If you think about it, for most of us with city water, we get two things when we get the water: water itself, of course, but also energy in the form of the water pressure. For instance, if the water was free, we could hook a hose up to an appropriately sized turbine, and generate electricity from it. Of course, in most cases the cost of the water would far exceed the value of the electricity generated.

The trick would be to use AND SAVE the water for purposes where high pressure is not needed. For instance, a shower would not really work, as we need the pressure (although, perhaps if we could make do with LESS pressure we could steal a bit of energy from the water). But then again, if your water tower is high enough, we could generate electricity while the water goes into an attic storage tank (like they oftern use in England), and then still get enough pressure from the water coming down from the attic tank to be useable. In addition, I believe hot water tanks create their own pressure, so the certainly shouldn't need a lot of pressure on the way in.
-- marquisdenet, Mar 05 2009

You would get the energy transfer of the height of the local water-tower to the height of your holding tank.
-- FlyingToaster, Mar 05 2009


You're not going to get much of this so called energy stuff from this highly sophisticated perpetual motion strategy. Anyways, here's a bun for being able to think and brush your teeth at the same time.
-- daseva, Mar 05 2009


Small scale hydropower is a pipe dream.
-- jhomrighaus, Mar 05 2009


if your "hot water tank" is creating it's own pressure then technically it's called a "steam boiler".
-- FlyingToaster, Mar 05 2009


Why would anyone want a steam boiler? I mean, steam is already boiling hot, so it doesn't need to be boiled.
-- marquisdenet, Mar 05 2009


If enough pressure existed from the municipal water main to generate significant electricity, you plumbing would be shot and your house flooded. Pressure reducing valves are common in most connections so the pressure will not burst you home plumbing. You could beef it up and extract some energy, but this would not be cost effective.
-- saprolite, Mar 06 2009


Let's say you use about 300 liters a day in your house, and the town water tower is 30 meters above your attic.

Energy = 300 liters x 9.8 m/s/s x 30 m = 88,200 J

Which is the equivalent of about 1 watt of continuous power throughout the day...

Average cost of electricity in the US is 11 cents/kWh, which means you are going to earn a grand total of 0.26 cents per day with your scheme, if 100% efficient! Sorry, but [-]

//Why would anyone want a steam boiler? I mean, steam is already boiling hot, so it doesn't need to be boiled.//

If you are running a steam system industrially or whatever, you often need to reheat the steam to avoid condensation, especially with rapid pressure changes.

I grant you, it is not called boiling, though. Also, I doubt marquis is awesome enough to have a mechanical steam system installed for opening his blinds and whatnot (sorry marquis)
-- Smurfsahoy, Mar 06 2009


A "Boiler" is a pressure vessel in which water is heated to 100C or greater, a "Heater" is a vessel in which water is heated to a temperature below 100C. In commercial settings a "boiler" is the generic term for any vessel that is used to heat water for use in a heating or power generation/transmission application.

A "Steam Boiler" is a Boiler system that is designed to produce steam which is then piped(as live steam) to the point of use where it is condensed and then returned via gravity to the boiler or discharged to the air(like in trains). These come is 2 flavors, High Pressure and Low Pressure, which dictates the overall temperature range of the steam that is produced by increasing the boiling temperature of water by increasing the pressure allowing for the production of steam at much higher temperatures than 100C.

A "Hydronic Boiler" is a boiler system that produces heated water that is circulated either by pumps or by gravity, generally these operate at low pressure and below 100C
-- jhomrighaus, Mar 06 2009


If you have a header tank in the attic, then the energy to pump water up there is already spent and it would technically be possible to extract some useful energy as it descends. The problem is that the energy you get out of this scheme won't come close to the energy or monetary costs of building or maintaining the turbines.
-- Srimech, Mar 06 2009


[Srimech], He's talking about stealing energy from the city. They pump water up to the town tower, and then he takes some of it that he doesn't need in pressure and squirrels it away in energy.

It would definitely work in a physics sense, but only for like 1 watt. Which no, does not pay for turbines.
-- Smurfsahoy, Mar 06 2009



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