The investment for installing millions of tiny electric generators for the harvesting of water power makes little sense when the same energy could be obtained by running the water supply through a central generating system. But the energy converted to electricity might have to be fed back into the system through pumps to restore the free flow of water to users. Not worth the effort unless you are a manufacturer of pumps.

No, sand, if you take the energy out before the water gets to the user, it won't get there.

Now, making this idea economically feasible would depend on some extremely cheap generators (not "pumps," I'm sure you meant generators), and I don't see anything like that on the horizon, but at least the energy is there to recover. Recovering enough energy from the water to pay for the generator, that's the problem, I believe.

If generators were that cheap, then there would be lots of places to recover a little energy. The end of the faucet would be one; there'd be others of similar capacity. The problem is making generators cheaply. They don't even have to be efficient if they're cheap enough.

Oops, I misread your comment completely. Of course, if you take the energy out "centrally," the water stops flowing -- but you'll never get as much energy out as you'd need to restore the flow because of losses in the generator and in the pumps. Even if the generator and pumps were perfectly efficient, it would be a net-zero process. No energy saving could result.

So, back to my comment -- if turbine generators were free, this would be a great idea even if they had lousy efficiency. But the opposite isn't true -- even if they were 100% efficient, there's not enough energy there to pay for even a cheap generator.

There, I think that's what we were trying to say.

I did mean generator.

I guess it would make more sense applying it where the water comes into the house would produce pretty much the same effect

Although, using a small toy electric motor which when run backwards would become a generator.

Although the addition of nuisance technology might generate a tiny amount of electrical energy, it probably would encourage people to run their taps more than necessary and the waste of water which is rapidly becoming a valuable resource is an exceedingly negative activity for very small gain.

If the generators were attached to the drains, we would be recovering lost/wasted energy that would normally be flushed down the toilet, instead of loseing water pressure to gain a couple of watts of power that would spent to return the water pressure to normal.

I have all sorts of crap (literally and figuratively) blocking my drains and I wouldn't really appreciate anything else that might impede the flow of waste out of my living quarters. There is a reason for the expenditure of energy to get rid of waste.

I recently suggested to someone that we should put water turbines in our downspouts on our houses. It has been raining about 2 weeks straight.

Another down-the-drain energy idea is to reclaim the heat energy from our waste water. The idea would be to use a heat exchanger to pre-heat your hot water. I suspect that such a system would be more efficiently way to recover wasted energy.

As someonelse said however, slowing down the drains in your house can lead to other troubles.

and now your water dribbles from the faucet. #4 nothing is free

and now your water dribbles from the faucet. #4 nothing is free

if you take the energy out "centrally," the water stops flowing

What if you take it out "centrally", in the attic?

it will still dribble, a little faster. i dont think youre even going to extract enough energy to pay for the modifications.

i bought a "novelty" shower head as a Christmas gift. there is an LED light in there somewhere and it changes from blue for cold to red for hot as the water temperature heats up. the relevance is that there is no battery but that the electricity required is provided by the water flowing through the shower head turning a tiny turbine. it's cute and has gotten rave reviews from the occasional sleepover partner.

The main obstacle to this idea is that most of product available on the marketrequires that flow rate is double that what some of the codes allow (1.0 gpm vs 0.5 gpm) - in order for the devices to produce enough energy…So saving pennies and spending nickels does not make much sense