Anyone have any thoughts on the news that two electricians have invented a "new waterwheel that powers a whole house" with a 20cm water head?
Even without calculations I cannot imagine anything that would have the torque on that head.
20cm? - that's *eight* inches? - I can't see this being genuine, do you have any links?
Don't see a problem. 8" drop across the width of the Thames at Tilbury should achieve this without a problem. It's no more unrealistic than the claim that the new windmills to be built in the Thames estuary will power 1/3 of London.
Been trying to find some.
It was on Teletext this morning. I know they can be a bit flaky but there were no spelling mistakes in this one so I took it as gospel.
It was headed something like "Lower electric bill for thousands", and said a couple of UK electricians had invented a new waterwheel and a head of just 20cm could power a house. It seemed utter bollocks to me but I wondered if any of the Brains in here had found it and had any opinions.
It conjours up an image of a 200 meter wide 20cm deep wheel connected to a B&Q windmill generator by a large gearbox.
Quite. One can power a house off a 4" head if you've got enough water flow - but by god it would have to be a lot. Or alternatively you could make it a very frugal house.
NT
In message , EricP wrote
myself for dodgy posting!
Theres a longer article here
Numbers dont even begin to add up. I guess he's been inspired by sales of the famous windmils.
NT
1kw per hour from a 20cm head at 70% efficiency!
Anybody do the maths please?
We were somewhere around Barstow, on the edge of the desert, when the drugs began to take hold. I remember "df" saying something like:
720 litres/second. ( PE = mgh )
Just assuming a figure pulled out of the air of a 1m/s flow rate for the water source, that'd need a duct of cross section 0.72 sq. metres. Since that's a duct 0.85m x 0.85m that's a lot higher than the drop involved that can't be right, so assuming a very shallow duct 2" ( 5cm ) high at most, the duct needs to be 47 feet across. That's about 14.4 metres. Could be done with a 10" ( 25cm )sluice on a small river.
Andy
Read the articles carefully. With 20cm head you get a "useful amont of power" not the 24kWHr's/day that they also mention.
What I do question is the demand of a "household" 28kWHr's/day? We don't have gas so cook by electric and still only consume 21 or 22 units/day. With 3 or 4 computers on, a fridge, a fridge/freezer and freezer, lights on 18hrs/day and normal TV DVD Sat boxen etc with two young children.
The picture of it shows a tiny water flow. Might be good for 25 watts.
NT
Something similar was used during the war. It was a handful sized mini gen that attached to a house tap and provided electricity. ISTR a max
40w output. The mains water pressure head would I guess be tens of feet.NT
R.
Quote from article
Mr Gilmartin is an electrician by trade, but does not own a TV and has never lived in a house with electricity.
So why did he bother, apart from the grant money and a load of "something to do" ideas resulting in this?
I certainly agree with that.
The rather old looking B/W photograph in the other URL provided, looks as if the idea is based upon a series of buckets on a loop of chain. I would suggest the rolling resistance of the chain would make the contraption less efficient than a straight forward wheel with buckets, assuming the buckets were designed to pivot to retain the water right to the bottom of the fall. Both would need to be carefully matched to the actual flow of water. High efficiency will only be possible at low flow rates, as the flow increases and overspill of the buckets occurs its efficiency will drop dramatically.
The trouble with most water wheels is that they loose most of the impact of the falling water off the sides of the paddles. Pivoting buckets will be much more efficient.
Robbo presented the following explanation :
Perhaps he doesn't have a supply because he lives a long way from a source and cannot afford the installation cost. This contraption might be a means to and end.
Yep a little high for average - we are all electric/2 kids/ 4 computers etc etc same as you, use solid fuel for heating (no gas). Just did a tot up over the last 2 years we average 8.4MWh/year, around
23kWh/day.Lorne
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