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> "100 hours" is not a meaningful number for a battery. It is a meaningful number... in the grid scale energy storage market. It's a term that summarizes many

> "100 hours" is not a meaningful number for a battery. It is a meaningful number... in the grid scale energy storage market. It's a term that summarizes many of the complex properties you mentioned. For a given energy storage technology, there is a certain duration that it tends to be most effective at. For traditional lithium ion batteries, that duration is about 4 hours. If you want to use lithium ion storage for longer durations than that, then you're making substantial sacrifices in cost effectiveness, utilization rate, etc. Obviously one of the huge areas of research is long duration energy storage, to smooth over energy availability fluctuations that last weeks or months. Some might argue that Form Energy is addressing medium duration energy storage, and there isn't really any technology suited for true long duration energy storage yet. If Form Energy's technology works out, then they're saying they've developed a battery technology that is 10x more cost effective than lithium ion on a per kWh basis, but that the technology cannot discharge as quickly as lithium ion, which makes it better suited for medium duration energy storage. You could do the same thing with Lithium Ion, it would just be cost prohibitive... 10x as expensive, supposedly. What I've shared above is my understanding from following lots of news about green energy tech for years now, but I'm not an expert who can answer a bunch of additional questions... but your comment about 100 hours not being a meaningful number isn't accurate. It is meaningful to the target audience.

lazide 5y ago
I’m sorry, that really doesn’t make any sense. There is several missing factors here, and it’s a useless metric. Lithium ion can do ‘100 hours’ as well - based on discharge rate. It can also do 10 minutes - based on discharge rate. 100 hours is literally useless on it’s own because it doesn’t tell you anything concrete. 100 hours….. of what? It looks like a classic science writing article where they left all the important units off, misunderstood the whole thing the audience was looking for, and made it all super confusing and pretty useless compared to an actual paper.
- coder543 5y ago
  > > You could do the same thing with Lithium Ion, it would just be cost prohibitive... 10x as expensive, supposedly. > Lithium ion can do ‘100 hours’ as well Did you reply to the wrong person? I already addressed your entire comment several different ways in my original comment, and you didn't address anything I wrote in mine, as far as I can tell. Maybe I'm not the best at explaining things? > 100 hours... of what? Cost effective energy storage solutions that can discharge for 100 hours at maximum operating output. "Cost effective" is absolutely the key factor. Lithium ion is not currently cost effective at such durations. It is cost effective at about 4 hours, but some sources will say anywhere from 2 to 8 hours. If you aren't familiar with a particular industry, it's perfectly logical for that industry's shorthand to sound like total nonsense. You (and most of HN) are not the target audience for a statement like "100 hour battery". Grid scale energy storage operators are the target audience, and they understand what that means. It means slow batteries, which also implies cheap, because no one would buy slower battery technology if it weren't a lot cheaper. Form Energy explicitly declares the technology to be 10x cheaper. We'll see if that holds up in reality. Someone unfamiliar with computer science who overhears a conversation about "garbage collection" would likely be very confused. "Computers don't emit garbage! RAM is reusable, how could bytes of RAM become garbage?" But, obviously garbage collection is a real thing with computers, even if it sounds like nonsense to someone outside the industry who just knows enough to know what RAM is. Here's an article[0] that talks about long duration energy storage, and they even mention Form Energy. Relevant quote from the article: > Lithium-ion batteries have absolutely dominated new storage construction in recent years. But they rarely can deliver their full power capacity for more than four hours — that’s what people mean when they say “discharge duration.” Batteries technically can go for longer, but it generally costs more than it’s worth in today’s market dynamics. One more choice quote: > Batteries cannot yet compete with gas plants in providing prolonged power for multiple days. But a cost-effective 24-hour duration storage system could handle longer demand peaks, and a 48-hour system could do even more. It's all about cost effectiveness. [0]: https://www.greentechmedia.com/articles/read/so-what-exactly-is-long-duration-storage-explained https://www.greentechmedia.com/articles/read/so-what-exactly...
  - lazide 5y ago
    Huh, that is almost as ridiculous as using nameplate disk capacity units that sound the same, but are are different than the ones used and reported by the operating system. In your first comment you seemed to be talking right by the person, but I guess not. Thanks for the correction.
- azernik 5y ago
  100 hours = (kWh/kg) / (kW/kg) - ie capacity divided by the most cost-effective discharge rate.
  - amelius 5y ago
    What if the discharge rate versus cost plot is mostly flat?
    - azernik 5y ago
      Then typically you'll run it at a higher discharge rate, and has something cheaper with a higher capacity/discharge ratio.
  - ComputerGuru 5y ago
    I agree but that’s a highly misleading number because there’s a conflation of scenarios. Capacity is one thing, useable capacity at the requested discharge rate is another. You can’t pick and choose which numbers to use.
    - azernik 5y ago
      The combination of duration class and capacity is useful, though. 1MWh of 10-hour storage gives you a very clear idea of usable energy.
lowercase1 5y ago
Anyone can take a battery and just decrease the discharge rate and claim "long duration storage". The hard part is making it cheaper per kWh. If they made it cheaper per kWh then they should say that
- coder543 5y ago
  > If they made it cheaper per kWh then they should say that They do say that. Quote from the article: > at less than 1/10th the cost of lithium-ion "100 hours" isn't an advantage for this technology. The advantage is the cost effectiveness. "100 hour battery" mostly means that it will take 100 hours to discharge one of these batteries (of any capacity) at the maximum discharge rate that the technology allows. Obviously that is a huge downside compared to lithium ion, which is able to respond to grid energy needs with much higher power density! But it doesn't really matter, if the price is right. Long duration energy storage is all about lowering the cost per kWh by developing technologies that have lower power density in exchange for also lowering cost per kWh of storage. Lithium ion isn't cost effective for long duration storage right now. Also, people in that industry know that surely no one would proudly advertise a "100 hour battery" if it weren't significantly cheaper than lithium ion on a per kWh basis, so the term "100 hour battery" also means (to the right audience) that the batteries have to be cheaper than lithium ion. Whether Form Energy will succeed in their claims at scale is TBD. I hope they do well, because cheaper energy storage is immensely helpful for decarbonization of the grid.
  - __sy__ 5y ago
    thank you for all the great comments in this thread. I'm a former Li-Ion researcher (Yi Cui group). I'm less familiar with grid storage. Would you be open to chatting a bit more about this? My email is in my profile. Thank You!
  - Dylan16807 5y ago
    > Also, people in that industry know that surely no one would proudly advertise a "100 hour battery" if it weren't significantly cheaper than lithium ion on a per kWh basis, so the term "100 hour battery" also means (to the right audience) that the batteries have to be cheaper than lithium ion. That seems like a stretch or an unwise convention. It could have some other advantage instead. Loudly proclaiming a disadvantage doesn't tell you what's good about a product, or what circumstances it's useful in.
amelius 5y ago
> It's a term that summarizes many of the complex properties you mentioned. Ok, then would you be so kind to show how to compute these properties from this single term?
- coder543 5y ago
  Would you be so kind as to show how to reverse a hash? A summary is like a hash; it throws away information deemed irrelevant to the task at hand, but it is still related to the input information. So, no, I won't show how to do that, because it's impossible, and I never claimed otherwise. I just love these "gotcha!" comments that pop up on HN so frequently. I'm having to explain what it means to summarize information. Hashes aren't useless or meaningless, they just aren't a substitute for the full information if you need the full information. I'm sure that if you're a serious potential customer, you can contact Form Energy and get whatever detailed information from them that you need. Otherwise, you obviously only get the information they choose to disclose publicly. Your desire for more information doesn't somehow make "100 hour battery" a meaningless statement. When you see the mpg rating of a car, that is a summary that has thrown away detailed test results that could tell you more about the fuel economy of the vehicle under various conditions. EPA testing involves multiple test "cycles" that represent different conditions, but you don't typically get to see the results of each cycle. People still like to see mpg ratings and compare them.
  - specialist 5y ago
    > I'm having to explain what it means to summarize information. It is what it is. FWIW, I use HN as batting practice, to refine my talking points. A terrific recent example is Scott Galloway advocating breaking up big tech. Observing his message craft over the years is instructive, inspirational. He now says stuff like "oxygenate the market". Brilliant. Choice of metaphor matters. "The different between the right word and almost right word is the different between lighting and a lightning bug." -- Mark Twain (from memory) Keep going. You're doing great!
  - amelius 5y ago
    I didn't ask for exact values, and never expected them. But if you say "summary", then I'd expect at least to get some info in the right ballpark. Otherwise it is not a summary, but just some alternative bit of (possibly relevant) information. Also, a hash is not a right analogy for a summary because typically hashes don't hold any bits of useful information, at least within reasonable computational limits.

lazide 5y ago

I’m sorry, that really doesn’t make any sense. There is several missing factors here, and it’s a useless metric. Lithium ion can do ‘100 hours’ as well - based on discharge rate. It can also do 10 minutes - based on discharge rate. 100 hours is literally useless on it’s own because it doesn’t tell you anything concrete. 100 hours….. of what? It looks like a classic science writing article where they left all the important units off, misunderstood the whole thing the audience was looking for, and made it all super confusing and pretty useless compared to an actual paper.

coder543 5y ago
> > You could do the same thing with Lithium Ion, it would just be cost prohibitive... 10x as expensive, supposedly. > Lithium ion can do ‘100 hours’ as well Did you reply to the wrong person? I already addressed your entire comment several different ways in my original comment, and you didn't address anything I wrote in mine, as far as I can tell. Maybe I'm not the best at explaining things? > 100 hours... of what? Cost effective energy storage solutions that can discharge for 100 hours at maximum operating output. "Cost effective" is absolutely the key factor. Lithium ion is not currently cost effective at such durations. It is cost effective at about 4 hours, but some sources will say anywhere from 2 to 8 hours. If you aren't familiar with a particular industry, it's perfectly logical for that industry's shorthand to sound like total nonsense. You (and most of HN) are not the target audience for a statement like "100 hour battery". Grid scale energy storage operators are the target audience, and they understand what that means. It means slow batteries, which also implies cheap, because no one would buy slower battery technology if it weren't a lot cheaper. Form Energy explicitly declares the technology to be 10x cheaper. We'll see if that holds up in reality. Someone unfamiliar with computer science who overhears a conversation about "garbage collection" would likely be very confused. "Computers don't emit garbage! RAM is reusable, how could bytes of RAM become garbage?" But, obviously garbage collection is a real thing with computers, even if it sounds like nonsense to someone outside the industry who just knows enough to know what RAM is. Here's an article[0] that talks about long duration energy storage, and they even mention Form Energy. Relevant quote from the article: > Lithium-ion batteries have absolutely dominated new storage construction in recent years. But they rarely can deliver their full power capacity for more than four hours — that’s what people mean when they say “discharge duration.” Batteries technically can go for longer, but it generally costs more than it’s worth in today’s market dynamics. One more choice quote: > Batteries cannot yet compete with gas plants in providing prolonged power for multiple days. But a cost-effective 24-hour duration storage system could handle longer demand peaks, and a 48-hour system could do even more. It's all about cost effectiveness. [0]: https://www.greentechmedia.com/articles/read/so-what-exactly-is-long-duration-storage-explained https://www.greentechmedia.com/articles/read/so-what-exactly...
- lazide 5y ago
  Huh, that is almost as ridiculous as using nameplate disk capacity units that sound the same, but are are different than the ones used and reported by the operating system. In your first comment you seemed to be talking right by the person, but I guess not. Thanks for the correction.
azernik 5y ago
100 hours = (kWh/kg) / (kW/kg) - ie capacity divided by the most cost-effective discharge rate.
- amelius 5y ago
  What if the discharge rate versus cost plot is mostly flat?
  - azernik 5y ago
    Then typically you'll run it at a higher discharge rate, and has something cheaper with a higher capacity/discharge ratio.
- ComputerGuru 5y ago
  I agree but that’s a highly misleading number because there’s a conflation of scenarios. Capacity is one thing, useable capacity at the requested discharge rate is another. You can’t pick and choose which numbers to use.
  - azernik 5y ago
    The combination of duration class and capacity is useful, though. 1MWh of 10-hour storage gives you a very clear idea of usable energy.

lowercase1 5y ago

Anyone can take a battery and just decrease the discharge rate and claim "long duration storage". The hard part is making it cheaper per kWh. If they made it cheaper per kWh then they should say that

coder543 5y ago
> If they made it cheaper per kWh then they should say that They do say that. Quote from the article: > at less than 1/10th the cost of lithium-ion "100 hours" isn't an advantage for this technology. The advantage is the cost effectiveness. "100 hour battery" mostly means that it will take 100 hours to discharge one of these batteries (of any capacity) at the maximum discharge rate that the technology allows. Obviously that is a huge downside compared to lithium ion, which is able to respond to grid energy needs with much higher power density! But it doesn't really matter, if the price is right. Long duration energy storage is all about lowering the cost per kWh by developing technologies that have lower power density in exchange for also lowering cost per kWh of storage. Lithium ion isn't cost effective for long duration storage right now. Also, people in that industry know that surely no one would proudly advertise a "100 hour battery" if it weren't significantly cheaper than lithium ion on a per kWh basis, so the term "100 hour battery" also means (to the right audience) that the batteries have to be cheaper than lithium ion. Whether Form Energy will succeed in their claims at scale is TBD. I hope they do well, because cheaper energy storage is immensely helpful for decarbonization of the grid.
- __sy__ 5y ago
  thank you for all the great comments in this thread. I'm a former Li-Ion researcher (Yi Cui group). I'm less familiar with grid storage. Would you be open to chatting a bit more about this? My email is in my profile. Thank You!
- Dylan16807 5y ago
  > Also, people in that industry know that surely no one would proudly advertise a "100 hour battery" if it weren't significantly cheaper than lithium ion on a per kWh basis, so the term "100 hour battery" also means (to the right audience) that the batteries have to be cheaper than lithium ion. That seems like a stretch or an unwise convention. It could have some other advantage instead. Loudly proclaiming a disadvantage doesn't tell you what's good about a product, or what circumstances it's useful in.

amelius 5y ago

> It's a term that summarizes many of the complex properties you mentioned. Ok, then would you be so kind to show how to compute these properties from this single term?

coder543 5y ago
Would you be so kind as to show how to reverse a hash? A summary is like a hash; it throws away information deemed irrelevant to the task at hand, but it is still related to the input information. So, no, I won't show how to do that, because it's impossible, and I never claimed otherwise. I just love these "gotcha!" comments that pop up on HN so frequently. I'm having to explain what it means to summarize information. Hashes aren't useless or meaningless, they just aren't a substitute for the full information if you need the full information. I'm sure that if you're a serious potential customer, you can contact Form Energy and get whatever detailed information from them that you need. Otherwise, you obviously only get the information they choose to disclose publicly. Your desire for more information doesn't somehow make "100 hour battery" a meaningless statement. When you see the mpg rating of a car, that is a summary that has thrown away detailed test results that could tell you more about the fuel economy of the vehicle under various conditions. EPA testing involves multiple test "cycles" that represent different conditions, but you don't typically get to see the results of each cycle. People still like to see mpg ratings and compare them.
- specialist 5y ago
  > I'm having to explain what it means to summarize information. It is what it is. FWIW, I use HN as batting practice, to refine my talking points. A terrific recent example is Scott Galloway advocating breaking up big tech. Observing his message craft over the years is instructive, inspirational. He now says stuff like "oxygenate the market". Brilliant. Choice of metaphor matters. "The different between the right word and almost right word is the different between lighting and a lightning bug." -- Mark Twain (from memory) Keep going. You're doing great!
- amelius 5y ago
  I didn't ask for exact values, and never expected them. But if you say "summary", then I'd expect at least to get some info in the right ballpark. Otherwise it is not a summary, but just some alternative bit of (possibly relevant) information. Also, a hash is not a right analogy for a summary because typically hashes don't hold any bits of useful information, at least within reasonable computational limits.