University Waterwheel Help

[Dannbodge]

Hello.
I am a third year student at Portsmouth University, and for my final year project I am designing and building a waterwheel for my parents house in north Devon.
The wheel will be undershot due to the river restrictions we have.
The river is 8m wide and has an average depth of 0.583m with a head of about 0.6m.
I did some measurements at the weekend and found the average speed was 0.7m/s.

The problem I am having is working out the flow.
I have found some equations but I get a flow of 115.8 M³ per minute, which works out to be around 30,591 gallons a minute.
To me that sounds like a massive amount, what does everyone else think? Have I done something wrong?


Thanks
Dann

[guydewdney]

GCSE maths:-

width x depth x distance flowed in one minute = flow per minute

8 x .583 x (0.7 x 60) = 196 M^3 / min or 196000 l/m

Head x flow (per second) x gravity = energy = .6 *(196/60)  x 9.81 = 19224 watts

realistically, probably 10kw max, using a more efficient type of waterwheel than an undershot Flipping Flowery Sunhats - do some research - buy a book called 'stronger than a hundred men'

look for sagebien poncelot zuppinger etc - sagebien was quoted at 98% efficient against undershot being 40%.......

[Tombo]

Hello  and welcome, always nice to reduce the mean age of the forum.
It sounds about right for a whole river. If your taking about a leat then it's high.  Think nearly 2 IBC's a second.
What river is it?

[Dannbodge]

Thanks for the help so far.

The river is the River Okemont, which goes through the town of Okehampton near Exeter.
It is controlled initially by a reservoir but the weather has a large effect on the flow.

I have done a fair bit of research so far and looked at Poncelot wheels.
I was going to experiment with a hybrid type of wheel due to the degree I am studying.

I will have a look at the book and research the other types suggested.

[Dannbodge]

Also
What PMA do people recommend?
It will be going into a battery bank and will be running the house lighting using an inverter. The house lights use 700W when all turned on

[guydewdney]

Why use a battery bank when / if you have the grid? You can get FITs from micro hydro if you do it properly, and do all the paperwork - see mha website for details iirc. batteries are a pain, and expensive to maintain.

[knighty]

also.... why limit yourself to 700watts and just the light ?

with a gti, you can produce as much power as is available from your wheel... 24/7... which should cancel out most of your loads ?

[Tombo]

If your house lighting is 700W then I suggest you look at energy efficiency first.
I looked a site on North road in Okehampton some time ago.

[Dannbodge]

I only have a small budget and the project has to be finished by mid April.
I don't want to set targets that are too complex or large as I don't have the time to meet them (I have 3/4 other units to concentrate on too)

All the lights being used in the house have energy efficient bulbs in. The actual possibility of every single light in the house being on at one time is small, as it is a holiday home for my parents.

North Road is literally 1/5 mile up the road from where I am looking at. It's on the same stretch of river and the same road.

[knighty]

no chance your parents will pay for the gti ?

it'll pay for itself in no time at all... just think... no more electricity bills... forever...

(or bills so close to zero they're not worth mentioning)

[smegal]

Have you looked into abstraction licences and what the EA will allow tou to do etc?  With such a small drop you'll need a lot of water and this may cause issues with planning etc.

The head may be a bit too law but have you looked into designing an archimedes screw type device?

[Dannbodge]

Sorry for being a n00b but what is a Gti?

Also we own half the width of the river and the length of our land.
The whole idea of using an undershot wheel is that the river won't need any modification. (The plan is to have everything connected around the wheel)
I have contacted the local authority about what we can do, but have had no reply yet.

I have not looked into Archimedes screws yet as so far I think an undershot wheel will work.

[smegal]

Sorry for being a n00b but what is a Gti?

Also we own half the width of the river and the length of our land.
The whole idea of using an undershot wheel is that the river won't need any modification. (The plan is to have everything connected around the wheel)
I have contacted the local authority about what we can do, but have had no reply yet.

I have not looked into Archimedes screws yet as so far I think an undershot wheel will work.

GTI =Grid tied inverter.

[smegal]

Can you PM me your email address please. I have a document for you but can't attach it and we aren't allowd to go to filehost sites at work.

[Baz]

You will need planning permission that will cost more than the value of the electricity you generate. You will probably need an environmental impact assesment that will be enough to pay a full time WOS (waste of space) for a year, probably some sort of bat survey or the equivalent for the fish who are going to be killed by the thousands when they hit your wheel, and have to relocate any beavers who were planning to dam the river.
When filling in the forms it will probably help if you can spell the name of the river correctly. It actually has a dozen water authority measuring stations along it http://www.environment-agency.gov.uk/homeandleisure/floods/riverlevels/120720.aspx?stationId=3101 and although that shows the level I expect there is something that equates this to a flow rate somewhere.