I'm writing this to get my head around what I've just found out. I hope it provides you with food for thought.
I've noticed our electric bill climb as I continue to add to my
aquaponic systems, so using a Watt meter I did an energy audit .
first thing to surprise me is the cost of moving air. I'm using a whole
house fan and a 20" box fan. Both use more than I expected. The whole
house fan consumes 530W, and the box fan 90W.
My submersible pumps are not too bad for submersibles, but one is not as large as I would like.
The Alpine Hurricane 2400 GPH is drawing 129W. It is delivering 1750 GPH at 4 foot head.
The undersized 'No Name' pump I am using in the outside IBC system is drawing 20W and delivers 268 GPH at 4 foot head.
Expanding the grow beds in this IBC system is going to require a larger pump, so I just purchased an AZFlo 2400/4000 External Pump for 299.00. It will deliver 1900 GPH using 105W at 4 foot head.. This is 20W less than the Alpine Hurricane delivering 1700 GPH. If I were to replace that submersible with this external pump I would break even in 5.7 years.
Now here's something I find interesting. Pump power usage is non-linear. These
tables show as head increases GPH decreases as would be expected, but
the Watts seem to peak around the midpoint of maximum head.
I have also have a Sequence 3600 700 series pump on my pond. 139W delivers 2820 GPH at a 4 foot head. As you can see the external pumps are a lot more economical.