Is it possible to partially power a pump by recovering the hydraulic energy produced?

[nico7s]

Hello everybody

I've had an idea that's been bothering me for some time and no matter how much I look, I can't see if (economically) it's a good or bad idea. I'm not an engineer... at best some knowledge of electricity and DIY so before wasting money on a system that won't work I'm trying to find advice

Would it be possible to (partially) power a pump which operates in a closed circuit (filtration) by inserting an outlet turbine on its water network.

The goal would be to cover as much electricity as possible, here are the parameters available to me:
- pump flow rate 15m3/h (i.e. 4,17l/s)
- pipe diameter: 50mm inlet and outlet
- pump consumption approximately 1kwh
- operation approximately 10 to 12 hours per day

For the moment I thought about putting the two current inlets (EDF and hydroelectric) as inputs to an inverter with battery and connecting the pump to it. Using a relay or switch system I will cut off the EDF, switch to the battery inverter, start the pump and re-power the inverter with the energy produced by the turbine.

Do you think this is feasible? at a reasonable price?

Thank you in advance to everyone who takes the time to answer me and above all, sorry if technically speaking it seems far-fetched to you...

[Ahmed]

This is not an economic problem, but of physical principle: given that the consumption of an electric motor (that of the pump in this case) is proportional to its load (in its operating range, of course), if you add a turbine to take energy and transform it into electricity, you can in theory hope to harvest a little less (there are losses) of what you additionally inject into the system.
This in the case where the turbine device would be installed in the downstream pipeline; if it is out of the pipe, before diving into the pool (?), the amount of recoverable energy is negligible...
Thermodynamics is merciless!

[nico7s]

Thank you for this quick response, yes the idea would be to put the turbine (I have seen small Peltons with alternators advertised for 1000w on Chinese sites) at the pump outlet before the sand filter ;)
I suspected that there must be some loss but I thought that with 1000w announced, let's say that it lowered the flow rate of the pump a little and that the Chinese lied a little... even if only half came out (500w) for example it would still be interesting compared to doing nothing at all...

[Ahmed]

A small Pelton will only give in proportion to what it receives and any effective withdrawal* (I cannot imagine the envisaged assembly) will result in an increase in the consumption of the pump.
It's a bit like the idea that was discussed here, of an electric bike (commercially produced) powered by a pedal generator supposed to smooth out the cyclist's efforts: this probably results in permanent virtual hills, which will contrary to what is sought by the concept of VAE.

* If the turbine is placed outside the piping, given the low usable head of fall, the result will be insignificant compared to the complication and cost of the device...

[sicetaitsimple]

Thank you for this quick response, yes the idea would be to put the turbine (I have seen small Peltons with alternators advertised for 1000w on Chinese sites) at the pump outlet before the sand filter ;)
I suspected that there must be some loss but I thought that with 1000w announced, let's say that it lowered the flow rate of the pump a little and that the Chinese lied a little... even if only half came out (500w) for example it would still be interesting compared to doing nothing at all...

I agree with Ahmed's explanations.
But if you are ready to invest in an inverter + battery system, why not think instead of a photovoltaic panel placed on the ground near your swimming pool?