6 ms·

Would this also be 70-80% efficient on a smaller scale? Our land has a few meters elevation so I could create a 'pond' at the high end.

by Gys 2y ago

ben_w 2y ago
Probably about the same efficiency, but be aware the energy density for gravity storage is terrible. Every cubic meter of water you raise by 1 meter, stores about enough to charge an iPhone 15 by 20%. http://www.wolframalpha.com/input/?i=1000kg%20%2A%209.8m%2Fs%2Fs%20%2A1m%20in%20Wh http://www.wolframalpha.com/input/?i=1000kg%20%2A%209.8m%2Fs...
- Titan2189 2y ago
  I was getting ready to write an angry comment that you've got an error in your thinking / maths, because my intuition tells me that doesn't feel right. I've run the numbers myself and am still in disbelief that raising 1,000 kg by 1 meter is the energy equivalent of an AA battery (= 20% iPhone 15 charge)
  - konschubert 2y ago
    If it was any more than that, electric cars would not be able to drive up a mountain.
  - Mistletoe 2y ago
    It’s also why if you’ve ever had a well, you discover how cheap it is to have your own water source compared to paying for municipal water. You just pay for the electricity to pump it up to your faucet, and the electricity to charge an AA battery is quite cheap.
    - ben_w 2y ago
      I suspect most people have never had a well. One of the first indicators my family had about my grandmother's Alzheimer's was an Easter lunch in a small village, where she suggested the village was not connected to the water main and the residents probably still used wells — that was about 15 years ago when she was about 90. Part of the justification for price difference between wells and municipal water also comes with guarantees from the latter about it being clean and free from contamination, and that they'll treat your waste water. How much this happens in practice… well (no pun intended), I'll leave that to news stories about Flint's flammable water and Thames Water's sewage discharges.
      - s1artibartfast 2y ago
        Where is this story based? Where I grew up, most small villages do have their own municipal wells, and there are even communities where every household has their own well. Heck, even in my urban bay area neighborhood, I know of 3-4 people on my block with their own wells. I think it largely has more to do with when the neighborhoods were built than anything else.
        ben_w 2y ago
        South coast of the UK, Hampshire-Sussex border area. I'm not at all sure what the law says about getting on the water main in the first place, but I believe it's not lawful to be disconnected even at your request.
        s1artibartfast 2y ago
        just to be clear, are you talking about the village being connected to a larger water infrastructure, or specific residents and businesses in the village being connected to the village infrastructure?
        ben_w 2y ago
        I'd have to look up the exact network topology to even be able to distinguish between those two. The rules are at the level of homes and the companies which supply them with water, of which there are a small number nationwide: https://en.wikipedia.org/wiki/United_Kingdom_water_companies https://en.wikipedia.org/wiki/United_Kingdom_water_companies Places are not incorporated in the UK the way they are in the US, so "the village infrastructure" doesn't (so far as I know) even get well-defined, which makes it hard to make national laws that prevent it being disconnected from a wider network if that's what the suppliers want to do while supplying some particular house.
        s1artibartfast 2y ago
        That's really interesting. In the US, it is common for water distribution to be managed at the level of town or city water districts. these may purchase water from larger scale state infrastructure, but will try to source water locally via wells where possible. There are some cities where building codes require connection to the water grid for habitability, but this is much less common for unincorporated county land.
    - msisk6 2y ago
      It's all fun until lightning strikes your wellhead, shorts out your well pump, and your insurance denies the claim. Then you discover there is a large capital cost to delivering water besides the electricity cost.
      - s1artibartfast 2y ago
        Sounds like there is a personal story in there somewhere. We have 5 wells, ranging from 20 to 300 ft, and I can confirm they are always a struggle to keep operational.
  - pjc50 2y ago
    This is why pumped and all the other forms of gravity storage (cranes, trains etc) have low ROI unless you can make a really big reservoir with a minimum of work.
- AndrewDucker 2y ago
  (Which is a little less than a AAA battery)
  - NikkiA 2y ago
    A little less than a AA battery. AAA rarely breaks past 1000mAh
- Gys 2y ago
  I was looking for something like this. Thank you! Indeed not very interesting, it would take a lot of water and height to store for example 1 KWh.
- yheru76trd 2y ago
  [dead]
- Symbiote 2y ago
  The water: 1000 kg × 9.8 ms¯² × 1m = 9800 km m² s¯² = 9800 J The "heavy duty" AA battery: 1.5 Ah × 1.5 V = 5400 As × 1.5 V = 8100 J
082349872349872 2y ago
back-of-the-napkin it with `mgh`. I'd kind of expect that it wouldn't scale down that far unless you plan on storing very little energy; by way of comparison our local PSHE has the same g as your land, but stores O(1e11) kg with an O(1e3) m vertical.

Would this also be 70-80% efficient on a smaller scale? Our land has a few meters elevation so I could create a 'pond' at the high end.

by Gys 2y ago

Would this also be 70-80% efficient on a smaller scale? Our land has a few meters elevation so I could create a 'pond' at the high end.

ben_w 2y ago

Probably about the same efficiency, but be aware the energy density for gravity storage is terrible. Every cubic meter of water you raise by 1 meter, stores about enough to charge an iPhone 15 by 20%. http://www.wolframalpha.com/input/?i=1000kg%20%2A%209.8m%2Fs%2Fs%20%2A1m%20in%20Wh http://www.wolframalpha.com/input/?i=1000kg%20%2A%209.8m%2Fs...

Titan2189 2y ago
I was getting ready to write an angry comment that you've got an error in your thinking / maths, because my intuition tells me that doesn't feel right. I've run the numbers myself and am still in disbelief that raising 1,000 kg by 1 meter is the energy equivalent of an AA battery (= 20% iPhone 15 charge)
- konschubert 2y ago
  If it was any more than that, electric cars would not be able to drive up a mountain.
- Mistletoe 2y ago
  It’s also why if you’ve ever had a well, you discover how cheap it is to have your own water source compared to paying for municipal water. You just pay for the electricity to pump it up to your faucet, and the electricity to charge an AA battery is quite cheap.
  - ben_w 2y ago
    I suspect most people have never had a well. One of the first indicators my family had about my grandmother's Alzheimer's was an Easter lunch in a small village, where she suggested the village was not connected to the water main and the residents probably still used wells — that was about 15 years ago when she was about 90. Part of the justification for price difference between wells and municipal water also comes with guarantees from the latter about it being clean and free from contamination, and that they'll treat your waste water. How much this happens in practice… well (no pun intended), I'll leave that to news stories about Flint's flammable water and Thames Water's sewage discharges.
    - s1artibartfast 2y ago
      Where is this story based? Where I grew up, most small villages do have their own municipal wells, and there are even communities where every household has their own well. Heck, even in my urban bay area neighborhood, I know of 3-4 people on my block with their own wells. I think it largely has more to do with when the neighborhoods were built than anything else.
      - ben_w 2y ago
        South coast of the UK, Hampshire-Sussex border area. I'm not at all sure what the law says about getting on the water main in the first place, but I believe it's not lawful to be disconnected even at your request.
        s1artibartfast 2y ago
        just to be clear, are you talking about the village being connected to a larger water infrastructure, or specific residents and businesses in the village being connected to the village infrastructure?
        ben_w 2y ago
        I'd have to look up the exact network topology to even be able to distinguish between those two. The rules are at the level of homes and the companies which supply them with water, of which there are a small number nationwide: https://en.wikipedia.org/wiki/United_Kingdom_water_companies https://en.wikipedia.org/wiki/United_Kingdom_water_companies Places are not incorporated in the UK the way they are in the US, so "the village infrastructure" doesn't (so far as I know) even get well-defined, which makes it hard to make national laws that prevent it being disconnected from a wider network if that's what the suppliers want to do while supplying some particular house.
        s1artibartfast 2y ago
        That's really interesting. In the US, it is common for water distribution to be managed at the level of town or city water districts. these may purchase water from larger scale state infrastructure, but will try to source water locally via wells where possible. There are some cities where building codes require connection to the water grid for habitability, but this is much less common for unincorporated county land.
  - msisk6 2y ago
    It's all fun until lightning strikes your wellhead, shorts out your well pump, and your insurance denies the claim. Then you discover there is a large capital cost to delivering water besides the electricity cost.
    - s1artibartfast 2y ago
      Sounds like there is a personal story in there somewhere. We have 5 wells, ranging from 20 to 300 ft, and I can confirm they are always a struggle to keep operational.
- pjc50 2y ago
  This is why pumped and all the other forms of gravity storage (cranes, trains etc) have low ROI unless you can make a really big reservoir with a minimum of work.
AndrewDucker 2y ago
(Which is a little less than a AAA battery)
- NikkiA 2y ago
  A little less than a AA battery. AAA rarely breaks past 1000mAh
Gys 2y ago
I was looking for something like this. Thank you! Indeed not very interesting, it would take a lot of water and height to store for example 1 KWh.
yheru76trd 2y ago
[dead]
Symbiote 2y ago
The water: 1000 kg × 9.8 ms¯² × 1m = 9800 km m² s¯² = 9800 J The "heavy duty" AA battery: 1.5 Ah × 1.5 V = 5400 As × 1.5 V = 8100 J

082349872349872 2y ago

back-of-the-napkin it with `mgh`. I'd kind of expect that it wouldn't scale down that far unless you plan on storing very little energy; by way of comparison our local PSHE has the same g as your land, but stores O(1e11) kg with an O(1e3) m vertical.