| Archive for Downsizer For an ethical approach to consumption |
| gil |
Waterwheels and other means of waterpowerDoes anyone have (fresh)water power ? If you do, what kind, and what is your experience of it ?Just been reading the 'it's Not Easy being Green' thread (which is another programme that I won't see, not having TV) and thinking again about making use of the running water on my land for power generation. I have single-bank rights to a large burn with slight fall that always flows (5-6' deep when in spate, normally about 1'6", down to 6" in drought), and both banks of a smaller burn with steep fall, that usually flows, but dries in drought). There would be space to divert the large burn (subject to neighbour's permission) onto my side and through a race, and also for the construction of some kind of holding pond. The smaller burn has a small area above the main fall which could be dammed, but I think it is less promising. There was at some point a mill round here (tho' not sure whether wind or water). Any ideas ? Useful web sites ? |
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| Treacodactyl |
Great thread, I'll be keeping a close eye on the comments as it's something I'd love to have a go at if possible. I would love to hear of any problems experienced as well as what's best to do.
Do the CAT have any details on their web site? |
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| tahir |
A related question, how does the extraction of energy affect the functioning of the watercourse downstream of the power extraction unit. | ||||
| gil |
My guess would be that it might depend on the fall at the outflow, and the speed at which the water is released from the power extraction unit. If damming a major watercourse for significant periods, there might be signficant effects, but if it were a case of damming one of many tributaries close-ish to where it joins the main river, perhaps less so. |
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| dougal |
Gil - the first things to determine are the 'head' and flowrate that are available to you.
The 'head' is the vertical drop that the water makes through your system, and from which you could gain energy. The flowrate is the more obvious, but more awkward to measure, quantity. Its not the depth, but the quantity (litres or gallons passing per second). Waterwheels are lovely - but require a heck of a lot of 'foundations', etc and aren't fantastically efficient. The maximum head they can use is determined by the diameter of the wheel! So, realistically, they'd want 6-20 ft of head. They are within the province of DIY (apart from the hub and bearings) albeit advanced DIY - fancy building a wheel 15ft across? Water Turbines aren't sexy. But you can use a piped feed to exploit a 'head' of 100 feet or more (if you have a proper hillside), while building your own London Eye would be out of the question. But you can't make your own turbine. Install, yes - make, no. Turbines are more fussy about 'stuff' in the water, but are probably less vulnerable to flood damage when your burn is in spate... So they need some form of strainer and/or filter - which is likely to require periodic cleaning. Again, less than 6ft of head probably wouldn't be worth trying to exploit... If you have plenty head, you don't need much flow to generate a useful amount of power. The question then arises of whether you fancy faffing around with batteries, or just tie it into the grid... but first - what's the resource - head and flow... I'd think the small burn would be most interesting - even if it gave you nothing at all in summer - partly from the head aspect, and partly from the aspect of Environment Agency concerns (fish movement, etc). {**Dunno** at all about regulation in Scotland.} |
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| gil |
Thanks for useful guidelines / information, Dougal. Much to think about / measure there. I had been thinking about the turbine option. Re waterwheels - the one at Barony Mills on Orkney Mainland does not appear to require a massive amount of fall (30' at a guess, some of which was obtained by digging out the banking so the wheel is in a channel low down) - the island is pretty flat round there, so it must have more flow - achieved with a millpond / tank system, and by diverting a second stream to join the first (AFAIK). In Scotland, it would be the Scottish Environmental Protection Agency (SEPA) |
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| dougal |
Tahir - its not removal of the energy that matters, not directly anyway. The energy would normally be wasted largely as flow drag, turbulence. The questions that arise would mainly be about river levels, wildlife barriers (like a dam), and maybe even more indirect things like water oxygen levels and the impact on plantlife on the banks... |
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| dougal |
30 feet is big for a waterwheel. The question is how far the water can *usefully* fall. With a wheel its limited to the size of the wheel. A turbine can make full use of a head of a hundred feet or more - which a waterwheel cannot! I'll post some links later. |
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| dpack |
a 3m overshot wheel with quite a small flow produces enough power for merton abbey mills market (as it did for the 19th c liberty factory on the same site.
a good head of water and a small turbine will do the same with even less volume flow. water power good and it can be arranged so as not to destroy the ecology of the waterway (or badly like most large scale schemes) water is a 1000x as dense as air and for a given speed and volume has 1000x as much energy to be tapped . water power good . 
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| dougal |
For an introduction, take a look at
http://www.microhydropower.net/intro.html and its associated pages (although the electrical power one isn't very helpful). These should give you a grasp of what the basic questions are. For a small 'high head' scheme, you would probably consider a 'Pelton' or 'Turgo' type of impulse turbine. The water is jetted under high pressure against a really small waterwheel. But because the water becomes so fast moving, any silt will 'sandblast' the nozzle and the wheel - so adequate settling becomes important. Judyofthewoods has a *tiny* microhydro installation - producing 25 watts or thereabouts, (I think her record is about 45w). She is limited by her water supply rate - maybe a litre in 5 seconds - thats a slowish tap! Nevertheless, with 100ft of head (and using 650 ft of oversized hosepipe) she can make enough power to charge her batteries to power her through the winter. (Her 'springs' go slow a few days after the last rain.) However, given 10x as much water, her turbine (with the appropriate jet nozzle) could deliver 250 watts - which as a steady output is seriously useful... I think Judy's turbine (with its directly-connected 12 volt generator) is about £1000 worth of kit. Add on the penstock pipe, and whatever electrical storage or grid-linking kit you might be thinking of... http://www.judyofthewoods.net/hydro.html do click on the 'gallery' links at the right hand side There's a collection of useful info in this pdf (including a 'weir table' for estimating stream flowrate http://www.waterturbine.com/media/final%20pdfs/appendix.pdf They also sell a number of small turbines. Navitron sell some chinese-made turbines in the UK with AC integral generator - and one might almost say they were cheap... http://www.navitron.org.uk/hydro_power.htm |
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| dpack |
the right kit for the situation , green power .
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