4 ms·

I know there are options like pumped water, compressed air, spinning disc. No idea how feasible they are at scale, but I can imagine a world where physical stor

I know there are options like pumped water, compressed air, spinning disc. No idea how feasible they are at scale, but I can imagine a world where physical storage like that could be lower maintenance & cost in the long-term compared to chemical batteries. Even if less efficient, you can get enormous potential storage from pumped water with relatively simple machines compared to massive battery farms.

sanderjd 4y ago
I'm interested in those alternative technologies, but I suspect they won't scale as well as batteries. Pumped hydro has been around a long time but it hasn't scaled because it is just very geographically specific.
- ncmncm 4y ago
  Pumped hydro is far, far less geographically specific than always assumed. This is partly because it needs no watershed, and partly because transmission lines mean it need not be local. Anyway pumped hydro is only one of many equally viable alternatives. All will be used. Eventually which ones are cheapest will become clear.
  - sanderjd 4y ago
    I think my assumption with pumped hydro is that there must be something holding it back because it's been mature for a long time, so if it were as useful and scalable as you say, I think it would have been scaled a lot more by now.
    - ncmncm 4y ago
      The overwhelming majority of utility-scale storage today is pumped hydro. It stores and releases many GWh every day. You don't hear much about it because it just works.
      - sanderjd 4y ago
        Yes but is still a small amount of energy relative to total demand and there don't seem to be serious efforts to scale it up massively. I don't claim to know why there aren't. Maybe there should be. It just makes me suspicious when I see a mature technology that still sees limited deployment, that there is a good reason for that.
- ncmncm 4y ago
  Batteries have the very large disadvantage that cost is per Wh stored. Flow batteries can reduce this, as capacity becomes a matter of tankage and electrolyte. The sweet spot for storage is near-zero opex, very low per-Wh stored capex, and cheap capex per-W in and, particularly, out. Thus, weight for watt-hours, and simple motor / generator for watts in and out. Synthetic fuel has the appeal that the stored energy is readily tanked and transported, and very saleable; enough so to overcome low round-trip efficiency, expensive electrolysers for W-in, and complicated combined-cycle turbines for W-out.
WalterBright 4y ago
I know a fellow who is running a startup that moves a (very) heavy weight up a hill, and going back down it provides power. He says it is something like 90% efficient at energy recovery, whereas pumped water is far less due to friction in the pipes. He also said the inertia of a falling weight is enormous, and would help stabilize the grid.
- paledot 4y ago
  Okay, but if his startup isn't named Sisyphus Energy, I don't know what he's doing with his life.
- californical 4y ago
  This is a genius idea, especially because it could be done anywhere with a hill, which makes it a lot more geographically accessible (since most places have hills)
  - qsdf38100 4y ago
    It’s actually not a good idea at all. When you do the math ( or rather the physics) gravity batteries need so much mass and height to compete with other technologies that it’s just not worth it. Except if water, pipes and pumps are used, as water is heavy, and pipes and pumps can transport a lot of it very efficiently and cheaply. That’s called pumped hydro storage and is currently the #1 grid scale storage in the world. Trying to do the same with solid materials can sound like a genius idea but it’s really not.
    - WalterBright 4y ago
      Well, his company is building a pilot plant in Brazil. I suppose we'll find out if he's a genius or not. > efficiently Are you sure about that? He said the losses due to pipe friction were considerable.
      - ncmncm 4y ago
        Losses turn out not to matter much when opex is near zero and generation capex is very low. You just build a little more top-line generating capacity.

sanderjd 4y ago

I'm interested in those alternative technologies, but I suspect they won't scale as well as batteries. Pumped hydro has been around a long time but it hasn't scaled because it is just very geographically specific.

ncmncm 4y ago
Pumped hydro is far, far less geographically specific than always assumed. This is partly because it needs no watershed, and partly because transmission lines mean it need not be local. Anyway pumped hydro is only one of many equally viable alternatives. All will be used. Eventually which ones are cheapest will become clear.
- sanderjd 4y ago
  I think my assumption with pumped hydro is that there must be something holding it back because it's been mature for a long time, so if it were as useful and scalable as you say, I think it would have been scaled a lot more by now.
  - ncmncm 4y ago
    The overwhelming majority of utility-scale storage today is pumped hydro. It stores and releases many GWh every day. You don't hear much about it because it just works.
    - sanderjd 4y ago
      Yes but is still a small amount of energy relative to total demand and there don't seem to be serious efforts to scale it up massively. I don't claim to know why there aren't. Maybe there should be. It just makes me suspicious when I see a mature technology that still sees limited deployment, that there is a good reason for that.
ncmncm 4y ago
Batteries have the very large disadvantage that cost is per Wh stored. Flow batteries can reduce this, as capacity becomes a matter of tankage and electrolyte. The sweet spot for storage is near-zero opex, very low per-Wh stored capex, and cheap capex per-W in and, particularly, out. Thus, weight for watt-hours, and simple motor / generator for watts in and out. Synthetic fuel has the appeal that the stored energy is readily tanked and transported, and very saleable; enough so to overcome low round-trip efficiency, expensive electrolysers for W-in, and complicated combined-cycle turbines for W-out.

WalterBright 4y ago

I know a fellow who is running a startup that moves a (very) heavy weight up a hill, and going back down it provides power. He says it is something like 90% efficient at energy recovery, whereas pumped water is far less due to friction in the pipes. He also said the inertia of a falling weight is enormous, and would help stabilize the grid.

paledot 4y ago
Okay, but if his startup isn't named Sisyphus Energy, I don't know what he's doing with his life.
californical 4y ago
This is a genius idea, especially because it could be done anywhere with a hill, which makes it a lot more geographically accessible (since most places have hills)
- qsdf38100 4y ago
  It’s actually not a good idea at all. When you do the math ( or rather the physics) gravity batteries need so much mass and height to compete with other technologies that it’s just not worth it. Except if water, pipes and pumps are used, as water is heavy, and pipes and pumps can transport a lot of it very efficiently and cheaply. That’s called pumped hydro storage and is currently the #1 grid scale storage in the world. Trying to do the same with solid materials can sound like a genius idea but it’s really not.
  - WalterBright 4y ago
    Well, his company is building a pilot plant in Brazil. I suppose we'll find out if he's a genius or not. > efficiently Are you sure about that? He said the losses due to pipe friction were considerable.
    - ncmncm 4y ago
      Losses turn out not to matter much when opex is near zero and generation capex is very low. You just build a little more top-line generating capacity.