On 29 Mar 2006 01:53:56 -0800 someone who may be snipped-for-privacy@hotmail.com wrote this:-
The question they didn't answer is why they went for a water wheel, rather then a turbine. A turbine would produce more electricity, but doesn't look as attractive.
I think they have plans for a wind turbine as well...
I think that the water wheel was perhaps an 'easier' first project, and would probably provide a continuous source of power (as long as the stream is flowing) whereas the wind turbines will only produce power when there's enough wind....
As with all of these things - the challenge is to store the energy 'somewhere' until you need it. If you can find a cost-effective way to store it, then it may be 'better' to have something like a water-wheel that produces a reliable (although lower) output - rather than a wind turbine which produces higher output but intermittently....
Regards Adrian
======return email munged================= take out the papers and the trash to reply
On Thu, 30 Mar 2006 07:44:41 +0100 someone who may be Adrian Brentnall wrote this:-
I was thinking of a water turbine. Although these don't look as attractive their output is more closely matched to the input needed for generating electricity, usually avoiding the need for a gear box. Water wheels need gear boxes to convert the slow rotation of their output shaft into something suitable for connection to a generator, which adds more losses. Although advances in electronics, driven by the wind turbine industry, make this less of a problem than it was such electronics are not 100% efficient either.
Water wheels were used to drive machinery by line shafting in mills, but if/when electricity was installed it was provided by a turbine, fed from the same water supply.
It will be interesting to see how much more slowly the water wheel rotates when electricity is being taken from it.
But their plans included two WTs eventually, the graphics showed them two or three times. Whether or not they should have sought planning permission for the leat and wheel is a moot point, they certainly would need to for a couple of WTs. At least this way they were able to show something more or less at the outset.
I'm not convinced this series is really about how green they were trying to be, although the wife seems to be quite passionate about it. Anyone who has watched progs that have featured this guy in the past will know he revels in the engineering challenges, and I reckon that is what this series is going to be about.
Did anyone notice how they'd waterproofed the leat? Liberal applications of silicone sealant somehow doesn't seem too green to me.
I would hazard the guess that at these small power levels the waterwheel is less lossy, as long as the buckets don't leak.
Pelton wheels seem to be most efficient at high head, then as the head gets lower propeller type devices are better.
This interest me, I take it that a Pelton wheel is only power matched at one speed, when the buckets are moving at half the water velocity, so to avoid throttling losses you either drive it constantly or change nozzles?
What struck me about the breast shot wheel is that it is not lossy and there is some feedback, with it's speed adjusting to the torque extracted from it. As the load increases then the wheel slows and allows the buckets to fill a bit more, presumably maximum power is then when the buckets are brim full, which is maximum torque times the slowest speed is it not?
I did a rapid calculation that, I am ashamed to say, seemed to indicate my family's (total) energy needs would be provided by 500m^3 falling through 30 metres every day!
On Thu, 30 Mar 2006 19:57:44 +0100 someone who may be AJH wrote this:-
Changing nozzles is possible, but is a spanner job. Having two or three turbines, like two or three boilers, gives flexibility. Also excess electricity can be dumped into storage.
Indeed. I expect to see it rotating rather more slowly when electricity is being generated.
On Thu, 30 Mar 2006 08:21:53 +0100 someone who may be The Wanderer wrote this:-
I assume one of the intentions is to show that "being green" is not about going unwashed and eating lentils all the time. If it shows that "being green" can be fun that will be good.
Probably. It is certainly more fun to design and build a water wheel than pop in a few turbines from
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which is where they apparently got the solar system they install later in the series.
Makes more sense to store it as water at the higher head where possible.
This is one of the things we calculated when deciding on the diesel genset, the cost of storing electricity as chemical energy was more that the value of the generated electricity, storing it as diesel was cheaper even if the specific consumption went up.
I shouldn't imagine there is a great deal to building a power station once the design is chosen. They are after all only engines. If a large power station can power a city, then working around the clock day and night as part of grid it should pay back one hell of a lot of money if my leckie bill is anything to go by.
Say a tenner a week per person for domestic supplies; that is something around 5 million quid each week in a city of half a million people. That's =A3130 million.
(Less =A330 million in c*ck ups by OnStream and another =A360 million by conmen running firms like British Gas, I know. Still, it soon mounts up.)
Then there's shops and industry and all the other stuff from street lights to hospitals, railways to lighthouses. We must use one hell of a lot of it in 6 months.
I don't know what sort of mark-up they put on converting coal to ergs but 6 months seems reasonable in my ignorance. I bet you can find out the cost of a station from a websearch.
She's passionate the idea of being green, and passionate about being able to tell people she's being green.
Actually being green in ways that impinge on her lifestyle, or involve physical work don't seem to appeal to her quite so much.
In the program, they seems to be "playing" at gardening.
With 2 overgrown acres to go at, I expected them to get in a tractor, day 1, and plough it up, and get it PRODUCING. And if fertility is wanted, get 20 tons of rotted manure (easily available from any dairy farmerm trust me) dumped and spread.
Not dabbling daintily with trowels whilst wearing Laura Ashley dresses.
"Adrian Brentnall" wrote in message news: snipped-for-privacy@4ax.com...
What they need is for the water wheel to pump water into a holding tank (lake) as high up as possible. Then use this water to drive the wheel faster when power is demanded. That way you can take the small continuous output and generate large amounts for shorter periods as required.
You can add wind energy into it as well if available.
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