I work on a water production site, we have a staggering amount of water flowing, much of which is just using gravity pressure and feeding into reservoir tanks. (flow on various sites ranges from 100 litres per second to over 1,500). I am wondering if there is a potential here for energy recovery? Either a kelvin thunderstorm (unlikely I guess but would love to see why it may or may not work) or a waterwheel generator inside the pipes or at the outlet? But I am struggling to find any real figures to help me ascertain what kind of power this could generate and if it would be feasible / cost effective?
any input would be greatly appreciated.

If an example helps to give some base figures, I can think of one specific pipe that drops about 10 meters and has an average flow of 240litres per second. the pipes diameter is about 1 meter

  • $\begingroup$ The formulae to calculate power generation from Pelton, Francis or Kaplan turbines are easily available. There are also some research papers on using micro turbines in place of pressure reducing valves. $\endgroup$
    – Solar Mike
    Apr 12, 2021 at 9:34
  • $\begingroup$ @SolarMike many thanks, thats helped. im seeing the pelton and francis turbines require quite a high head pressure. i think in our situation the max head would be around 10 meters. are there any other kinds of turbines i could look into that can use high flow rates and lower heads? such as 2 meter head and a flow of 250 liters per second?. the generators as prvs is very interesting, ive only found reference to applications with steam thus far but will keep looking $\endgroup$ Apr 12, 2021 at 9:45
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    $\begingroup$ Remember that extracting energy will likely result in slowing the flow. First question to answer is how slow can I afford to make it? This will usually depend on things upstream but can depend on downstream elements too. Stagnation can also cause particles to deposit, etc so you need to know your process and fluid. $\endgroup$
    – Abel
    Apr 12, 2021 at 12:38
  • $\begingroup$ In all likelihood ,an engineer has already determined that the cost of necessary equipment is not justified by the value of the power generated. $\endgroup$ Apr 12, 2021 at 15:18

1 Answer 1


All the water moving around inside your plant was originally set into motion with pumps designed to get the right amount of water to the right point in the plumbing in the right amount of time.

Imagine now that we insert power-extraction turbines in the flow through those pipes. This extracts the energy content of the moving water and leaves no dynamic head or pressure head with which to move the water to its destination.

You can fix that by increasing the horsepower rating of the pumps, but you just wind up putting more power into the flow to accommodate the fact that you are extracting power from it somewhere else. There is no free lunch to be had here.

  • $\begingroup$ All the water in our pipes starts high on the mountain so no pumps required, but lots of pressure regulation.... $\endgroup$
    – Solar Mike
    Apr 12, 2021 at 17:53

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