5 ms·

I visited a pumped storage facility a while back that stored electricity by pumping water uphill to store it and then draining it past a turbine to reclaim it.

I visited a pumped storage facility a while back that stored electricity by pumping water uphill to store it and then draining it past a turbine to reclaim it. Ever since I’ve been intrigued by using gravity instead of batteries. For home use, it seems like you could rig up some heavy stones on pulleys to do the same thing could be fun because you’d get to physically see your batteries filling up. Back of the envelope calculations suggest that an array of ten 10-ton concrete blocks lifted 10m in the air could power a house for a day (ignoring generator inefficiencies)

empyrrhicist 1y ago
Hoisting 100 tons of stuff high into the air, and then efficiently converting that into the high RPM needed to drive a generator seems like it would take a truly staggering construction effort. Suspending that amount of weight high above your house also has some... interesting potential failure modes.
- sfn42 1y ago
  Why would you put it above your house? Just construct a sort of battery tower nearby.
  - zozbot234 1y ago
    Why not just build a water tower? Easier to manage, it's a proven technology and it has well-known ancillary uses beyond energy storage.
    - sfn42 1y ago
      I don't even think the gravity battery thing is viable for individual residential power storage at all. I was just wondering why you'd assume that the 100 ton weight would be placed directly above your house given the obvious problems with that approach, and the obvious way to avoid those problems.
  - empyrrhicist 1y ago
    The comment I was replying to literally said "For home use", and a heavy object 10m in the air does not have to be directly above something to be meaningfully (and dangerously) above something. It's a silly scenario anyway, but I was doing a bit of guesswork about typical "home" lot sizes.
    - sfn42 1y ago
      Yeah I understand it's for home use. I am imagining a tower in the back yard or something. It would be closed so that nobody can walk under the weight. Or it could be internal to the house like an elevator shaft. Anyway I agree it's silly, definitely not a realistic idea
      - empyrrhicist 1y ago
        Right - if a tower in the back yard falls down it can still hit your house, since it isn't guaranteed to neatly collapse straight down. Worst case, it may tip over from the base and directly smash stuff up to its height away (and 10m is pretty far). I have trees in my back yard I'm kind of worried about, which is why this immediately came to mind.
  - lawlessone 1y ago
    Just suspend your house, become the battery.
vitro 1y ago
Someone has already been thinking along the same lines: https://www.swissinfo.ch/eng/business/energy-vault_revolutionary-idea-to-store-green-power-for-the-grid/45467684 https://www.swissinfo.ch/eng/business/energy-vault_revolutio...
javcasas 1y ago
Every time I see again the idea of moving big concrete blocks for storing energy, I remember the time I made the calculations, and estimated around USD100K of infrastructure to store the same amount of energy as a nissan leaf.
- standeven 1y ago
  I did the same calculation. Gravity energy storage is a joke. Came to similar conclusions when running numbers on hydrogen-powered vehicles. Pumped hydro storage and flywheels are cool but ultimately battery storage, distributed everywhere, will win.
  - javcasas 1y ago
    Gravity storage is cool when nature has already made most of the work, I/E pumped hydro where nature has already built this huge canyon with a river in the middle just waiting for someone to put a dam at the end.
- imtringued 1y ago
  It is really perplexing when people come up with an energy storage method that is even more expensive than just straight up batteries.
maxbaines 1y ago
This type of plant is generally used for emergency power to balance the grid, whilst other plant come online.
raincole 1y ago
Pumping water up is a super old idea, but as far as I know you'll need some natural terrain to build it efficiently.
- teiferer 1y ago
  And environmentally, that tends to be pretty bad for a long time. Looks more peaceful than a fracking site, but it's still pretty bad. There is no magic solution. I'm happy to see all those efforts, but am missing a mention of saving energy. In the age of record-setting data centers for AI training, that's not a popular aspect to mention. Though at least we get higher res more realistic artificial cat videos out of it.
  - pfdietz 1y ago
    It's only bad if it's placed on and disrupts an existing river. But PHES can be placed far from any river, even in a desert. https://www.whitepinepumpedstorage.com/ https://www.whitepinepumpedstorage.com/ I suspect this project may not happen, what with batteries getting so cheap.
- pfdietz 1y ago
  You just need some change in elevation over moderately short distances. You don't even need rivers.
wickedsight 1y ago
There are some videos on Youtube discussing the hypotheticals of this. They're never really very positive about the feasibility. Neither on a small scale nor on a country-wide scale. If you'd want to store 1kWh at 10m height, assuming no loss at all from heat, friction, etc, you'd need about 4 of those blocks block weighing 10 tons (according to ChatGPT). So you'd need a lot of those blocks to power a house for a day, unless you're very efficient.
- Cthulhu_ 1y ago
  Please don't cite ChatGPT as a source or as a caveat, instead show the actual math, which should only be about high school level; kinetic energy formula ½mv² = e, In perfect conditions assuming no loss through drag, you're looking at the kinetic energy formula which is ½mv² = E (in joules). E = 1 kWh = 3,600 kilojoules, velocity v at 10 meters is 14 m/s, so we need to calculate m for v = 14 and E = 3600k, which is just under 36735 kg. "about four of those blocks" is "about" correct.
  - wickedsight 1y ago
    This is exactly what ChatGPT provided. Me, the person, then chose to describe it as 'about 4'.
  - michaelgburton 1y ago
    Simpler to use the potential energy formula, surely. E = mgh m = E/gh m = 3.6 * 10^6 J / (9.8 m/s^2 * 10m) = 3.6735 * 10^4 kg
AndrewDucker 1y ago
An AA battery contains approximately the same as 1 ton raised 1m. (About 3Wh) A Tesla Powerwall contains about 13.5kwH (about 4,000 times as much) So you can either raise 100 tons 10m above your house, or you can have 1/13 of a Tesla Powerwall.
- staticlink 1y ago
  And this is why gravity is considered a weak force.
  - javcasas 1y ago
    Sit down. Now stand up. Congratulations, you just beat the gravity force generated by a whole f*cking planet.
    - ncruces 1y ago
      Now try to escape it.
      - javcasas 1y ago
        What limits me is the lack of solid matter to push against, not lack of strength in my muscles.
        galangalalgol 1y ago
        Gpt says that would require about 275 million steps on a magic rigid weightless stairway. Roughly 4.1 million calories. So at Phelps level energy expenditures you are still talking over a year of climbing every day.
        LgWoodenBadger 1y ago
        Well, 100kg raised 10000m is only about 2350 food calories, from a purely physics perspective.
micromacrofoot 1y ago
You need a lot of weight. IMO for home use the risks heavily outweigh the benefits for anything outside of a hobbyist project... that's just a lot of potential energy in a system that can go wrong. Weights falling quickly, pullies and cables under tension. The same is true for batteries of course, but at the very least there are protections and checks for failures in most consumer accessible home solutions (and decades of engineering at this point). Worst case you at least have smoke detectors... not sure if there's a "cable is wearing thin and might snap and decapitate you" warning system.
Cthulhu_ 1y ago
Gravity based with weights is generally considered not cost effective; others already did the math that your 100 ton proposal can still only store a fraction of what a consumer grade battery pack can do, but on top of inefficiency there's space and maintenance requirements. It works in situations where e.g. trains go uphill empty and full downhill, but generally it doesn't work. Water based systems work better because water is easy to move, plentiful, and there's natural basins to pump into / flow out of that can contain billions of liters.
naasking 1y ago
Stones are typically not very dense. Iron or lead or 2-4x denser than typical stones, and so will net you better energy density.
- __d 1y ago
  Go all the way: depleted uranium
cromulent 1y ago
EnergyVault are building these GESS (Gravity Energy Storage System) arrays right now. https://www.energyvault.com/projects/cn-rudong https://www.energyvault.com/projects/cn-rudong
g-b-r 1y ago
You already have some decent amount of weight in the house itself, so I'd look into raising it all or parts of it Of course it's probably not the simplest engineering effort...
IshKebab 1y ago
> an array of ten 10-ton concrete blocks lifted 10m in the air could power a house for a day No, that's only 2.7 kWh. Most homes use 10-20 kWh/day. A battery of that size is easily under $1k. Good luck building your ridiculous concrete block system for that. Batteries are really good. Gravity, not so much. It only works when you can lift & store a tremendous amount of stuff "for free" because nature has done most of the work, e.g. in valleys, mountains, aquifers, caves, etc. If you have to build the whole thing it will never be viable.
- avalys 1y ago
  I’d love to buy a 20 kWh battery for under $1k. Can you give me a link to what you’re thinking of?
  - jmpman 1y ago
    People have been able to get their Tesla Model 3 batteries (75kWh iirc) replaced with used battery packs for around $5k, so quite close to what you’re asking.
    - lawlessone 1y ago
      Do they get much for the old used battery? the materials are still lithium etc are still inside it, they're just no longer in the right places..
  - IshKebab 1y ago
    Sorry my wording was ambiguous; when I said "that size" I meant 2.7 kWh, which is what the hypothetical concrete blocks might provide. Nevertheless, you can get a 16 kWh battery (which is enough for most days of a typical house) for only £2k, which is kind of insane really: https://www.fogstar.co.uk/products/fogstar-energy-16kwh-48v-solar-battery https://www.fogstar.co.uk/products/fogstar-energy-16kwh-48v-...
- parpfish 1y ago
  Batteries are good, but you can’t repair a broken battery with odds and ends you find at the hardware store. If you’re living off grid space isn’t really an issue.
chiffre01 1y ago
Some guy on Youtube tried this. I think the conclusion was, not worth it. https://www.youtube.com/watch?v=l19AMYd0oks https://www.youtube.com/watch?v=l19AMYd0oks
adrco 1y ago
Relevant video on a pumping water on the roof + turbine system : https://youtu.be/CMR9z9Xr8GM https://youtu.be/CMR9z9Xr8GM It's quite far from powering your whole house tho !
iamgopal 1y ago
Gravity is weakest force of nature. Any strong force battery idea ?

empyrrhicist 1y ago

Hoisting 100 tons of stuff high into the air, and then efficiently converting that into the high RPM needed to drive a generator seems like it would take a truly staggering construction effort. Suspending that amount of weight high above your house also has some... interesting potential failure modes.

sfn42 1y ago
Why would you put it above your house? Just construct a sort of battery tower nearby.
- zozbot234 1y ago
  Why not just build a water tower? Easier to manage, it's a proven technology and it has well-known ancillary uses beyond energy storage.
  - sfn42 1y ago
    I don't even think the gravity battery thing is viable for individual residential power storage at all. I was just wondering why you'd assume that the 100 ton weight would be placed directly above your house given the obvious problems with that approach, and the obvious way to avoid those problems.
- empyrrhicist 1y ago
  The comment I was replying to literally said "For home use", and a heavy object 10m in the air does not have to be directly above something to be meaningfully (and dangerously) above something. It's a silly scenario anyway, but I was doing a bit of guesswork about typical "home" lot sizes.
  - sfn42 1y ago
    Yeah I understand it's for home use. I am imagining a tower in the back yard or something. It would be closed so that nobody can walk under the weight. Or it could be internal to the house like an elevator shaft. Anyway I agree it's silly, definitely not a realistic idea
    - empyrrhicist 1y ago
      Right - if a tower in the back yard falls down it can still hit your house, since it isn't guaranteed to neatly collapse straight down. Worst case, it may tip over from the base and directly smash stuff up to its height away (and 10m is pretty far). I have trees in my back yard I'm kind of worried about, which is why this immediately came to mind.
- lawlessone 1y ago
  Just suspend your house, become the battery.

vitro 1y ago

Someone has already been thinking along the same lines: https://www.swissinfo.ch/eng/business/energy-vault_revolutionary-idea-to-store-green-power-for-the-grid/45467684 https://www.swissinfo.ch/eng/business/energy-vault_revolutio...

javcasas 1y ago

Every time I see again the idea of moving big concrete blocks for storing energy, I remember the time I made the calculations, and estimated around USD100K of infrastructure to store the same amount of energy as a nissan leaf.

standeven 1y ago
I did the same calculation. Gravity energy storage is a joke. Came to similar conclusions when running numbers on hydrogen-powered vehicles. Pumped hydro storage and flywheels are cool but ultimately battery storage, distributed everywhere, will win.
- javcasas 1y ago
  Gravity storage is cool when nature has already made most of the work, I/E pumped hydro where nature has already built this huge canyon with a river in the middle just waiting for someone to put a dam at the end.
imtringued 1y ago
It is really perplexing when people come up with an energy storage method that is even more expensive than just straight up batteries.

maxbaines 1y ago

This type of plant is generally used for emergency power to balance the grid, whilst other plant come online.

raincole 1y ago

Pumping water up is a super old idea, but as far as I know you'll need some natural terrain to build it efficiently.

teiferer 1y ago
And environmentally, that tends to be pretty bad for a long time. Looks more peaceful than a fracking site, but it's still pretty bad. There is no magic solution. I'm happy to see all those efforts, but am missing a mention of saving energy. In the age of record-setting data centers for AI training, that's not a popular aspect to mention. Though at least we get higher res more realistic artificial cat videos out of it.
- pfdietz 1y ago
  It's only bad if it's placed on and disrupts an existing river. But PHES can be placed far from any river, even in a desert. https://www.whitepinepumpedstorage.com/ https://www.whitepinepumpedstorage.com/ I suspect this project may not happen, what with batteries getting so cheap.
pfdietz 1y ago
You just need some change in elevation over moderately short distances. You don't even need rivers.

wickedsight 1y ago

There are some videos on Youtube discussing the hypotheticals of this. They're never really very positive about the feasibility. Neither on a small scale nor on a country-wide scale. If you'd want to store 1kWh at 10m height, assuming no loss at all from heat, friction, etc, you'd need about 4 of those blocks block weighing 10 tons (according to ChatGPT). So you'd need a lot of those blocks to power a house for a day, unless you're very efficient.

Cthulhu_ 1y ago
Please don't cite ChatGPT as a source or as a caveat, instead show the actual math, which should only be about high school level; kinetic energy formula ½mv² = e, In perfect conditions assuming no loss through drag, you're looking at the kinetic energy formula which is ½mv² = E (in joules). E = 1 kWh = 3,600 kilojoules, velocity v at 10 meters is 14 m/s, so we need to calculate m for v = 14 and E = 3600k, which is just under 36735 kg. "about four of those blocks" is "about" correct.
- wickedsight 1y ago
  This is exactly what ChatGPT provided. Me, the person, then chose to describe it as 'about 4'.
- michaelgburton 1y ago
  Simpler to use the potential energy formula, surely. E = mgh m = E/gh m = 3.6 * 10^6 J / (9.8 m/s^2 * 10m) = 3.6735 * 10^4 kg

AndrewDucker 1y ago

An AA battery contains approximately the same as 1 ton raised 1m. (About 3Wh) A Tesla Powerwall contains about 13.5kwH (about 4,000 times as much) So you can either raise 100 tons 10m above your house, or you can have 1/13 of a Tesla Powerwall.

staticlink 1y ago
And this is why gravity is considered a weak force.
- javcasas 1y ago
  Sit down. Now stand up. Congratulations, you just beat the gravity force generated by a whole f*cking planet.
  - ncruces 1y ago
    Now try to escape it.
    - javcasas 1y ago
      What limits me is the lack of solid matter to push against, not lack of strength in my muscles.
      - galangalalgol 1y ago
        Gpt says that would require about 275 million steps on a magic rigid weightless stairway. Roughly 4.1 million calories. So at Phelps level energy expenditures you are still talking over a year of climbing every day.
        LgWoodenBadger 1y ago
        Well, 100kg raised 10000m is only about 2350 food calories, from a purely physics perspective.

micromacrofoot 1y ago

You need a lot of weight. IMO for home use the risks heavily outweigh the benefits for anything outside of a hobbyist project... that's just a lot of potential energy in a system that can go wrong. Weights falling quickly, pullies and cables under tension. The same is true for batteries of course, but at the very least there are protections and checks for failures in most consumer accessible home solutions (and decades of engineering at this point). Worst case you at least have smoke detectors... not sure if there's a "cable is wearing thin and might snap and decapitate you" warning system.

Cthulhu_ 1y ago

Gravity based with weights is generally considered not cost effective; others already did the math that your 100 ton proposal can still only store a fraction of what a consumer grade battery pack can do, but on top of inefficiency there's space and maintenance requirements. It works in situations where e.g. trains go uphill empty and full downhill, but generally it doesn't work. Water based systems work better because water is easy to move, plentiful, and there's natural basins to pump into / flow out of that can contain billions of liters.

naasking 1y ago

Stones are typically not very dense. Iron or lead or 2-4x denser than typical stones, and so will net you better energy density.

__d 1y ago
Go all the way: depleted uranium

cromulent 1y ago

EnergyVault are building these GESS (Gravity Energy Storage System) arrays right now. https://www.energyvault.com/projects/cn-rudong https://www.energyvault.com/projects/cn-rudong

g-b-r 1y ago

You already have some decent amount of weight in the house itself, so I'd look into raising it all or parts of it Of course it's probably not the simplest engineering effort...

IshKebab 1y ago

> an array of ten 10-ton concrete blocks lifted 10m in the air could power a house for a day No, that's only 2.7 kWh. Most homes use 10-20 kWh/day. A battery of that size is easily under $1k. Good luck building your ridiculous concrete block system for that. Batteries are really good. Gravity, not so much. It only works when you can lift & store a tremendous amount of stuff "for free" because nature has done most of the work, e.g. in valleys, mountains, aquifers, caves, etc. If you have to build the whole thing it will never be viable.

avalys 1y ago
I’d love to buy a 20 kWh battery for under $1k. Can you give me a link to what you’re thinking of?
- jmpman 1y ago
  People have been able to get their Tesla Model 3 batteries (75kWh iirc) replaced with used battery packs for around $5k, so quite close to what you’re asking.
  - lawlessone 1y ago
    Do they get much for the old used battery? the materials are still lithium etc are still inside it, they're just no longer in the right places..
- IshKebab 1y ago
  Sorry my wording was ambiguous; when I said "that size" I meant 2.7 kWh, which is what the hypothetical concrete blocks might provide. Nevertheless, you can get a 16 kWh battery (which is enough for most days of a typical house) for only £2k, which is kind of insane really: https://www.fogstar.co.uk/products/fogstar-energy-16kwh-48v-solar-battery https://www.fogstar.co.uk/products/fogstar-energy-16kwh-48v-...
parpfish 1y ago
Batteries are good, but you can’t repair a broken battery with odds and ends you find at the hardware store. If you’re living off grid space isn’t really an issue.

chiffre01 1y ago

Some guy on Youtube tried this. I think the conclusion was, not worth it. https://www.youtube.com/watch?v=l19AMYd0oks https://www.youtube.com/watch?v=l19AMYd0oks

adrco 1y ago

Relevant video on a pumping water on the roof + turbine system : https://youtu.be/CMR9z9Xr8GM https://youtu.be/CMR9z9Xr8GM It's quite far from powering your whole house tho !

iamgopal 1y ago

Gravity is weakest force of nature. Any strong force battery idea ?