Indeed. However, this stretch of the Lea was extensively used for cress growing. The shallow rectangular pans also require a source of clean flowing water. The leat bank is slotted for just this purpose. Perhaps a later modification as the cress was said to be transported by rail to London and our line was not built until 1850 or so.
How many of such schemes would it take to make any meaningful difference to CO2 reduction?
The scheme I linked above generates around average of 20kW and cost £400k ten years ago. The output varies month to month by 4:1.
It's another technology that requires a backup for when the water doesn't flow too well in the river.
OK so we get 100kW from the Severn. Care to tot up how many such installations would make sense and how much power that would produce? Think you could reach, say, 20MW? That is f*ck all in the scheme of things and would most likely cost a lot to maintain.
Why d'ye think that, historically, power stations have been built typically to produce 500MW and upwards? Economies of scale, that's why.
I installed one such scheme. Winmill, alongside a steam pump, them diesel pumps, finally automated electric pumps I installed. There was a very good reason for the progress, at each stage - running cost, reliability, and efficiency.
+1
Thousands, but how many weirs are there in the UK? Every bit helps.
At 20kW it would take 10 years to pay back, and not be an eye-saw in the mean time.
Except a weir creates a dam in it's own right where water levels could be allowed to drop during times when it doesn't blow or is sunny.
All 'green' sources of power have issues of availability, apart from nuclear of course.
I confess I only added Clive Sinclair as I'm sure the TNP would appreciate the mention. I feel his biggest problem is he hit the market too early with product that wasn't sufficiently engineered.
I thought his calculator did work? I see this article suggests the inaccuracy was on a specific variation?
10 years assuming no staff costs, no ongoing maintenance and repair costs, no distribution costs, no local council business rates etc.
The debris carried by the river has to be stopped from going through. Another generator on the River Teme is around half a mile away, at the side of another weir and it's more accessible for viewing. The filters are just metal grates but every time I've seen them they have been full of rubbish (man made and organic material that has been washed down the river). From memory, one of the two generators was offline for around 3 months when it was damaged by something getting through the filters.
A weir is effectively just a very low dam that can redirect water but doesn't hold a lot water. There is no great volume of water to drop lower. These generators just don't work when the river flow is low.
The generation figures are shown and from one of the other links in this tread appear to be similar in the variation in generation capacity thought the year. These generator don't work when the river flow is low and one of the web sites states also switched off if the flow becomes too high. I assume that the grit and small stones carried in a river in flood conditions acts as a powerful abrasive damaging turbines and screw mechanisms.
Isn't renewable meant to be much cheaper than we are paying now plus Labours promise to cut our energy bills by £1400 by 2030? The payback would be more like 25 years based solely on the future national cost of a "unit" of electricity and ignoring any other running or maintenance costs etc., and assuming there was no costs and interest on the money borrowed to build it in the first place.
It's this line of argument that I have a problem with. What would be 'enough saved', then, for you? How big would a scheme have to be before you'd vote for it?
We all disagree on true costs and benefits. But to not do something that helps mainly because it's not enough is daft (IMVHO!).
The point is best illustrated on this group on the demand side - people who fill the kettle to make one cup of tea. From past discussions, about half of this group. Because to boil just enough would make 'no meaningful difference'.
Never mind the right thing to do . . .
Plenty of examples, with detailed accounts, in this thread.
I don't think anyone's suggesting it'll replace all sources currently feeding into the grid. Just maybe consider it in situations where it can contribute. That's all.
That's a trick question. If the UK stopped all CO2 production (i.e. all life magically vanished) it would make no measurable difference to the atmospheric CO2. That would continue to rise, since many countries are building new carbon/hydrocarbon-burning power stations, and I doubt that they're paying anyone a carbon tax to do so.
Enough to be economic, i.e. to give a useful net return on capital. If tiny schemes were economic, they would already have been done, exactly the same argument as about any of the 'renewable' ideas. These things are only 'renewable' in terms of fuel, the rest of the necessities to harvest and utilise that fuel are *not* renewable and do not last forever.
I can remember, as a child, seeing demonstration models of tide and wave generators on programmes like Tomorrow's World and Futurama.
A few examples exist in the world today, more than half a century later, but if they were practical, our coastline and everyone else's would be surrounded by them.
Which maybe takes us back to the starting point of the thread. I believe the context was US farms or other private land that have a stream or very small river running through them, where it might be possible to generate enough power to run the farm household. I don't believe that a DIY context covered contributions to the national power grid.
From the article you linked: Compared to contemporary scientific calculators, some functions were slow to execute, and others had limited accuracy or gave the wrong answer, but the cost of the Sinclair was a fraction of the cost of competing calculators.
Unfortunately I got caught out by the "wrong answer" bug with mine. I was dividing one number by the difference between two similar numbers and the lack of proper floating point meant that there was an error of around 10% which I didn't notice until it was too late.
John
I mentioned that I had seen such schemes on Youtube mainly from the USA, built on there own land with streams running through them and most, if any, don't work that well.
I remember seeing a series of videos (Youtube or one of the lesser TV channels) on fitting an overshot water wheel to provide electricity to to an off grid property. The series went from design, installation, commissioning and performance testing.
The wheel was larger than shown in the article that started this thread (from memory a diameter of around 3m). This was for a system here the "head" of water referenced to the bottom clearance of the wheel was around 4m.
On first installation, and on first turning of the wheel, it underperformed the designed aim by a very long way.
There were many problems controlling the water flow and the speed of the wheel. It was a balancing act between the amount of water, the position of where the water fell into the buckets and the speed of the wheel. Not enough water and the wheel wouldn't turn - too much water and the speed of the wheel "ran away" which was not too good for rest of the connected equipment, nor the mechanical interconnects. The buckets had to be completely empty of water before continuing their upward journey on the return side of the wheel.
There is probably a very good reason why waterwheels of the past are gigantic and not constructed of lighter weight materials :)
They spent a considerable amount of time fettling (sometimes in a fairly major way) before they got close to the design aim.
Possibly the design shown in the original article is not very practical for DIY and why some of the other river generators mentioned in this thread don't use waterwheels.
Anyone remember that TV series with "Dick" Strawbridge living the green life and suggesting that we could all do it. He had a stream and a DIY generator powered by water - just enough to light a low wattage light bulb or to trickle charge a battery. And, how we could all run our ICE vehicles from used chip shop oil - but only if the number of fish and chip shops outnumbered to cars on the road :)
The Romans built a waterwheel with buckets as a pump from the Thames in London (unknown anywhere else in the Roman world, so suggesting Britain was actually worth serious investment).
A team of 21st century experts were unable to replicate it in their first attempt.
Water management needs real science and engineering. Not the sort that tells you things need to be pink to sell better.
Is an eye-saw something similar to an Eeyore?
-- "Anyone who believes that the laws of physics are mere social conventions is invited to try transgressing those conventions from the windows of my apartment. (I live on the twenty-first floor.) "
Alan Sokal
The point is that it does make a meaningful difference. It takes more time and concentration, and that is more valuable than a penny's worth of electricity.
Far better to stop drinking tea altogether.
If you want to make a *real* difference, you start with the big things first. Like ditchiing all renewable energy in favour of nuclear power.
But you don't want to make a*real* difference, do you? You want to feel morally smug.
We did, and discarded the idea years ago,
Why keep bringing it up?
Maybe some Gaviscom would help
Tomorrows world was more about reporting technology at the "Peak of inflated expectations" on the hype cycle :)
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