Solar Cells Get Boost 108
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."
Re:Electrons are not "produced" by solar cells (Score:5, Informative)
Second, the description does not say that the electrons are being created at all. The dictionary definition [reference.com] of the word produce indicates, in the first entry, that produce means "To bring forth; yield", which is good enough, but skim the third entry and its example, "To bring forth; exhibit: reached into a pocket and produced a packet of matches". I think the first is more accurate, but the second indicates just how far the definition of produce does not imply creation.
=Brian
Re:Not quite there yet (Score:4, Informative)
Nanocrystal films would typically be grown by chemical vapour deposition (chemical constituents react as a gas at low pressure, seed crystals grow in-flight, and grow further after being deposited).
The problem is that it's very hard to produce crystals that small (they tend to keep growing after being deposited, because the source materials are still present - this is how you normally do CVD, actually). You also have difficulty producing a narrow range of sizes, because that requires that the growing environment of each crystal be identical.
Still an interesting discovery, though. The fabrication problems will eventually be solved.
What's especially interesting is looking at what happens when you fabricate oher types of semiconductor microstructure or nanostructure by more conventional techniques. As the size of a feature shrinks, you can no longer pretend it's near-infinite in extent when figuring out what the energy levels are within the crystal. This has already been used to alter the properties of silicon (fabricating LEDs in silicon, which normally emits very poorly due to having an indirect bandgap). Quantum wells, wires, and dots are an extreme case of this (dimensions comparable to a few electron wavelengths). When lithographic feature sizes start approaching this range, lots of new devices will be possible in mass-market chips that are only possible now if you have an e-beam lithography setup handy.
Re:Will this work with other materials? (Score:4, Informative)
I'm on shaky ground here, but I think the answer is likely "no". The idea behind this technique is that you can use surplus energy from a photon absorption event to release a second electron, while the point of split bandgap cells is that you can absorb light with less surplus energy (more deposited in a useful manner into the first electron).
Ask a semiconductor physicist to get the correct answer
Re:Storage Storage Storage (Score:3, Informative)
Solar cells are actually very good for this purpose, as electricity is produced directly, as opposed to having to be converted from another energy form (like heat, in the case of a coal or oil fired power plant).
You can produce hydrogen from fossil fuels fairly efficiently by "reforming", though. What this essentially does is strip hydrogen off of hydrogen-rich hydrocarbons, giving you carbon-rich hydrocarbons and hydrogen gas. The hydrocarbons can still be burned in a suitably tuned power plant, and the hydrogen gas can be used in fuel cells.
If you're using a fuel cell for storage, as opposed to generation, though, you'd just keep the water produced when you feed hydrogen and oxygen in it, and break that down to get your source gases back out (though you'd probably dump the oxygen instead of storing it, since you can pull more out of the atmosphere easily).
The real problem with hydrogen as a storage medium is difficulty storing it at any reasonable density (cheaply - we can't afford palladium storage cells, and they're horribly heavy anyways).
Or it might be a way to bridge the energy gap in ethanol (either for combustion or in fuel cells), where currently you have to burn an amount of fossil fuels to produce the ethanol, some say more than you get out.
You'll always use more feedstock than you get ethanol out, so I assume you're talking about power spent converting the feedstock to ethanol.
I actually think that alcohol makes a better storage medium than hydrogen, because it's easy to store, can be burned in internal combustion engines, and can be reformed (see above) and used fairly efficiently as a fuel for fuel cells. The only catch is that it's annoying to synthesize. Methane can be synthesized relatively efficiently, and you can partially burn it to produce methanol, but that's still not very efficient.
Probably efficient enough for many applications, though (you don't care much if your notebook takes twice as much power to charge as you get stored in the battery, even if you do care for things like your car, and even more so for a city's "week of bad weather" power reserve).
At the moment I'm more worried about being in thrall to a rather unstable part of the world for oil than I am about the atmosphere's CO2 load, but it is also pretty scary.
I'm somewhat puzzled by this situation, as it appears to be one of choice as opposed to necessity. Here in Canada, we could get all the oil we'd need for quite some time from Alberta, and there are enough offshore natural gas reserves to satisfy that demand as well. Last I heard, the gas reserves off the US's coasts were *huge*. We'd see a price increase switching to local supplies (maybe even a hefty one), but nothing that would bring western society crashing down.
After those ran out, a century or two down the road, Canada has enough uranium to last us indefinitely, and the political will to use it for power. The US would need a creative political gimmick to be able to use it now, but a century is more than enough time for public opinion to change. Even without a breakthrough in power production, I don't see any serious problems.
Re:Storage Storage Storage (Score:3, Informative)
For those curious on how a solar cell works.. (Score:2, Informative)
Re:If I had a nickel... (Score:2, Informative)
It seems the parent site doesn't like linking to the actual search results only the heading, Que Sera Sera
Available at Canadian Tire (Score:2, Informative)
Go here [canadiantire.ca] and enter SOLAR as the keyword. (enter postal code: K1J 1J8)
I found this:
45W Cottage Solar Panel Kit
Special Offer
Product# 11-1588-0
View larger image
Price $499.99
Availability
In Store Online
Qty.
*
Harness the sun's power to run small appliances (both AC and DC) such as TVs, lights, computers and to recharge your 12V DC batteries in your RV, boat or cottage. The 45-watt Cottage Solar Panel Kit is completely weather-resistant and works under all light conditions.
* Ideal for charging deep-cycle batteries and running small appliances
* ICP solar panels are completely weatherproof and can withstand 1/2" hailstones, up to 80C (176F) heat and can operate under 3" of snow (on sunny days)
* Works under all light conditions
* Kit includes three 15W solar panels
* Can run both AC and DC appliances
* Comes complete with 7A charge controller, ultra-bright fluorescent light and 140W DC to AC power inverter
* Includes 12V socket with 10' (3m) of wire, PVC frame, mounting hardware and battery clamps
* Manufacturer's limited 5-year warranty on power output
* Model No. 10058