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[dysonhooverman] 06/10/2010 08:25

Couldn't agree more re transmission costs - only the more local the power source, the less it matters. On the other hand, Tesla's theory of wireless power transmission over distance looked like a fireworks display in practice- and I wouldn't have wanted to see him cut down to size- especially as he wasn't a voracious greedy so and so like Eddison.

I've never been a fan of the cold, blue light that comes from 'efficient' bulbs- although it's astounding the way they can twist and turn fluorescents these days - and the 'cool whites' aren't that bad. The comparable warm glow from an LED is a joy.

Anyhow, voltage is voltage and current is current, step up, step down- but what we really want is a local low power solution for our low power devices. Not least because it exposes the real high power users who should be justifying their excessive use rather than obtaining a bulk discount from the power generating companies.

[freddie ferret] 05/10/2010 15:10

Some 240v items are highly efficient too. Low energy bulbs work really well if you put 260v into them, transmission losses through cables are a lot less. 12v requires 20x the cross sectional area of cable compared with 240v, for transmission.

[dysonhooverman] 05/10/2010 09:18

Hmmm. It's all a bit 'mega' for me- and I've no desire to get involved with the surface temperature of the Sun, even though it's a fascinating goal for someone of that mind.

I'm much more of the 'small is beautiful'- mind and would like to see local solutions to the kind of power demands that we have. Most large scale power consumption is by big industry, which is why we have some large power plants built right by large factories (or at least used to)- domestic consumption was/ is most definitely secondary. The 'power of the sun' may well be useful in this capacity.

I'm more interested int he way that low voltage technology and efficiency savings in domestic environments are opening the door to lower power solutions which were previously considered unsuitable. Phones, led lights, laptops, LCD tvs- all seem to be converging around a 12v standard, down from the 240v - I believe the current draw is substantially less too.

Although China doesn't like it, industry is where the efficiencies need to be made. I think this was one of the reasons that the West used to export a great deal of manufacturing to the East- saves having to deal with environmental issues. Quite cynical really, by no means less pressing simply because we're nimbys. Can we use the few cards we hold in this fast fading consumer led society in order to set a good example on high standards of responsible consumption?

If that doesn't work we can get back to death rays. :-)

[freddie ferret] 04/10/2010 13:28

Post script, it might be interesting to try the reduction of Uranim oxide with charcoal, carbide formation might be a problem however uranium might distill off at these temperatures.

[freddie ferret] 04/10/2010 13:20

I have considerd this matter in the past. At the focal point place a lens that bends the light paralell (forgotten how you spell that) again. Of course there will be some divergence.
With an ordinary magnifying glass it is possible to attain high temperatures. For example mix lead oxide with charcoal, heat with an ordinary blow lamp little happens, focus the spot from a magnifying glass on this mixture and reduction occurs surprisingly easily.
Taking a one or two metre silverd satellite dish then at its focal point place a clean unscratched lens it may be possible to concentrate down to a sub quarter inch spot. With this, expect to be easily able, to attain 2000c. Interesting experiments become possible, reduction of rust with charcoal to iron, formation of calcium carbide from limestone and charcoal, limelight experiments (formation of calcium oxide), formation of phosphorous or its oxide from phosphate (bones, superphosphate fertiliser and such like) with charcoal and silica, again boron and silicon should be accessible as should potassium by reduction of potassium carbonate with charcoal. Again it should be possible to melt many ceramics and produce fibres, Sialon for instance. As much as anything it is that it is a clean heat source that is significant however for many reactions the absence of air would be desirable.
It would not however IMHO be possible to straighten this out into a paralell beam with a lens due to lens heating (possibly filtering out the wave lengths that are absorbed by the glass with a sheet of glass early on might get over this problem). I believe the maximum temperature that can be attained with solar concentrators is 6000c at which point one is at the surface temperature of the sun, and emmission from the target will be as great as the emmission from the suns surface. This apparently is a limiting constraint.
The other question is whether it is possible to "transport" these high solar energies down optical fibres or a light tube.
I know with a large frisson lens (the type that is flat but has a scratched surface) it is possible to get the surfsce of a plank of wood up to a temperature that it immediately chars producing inflammable gas, the charing increases the adsorbtivity of the surface and a temperature is produced such as to ignite the inflammable gas with explosion.

Have fun.

[dysonhooverman] 04/10/2010 09:01

'Solar reflectors are a death ray in disguise.'- Should work well for the marketing boys at BNFL!

Either that or we could get that strange breed of gun loving Star Wars freak interested in solar energy.

Every cloud......is potentially a hazardous nuclear incident.

[freddie ferret] 02/10/2010 14:25

I would take issue with your "solar reflectors are also nice to look at". Small ones can be handled with safty, when the focal point is more than around a foot away from the thing it becomes a death ray, and is not nice to look at. Handle with care, carry with care your trousers and there within are at risk.

[dysonhooverman] 02/10/2010 13:30

I like windmills. I was enjoying watching an enormous (20Mw?) one one spin around quite slowly in a fair wind this morning- very relaxing.

Solar reflectors are also nice to look at.

[freddie ferret] 01/10/2010 16:07

Thanks. This will remain primarily a "read the header" thread as the header gets longer so fewer will get to the posts!

[dysonhooverman] 01/10/2010 10:55

Oh I'm not complaining- nothing better than creating threads imo. Good luck!

[freddie ferret] 30/9/2010 14:25

Only 4. Take a look at energyi, he's produced a few more than me.

[dysonhooverman] 30/9/2010 09:18

You're 'going viral' with your threads these days FF. What gives?

[freddie ferret] 29/9/2010 17:40

New ferret thread.

[freddie ferret] 28/9/2010 16:23

casino444.

Suggest you try one of the other QXL threads or TRAD thread (the company changed it's name to Tradus before being brought out by the South African company Naspers).

[casino444] 28/9/2010 03:33

came on here to find out about qxl online auction company ?? ' shock horror ' stephen hawkins has taken this board over !! hope your looking forward on my report regarding the inner exploration of a table tennis ball as my new found results once released could change the world forever !!

[freddie ferret] 22/9/2010 16:50

david77.
A simple trough rather than a dished parabola should work without rotation since the sun follows a straight line across the sky. It would be a good idea to reset the angle every couple of weeks as the year progresses. You lay this on the ground rather than having it upright.
I have considered this for improving the output from photovoltaics (some form of cooling would be needed, alternatively for hot water just run a blacked (use a candle) copper tube down the focus line.
The main problem with this set up is how to make it cheap and structurally rigid. The best I have come up with is two thin sheets if glass fibre laminate bent round male and female formers with a polyurethane foaming compound poured in between. The section would give some torsional stiffness, say separate the glass laminates with 3 inches of foam.
Improvement to the hot water set up could be made by surrounding the blacked copper pipe with a glass tube with a gap between this would be evacuated to reduce conduction. The tube would be best made from a glass that reflects in the IR.

[david77] 21/9/2010 19:44

"The next topic for this thread is the parabolic solar reflector.
Take an old satellite dish glue to it pieces of silver foil and there you have your solar reflector. ..."

A long, long time ago (40 years, maybe), I proposed a parabolic trough 6 ft tall that would be set due east at 6am and rotates slowly to due west at 6pm. There would be a 4 inch tube down the centre of the trough to circulate a fluid to a hot water cylinder. There would need to be some control of the flow - maybe a thermostat at the top of the heating tube - turn a pump on when the water is hot for enough time to change the tube content. As long as the connecting pipes are well insulated then this could be a practical way to get hot water.

The trough would be rotated back overnight - or maybe continue round if that was easier.

I wrote to the Royal Observatory and they advised that it ought to work with a graph showing the error during the day. I reckon that if the heat pick-up tube is big enough (which is why I suggested 4 inches) then the inaccuracy would not matter much.

This was gonna make my fortune but I never actually built one!

[hectorp] 21/9/2010 19:02

I'll not be going for a turbine, freddie, I might go for CFU's fuel cell device.

[hectorp] 21/9/2010 19:01

Dyson- isn't life an incredible thing, and even if an accident? We are maybe one of countless trillions of Universes, if string theory is right, never mind billions of galaxies, where life happens to exist like ours does (no doubt there are billions of other ways 'life' could erupt in other places.

Even so it is quite amazing to be one of the 'alive ' one of the living, one of the one million trillionth of existence that is somehow sentient. Then I feel how utterly alone we animals on Earth happen to be. Then I start to wonder, is this by pure accident? And I will never be able to answer that.

[freddie ferret] 16/9/2010 01:48

I'll have to get on with finishing the header shortly.