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.
quote: By your own words, you suggested the amount of land was enough to provide "a fat percentage" of the nation's power. If something between 1 and 2% is "fat" in your book, then I concur.
quote: I identified several, the two largest being a) the amount of land is only enough to provide a tiny fraction of our power needs, and b) Highway siting would be far more expensive than using undeveloped land somewhere, despite the space above the highway being "free", due to the need for elevated supports.
quote: If you think that's still a viable alternative just from those two factors alone, I don't know that continuing the discussion will be fruitful.
quote: This is a little silly. A tunnel 100' long is quite dark in the middle.
quote: Take a look at any large wall-less structure, for instance a large horse arena. There's one near my house, that is roughly 100' x 300'...and lit from above, even during daylight shows