The problems stem from losses experienced along the way.
Energy has to be employed or wasted to make everything do anything.
Every thing, even sound generated by something represents a loss. If it makes a sound it is wasting energy. If there is some friction there is a waste of energy. If you lift something uphill, you wast energy.
Now if you let something fall, you can regain some of that energy, but a lot less than you lost buy putting it up there in the first place.
The system losses in a pump are many. Brarings, friction sound heat etc etc. You put 10 lumps of power in and typicaly get only 9 lumps of power out. The higher you pump, the more lumps of power it takes to shift a lump of stuff up the hill. Evey foot you pump up costs you more energy.
So to move one lump of stuff up the hill costs 8 lumps of power.
So you have a 8 lump debt and 1 lump at the top.
When you let that fall you have some potential energy, but there is friction in the pipe, friction in the generator at the bottom, sound to be created etc etc etc.but you can definately generate some energy. Perhaps as much as 7 lumps of energy.
7 - 8 = angry shareholders
The problem is that by the time it gets back to where it's started, there is a net energy loss and always will be. A better approach is to avoid pumping up to the kind of height that you need to gain the kind of flow you would need to generate a usefull amount of energy.
That way you can avoid using the full 8 lumps of energy to get it up there in the first place.
Someone once asked me if they could run a generator with a windmill on their exhaust fan. They could, but anything you put behind an exhaust fan if causing a restriction to the flow exiting the flow. It's a little tricky to get your head around, They never did quite believe that any power they captured would be a drain on the thing providing the energy in the first place.
In order for a turbine to collect power, it requires power to back up behind it and exert some force. By putting a windmill 10 feet behind an exhaust fan you wouldn't be causing very much back pressure at all. And you wouldn't be generating very much power at all either.
To make usable power, as mentioned, you would need to use more power than you could collect.
But I'd still do it anyway because doing stuff is very cool
Make it run an insect attracting light of something to attract fish food.
Backyard Aquaponics
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