Waste water generator
 

This is a pretty sweet idea. Use the falling water in plumbing to spin a generator. The article says it was mainly designed for multi-story buildigns. The prototype in the picture looks fairly simple too. I'm not sure how it deals with solids, but I'm sure thats been accounted for.

Waste Not Want Not with DMU Student’s Electric Idea | Creative Boom

http://www.creativeboom.co.uk/files/...nt-524x786.jpg

This would be great in a building with a grey water recycling system, ie put it on the sink/shower pipe, not the solids pipe.

Looks like the solids go through that pipe on the left. They likely use a screen or something to keep the &#*% from hitting the fan.

Edit: From a closer reading it looks like I am wrong- it uses a waterwheel design to keep solids from blocking it up.

I think you're right, the by-pass is only for when the wheel gets blocked. Falling solids also have a lot of energy...

This is very similar to catching the energy of rain falling down a gutter. I wonder why that never caught on? Or has it?

Piwoslaw,
Here is a short post on another message board about "gutter power":
Watermills in rain pipes - Creativity Pool
I was thinking that the power generation would be very low since it is a relatively small amount of water at any time. Also, it is intermittent. I guess if you lived in the tropics where it rains every day in the wet season and you were far from the power mains it could make sense to add it to supplement a PV system.

Thanks for the link, Ben. I don't live in the tropics, but the last few weeks of rain got me thinkin'...
The small amount of water is partially made up for by the height from which it is falling. Minimum useful head for a hydro install is 3m/10ft, while buildings here are up to 40m/130ft (15 stories) tall. If the cost of installation was very low, then a few extra watts every now and then wouldn't hurt. Especially if you could have electricity during a T-storm when the grid goes down. But I doubt that either rain od waste water generators would be worth while for small homes.

EDIT: After reading the discussion once again I see this may be more complicated. And also not suitable for climates with many months owith temperature below freezing. It would be nice to use the potential energy of all that melting snow, though. A heated water collection tank? Too complicated...

This looks nice. Free energy is always welcome. How much energy can this generate?

The only thing the article says is it can save £926 per year. £926 is currently ~$1550 US dollars. Average cost of a kWh is $.10. So, its estimated it can make roughly 15,500 kWh/year. Not an incredible amount of power, but I'd imagine it would pay for itself quickly enough.