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Research team is looking to make solar panels more efficient and give LEDs color changing capability

A pair of researchers at Arizona State University has announced a new advancement in making nanowires that could one day lead to significantly more efficient solar panels and LED lighting that is color changeable. The engineers who made the advance are Cun-Zheng Ning and Alian Pan.

The pair are working on ways to improve the quaternary alloy semiconductor nanowire raw materials. The nanowires the pair work with are nanometers in diameter and tens of microns in length. They are made from four elements, typically by alloying two or more compound semiconductors.

The researchers say that the band gap is the most important thing that controls how solar panels absorb sunlight and what color light LEDs produce. The more available band gaps for solar panels, the more of the spectrum of light panels will be able to absorb. With LEDs, more band gaps mean more colors of light can be produced. 

The big hurdle for the researchers is that naturally occurring and manmade semiconductors today only have a specific band gap. The only way to widen the band gap available to the semiconductor is to compound two or more semiconductors. The trick to accomplishing the alloy of semiconductors is that they two have to have a lattice with similar inter-atomic spaces to match and be grown together.

Ning said, "This is why we cannot grow alloys of arbitrary compositions to achieve arbitrary band gaps. This lack of available band gaps is one of reasons current solar cell efficiency is low, and why we do not have LED lighting colors that can be adjusted for various situations."

So far, the team has been able to create a zinc sulfide and cadmium selenide alloy to produce a quaternary semiconductor – this is the first time that a quaternary semiconductor has been produced in the form of a nanowire or nanoparticle. The team is now studying the application and use of the quaternary alloy materials for making solar cells and has developed a lateral multi-cell design panel.



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RE: Promises promises
By Keeir on 3/22/2010 7:21:28 PM , Rating: 2
Here... let me add some numbers.

The US currently produces/uses ~
4 x 10 ^15 Wh a year.

Solar Insolation
http://rredc.nrel.gov/solar/old_data/nsrdb/redbook...
I assumed Horizontal Flat Plate.

Across the US, we are looking at an Average of ~ 4500 Wh/m2/day

A really good solar panel is 20% efficient.

So that leaves use with

4 x 10 ^ 15 Wh / 4500 wh /356 days * 1 m2 / .2 efficieny = 12.45 x 10 ^ 9 m2 or about 4,800 square miles

Since you have decide that 100' wide or so is adequate, we would need approx 250,000 miles of roadway to provide 100% of the power needs, at generation source. This of course leaves off the ~10% due to current lines losses, which I can't imagine would get any better with the above system. In fact, assuming 10% line losses and near magical 20% solar panels, covering the entire ~47,000 mile could provide ~16%. I guess we could describe that as fat.

Oh, and for your information, the structure we are talking about would be a continous strip of solar panels with no breaks. It would need to be mounted a minimum of 33' in the air if you didn't want to light the area underneath and even higher in some situations. A larger problem would be the wind breaks. Since a 100' wide structure would likely catch the wind, we would need to design in ways to lighten the wind load... which would let direct sunlight down below... which is in turn would likely require the additional lighting as Human eyes can't really adjust that fast.

I doubt covering the entire US highway system would result in more than 10% of our power needs... and I doubt it could be accomplished much less than the original cost of the system (~425 Billion dollars).

(Oh by the way, nothing can really help the system if a tractor trailor full of gasoline smashes into a post. A large section will be destroyed... there are reasons why that land is not readily availble.)


"Young lady, in this house we obey the laws of thermodynamics!" -- Homer Simpson











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