Solar Events

Is THIS the future of solar energy instead ? Chug-chug-chug ?

Early in 2008 a US company will be offering you a solar energy system which goes “chug-chug-chug” in your backyard. A cross between a baby steam engine and a satellite dish.

Sounds crazy, doesn’t it, but it claims an electricity-producing efficiency of 24%, just better than the best silicon photovoltaics, and more or less on their theoretical limit.

And allegedly more environmentally friendly, both in the materials used, and in the manufacturing techniques.

This is so fascinating, I have prepared a detailed article telling you exactly how it works and why it looks so good.

Read it here

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Ozone layer depletion reaches all time high

This fall, when the ozone layer depletion peaked for the year, the area of the “hole” or depletion zone equalled the highest ever measured, in September 2000.

Our anti-pollution measures have not yet initiated a downward trend, and indeed the situation is not predicted to start improving until around 2020, even assuming we all do our best.

It may return to normal (ie pre-1979 levels) around 2070, but until then ozone depletion is something we have to live with and maybe more of us will have to take sun protection seriously, and look at sun protection clothing and cremes. SPF looks like three letters we will all get to know only too well.

ozone-hole-tiny.gifmore….

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Remember Invisibility Cloaking and the Robot rope climbers ?

Remember those two previous posts ?

Well now I have tracked down the definitive movie on each. No more guesswork - straight from the horses mouth.

First the NASA-sponsored light-powered robot rope climbers at the competition in New Mexico this weekend. Practicing to climb a 30,000km cable up into space ? Well here is a video showing one of them making it to the top of the 200 ft test climb:

Robot climber video is here (page down a bit)

But what about the invisibility cloaking ?

Now that I see the video it looks totally overhyped to me. Any wave can pass round obstructions which are not substantially bigger than the wavelength, and pass through multiple gaps smaller than the wavelength. Now I see the pictures of the wavefronts and the multiple large concentric gapped rings round the small object to be cloaked, the acclaimed reduction in waveform disturbance seems to verge on the insignificant to me. I see that the diameter of the object is in fact about one wavelength, and therefore we would expect the radiation to pass round it fairly successfully with no cloak, and this is exactly what we see.

invisibility cloak
Do you see a dramatic difference between the waves leaving on the right ? Is the fancy cloaker at the top doing much, or do the waves make it round fairly well without ? I think they do. To do the same with visible light the object would have to be a sub-microscopic speck. The microwave illumination here is 8.5GHz, with a wavelength of 3.5cms, close to the object diameter.

Furthermore, all this bragging about fancy metamaterials is highly misleading. Reading the paper itself tells us that this allegedly amazing shield was in fact fabricated by a local printed circuit company, using bogstandard etched copper technology. To make it very small would indeed require metamaterials (read “is currently impossible”), but this isn’t small, and doesn’t use them. Though the publicity does everything possible to imply that amazing new metamaterials are actually used and part of the “breakthrough”

The more I read, the more appalled I am at this shameless hype.

Remember, the sky is blue precisely because the red and yellow light has long enough waves to pass round all the tiny particles, but the blue light finds them too big to get round, and gets deflected out of the straight line from the sun, and bounced into our eyes. This “particle” is just small enough for its waves to more or less make it round, and the “cloak” helps a tiny bit. That’s all. Ugh !
Have a look at the detailed video on the overhyped cloaking device

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Should you be in Egypt tomorrow ?

Tomorrow, 22nd October, is the day when at dawn a shaft of sunlight strikes deep into the Sun Temple of Rameses ll at Abu Simbel in Egypt. This is one of the two days per year when the sunlight passes between the four great seated 65ft statues of Rameses as sun God, and illuminates the four images in the sanctuary. Reputedly the Temple was oriented so that this would occur on the Pharaoh’s birthday, but if so it is now a day late. This is the angular error introduced when this temple was bodily moved and reconstructed on higher ground to save it from flooding by the Aswan dam in the 1960’s.

At the magic moment the temple is apparently crowded with expectant significance-hunters. From my personal experience even running the usual compulsory gauntlet of importunate tat-purveyors cannot quite sully the grandeur of Abu Simbel.

Though you do have to keep calm when you enter the 727 aircraft for the flight and see the torn and hanging roof lining and damaged locker hinges. You try not to imagine the maintenance levels on the bits which matter but are out of sight.

Interestingly, another much more extensive Sun Temple of Rameses ll was earlier this year newly-discovered beneath a Cairo suburb, and is currently being excavated, within the limits of practicality.

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First step to cloaking a starship

Researchers have successfully “cloaked” a half-inch copper cylinder. This is genuine invisibility, with the light being actually bent around the object so that it is simply “missed out” of the view, with what is beyond it clearly visible. The implications if this can be extended are obvious and of huge military significance. The techniques may also be usable for focussing and concentrating radiation, as in solar energy applications.

But there are still huge problems to overcome. The technigue works by covering the surface of the object with a sort of conducting pattern like an antenna array, which must be tuned to the precise wavelength to be bent. The demo therefore uses a single wavelength, which is a longer wavelength than visible light (microwave), because this allows a coarser “antenna pattern” which is easier to fabricate.

Huge problems remain to cloak a full sized vehicle at a wide range of wavelengths including the visible light we see with. It would need an “antenna pattern” all over, so fine that it would need to be built with nano-technology, and getting it multiwavelength is hard to imagine. If it needed to work from every direction, the vehicle would probably have to be spherical. More starship than cadillac.

Read more

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Protected from Alzheimer’s by your wicked, wicked past ?

Nothing to do with the Sun or anything Solar, but I just couldn’t resist this oh so reassuring snippet:

“Evidence suggests that people who regularly smoked marijuana in the 1960s and 1970s rarely develop Alzheimer’s disease, said Wenk, ………”

Oh dear, no justice, eh ? Or is there ?

Here is the link to the full article in Cosmos

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Solar Powered Catamaran to tackle Atlantic

A team of Swiss solar power enthusiasts in Basel has launched its bid to cross the Atlantic Ocean to New York using a specially designed catamaran.
The organisers say the purpose of the exclusively solar-powered trip is to raise public awareness of environmentally friendly forms of energy consumption.

Link

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Google Solar Power Plans

Google plans a solar-powered electricity system at its Silicon Valley headquarters that will rank as the largest U.S. solar-powered corporate office complex, the company said on Wednesday.

The Web search leader said it is set to begin building a rooftop solar-powered generation system at its Mountain View, California, headquarters capable of generating 1.6 megawatts of electricity, or enough to power 1,000 California homes.

Reuters

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Sun Powered Robots try Indian Rope Trick

On 21st - 22nd October, New Mexico will host the second of NASA’s annual Beam Power Challenge competitions, for a $150,000 prize.

The idea is to progress the technology required for “Space Elevators”, a projected method for achieving space travel by starting off taking an elevator up a rope into the sky. Yes, really ! The top end is held up not by a structure, but by the centrifugal (or “outward-flinging”) force of the earth’s rotation.

Since it is impractical to climb so far carrying fuel, the competing robot climbers (with a 200m rope to climb) must be powered by light.

The current favorite is from British Columbia and claims that it will win using sunlight alone, avoiding the complexity of lasers shone from below. Link

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Californian Company gets within 2% of Silicon max efficiency

SunPower, which makes solar cells and panels, has announced at Solar Power 2006 that it has boosted the efficiency of its solar panels from 20% to 23%. They state that this brings it within 2% of the theoretical limit of monocrystalline silicon cell efficiency, which is about 25 percent.

News Item here

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