6 ms·

Energy Vault – Gravitational Batteries

imtringued 6y ago
Building cranes is most the boring part of this project. It's far more interesting to know how they are going to make the 35 ton weights. I don't know anything about the construction industry but some googling showed that 1 m^3 of concrete weighs 2.4 tons. You will need 15 m^3 weights. 1 m^3 costs $200 so each weight costs $3000. 35000kg×9.81m/s^2×100m is 34335000 Joules or 9.5kWH. $3000 / 9.5kWH is $315 per kWH. I'm generous and assume that the tower is 100m high. I haven't seen a real number on the website. It's possible that they are using a cheaper material mix but that's the entire problem. What materials are they using? They never say so on the website. This is not rocket science. We are merely talking about how to build the cheapest 35 ton rock on earth and yet these people are silent about that.
- londons_explore 6y ago
  But each weight can be reused almost infinitely... The cost doesn't matter too much.
  - ktpsns 6y ago
    That's not right. Refinforced concrete will suffer from environmental influences and have a durability from maybe 30 years. That means you have a cost overhead of 3-4% per year for the replacement value. Water tanks certainly have a much worse life time, given that they will start lacking after a short time and you don't only have to repair the tanks but also provide liquid to refill.
    - Retric 6y ago
      Cycling stress like that is going to dramatically reduce the lifespan due to tress fractures. I think they would be lucky to get 10-20 years from the blocks. Stress fracture are already a significant issue for concrete dams when you frequently vary the water levels, and this is much worse as different stacking is going to stress each block slightly differently every time. In theory they might be perfectly flat surfaces meeting evenly, but in practice that’s far from the case.
      - leonletto 6y ago
        Wouldn’t you just grind them up and recycle them?
        Retric 6y ago
        They can’t recycle it into blocks of the same material properties. It’s not worthless by any stretch, just a poor fit for such demanding applications.
- micmoc 6y ago
  This was already busted by Thunderf00t: https://www.youtube.com/watch?v=NIhCuzxNvv0 https://www.youtube.com/watch?v=NIhCuzxNvv0
- choeger 6y ago
  > This is not rocket science. it is literally rock science ;) Seriously, in Germany, concrete costs arount 100 EUR per cubic meter. So we would end up with around 150 EUR per kwh capacity. But they would not have to use concrete for the task. They could as well use 23 m^3 gravel (which goes down to 10EUR) and some steel scaffolding. Or even just plain water (35m^3).
  - vidarh 6y ago
    They're using "composite" bricks that include waste material (I can't find any obvious references to exactly what kind of mix of materials), so my guess would be the material cost will be rather low.
- moneytide1 6y ago
  > What materials are they using? "Just Have a Think" put out a video about this recently [1]. The project he reports on claims 30MW with 4MW available within 3s for frequency stabilization and the weight is not solid concrete (emissions penalty), but rather compressed refuse that otherwise cannot be recycled (coal ash, demolition debris). The friction would occur as long term tensile strength durability of lifting cables and high torque electrical hoists, which are the primary material penalties. But these things may be relatively cheap to produce and rotate out of service as their known operational lifetime approaches (Tesla has designated labor that changes out public charger cables within a reasonable buffer before they are expected to wear out). [1] https://youtu.be/lh1--ftWWvY https://youtu.be/lh1--ftWWvY
  - tambourine_man 6y ago
    That’s where I got the link from
- walrus01 6y ago
  I wonder how they've calculated the costs of building this giant crane and concrete block system, vs building small scale pumped storage hydroelectricity. Not by the usual method of impounding a reservoir at the top of a hill, but putting a giant array of load-balancing medium sized water tanks at the top of a hill, running a pipe to the bottom where there's the pump/generator, and a similarly sized array of tanks.
  - ncmncm 6y ago
    A big tank is overwhelmingly cheaper than a collection of small tanks. Ground water makes a remarkably capacious reservoir, which may be deeper than your hill is high, doubling the energy storage capacity, for a possible upper limit on instantaneous wattage.
- simonebrunozzi 6y ago
  I would use depleted uranium for that. Many countries have to store thousands of tons of it, and governments will pay you for storing it. Instead of making it sit idle, you might as well use one of its finest qualities (density).
  - fsh 6y ago
    Thousands of tons is a very small amount of mass for gravitational energy storage. The capacity of small pump storage reservoirs is measured in millions of tons. Also one probably wouldn't want to use a somewhat toxic and slightly radioactive material at large scale.
  - lovemenot 6y ago
    Let's make Fort Knox fully renewable by storing wind/solar in stacked gold bars.
villgax 6y ago
This is the best thing, a lot of waste can be repurposed as well
walrus01 6y ago
This giant crane with three arms looks like something you would climb in a FPS stealth game (dishonored 2, deus ex series, etc). Of course it would be populated with various difficulty levels of private military company henchmen.
kumarvvr 6y ago
1 Ton of mass, at 100 m height, holds 0.2778 kWh of energy. 100 tons (3 bricks as per their design) - 27.778 kWH 100 x 100 Tons (300 bricks ) - 27.78 MWH. However, as per their design, not all bricks store the same amount of energy. The lower section of bricks would not be economical. Every Ton of Concrete, on average produces 0.9 Tons of CO2 during its manufacturing process. 1 MWH of electricity generation, on average, produces 0.417 Tons of CO2. 1 Ton of weight, lifted to 100 m and put down, if say, takes 3 minutes (Average estimate, someone correct me on this), then working without break for 7 years, it will break-even for the amount of CO2 it has saved vs. amount of CO2 it has produced. After that, it offsets CO2 produced. However, this is only true for those blocks that are lifted to 100 m. Those at lower levels, will have progressively more years to break-even. A better design would be to build the platform to store the bricks from say, 50 m or so onwards, or use natural geographic features to increase height, like on cliffs, etc.
- desman 6y ago
  ...and using water instead of concrete. And then you get pumped storage https://en.wikipedia.org/wiki/Pumped-storage_hydroelectricity https://en.wikipedia.org/wiki/Pumped-storage_hydroelectricit... which is reasonably widely used and doesn't attract as much investors' attention as this "innovation"
  - kumarvvr 6y ago
    To be fair, Pumped Storage is really dependent on Geography. It has downstream affects on environment due to having reservoirs where none have been and all. It's powerful, cheap and long lasting, but not easily available. One can't eat the cake and have it too.
    - desman 6y ago
      Well, this thing also depends on geography. There aren't many places where such a construct would be easy to build: seismic situation, static stability for these enormous weights, winds (it's actually quite funny to see cranes side by side with wind turbines in their commercial)
kumarvvr 6y ago
I really wish humanity comes up with a good way to store large quantities of electricity (not counting Hydro Batteries). Compressed air in mines is a good alternative, with heat of compression also stored. I am actually looking for ways to make this small scale. As in, creating a storage system for domestic use. In developing countries, average energy usage per house hold, would be not more than 10 kWh per day. Compressed air is slightly dangerous, so are flywheel systems, not to mention complexity of operation. Chemical conversion of captured carbon to liquid fuels seems to be a viable solution.
- jedimastert 6y ago
  > I am actually looking for ways to make this small scale. As in, creating a storage system for domestic use. Mildly interesting thought: grandfather clocks have been using this form of battery for a very long time
- Tade0 6y ago
  We already have that in the form of LiFePO4 batteries. They last over 2000+ cycles, use no rare/expensive/conflict minerals and are safe. Also just recently they crossed the $100/kWh barrier in some markets: https://about.bnef.com/blog/battery-pack-prices-cited-below-100-kwh-for-the-first-time-in-2020-while-market-average-sits-at-137-kwh/ https://about.bnef.com/blog/battery-pack-prices-cited-below-... An ISO container(40ft) of those can store 10-15MWh. For the cost of the Astravets Nuclear Power Plant in Belarus ($11bln, 2GW) you could have 80GWh worth of batteries - that's a week of backup power for one million households in the EU. One disadvantage of them has always been their performance in terms of power and energy density, but given that they're currently installed in Chinese-made Teslas, I guess it's more or less a solved problem.
  - newyankee 6y ago
    i have never seen retail prices of lfp batteries below 300$/kwh yet. Although i am confident near future versions of these batteries can last > 5k and may be even 10k cycles
    - 6y ago
sergioisidoro 6y ago
The structure would have to be fully enclosed. Lowering and raising concrete blocks in heavy wind conditions (required for wind energy) does not sound like the most safe and deterministic process to automate.
ulnarkressty 6y ago
Water towers could also be economical and straightforward to produce / maintain as power storage sites for a small community.
- lovemenot 6y ago
  A large water tank of 500m3 on a high tower at 50M above an underground storage tank yields approx 70 kWh at best. Not much, but a bit better than nothing. Especially if the tower and upper tank can be dual-purposed. Of course in that case you'd lose some energy capacity to maintain water pressure head.
  - zupa-hu 6y ago
    > A large water tank of 500m3 on a high tower at 50M above an underground storage tank yields approx 70 kWh at best. Correct, so if you want 70 MWh you need 1000x more water. 500.000m3 is merely a 80x80x80m cube. Or to put it in different perspective, to lift it by 50m you need 2x this volume (another container 50m higher), which is 1.000.000m3, or 1M m3. The volume of the Pyramid of Gyza [1] is 2.5M m3. So that wouldn't even be the biggest building on Earth. [1] - https://en.wikipedia.org/wiki/Great_Pyramid_of_Giza https://en.wikipedia.org/wiki/Great_Pyramid_of_Giza
J-dawg 6y ago
I'm quite fascinated about how an idea like this gets as far as somebody founding a company when, as several people here (as well as the linked videos) have argued quite convincingly, it appears to be easily debunked. Are the founders knowingly trying to scam investors? Are they just naive/stupid? Or am I (and the debunkers) being too negative, and this is just the first iteration of an idea that could one day change the world? What's really going on?
- newyankee 6y ago
  I think the main founder is a CalTech alumnus who also has another company (Heliogen) which promised solar heat at 1 cents/kwh. Backed by Breakthrough new energy ventures. I believe this idea and kite power ideas are crazy but they might just work.
- __alexs 6y ago
  "SoftBank Vision Fund" is all you need to know.
pontifier 6y ago
The higher you lift the weight, the more energy is stored in each one. I'd rather see something like a ski lift hauling the blocks up a mountain.
goldenkey 6y ago
Flywheel energy storage anyone? https://youtu.be/_QLEERYS5C8 https://youtu.be/_QLEERYS5C8

Building cranes is most the boring part of this project. It's far more interesting to know how they are going to make the 35 ton weights. I don't know anything about the construction industry but some googling showed that 1 m^3 of concrete weighs 2.4 tons. You will need 15 m^3 weights. 1 m^3 costs $200 so each weight costs $3000. 35000kg×9.81m/s^2×100m is 34335000 Joules or 9.5kWH. $3000 / 9.5kWH is $315 per kWH. I'm generous and assume that the tower is 100m high. I haven't seen a real number on the website. It's possible that they are using a cheaper material mix but that's the entire problem. What materials are they using? They never say so on the website. This is not rocket science. We are merely talking about how to build the cheapest 35 ton rock on earth and yet these people are silent about that.

londons_explore 6y ago
But each weight can be reused almost infinitely... The cost doesn't matter too much.
- ktpsns 6y ago
  That's not right. Refinforced concrete will suffer from environmental influences and have a durability from maybe 30 years. That means you have a cost overhead of 3-4% per year for the replacement value. Water tanks certainly have a much worse life time, given that they will start lacking after a short time and you don't only have to repair the tanks but also provide liquid to refill.
  - Retric 6y ago
    Cycling stress like that is going to dramatically reduce the lifespan due to tress fractures. I think they would be lucky to get 10-20 years from the blocks. Stress fracture are already a significant issue for concrete dams when you frequently vary the water levels, and this is much worse as different stacking is going to stress each block slightly differently every time. In theory they might be perfectly flat surfaces meeting evenly, but in practice that’s far from the case.
    - leonletto 6y ago
      Wouldn’t you just grind them up and recycle them?
      - Retric 6y ago
        They can’t recycle it into blocks of the same material properties. It’s not worthless by any stretch, just a poor fit for such demanding applications.
micmoc 6y ago
This was already busted by Thunderf00t: https://www.youtube.com/watch?v=NIhCuzxNvv0 https://www.youtube.com/watch?v=NIhCuzxNvv0
choeger 6y ago
> This is not rocket science. it is literally rock science ;) Seriously, in Germany, concrete costs arount 100 EUR per cubic meter. So we would end up with around 150 EUR per kwh capacity. But they would not have to use concrete for the task. They could as well use 23 m^3 gravel (which goes down to 10EUR) and some steel scaffolding. Or even just plain water (35m^3).
- vidarh 6y ago
  They're using "composite" bricks that include waste material (I can't find any obvious references to exactly what kind of mix of materials), so my guess would be the material cost will be rather low.
moneytide1 6y ago
> What materials are they using? "Just Have a Think" put out a video about this recently [1]. The project he reports on claims 30MW with 4MW available within 3s for frequency stabilization and the weight is not solid concrete (emissions penalty), but rather compressed refuse that otherwise cannot be recycled (coal ash, demolition debris). The friction would occur as long term tensile strength durability of lifting cables and high torque electrical hoists, which are the primary material penalties. But these things may be relatively cheap to produce and rotate out of service as their known operational lifetime approaches (Tesla has designated labor that changes out public charger cables within a reasonable buffer before they are expected to wear out). [1] https://youtu.be/lh1--ftWWvY https://youtu.be/lh1--ftWWvY
- tambourine_man 6y ago
  That’s where I got the link from
walrus01 6y ago
I wonder how they've calculated the costs of building this giant crane and concrete block system, vs building small scale pumped storage hydroelectricity. Not by the usual method of impounding a reservoir at the top of a hill, but putting a giant array of load-balancing medium sized water tanks at the top of a hill, running a pipe to the bottom where there's the pump/generator, and a similarly sized array of tanks.
- ncmncm 6y ago
  A big tank is overwhelmingly cheaper than a collection of small tanks. Ground water makes a remarkably capacious reservoir, which may be deeper than your hill is high, doubling the energy storage capacity, for a possible upper limit on instantaneous wattage.
simonebrunozzi 6y ago
I would use depleted uranium for that. Many countries have to store thousands of tons of it, and governments will pay you for storing it. Instead of making it sit idle, you might as well use one of its finest qualities (density).
- fsh 6y ago
  Thousands of tons is a very small amount of mass for gravitational energy storage. The capacity of small pump storage reservoirs is measured in millions of tons. Also one probably wouldn't want to use a somewhat toxic and slightly radioactive material at large scale.
- lovemenot 6y ago
  Let's make Fort Knox fully renewable by storing wind/solar in stacked gold bars.

villgax 6y ago

This is the best thing, a lot of waste can be repurposed as well

walrus01 6y ago

This giant crane with three arms looks like something you would climb in a FPS stealth game (dishonored 2, deus ex series, etc). Of course it would be populated with various difficulty levels of private military company henchmen.

kumarvvr 6y ago

1 Ton of mass, at 100 m height, holds 0.2778 kWh of energy. 100 tons (3 bricks as per their design) - 27.778 kWH 100 x 100 Tons (300 bricks ) - 27.78 MWH. However, as per their design, not all bricks store the same amount of energy. The lower section of bricks would not be economical. Every Ton of Concrete, on average produces 0.9 Tons of CO2 during its manufacturing process. 1 MWH of electricity generation, on average, produces 0.417 Tons of CO2. 1 Ton of weight, lifted to 100 m and put down, if say, takes 3 minutes (Average estimate, someone correct me on this), then working without break for 7 years, it will break-even for the amount of CO2 it has saved vs. amount of CO2 it has produced. After that, it offsets CO2 produced. However, this is only true for those blocks that are lifted to 100 m. Those at lower levels, will have progressively more years to break-even. A better design would be to build the platform to store the bricks from say, 50 m or so onwards, or use natural geographic features to increase height, like on cliffs, etc.

desman 6y ago
...and using water instead of concrete. And then you get pumped storage https://en.wikipedia.org/wiki/Pumped-storage_hydroelectricity https://en.wikipedia.org/wiki/Pumped-storage_hydroelectricit... which is reasonably widely used and doesn't attract as much investors' attention as this "innovation"
- kumarvvr 6y ago
  To be fair, Pumped Storage is really dependent on Geography. It has downstream affects on environment due to having reservoirs where none have been and all. It's powerful, cheap and long lasting, but not easily available. One can't eat the cake and have it too.
  - desman 6y ago
    Well, this thing also depends on geography. There aren't many places where such a construct would be easy to build: seismic situation, static stability for these enormous weights, winds (it's actually quite funny to see cranes side by side with wind turbines in their commercial)

kumarvvr 6y ago

I really wish humanity comes up with a good way to store large quantities of electricity (not counting Hydro Batteries). Compressed air in mines is a good alternative, with heat of compression also stored. I am actually looking for ways to make this small scale. As in, creating a storage system for domestic use. In developing countries, average energy usage per house hold, would be not more than 10 kWh per day. Compressed air is slightly dangerous, so are flywheel systems, not to mention complexity of operation. Chemical conversion of captured carbon to liquid fuels seems to be a viable solution.

jedimastert 6y ago
> I am actually looking for ways to make this small scale. As in, creating a storage system for domestic use. Mildly interesting thought: grandfather clocks have been using this form of battery for a very long time
Tade0 6y ago
We already have that in the form of LiFePO4 batteries. They last over 2000+ cycles, use no rare/expensive/conflict minerals and are safe. Also just recently they crossed the $100/kWh barrier in some markets: https://about.bnef.com/blog/battery-pack-prices-cited-below-100-kwh-for-the-first-time-in-2020-while-market-average-sits-at-137-kwh/ https://about.bnef.com/blog/battery-pack-prices-cited-below-... An ISO container(40ft) of those can store 10-15MWh. For the cost of the Astravets Nuclear Power Plant in Belarus ($11bln, 2GW) you could have 80GWh worth of batteries - that's a week of backup power for one million households in the EU. One disadvantage of them has always been their performance in terms of power and energy density, but given that they're currently installed in Chinese-made Teslas, I guess it's more or less a solved problem.
- newyankee 6y ago
  i have never seen retail prices of lfp batteries below 300$/kwh yet. Although i am confident near future versions of these batteries can last > 5k and may be even 10k cycles
  - 6y ago

sergioisidoro 6y ago

The structure would have to be fully enclosed. Lowering and raising concrete blocks in heavy wind conditions (required for wind energy) does not sound like the most safe and deterministic process to automate.

ulnarkressty 6y ago

Water towers could also be economical and straightforward to produce / maintain as power storage sites for a small community.

lovemenot 6y ago
A large water tank of 500m3 on a high tower at 50M above an underground storage tank yields approx 70 kWh at best. Not much, but a bit better than nothing. Especially if the tower and upper tank can be dual-purposed. Of course in that case you'd lose some energy capacity to maintain water pressure head.
- zupa-hu 6y ago
  > A large water tank of 500m3 on a high tower at 50M above an underground storage tank yields approx 70 kWh at best. Correct, so if you want 70 MWh you need 1000x more water. 500.000m3 is merely a 80x80x80m cube. Or to put it in different perspective, to lift it by 50m you need 2x this volume (another container 50m higher), which is 1.000.000m3, or 1M m3. The volume of the Pyramid of Gyza [1] is 2.5M m3. So that wouldn't even be the biggest building on Earth. [1] - https://en.wikipedia.org/wiki/Great_Pyramid_of_Giza https://en.wikipedia.org/wiki/Great_Pyramid_of_Giza

J-dawg 6y ago

I'm quite fascinated about how an idea like this gets as far as somebody founding a company when, as several people here (as well as the linked videos) have argued quite convincingly, it appears to be easily debunked. Are the founders knowingly trying to scam investors? Are they just naive/stupid? Or am I (and the debunkers) being too negative, and this is just the first iteration of an idea that could one day change the world? What's really going on?

newyankee 6y ago
I think the main founder is a CalTech alumnus who also has another company (Heliogen) which promised solar heat at 1 cents/kwh. Backed by Breakthrough new energy ventures. I believe this idea and kite power ideas are crazy but they might just work.
__alexs 6y ago
"SoftBank Vision Fund" is all you need to know.

pontifier 6y ago

The higher you lift the weight, the more energy is stored in each one. I'd rather see something like a ski lift hauling the blocks up a mountain.

goldenkey 6y ago

Flywheel energy storage anyone? https://youtu.be/_QLEERYS5C8 https://youtu.be/_QLEERYS5C8