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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 amirite on 3/22/2010 2:24:49 PM , Rating: 2
For large densely populated cities, solar would not be feasible. Nuclear would be ideal for NYC. For the suburbs that don't have multi-family homes, it would work for them.

Storage is not really an issue. Most solar installations don't use storage. They are hooked up to the grid and continualy send power to the grid when not powering the home during the day. There is normaly enough excess during the day to offset what is used at night. The electric company buys or gives you credit for the energy you send to them. During the day, that electricity costs more due to high demand. At night, when you will need to draw power fromt he grid, it costs you much less due to less demand. You can still pay for electricity for a small installation, to nothing or get paid for a larger installation depending also on the power company's policy.


RE: Promises promises
By porkpie on 3/22/2010 2:32:43 PM , Rating: 2
" At night, when you will need to draw power fromt he grid, it costs you much less due to less demand."

Err, but if solar became popular, nighttime demand would be far larger than daytime demand, reversing the situation. In fact, night time demand is already larger than day, in the winter in many locations.

But there's an even bigger problem. If you're assuming dirty coal and gas power for your baseline demand, then peak shaving saves you money. But if you assume clean nuclear power, then over 98% of the cost is capital costs, rather than fuel.

What does that mean? It means shutting down your nuclear plants during the day (when the sun is shining) doesn't save you any money. It means your "free" solar power isn't saving you a penny. You're still having to build and operate those plants for peak nighttime (and cloudy day) demand.


RE: Promises promises
By amirite on 3/22/2010 3:42:50 PM , Rating: 2
I would have to disagree that night time demand is higher than day. Look at your electric bill. You get charged more during the day because it is considered peak time. My power company states that its peak times during the summer are from 1pm -7pm and during winter they are from 7am - 12pm. You can use more power at your home during off peak times than on peak times as many do. I am not sure how they calculate peak times, but I am assuming that large businesses play a huge roll.

http://www.duke-energy.com/pdfs/NCScheduleRT.pdf

The electric company wants you to use more power at night to balance their distribution as much as possible. I guess I'm looking at this at a consumer's point of view. I doubt they would have to idle nuclear power plants during the day unless everyone has a large solar panel array installed. This is not feasible for everyone. I would say maybe less than half (probably closer to 25%) the homes in the US can have an even balance of what they put into the grid and what they draw from it.

In the end, solar power is very inefficient and can only act as a supplement to most people's needs. It is an option to reduce our dependency on oil and coal.


RE: Promises promises
By SPOOFE on 3/22/2010 4:24:44 PM , Rating: 2
quote:
I would have to disagree that night time demand is higher than day.

He didn't say it IS higher, he said it would be, IF solar was a significant percent of our power generation.


RE: Promises promises
By amirite on 3/22/2010 4:29:26 PM , Rating: 2
"In fact, night time demand is already larger than day, in the winter in many locations"

Peak hours during the winter for my electric company is 7am - 12pm.


RE: Promises promises
By porkpie on 3/22/2010 5:57:53 PM , Rating: 2
Your electric company is in NC. Locations that currently have higher peak energy demand at night are in northern (and thus very cold) locations. Also remember that northerly climes tend to get a much higher percentage of their total energy needs from oil and gas heating, rather than electric heat pumps (which are less efficient as ambient temperature drops).

But that's a side issue. The real point is that any serious usage of solar power would reverse the situation, causing night time demand to be greater than day.

And yes, while that would still reduce coal and oil usage, it can't make a very large dent in it. The only thing that can is nuclear...and if we have to build nuclear plants anyway, its far cheaper and more sensible to run them during the day, as well as the night.

Conclusion? Even if we solve the cost problems, solar is really only viable for a peak-shaving approach, rather than substantially filling our energy needs.


"There is a single light of science, and to brighten it anywhere is to brighten it everywhere." -- Isaac Asimov











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