 96% on storage side and 77% on recovery. ("Thermodynamic analysis of a hybrid energy storage system based on compressed air and liquid air" by Bharath Kantharaj, Seamus Garvey, Andrew Pimm) https://nottingham-repository.worktribe.com/OutputFile/758034 https://nottingham-repository.worktribe.com/OutputFile/75803...

hippich 5y ago

Interestingly, if my calculations are correct, a 1kWh car lead acid battery costs $80+tax retail - https://www.autozone.com/batteries-starting-and-charging/battery/econocraft-battery-h6-e-group-size-48-615-cca/811871_0_0 https://www.autozone.com/batteries-starting-and-charging/bat... Obviously, besides batteries, you need other components to transmit, convert, etc electricity, yet the difference is quite large. I guess question becomes - how much it will cost to maintain such cryogenic storage solution vs replacing lead acid batteries over time. EDIT: while shopping for a used UPS unit for my server rack, with expectation that the unit itself will come without batteries and I will purchase new batteries separately, I was getting about $125-$150 per kWh for everything, including UPS itself and a set of new batteries. I am not proposing to use used tech to build such a storage, just interesting to look at prices.

AYBABTME 5y ago
Lead acid has a very poor cycle life and poor round trip efficiency as well. Also, its advertised capacity isn't usually reachable even at very low C rates. biased/sponsored test but still casually informative test of actual lead-acid performance: https://youtu.be/iy3hga_P5YY https://youtu.be/iy3hga_P5YY
justshowpost 5y ago
Besides inefficient chemistry remark above, car batteries classified as high-discharge as opposed to deep-cycle. We need the latter for energy storage. If you'd like to assess the cost of lead-acid, check out «marine» batteries instead. PS: lead-acid is very dull at self discharge.
tgtweak 5y ago
Using Tesla's own numbers for a turnkey installation such as this. Costs will probably come down another $50-80 per kWh with improvements in battery costs.