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My question is about differences between reservoir-hydropower and run-of-river power plants. Are run-of-river plants less efficient? what would be an approximate guess of the differences? (assuming they are placed in the same catchment). Would annual capacity factors (% of time in operation) differ? by how much?

This answer makes me think that reservoir hydropower would be more efficient because it can capture a larger % of the kinetic energy than wind power. Arguably the run-of-river plants would be in a similar situation, because they are less able to slow down the water flow in comparison with reservoir hydropower. Obviously water and air are very different fluids and I can't just translate the efficiencies from windpower.

Regarding capacity factors, in principle I have no reason to think ROR has lower capacity factors. Water throughput would depend on the catchment area and I guess both have similar maintenance requirements. However, all these are intuitions, I have not found real data to corroborate my hypothesis.

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Capacity factors over a plant's lifetime are largely a design decision. There is no standard one-size-fits-all answer. The situation in any one particular case will be determined by the local climate and the design decisions made that reflect the local economics.

There are no "same local conditions", it's not a meaningful question really. If there's a reservoir, one builds reservoir storage. But all other things being equal, they'd yield the same energy. (NB that's not the same as capacity factor or efficiency.)

And you've misunderstood the other answer. Hydro can be more efficient than wind. I didn't say that storage hydro was more efficient than run-of-river.

Furthermore, efficiency and capacity factor are completely different things. Don't confuse the two.

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  • $\begingroup$ I am not trying to get an efficiency or capacity factor value representative of all possible working conditions. I am asking about the difference between these parameters for the same "local conditions". $\endgroup$
    – Nabla
    Dec 3, 2016 at 13:15
  • $\begingroup$ Concerning the other answer, it talks about the capacity of reservoirs-hydropower to capture a large proportion of the kinetic energy compared with windpower. ROR plants because the way are constructed, probably do not reduce run-off speed to the levels a reservoir power plant can, which makes me think they are less efficient. I am aware capacity factors and efficiency are different. $\endgroup$
    – Nabla
    Dec 3, 2016 at 13:44
  • $\begingroup$ There are no "same local conditions", it's not a meaningful question really. If there's a reservoir, one builds reservoir storage. But all other things being equal, they'd yield the same energy. (That's not the same as capacity factor or efficiency.) $\endgroup$
    – 410 gone
    Dec 3, 2016 at 15:36
  • $\begingroup$ Don't get me wrong. I wrote "this answer makes me think", that reservoir hydropower is more efficient than ROR. I am not saying that you said that reservoir is more efficient than ROR. $\endgroup$
    – Nabla
    Dec 3, 2016 at 19:01

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