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  1.  (6742.1)
    - and I can't see why it wouldn't work.

    Where I live the municipal water supply relies primarily on the fact that the dams are at a higher elevation than the city. There's a little bit of pumping in some areas but in general the whole system works on a gravity feed system.

    So what I'm thinking is: put a storage tank under the eaves automatically refilling from that municipal water supply.

    Put a second storage tank on the ceiling - about 1.5 to 2 metres lower. Use water from the higher of the two tanks to refill the lower.

    Set up a Pelton wheel micro-hydro generator to extract power from the water flowing from the higher to the lower tank.

    Free power - not a lot but the total set-up cost would probably only be a few hundred dollars.
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      CommentAuthorKPeff
    • CommentTimeSep 6th 2009
     (6742.2)
    Only a Godless communist would conceive of such a thing.
  2.  (6742.3)
    Come to think of it - you could fill the upper tank at least in part from rain water and simply top it up from the municipal water supply.
  3.  (6742.4)
    @Kosmopolit

    Don't you still need the pressure to make it come out of the tap and shower? Your system would act as a "clog" in the pipes, regardless of how passive it is.

    At least here in my town in Brazil, the pressure from the street alone is barely enough to wash the garden and stuff.. but in the past I lived in houses that had much stronger water pressure..
  4.  (6742.5)
    We have quite good water pressure and you'd have several feet of head of water from the ceiling to the taps.
  5.  (6742.6)
    A lot of people use water from a solar water heater on the roof, so there is definitely pressure. Since you won't have the water running constantly you'll want a generator/battery storage system and it will probably be supplemental...
    • CommentAuthorFan
    • CommentTimeSep 6th 2009
     (6742.7)
    Potential energy in earth's gravity (10 Newtons per Kilogram) is 10 Joules per kilogram-meter.
    Domestic water usage is 150 litres per person per day.
    Water is 1 kilogram per litre.
    You said a 1.5 metre drop.
    That would be potential energy of 10 x 150 x 1.5 ~= 2000 Joules per day per person.

    In a comment in another thread, rickiep00h claimed he was using "20 kilowatts per day", which (assuming he meant kilowatt-hours) is about 70,000,000 Joules per day -- recovering 2000 Joules per day (compared with 70 MJ expenditure) wouldn't be all that helpful.

    I don't know "microhydro", but maybe it's useful where you live next to some (more constantly) running stream.
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      CommentAuthorrickiep00h
    • CommentTimeSep 6th 2009
     (6742.8)
    ...I should probably go back and fix that...
    • CommentAuthorFan
    • CommentTimeSep 6th 2009 edited
     (6742.9)
    20 KW-hours/day (excluding laundry) is quite a lot of electricity, by the way.
    My bill tells me that I'm using 2 KW-hours per day: that's for a constantly-running fan, a computer, cooking, and lighting, and a fridge/freezer.
    Maybe you're running an A/C.
    •  
      CommentAuthorrickiep00h
    • CommentTimeSep 6th 2009
     (6742.10)
    I'm running four, actually. And two (well, three now) computers, a plasma TV, and a ton of other electronics. Plus I have a daughter that's yet to figure out the whole "turn the light off when you're done" thing.
  6.  (6742.11)
    @Val A Lindsay II

    The heating system directly drops the water to the showers, this system would have turbines or some other form of physical interaction reducing the pressure.

    Of course it's a matter of tweaking the turbines or whatever you use to only enforce as much resistance as the energy needed VS the pressure it will leave.. but within that range, the efficiency would go even lower than what Fan estimated above to keep enough pressure.

    Btw, I think storing the water up there first isn't the best design, coming from the street the speed/pressure of the water is superior to the speed/pressure you would get by releasing it from the storage above the house, when you store it, that extra energy will be lost as the water stops moving.

    So, a direct system, without the buffer, taking all the extra water pressure you don't need from the street, converting into energy and storing in batteries, would make more sense.
  7.  (6742.12)
    Fan, that calculation seems to pretty much explain the flaw. It's theoretically possible but wouldn't generate enough power to be useful. I'm in a house of 5 people, so we'd be generating around 1 kJ.
  8.  (6742.13)
    @Sage

    Yeah, I know there's a lot of flaws with Kos's idea, but I like to encourage such behavior. Little ideas sometimes bear fruit for larger ones. Like "It may seem ridiculous to tile my floor with solar panels, but at least I'm getting a percentage of any of the light hitting it." or "Maybe if I supplement my solar with two or three small wind turbines that would give me more juice."

    @Rickip00h

    Start thinking about combining all that equipment. It won't be long before your TV and computer are just one object. Plus a master switch for all the power warts will save a lot of energy. We are gluttons when it comes to electric things...
    •  
      CommentAuthorrickiep00h
    • CommentTimeSep 6th 2009
     (6742.14)
    @val - Yeah, I've been backing off on stuff like the warts, and swapping out lightbulbs and all that. Part of it's the fact that my fucking rental company won't fix things I tell them to fix, like the thermostats on my A/C units.

    Anyway, I'm done with my part of this particular thread derailment. Rick's power bill blows.