It's a non runner.

The quantity of water needed to generate any amount of power is enormous. E.g. to generate 1kw with a pressure of 2 bar needs about 9litres per second or 800 cu metres a day. If you have a community large enough to use that much water 24kwhrs a day isn't going to go very far!

The water company will have gone to some lengths and expenditure of energy to generate the pressure in the supply; they won't be happy to have it dissipated in a scheme like this.

Could serve as a handy 'ground source' of heat for a heat pump, but unkind to users downstream unless they're far away....

It would make more sense to get power from the flow of sewage!

And the archimedean screw used here:

http://www.torrshydro.co.uk/Scheme.htm

Is essentially the same as ones used to pump sewage up -- no reason why they could work the other way around for places with lots of hills and sewage, like Sheffield...

Powering a turbine with mains water is like putting an electric motor on a dynamo and expecting that the motor will turn the dynamo. Mains water doesn't just trickle through the pipes of its own accord, it's pumped through ... and a pump is often driven by an electric motor. The sewage idea has more merit as you'd effectively be recovering some of the pumping costs of the water - plus you could feed it through heat exchanges / heat pumps to recover some of the heat the sewage takes out of people's houses. I wouldn't want the job of de-sliming said heat exchangers though!

Believe it or not, it was quite legal up until quite recently to use mains water in Montreal in water source heat pumps - the cooled water just was dumped down the drain. A friend of mine who installed his own system used this method temporarily before his ground-loop was drilled!

At this time of year, the heat from the sewage is used to melt the snow that's removed from the streets in winter an put in large snow dumps - the melt water is then also treated in the sewage treatment plant rather than just being dumped in the river.

Paul in Montreal.

Sorry guys, the idea of using sewerage is not on

In the trade there's an item called a houdini. A houdini is a condom that someone has tied and flushed. Said houdini then rots producing gas and expands. The existing free flowing sewerage system then just about gets the houdinis out of the system before being caught at the gratings of a sewerage works.

well, guess that means you dont tell the water company what you are doing
Reminds me of those stories of people in Africa clipping some wires on to the overhead power lines to nick a bit of lecky.

Water powered appliances were available in early 1900s...

http://www.dself.dsl.pipex.com/MUSEUM/POWER/watermotor/watermotor.htm

For info: 40psi is about 2.8 bar

If someone were to extract energy from flow of water in a pipe which you got to flow you would probably be right in saying that they were stealing the energy which you put in to make it flow.

Or forums creating friction

And to take heat out of it?

...but say for the purposes my mains pressure was far in excess of what I needed at the taps, could I slow it down a bit with a turbine and get anything useful...?

J

I have been onto both our local water utility companies to put turbines on there river compensation flow outlets and have been refused by both. The excuse was "were into water supply not power generation". How stupid is that.

Posted By: renewablejohnwere into water supply not power generation

Not stupid at all. They are legislated to discharge at a minimum quality, the last thing they need is a conflict of interests (and a physical restriction) that may upset the flow rates and cause lagooning above a river. One heavy spell of rain and the effluent may well have to be discharged rapidly into a river.
Happens here a lot, why we have the most expensive water in the country, we do not have the geography to allow a safe distance between the centres of population and the sea (most towns are on the coast). One down poor and Portreath has a brown river running across the beach, mind you it smells there anyway.

Posted By: TheDoctorOK,

I was having a discussion with a neighbour (ahh! why does this site persist with a Yanky spellchecker!)

their words : "we have a f*ck off water main runnung through the estate, can we not get a turbine built into it for local electricity?"

my response:
Scottish water wont have any of it - will laugh in your general direction
flow isnt generated by gravity, but by use, so would be intermittent
risk of contamination
risks water supply for faults / maintenance
will reduce flow - may be high pressure here, but not by the last tap on the line

so - is there any mileage here, or is this a dafty thought?

I knew I read about this the other day:

http://www.scottishwater.co.uk/about-us/press-releases/latest-press-releases/scottish-water-starts-ambitious-hydro-scheme

Scottish Water are at it themselves just for their own treatment plants, must have stolen the idea from here a few years ago