3 ms·

> Having a reservoir as the potential to significantly increase the reduction in excess supply you can handle, that is true, but the lack of that option does no

> Having a reservoir as the potential to significantly increase the reduction in excess supply you can handle, that is true, but the lack of that option does not change the benefit of shutting off generating capacity. The point is to not turn off generation capacity that we don't control the start of, like wind. Why should we not generate if the wind is blowing at night?

vidarh 9y ago
What I commented on, and what you quoted above, was about hydro plants, not wind. With hydro plants, as long as the reservoir has capacity the reservoir acts like a battery, as hydro plants tend to be built with turbine capacity sufficient for a flow large enough to drain the reservoir. As such, unlike with wind, nothing is lost if you close the sluice gates or a while - the reservoir just builds up and you can generate more when needed. That's the entire point: That hydro plants can act as storage even if there's no lower reservoir to pump from. Which means they're good fast response plants exactly so that types of plants where turning them off wastes potential energy, like wind farms, can keep running. The original claim I took issue with, was that a hydro plant can't serve this purpose without a second reservoir, which is not true - a second reservoir can be used to increase total effective storage capacity, and to make the plant increase demand rather than just decrease supply, but a hydro plant on itself can improve grid responsiveness, given enough transmission capacity.
- jimktrains2 9y ago
  This whole discussion has been around the use of pumped hydro plants to store the output of other sources during times of low demand.
  - vidarh 9y ago
    Yes and no. The two comments leading up to my first comment was one suggesting that you could achieve a similar effect by simply closing a damn, followed by one implying that did not take power out of the grid. My first comment then stated: > You are taking power off the grid: The power otherwise produced by the hydro plant. > > Of course with a lower reservoir, you can go into negative territory instead of "just" taking the plant down to 0. In other words, my point from the beginning was that there is - absent transmissions limitations - no conceptual difference in the outcome of stopping a damn and pumping into a reservoir, as I've gone into at great length in the subsequent comments.

vidarh 9y ago

What I commented on, and what you quoted above, was about hydro plants, not wind. With hydro plants, as long as the reservoir has capacity the reservoir acts like a battery, as hydro plants tend to be built with turbine capacity sufficient for a flow large enough to drain the reservoir. As such, unlike with wind, nothing is lost if you close the sluice gates or a while - the reservoir just builds up and you can generate more when needed. That's the entire point: That hydro plants can act as storage even if there's no lower reservoir to pump from. Which means they're good fast response plants exactly so that types of plants where turning them off wastes potential energy, like wind farms, can keep running. The original claim I took issue with, was that a hydro plant can't serve this purpose without a second reservoir, which is not true - a second reservoir can be used to increase total effective storage capacity, and to make the plant increase demand rather than just decrease supply, but a hydro plant on itself can improve grid responsiveness, given enough transmission capacity.

jimktrains2 9y ago
This whole discussion has been around the use of pumped hydro plants to store the output of other sources during times of low demand.
- vidarh 9y ago
  Yes and no. The two comments leading up to my first comment was one suggesting that you could achieve a similar effect by simply closing a damn, followed by one implying that did not take power out of the grid. My first comment then stated: > You are taking power off the grid: The power otherwise produced by the hydro plant. > > Of course with a lower reservoir, you can go into negative territory instead of "just" taking the plant down to 0. In other words, my point from the beginning was that there is - absent transmissions limitations - no conceptual difference in the outcome of stopping a damn and pumping into a reservoir, as I've gone into at great length in the subsequent comments.