4 ms·

Batteries are extremely inefficient. Capacitors are much more resilient in terms of charge cycles (by orders of magnitude). If one were to build a "facility" t

by devmor 4y ago

Batteries are extremely inefficient. Capacitors are much more resilient in terms of charge cycles (by orders of magnitude). If one were to build a "facility" to hold short term load, that's likely what they'd use. They just can't be used in cars because they're incredibly volatile and don't hold a charge for a long period of time.

kragen 4y ago
capacitors are very low energy density and very high cost per joule of storage so they are never used this way
antipotoad 4y ago
The idea of super-capacitors in cars is positively horrifying, knowing how explosive just the small ones can be. At grid level though, is there anything that speaks against them? Edit: to answer my own question, they look pretty good [1]. Significantly lower storage density than batteries (roughly 50Wh/L versus 420Wh/L for Li-ion), but still dense enough for this to be workable at grid level. The linked presentation proposes converting decommissioned power plants into grid-level capacitor storage facilities, since the transmission switchyards are often intact. Furthermore, all the technology is available today, and when built, capacitors require almost zero maintenance. [1]: https://www.energy.gov/sites/prod/files/piprod/documents/Session_D_Miller_rev.pdf https://www.energy.gov/sites/prod/files/piprod/documents/Ses...
- londons_explore 4y ago
  Todays grids don't have much need for energy storage on the sub-10 second timeframe. Ie. there is rarely any money to be made by taking power from the grid now and returning it in 10 seconds. For technical reasons, thats because the 'spinning reserve' - which is momentum of every synchronous motor and generator across the nation - already adequately handles this. Also, large generation stations are required to have a 'load line' which damps high frequency oscillations. The load line can best be described as 'whenever the grid frequency starts slowing down, generators must put more energy in automatically'. Things like wind and solar typically don't have the ability to do that. For human reasons, it's because electricity markets tend to be minute by minute at most. For all those reasons, I don't think you'll make any money with capacitor energy storage banks (not to be confused with capacitors for grid scale power factor correction, which can be profitable).
  - fomine3 4y ago
    Isn't it expected that 'spinning reserve' will be decreasing because we shutting down dirty power plants? Possibly it is needed in the future.
danans 4y ago
> Batteries are extremely inefficient. Capacitors are much more resilient in terms of charge cycles (by orders of magnitude). If one were to build a "facility" to hold short term load,that's likely what they'd use The problem is that capacitors (assuming you mean super and ultra capacitors) don't have much capacity compared to batteries, so their cost per MWH of storage is high even if their cost per MW is low.

by devmor 4y ago

kragen 4y ago

capacitors are very low energy density and very high cost per joule of storage so they are never used this way

antipotoad 4y ago

The idea of super-capacitors in cars is positively horrifying, knowing how explosive just the small ones can be. At grid level though, is there anything that speaks against them? Edit: to answer my own question, they look pretty good [1]. Significantly lower storage density than batteries (roughly 50Wh/L versus 420Wh/L for Li-ion), but still dense enough for this to be workable at grid level. The linked presentation proposes converting decommissioned power plants into grid-level capacitor storage facilities, since the transmission switchyards are often intact. Furthermore, all the technology is available today, and when built, capacitors require almost zero maintenance. [1]: https://www.energy.gov/sites/prod/files/piprod/documents/Session_D_Miller_rev.pdf https://www.energy.gov/sites/prod/files/piprod/documents/Ses...

londons_explore 4y ago
Todays grids don't have much need for energy storage on the sub-10 second timeframe. Ie. there is rarely any money to be made by taking power from the grid now and returning it in 10 seconds. For technical reasons, thats because the 'spinning reserve' - which is momentum of every synchronous motor and generator across the nation - already adequately handles this. Also, large generation stations are required to have a 'load line' which damps high frequency oscillations. The load line can best be described as 'whenever the grid frequency starts slowing down, generators must put more energy in automatically'. Things like wind and solar typically don't have the ability to do that. For human reasons, it's because electricity markets tend to be minute by minute at most. For all those reasons, I don't think you'll make any money with capacitor energy storage banks (not to be confused with capacitors for grid scale power factor correction, which can be profitable).
- fomine3 4y ago
  Isn't it expected that 'spinning reserve' will be decreasing because we shutting down dirty power plants? Possibly it is needed in the future.

danans 4y ago

> Batteries are extremely inefficient. Capacitors are much more resilient in terms of charge cycles (by orders of magnitude). If one were to build a "facility" to hold short term load,that's likely what they'd use The problem is that capacitors (assuming you mean super and ultra capacitors) don't have much capacity compared to batteries, so their cost per MWH of storage is high even if their cost per MW is low.