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Nanotubes May Improve Solar Energy Harvesting

Zonk posted more than 7 years ago | from the just-put-in-a-direct-nuclear-tap dept.

Power 93

eldavojohn writes "Scientists are hoping that the 'coaxial cable' style nanotube they developed will resolve energy issues that come with converting sunlight to energy. The plants currently have us beat in this department but research is discovering new ways to eliminate inefficiencies in transferring photons to energy. Traditional methods involve exciting electrons to the point of jumping to a higher state which leaves 'holes.' Unfortunately, these electrons and holes remain in the same regions and therefore tend to recombine. The new nanotubes hope to route these excited electrons off in the same way a coaxial cable allows a return route for electrons. End result is fewer electrons settling back into their holes once they are elevated out of them yielding a higher return in energy."

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That's some hardcore nanotubes there... (0)

Anonymous Coward | more than 7 years ago | (#18856311)

oh yeah, and some nappy nanotubes also, you bet!

Concentrating existing power also important (3, Interesting)

pzs (857406) | more than 7 years ago | (#18856425)

If you believe these guys:

http://www.trec-uk.org.uk/index.shtml [trec-uk.org.uk]

All we need is to concentrate the power we already have. Apparently, less than 1% of the world's desert would be enough for all the world's power.

I'm not sure whether I believe this, but I certainly think we should be filling those otherwise useless deserts that cover a large portion of the globe with energy harvesting technology. Maybe the Arab countries, fairly replete with this kind of energy rich terrain, could convert from oil economy to exporting something better for the planet?

Peter

Re:Concentrating existing power also important (2, Insightful)

Rukie (930506) | more than 7 years ago | (#18856503)

Nanotubes have been around for some time now, but these look like they are structured differently and with different materials. Although, I do believe the problem isn't so much as "efficiency" as it is "price." Once solar energy becomes competitive/better than fossil fuels, I think we will see a huge increase in hydrogen storage (for batteries) and solar energy, along with wind mills for n ighttime power and cloudy days.

In fact, they even have clear glass windows that college solar energy as well (might have been on slashdot?) We definitely have the ability, were just willing to spend the resources.

Re:Concentrating existing power also important (4, Insightful)

Pxtl (151020) | more than 7 years ago | (#18856775)

That was my reaction too. Energy-innefficient solar collectors aren't really a huge concern so much as the dollar-per-watt efficiency. I mean really, the reason people aren't solar-panelling their rooftops isn't that they don't have enough roof, but that they don't have enough coin.

This depends (4, Insightful)

mdsolar (1045926) | more than 7 years ago | (#18857191)

At the 15% efficiency of silicon, quite a lot of roofs have enough area to cover what a building uses. Orientiation comes into this as well as the height of the building. Taller buildings have less roof per unit floor space which tends to track electicity use. At 7% efficiency, the number of roofs that can cover 100% of the building's use goes down a lot because we're at the edge of feasability at 15%. So, cheaper, lower efficiency solar panels, can turn out to work better where surface area is not at a cost premium. This tends to be in rural areas rather than where most houses are.

Commercial buildings can often benefit from lower cost, low efficiency panels because they are gaining from using space that they otherwise would not and they are more bottom line driven and can't cover they're full electic use under either senario.
--
Go Solar for what you already pay anyway: http://mdsolar.blogspot.com/2007/01/slashdot-users -selling-solar.html [blogspot.com]

Re:This depends (1)

div_2n (525075) | more than 7 years ago | (#18857605)

With a few exceptions, it's economics--period.

If [value of expected energy output over lifetime of panels] > [cost of panels] * [interest rate on lease/loan] then people/companies are more likely to buy.

The closer the number of years it takes to recover the cost of the investment gets to one year, the greater the likelihood of a buy goes up.

If the government would make the cost of buying solar cells a 100% tax credit with no limit, I bet you would see a huge increase in installations.

Re:This depends (1)

mdsolar (1045926) | more than 7 years ago | (#18858137)

There is some wiggle room on the fringe but I think you are mainly right. People will pay extra soemtimes fro green tags; in Texas this has turned out to be cheaper than regular power recently. And, there is more to your calculation than just the interest on the loan, you also want to look at what you might make from investing elsewhere if you were not paying on a loan.

I'm thinking in terms of silicon being at grid parity (as it already is in Hawaii) and some other technology being below grid parity but unable to do the whole job without using some yard space. Silicon insulates you from price hikes from the grid while the other gives you a choice of partial insulation or loss of area. In terms of convinience, you might go with the silicon or you might go with a partial reduction of your grid use. It will be pretty cool to have a choice, but for now only silicon is being offered at a grid competitive rate. This is because it is well characterized and lasts for a known duration so that lenders are comfortable with the collateral situation.

I suspect also that if coal, oil, gas and nuclear susbidies were ended, you'd see pretty rapid adoption as well.

Re:This depends (1)

QuickFox (311231) | more than 7 years ago | (#18858995)

if coal, oil, gas and nuclear susbidies were ended,
What? Are those things subsidized in the US? Amazing! No wonder your CO2 emissions per capita are through the roof! [grida.no]

Here in Sweden it's the other way round, renewable energy is subsidized (as a temporary measure to help the industry get started) and gasoline is taxed.

Re:This depends (1)

mdsolar (1045926) | more than 7 years ago | (#18859613)

I think nuclear power is subsidized in Sweden and Sweden is relying on it to meet Kyoto. Though we're losing our touch I think, if you want to send some of that gas tax to us to cover our defense spending, we might not act so stuck up this time: http://en.wikipedia.org/wiki/Swedish_response_to_H urricane_Katrina [wikipedia.org] . Glad you were so quick to offer help back then.

Re:This depends (3, Insightful)

QuickFox (311231) | more than 7 years ago | (#18860481)

Glad you were so quick to offer help back then.
I appreciate that you noticed.

if you want to send some of that gas tax to us to cover our defense spending,
Sorry, that's impossible, because Sweden disagrees with your methods. I don't know how Sweden's official motivation is worded, but among the general public the mainstream opinion is that the Iraq war is fueling terrorism rather than curbing it, and we don't want to fuel terrorism. This is not some after-the-fact observation, it has been the firm mainstream opinion since well before the Iraq war started.

OTOH we have Swedish troops in Afghanistan.

Speaking of our relationship, I do feel that we and the US, in fact the entire Europe and the US, need to be much stronger allies than we are, in spite of the differences that we have. We need to make every effort co-operate in those areas where we agree. We have lots of common goals, and there are lots of areas where we agree.

In fact, even when we disagree we could often co-operate. For instance, we might play good-cop/bad-cop roles when dealing with recalcitrant nations. That's far more constructive than building rivalries.

I think we could achieve lots of great things together if we could just co-operate better.

Re:This depends (1)

mdsolar (1045926) | more than 7 years ago | (#18861209)

I think that you are correct that cooperation on a broader scale would be good. I mentioned the gas tax because much of or defense spending supports "lower" oil prices. I've been wondering how soon we'll be asking for a fixed exchange rate with the euro in exchange for more controled spending on our part.

Re:This depends (1)

QuickFox (311231) | more than 7 years ago | (#18862281)

I mentioned the gas tax because much of or defense spending supports "lower" oil prices.
I'm not sure if I understand you correctly. No, we don't want lower gas prices, on the contrary. The gas tax is there to keep the gas prices artificially high. That's so people are discouraged from spewing more carbon dioxide than necessary.

This is why I'm astonished by gas subsidies, paying people to pollute more.

If a Swedish politician advocated war for the sake of some economic advantage, like keeping some prices low, there would be an extreme uproar and he would be totally fried. In future elections he wouldn't stand a chance. That kind of thinking is totally foreign here.

But as I said I'm not sure if I understood you correctly.

in exchange for more controled spending on our part.
Won't you have to rein in your spending regardless?

But reining in your military spending may turn out to be difficult. Your military industry has grown monstrously large and powerful. Power tends to corrupt. And of course like any industry it's always thirsty for more profit and more power.

Re:This depends (1)

mdsolar (1045926) | more than 7 years ago | (#18864469)

Yours is a refreshing view point. The way we say it is that the free flow of oil is in the nation's strategic interest. So, we spend a lot on making sure that it flows freely.

Ultimately we need the price of oil to fall below the cost of extraction but this will only come about by reducing demand to well below supply. Your method of taxing to reduce demand can be a part of this but I fear that doing this at the level that would cause productive wells to be shut down would be impoverishing. I suspect that rationing is the only equitable form of self restraint that will get us that far along the road to where we need to be.

Though there are some programs here to assist people with paying for home heating oil or gas if their income is low, most of our subsidies go to suppliers and producers rather than to buyers. Not all of the subsidies are in the form of money. Sometimes is is in the form of protection from liability or extreamly low royalites for using public land. And, for oil there is a blood subsidy as well.

We seem to be willing to spend as long as people are willing to lend so yes, there will be a time when continuing to borrow will be too expensive since people will no longer be willing to lend. I think we are begining to see some signs of this now as oil is starting to be traded in euros rather than dollars. This is the reason I am wondering about when we might seek a fixed exchange rate.

President Eisenhower made just the point you do. From my experience, however, from the inside, people feel that they are doing a very good thing protecting our country so that the coruption is easily overlooked. I don't know when spreading peace will become a priority again. There seems to be a slight turn happening here: http://securityandclimate.cna.org/report/ [cna.org] .

Re:This depends (1)

QuickFox (311231) | more than 7 years ago | (#18871875)

The way we say it is that the free flow of oil is in the nation's strategic interest. So, we spend a lot on making sure that it flows freely.

[...]

From my experience, however, from the inside, people feel that they are doing a very good thing protecting our country so that the coruption is easily overlooked. I don't know when spreading peace will become a priority again.
Very interesting. Several US behaviors that have seemed incomprehensible become more understandable when considering the parts I quoted.

Been nice talking to you.

Re:This depends (1)

mdsolar (1045926) | more than 7 years ago | (#18872297)

Same here. You might want to look at http://stepitup2007.org/ [stepitup2007.org] to see how our conception of stratigic interest might be changing in a way that is more aligned with your way of thinking.

Re:This depends (0)

Anonymous Coward | more than 7 years ago | (#18863071)

"What? Are those things subsidized in the US? Amazing!"

Yes, we are, thank you.

Oh, right, subsidies. Not really. There are benefits and tax breaks given to the energy corps, but the use is also taxed heavily in return which gets dumped back into the oil/coal coffers.

"No wonder your CO2 emissions per capita are through the roof!"

I've always viewed CO2 emissions per capita as sort of odd--we also have an economy that is through the roof as well, low unemployment, for awhile a reduction in crime (slight uptick but not as bad as the reactionaries on the newsfront would have you believe), a growing population still, etc. We are also a geographically spread out country too. If you add the accumulated business (look at trade deficits) we outsource and account for CO2 emissions from imported goods, it could be considered higher.

But it's easy to have a reduced energy policy with government directives (i.e. France go nuclear) and a stagnant economy and population. We exchange those problems with CO2. iow, you can choose to point the finger at, say, CO2 emissions, but by doing so and keeping it fair, you also have to consider your overall policy as well, such as increased crime, a slack economy, etc.

For example, if you look at simply economic growth due to population growth, usage of housing materials and commercial development, road laying, etc., look at how much and how concrete is produced and the energy that goes into that. It's really a totally different playing field, one that the EU clearly understand because they're trying to slow it (quite frankly, because you can't compete and haven't for some time; your economic development is because you had a better energy policy in the long term, but that will turn as we catch up as needed--be very careful what you ask for because I know in 20 years, the EU will be backing away from their proposals because then it won't suit them anymore).

LOL there would be no tax revenue left (1)

unassimilatible (225662) | more than 7 years ago | (#18866855)

My friend's solar install was $25K. A tax credit? I hope you mean tax deduction, because most people don't even pay $25K in taxes a year.

But yes, I do think that some tax break should exist. California has a large subsidy [californiaconnected.org] but it isn't unlimited (first come, first serve).

Re:Concentrating existing power also important (0)

Anonymous Coward | more than 7 years ago | (#18858585)

Next time you buy out on solar panels like I did, write it down within your taxes. You'll get the entire cost you spent on the solar panels back within your tax return.

I spent a few dozen thousand on solar panels and was refunded, for using renewable energy. Well in the US at least.

(Don't believe me? Then too bad. Just try it.)

Re:Concentrating existing power also important (1)

Urza9814 (883915) | more than 7 years ago | (#18862751)

From what I hear it pays for itself in 8 years and you can usually (in the US at least) get a government grant to cover half of that. Only problem is it's not normal yet. It takes a long time for people to start doing things differently.

Re:Concentrating existing power also important (1)

drix (4602) | more than 7 years ago | (#18863887)

There are 300 million Americans, and probably 80% of them live in single family dwellings. Figure 3 persons/household. That's 80 million roofs. It costs about $20,000 for a residential PV installation. So $1.6 trillion.

Current estimates say we will have spent $1 trillion invading Iraq when it's all said and done. We spend an additional $500 billion every year on off^H^H^Hdefense. I'm not some hippy saying we should abolish the military, but it definitely makes you think. We really could afford to do something as outlandish as blanket the entire country with solar panels, while still having enough $$ left over to pay for all the other things we like. It's crazy. We're that loaded. It's just a question of priorities.

God, this is so true (1)

unassimilatible (225662) | more than 7 years ago | (#18866831)

The price is unconscionable, even with California's partial subsidy. My friend paid like $25K for his system (before subsidy). Why haven't solar cell prices dropped like other technology has? If a DVD player can go from $1K to $100 in a few years, why isn't solar getting cheaper?

I'd adopt solar in a second and put a panel everywhere if I didn't have to pay my left nut for a kilowatt. Hopefully this new tech will be cheap some day.

Re:Concentrating existing power also important (2, Interesting)

TheMeuge (645043) | more than 7 years ago | (#18856511)

The costs of this endeavor would be enormous, in terms of the need to obtain the various materials needed for this, assemble them, then manufacture and set up both the finished equipment, as well as the infrastructure for distributing this energy. Couple that with the fact that transmitting electricity is a very lossy process over distance, and you wind up with a very difficult task indeed.

Rather than try to concentrate solar energy production, I think we're much better off distributing it. If every roof in the U.S. was covered with solar panels, we'd have a large part of the solution already figured out. Plus, we'd be largely immune to isolated grid problems, resulting in less power outages.

Re:Concentrating existing power also important (1)

stonecypher (118140) | more than 7 years ago | (#18928689)

in terms of the need to obtain the various materials needed for this
Yeah, because carbon, oxygen and argon are rare, whereas you can find copper and gallium pretty much anywhere you look.

assemble them, then manufacture
The difference is enormous!

set up ... the infrastructure for distributing this energy
Indeed, because we don't already have a framework for transmitting electricity. If only solar didn't make a different kind of electricity...

Couple that with the fact that transmitting electricity is a very lossy process over distance
Yeah, the distance from your house to the next house is tremendous when compared with the brief jaunt to the nuclear reactor in the middle of the state.

Amusingly, every single point you made is in solar's favor.

If every roof in the U.S. was covered with solar panels, we'd have a large part of the solution already figured out.
Solar panels aren't energy cost breakeven unless you're in a sunny area like Arizona. Solar panels in a place like Seattle are virtually worthless. As soon as you see someone suggesting solar at a national scale, ignorant of indigent weather, insolation and vertical population density, you know you're talking to someone without a clue.

Or, did you just not know that 85% of America doesn't have a house, but instead an apartment, condo or that ilk? Turns out that the vast bulk of the population is in cities, where the price of housing becomes prohibitive because of the number of people there. Roofing is a limited commodity.

You're like one of those people who fixates on the Farnsworth Fusor as the key to salvation. Maybe you should try looking at the economics yourself, instead of believing what someone told you. You'll find they're nowhere near as simple as they sound.

Germany's finding that out the hard way right now.

Centralization is the wrong way to go (2, Insightful)

StefanJ (88986) | more than 7 years ago | (#18856551)

The infrastructure required to transfer electricity from centralized facilities, and the losses suffered along the way, don't make this very appealing.

A panel on your roof may not be as efficient, but it's yours. In an sunny place, you may be able to sell power to the local grid during the daytime peak hours. (You might buy it back at night, but the rates are lower then.)

There will always be a need for a grid, and some big power plants, but making as much new capacity decentralized and as local as possible means addressing political, social, and security externalities that have been ignored thus far.

Re:Centralization is the wrong way to go (4, Insightful)

Rei (128717) | more than 7 years ago | (#18857117)

The problem is that insolation varies greatly around the world. I would very much love to get solar panels for my house, but up here in Iowa, we get half as much sun as the desert southwest. Yet, we're positively awash in solar energy compared to, say, Washington and Alaska, which have half what we get here.

Halving the amount of energy doesn't just double payback time when you consider cost amortization. It increases it many more times, often making it so that it will never pay back.

Now, up here, self-generated wind power is an economically viable alternative to grid power... *if you don't live in a city*. I've crunched the numbers. Inside city limits, your towers are more expensive (you can't use guyed towers -- not enough space) and your heights are limited too close to the ground. On the other hand, it's perfectly reasonable for farms (and power companies) to invest in. One great thing about the big tower wind turbines is that you lose almost no ground area; you can farm nearly up to their base.

Re:Centralization is the wrong way to go (1)

misleb (129952) | more than 7 years ago | (#18860323)

Just FYI, Washington isn't that much farther north than Iowa and eastern Washington gets plenty of sunshine.

Re:Centralization is the wrong way to go (1)

Rei (128717) | more than 7 years ago | (#18860603)

It's not just how far north you are; weather patterns play as much of a role as latitude. Looking at an insolation map, where I am in Iowa shows up as ~3.5 kWh/m^2/day. The Seattle area shows up as 2 kWh/m^2.day. No part of Washington shows up as better than ~2.8 or so. Meanwhile, the desert southwest approaches 6 kWh/m^2/day.

To get an idea of how important weather patterns are to insolation, the Congo gets significantly less than near the southern tip of Africa. Here in Iowa, we get almost as much as certain parts of the Congo. The same holds true with the Amazon; much of it gets minimally more insolation than we get here in Iowa. Get into the Andes, though, and the numbers jump way up. Some things can be just weird. For example, the Kamchatka Peninsula (the part of Siberia that sticks southward in the direction of Japan) gets as much insolation as most of Greece and the northern coast of Turkey.

Re:Centralization is the wrong way to go (1)

Rei (128717) | more than 7 years ago | (#18860859)

Sorry -- seattle is "less than" 2 kWh/m^2, not equal to 2. Looking at another map, it looks ot be something like 1.6, 1.7, something like that. this is for flat plate, fixed. For heliostat, I found a table of cities. Some numbers:

Chicago: 3.14(!)
Seattle: 3.57
Fairbanks: 3.99
Phoenix: 6.53
Inyokem (CA): 7.66

However, the lows matter more in terms of unit selection:

Chicago: 1.47(!)
Seattle: 1.60
Fairbanks: 2.12
Phoenix: 5.78
Inyokem (CA): 6.87

Notice the difference.

Re:Centralization is the wrong way to go (1)

misleb (129952) | more than 7 years ago | (#18862885)

It's not just how far north you are; weather patterns play as much of a role as latitude. Looking at an insolation map, where I am in Iowa shows up as ~3.5 kWh/m^2/day. The Seattle area shows up as 2 kWh/m^2.day. No part of Washington shows up as better than ~2.8 or so. Meanwhile, the desert southwest approaches 6 kWh/m^2/day.


That is suprising because eastern/central Washington is more or less a desert.. high desert. It's certainly nothing at all like the Seattle area. I wonder what causes the insolation.

-matthew

Re:Centralization is the wrong way to go (1)

mdsolar (1045926) | more than 7 years ago | (#18857377)

It's not just the power lines, transportation infrastructure takes less of a hit with solar as well. The amount of mass that has to be transported is about 200 times less for solar than for coal. http://mdsolar.blogspot.com/2007/01/saving-not-bor rowing.html#comment-4164085150001376667 [blogspot.com] .

Potent But Not Important (1)

EgoWumpus (638704) | more than 7 years ago | (#18857053)

In ideal conditions, it seems reasonable that a little bit of desert would yield an enormous amount of power. But conditions are rarely ideal. Your power arrays out there in the desert need to be maintained by someone - do you also build desert communities? You have to pipe the power from the desert out to where it's going to be used. Efficient? A 3% loss over a thousand kilometers means that sending power from Albuquerque, NM to Washington, DC would result in nearly 10% energy loss - assuming an absolutely straight route, which it would by no means be. Maine would be much worse off. Also, heat exchange is a notoriously lossy activity; the article suggests using gas when sunlight isn't available, in no way reducing the energy you need for shipping fuel there.

Further, there is a societal implication to concentrating power production. Power plants have to be protected, maintained and upgraded. Failure to do so can affect large swathes of people; why not focus on creating more spread out, more maintainable plants? The fact of the matter is that land we don't use abounds; desert isn't the only one. And deserts do serve important ecological functions; just because they're not generally inhabited by humans does not mean we don't benefit from them being there. This sort of one-sided approach to the matter smacks of Special Interest, and I don't know that it should be taken as The Solution.

Re:Potent But Not Important (1)

mdsolar (1045926) | more than 7 years ago | (#18857725)

I agree with you about the maintenance issue and I'd also be concerned about grit blown in the wind, but I'm not so sure you are correct about the issues with power transmission over long distances. The Pacific Intertie does pretty well bringing cheap hydro to LA, and I think that if we took a longer view, we might invest in lower resistance lines (by making them thicker). Here is a senario where you'd do that anyway: http://mdsolar.blogspot.com/2007/03/coast-to-coast .html [blogspot.com] . While you're reading, checkout the grounding arrangements for the Pacific Intertie. They are pretty amazing http://en.wikipedia.org/wiki/Pacific_Intertie [wikipedia.org] .
--
Spread Solar Smoothly: http://mdsolar.blogspot.com/2007/01/slashdot-users -selling-solar.html [blogspot.com]

Surface area, not cross-section, is important. (1)

Kadin2048 (468275) | more than 7 years ago | (#18859629)

The high-voltage DC systems may be different, but at least with AC, making the conductors thicker doesn't really help that much past a certain point.

I think it's actually a surface-area dependency rather than a cross-section one; that's why you see big high-tension power lines with multiple sets of small conductors rather than one really big one. Multiple small conductors give you more surface area and less weight (and cost in copper). This is due to the skin effect.

However you can't just pack multiple conductors next to each other, because there are other effects which will cancel out the gains if you put the individual conductors too close ... so you need to space them out at least a few diameters away from each other (assumedly this depends on the voltage in the wires).

I'm sure they're all basically solved engineering problems; it's basically an economics question how many conductors you hang and what kind of loss you find acceptable. I can only think that there are probably a lot of inefficiencies in the power grid today that were the result of decisions made back decades ago when power was cheaper in certain places.

Re:Surface area, not cross-section, is important. (1)

mdsolar (1045926) | more than 7 years ago | (#18860841)

I suspect your right that conductor geometery is pretty key. The cross-sectional area formula is a pretty gross approximation. Some HVDC underground cable seems to look a little like co-ax, perhaps because capacitance with the ground is an issue. I do think that going to higher voltage is possible with a (perhaps hollow) fatter conductor since the corona discharge is really about a gradient.

Re:Concentrating existing power also important (1)

PSU '11 (1092933) | more than 7 years ago | (#18864967)

at first it may seem logical to use the vast amount of land available to harvest the suns energy. However the problem is that these areas are not close to the major areas around the world that use the most energy. Also efficiency becomes a problem. Getting energy from a desert in the middle of nowhere creates the problem of transporting the energy to the places that need it. Not all of the energy would be transported from point A to point B because no system is 100% efficient. It also would make it necessary to build lots of power lines which in turn takes away land that could have been used in a more productive matter. This being said, I believe that solar power is an important source of energy that must be taken into consideration. I believe that a good way to increase the use of solar energy would be to increase incentives for having solar panels on personal property such as on the roof of your house. This system has been a huge success in Germany. Germany is on track to reach their goal of getting 1/3 of their energy from solar energy in 2015 or so compared to the united states 1%. I also think that with present technology we need to find a way to harness more power. right now the best solar cells only work at 15 % efficiency. These are a few ideas that I believe have the most merit up to this point. I will not take credit for these ideas. I am just expressing my opinion on them.

Efficient solar energy....2 billion years old (0)

Anonymous Coward | more than 7 years ago | (#18897287)

growing and burning plants can be considered a form of solar energy, and solar cells still have not exceeded the efficiency that is produced by simply burning plant matter.(including manufacturing cost of cells) Carbon? ha! The carbon produced by burning plants comes from the carbon the plants extracted from the air...it's carbon neutral.

Wrong headline (5, Funny)

rumblin'rabbit (711865) | more than 7 years ago | (#18856437)

The proper headline should be "global warming solved for 3rd time this week".

Re:Wrong headline (4, Interesting)

grungebox (578982) | more than 7 years ago | (#18856549)

Actually, the headling IS wrong, rumblin'rabbit. The use of the term "nanotubes" is incorrect. These are nanowires (that's what the field, and the article itself, call them). These aren't "tubes" in that they aren't hollow; the difference is not at all trivial.

Re:Wrong headline (2, Funny)

PPH (736903) | more than 7 years ago | (#18856817)

So does this mean that the Internet might actually be a bunch of wires as well, instead of a bunch of tubes?


Please say it ain't so!

Re:Wrong headline (1)

Saikik (1018772) | more than 7 years ago | (#18860733)

Wait? What? How long will it take for an internet to reach me now?

Re:Wrong headline (0)

Anonymous Coward | more than 7 years ago | (#18856829)

Yeah, but these nanowires, can they be used to get your mail off the truck and onto the internet?

Re:Wrong headline (1)

zotz (3951) | more than 7 years ago | (#18860679)

Man! And here I was hoping to build out a nano-internet in a bread box!

all the best,

drew

Re:Wrong headline (4, Insightful)

Rei (128717) | more than 7 years ago | (#18856651)

Unfortunately, "works in a lab" and "mass producable at a commercially viable price in the remotely near future" are two very different things. The former only rarely becomes the latter in fields like solar power. Thankfully, there are so many advancements that a few always tend to make it and push the industry forward.

Re:Wrong headline (1)

Alsee (515537) | more than 7 years ago | (#18857955)

"works in a lab" and "mass producable at a commercially viable price in the remotely near future" are two very different things.

More like theoretical computer simulation, "works in a lab", and "mass producable at a commercially viable price in the remotely near future" are three very different things. Unless I'm mistaken, the article sounds like a pure theoretical computer analysis of a neat mutilayer nanostructure they haven't been able to built yet at all, not even in a lab.

Not just vaporware, it's hypothetical vaporware.

-

a series of tubes? (1, Funny)

Anonymous Coward | more than 7 years ago | (#18856473)

nanotubes - what the nanonet is made of!

a series of nanotubes? (1)

ricree (969643) | more than 7 years ago | (#18856559)

So that's why they keep getting clogged so easily.

Re:a series of tubes? (1)

FMota91 (1050752) | more than 7 years ago | (#18857409)

It's not a big nanotruck.

Re:a series of tubes? (1)

Debug0x2a (1015001) | more than 7 years ago | (#18866113)

They need to be able to support enormous amounts of material... enormous amounts of material. Otherwise any power I send wont be received till the weekend.

Only 5 Years Away (3, Insightful)

Nom du Keyboard (633989) | more than 7 years ago | (#18856595)

And I'm sure this is only 5 years away from commercial use, just like every other such announcement.

Re:Only 5 Years Away (1)

musakko (739094) | more than 7 years ago | (#18865829)

If I ever get my hands on a time machine, I won't travel 100 years into the future, I'll just go 5 years. THAT'S where all the technology is!

nanotube antenna design (3, Interesting)

G4from128k (686170) | more than 7 years ago | (#18856611)

This really has the potential for providing a third way (versus semiconductor and photochemical systems) for converting light into electricity (for power or signals). Light is just extremely high frequency radio waves. With conductive nanotubes, one could create dipole antenna arrays for submicron wavelengths.

Re:nanotube antenna design (0)

Anonymous Coward | more than 7 years ago | (#18856753)

What do you do with the incoming 500THz signal?

What do you do with the incoming 500THz signal (2, Interesting)

G4from128k (686170) | more than 7 years ago | (#18857115)

1. Rectify it for power
2. Phase shift it to create a beam-former
3. The compare it to a local or global reference signal to extract phase information

Re:What do you do with the incoming 500THz signal (1)

revjd909 (749913) | more than 7 years ago | (#18858295)

Could you comment on this a bit further?

Re:What do you do with the incoming 500THz signal (1)

kurzweilfreak (829276) | more than 7 years ago | (#18865373)

Don't forget to calibrate the forward deflector array to scan for possible Cherenkov radiation resulting from tachyon emissions!

Re:nanotube antenna design (1)

Mr. Underbridge (666784) | more than 7 years ago | (#18860163)

This really has the potential for providing a third way (versus semiconductor and photochemical systems) for converting light into electricity (for power or signals). Light is just extremely high frequency radio waves. With conductive nanotubes, one could create dipole antenna arrays for submicron wavelengths.

Not really - this is still just a doped semiconductor system, jsut a different architecture (nanowire vs. crystalline). Really, they're not focussing on the problem of light capture - they're focussing on the problem of charge carrier separation, which is a problem inherent to all schemes of photoelectric generation. The usual way is to operate the cells at extremely high V bias, which tends to rip the holes and electrons apart, but that's not always optimal. These guys are simply trying to figure out a good way of getting the carriers apart once they're created by whatever means.

Hmm (2, Funny)

tttonyyy (726776) | more than 7 years ago | (#18856675)

"Hope", "may" and "unfortunately" all in one article.

It's like reading about Duke Nukem Forever.

Uh oh... (1)

baudilus (665036) | more than 7 years ago | (#18856705)

Ted Stevens is gearing up for a new diatribe...

I can see it now... countries that contribute the most to global warming will have to pay more for access to the technology... Solar Net Neutrality 4Eva!

So (1)

UPZ (947916) | more than 7 years ago | (#18856711)

Oh yeah? Well, Chuck Norris can create a thicker GnP layer with a well-placed roundhouse kick. :D

If ... (1)

BlueTrin (683373) | more than 7 years ago | (#18856747)

If you put a series of nanotubes ...

Do you get a Nanonet ?

Re:If ... (1)

smaddox (928261) | more than 7 years ago | (#18858963)

You know, people keep making fun of Ted Stevens for his series of tubes comment. Given, he is completely tech-illiterate, but series of tubes isn't that far off when you consider how much of the backbone is fiber-optic cable. Fiber-optic cable pretty much is a tube - for light. It has a core through which the substance (light in this case) travels, and a shell which holds the substance in. Sounds like a tube to me.

If you're going to make fun of Ted Stevens speech - make fun of how he called an email an "internet" multiple times.

Re:If ... (1)

BlueTrin (683373) | more than 7 years ago | (#18863479)

Yeah see what you mean, I thought about it while typing and thought that it wasn't that bad of an image, but, still, he became kind of a legend with this quote : )

Just the small matter of tdynamics and economics.. (3, Insightful)

Ancient_Hacker (751168) | more than 7 years ago | (#18856771)

Expecting nanotubes to act as "maxwell's Demons" is well on the way to Polyanna-Thinking. Fine for used-car ads, political spots, and grant proposals. But a bit far-fetched for rational discussion.

Plus on the economic issue, most nano-things cost kilobucks per square centimeter. Even if the cost came down by a factor of 10,000, it would still be uneconomical at ThunderDome prices.

Zeno's power cell (1, Insightful)

jfengel (409917) | more than 7 years ago | (#18856801)

I'm planning to tag every solar-power story "vaporware" until I see something that doesn't depend on additional breakthroughs before it comes to market. It seems like we get 50% of the way to something useful with every posting but never actually get anywhere.

OK, I have the middle steps (5, Funny)

gmcraff (61718) | more than 7 years ago | (#18856849)

1) Develop high efficiency, long life solar cells
2) Figure out how to process lunar resources with robotic factories to make said cells
3) Plate the entire far size of the moon
4) Transmit the energy back to earth with a few lunar horizon transmitting stations with atmosphere and cloud penetrating lasers/masers/whatever
5) PROFIT
6) Reserve fossil fuels for high-energy-density required transportation needs, not short distance ground transport or general power production
7) PROFIT plus ENVIRONMENTAL BENEFITS
8) Colonize the moon with the residual infrastructure from the power grid
9) PROFIT plus ENVIRONMENTAL BENEFITS plus OFF-PLANET HUMAN SUSTAINABILITY
10) Use short lunar gravity well to build interplanetary transport, colonize Mars
11) PROFIT plus ENVIRONMENTAL BENEFITS plus FULLY REDUNDANT HUMAN SUSTAINABILITY
12) ???
13) A fully armed and operational battlestation
 

Re:OK, I have the middle steps (1)

AgentSmith (69695) | more than 7 years ago | (#18857057)

Pave the earth. Chrome the moon!

Re:OK, I have the middle steps (1)

Gilmoure (18428) | more than 7 years ago | (#18860017)

Chrome the moon

Now I'm going to have to find a dem/3d map of the moon, obtain Bryce or some such similar dumbed down 3D app and go and render a chrome moon. Damn you Teh Interweb! Damn you to hell!

In other news (2, Funny)

Timesprout (579035) | more than 7 years ago | (#18856857)

The US declares war on shrubs. 'This energy theft can no longer be tolerated and we will strike back in order to bring freedom to sunlight' announced Dick Cheney standing beside a rather nervous looking President Bush.

Re:In other news (0)

Anonymous Coward | more than 7 years ago | (#18860703)

Just in case anyone is wondering, Bush = Shrub (loosely) in spanish

Bush = Arbusto = Shrub

Times have changed (2, Interesting)

solar_blitz (1088029) | more than 7 years ago | (#18856871)

It seems like two or three years ago nobody cared about research into solar energy, and now every other day an article pops onto slashdot about new ways of harnessing the sun's energy. Must be the Al Gore Effect. I'm not saying it is a bad thing, though.

As for this particular subject, it makes sense to research beings that already use this type of resource on their own. It would be interesting to see if we can even harvest chlorophyll so we could implant colonies of it onto solar cells. It'd be like the old potato and light bulb science project kids do.

Re:Times have changed (1)

Rei (128717) | more than 7 years ago | (#18857303)

It's only the first stage of plant light capture that's efficient. The entire cycle, from sunlight to sugar, is about 35% -- good, but not that incredible. However, plant cells need energy to live, so you need to look at how efficiently they store energy in a form that is useful to us. The most overall efficient plant at producing human-recoverable energy is sugarcane, at 8-11%. Most crops are a few percent efficient, while most native plants are a small fraction of one percent. Now, if we could harvest energy from cellulose, that would give an additional efficiency gain (especially notable in non-crop plants, but still major for crop plants), but we still wouldn't approach that 35% number. Plants need to keep themselves alive, staying alive consumes energy, and these facts simply aren't going to change.

No, times haven't changed, just economics (1)

postbigbang (761081) | more than 7 years ago | (#18857321)

I've been using photo cells for decades, I'm nearly off-grid now. The reason you see more in the media is because of the economics of using coal, oil, natural gas (non-renewable), and nuclear (renewable but with hideous waste byproducts) fuels: rough economics, enough to cause wars and craziness instead of rational fuel generation plans.

By rational, I mean the ability to prevent new housing and industry without having renewable fueling system in place and ready to fuel the needs of the new development. Worse, we don't recycle very well (planetwide) and spend exotic amounts of GNP just farting around-- rather than plan journeys, trips, or share fuel loads by carpooling. So, the prices go up, but people are loathe to change their consuming habits. They just pay the price. Now the price is high, and the media has latched on to the fact that there are alternatives. Hell, there've been alternatives for decades that are inexpensive (long term asset return) and quite viable.

Plants have us beat? (4, Insightful)

mdsolar (1045926) | more than 7 years ago | (#18856905)

The link to the situation with plants shows how plants work at the quantum level but just a bit of thought shows that we are more efficient than (rooted) plants at collecting solar power. A small area, say all of the roof tops in the country, can cover all of our electric use and more using 15% efficient silicon solar panels. On the other hand, all of the arable land in the US is not enough to cover our transportation needs through biofuels. Plants may be efficient for their own purposes, but in terms of energy harvesting we do better on our own http://mdsolar.blogspot.com/2007/02/photosynthesis .html [blogspot.com] . And, as the article points out, we are on the way to doing even better.
--
Sprout Silicon Leaves: http://mdsolar.blogspot.com/2007/01/slashdot-users -selling-solar.html [blogspot.com]

Re:Plants have us beat? (0)

Anonymous Coward | more than 7 years ago | (#18860843)

The 15% figure doesn't count the production cost of the solar cells against their efficiency; the total energy cost to produce, install, and maintain the panels needs to be subtracted from their total energy production. The plants take into account recovery from wind damage and many other contingencies and also build themselves in place with solar energy. Where PV panels need a stiff and costly frame to keep them from being blown around, plants use much less material by making flexible stems and compound leaves. In the end, it will be hard to truly beat millions of years of evolution without substantial energy subsidies from fossil fuel (plants).

shitty solar panels (2, Interesting)

jcgf (688310) | more than 7 years ago | (#18857105)

I hope this leads to better consumer solar technology. I was looking at those 12V solar panels at Canadian Tire the other day. The ones that produce about half a watt and have a cigarette lighter plug on a wire. Talk about junk. What am I going to do with that? It would not even run my 2m handheld on the low power setting let alone charge your car battery (which is what they were being advertised as doing). I suppose they didn't say how long it would take to charge it so they weren't lying exactly...

Re:shitty solar panels (1)

Ogive17 (691899) | more than 7 years ago | (#18858021)

I doubt those chargers are meant to give you a full charge, most likely they were designed to give you a jump start.

If your alternator is dead, charging the battery really doesn't do much good over the long term.

Re:shitty solar panels (3, Informative)

mdsolar (1045926) | more than 7 years ago | (#18858281)

Definitely not a jump start! That takes the highest current draw of all. These things are good if you leave a vehicle parked for a long time. They keep the battery topped off.

surface area (0)

Anonymous Coward | more than 7 years ago | (#18857127)

Stand the tubes on end and you increase the available surface area for sunlight to interact with. I think this was mentioned in an earlier slashdot but I'm too lazy to search for it.

Nanowires (not nanotubes) (2, Informative)

pmosh (1092661) | more than 7 years ago | (#18857301)

This could really be a fascinating technology -- although technically it's "nanowires" and not nanotubes. As an experimentalist, I really hope that when it comes to actually growing these things it is feasible; it also might be difficult to make contact to the nanowires after you've made them to collect the electricity. Nonetheless, I think that nanostructured devices (while expensive at the moment) may be the solution to making high efficiency photovoltaics possible. Sometimes it's surprisingly easy to grow nanowires/nanorods just by flowing gas over a material and a substrate in a tube furnace, so cost may turn out to be fairly low. Patterning these by photolithography (how computer chips are made) would definitely be too expensive, along with molecular beam epitaxy or atomic layer deposition. My hope is that a simple inexpensive thermal process would work to grow these or other photovoltaic nanorods. The reason that so many stories are posted about solar energy is that it's our one scaleable renewable energy that could eventually displace a significant fraction of the fossil fuel energy that we currently use and spew CO2 into the air. For a really interesting lecture about world energy and alternatives check out Dr. Nate Lewis' presentation at http://nsl.caltech.edu/energy.html [caltech.edu] (the video is probably the best). Who knows, one of these breakthroughs if it works well could change a lot for us.

Re:Nanowires (not nanotubes) (1)

Goldsmith (561202) | more than 7 years ago | (#18860699)

I'm glad someone else noticed that they didn't actually "make" anything. There are lots of theoretical nanostructures out there, but only so many ways of making them, and even fewer ways of making electrical contact.

A different problem with photovoltaics (2, Interesting)

necro81 (917438) | more than 7 years ago | (#18857501)

There is, as the article mentions, the problem of electron-hole recombination.

Another difficulty with semiconductor photovoltaics, not addressed by this new development, is that the semiconductors make poor use of energetic photons. There are limitations, derivable from solid-state physics, that limit the maximum light-->electricity efficiency of photovoltaics. A little background:

Depending on the chemistry, the bandgap energy of the semiconductor corresponds to a photon of a certain minimum energy. A photon with less energy (longer wavelength) than the bandgap energy will not have enough umph to create an electron-hole pair, while a photon with energy >= the bandgap energy can create an electron-hole pair. In silicon-based semiconductors, the bandgap energy corresponds to a photon in the very near infrared, almost a visible red.

The electrical energy you get from the electron-hole pair comes from those charges being separated by the electrical potential at the semiconductor junction. Unfortunately, it doesn't matter if the electron-hole pair was created by a red photon, a blue photon, or ultraviolet. You'll get the same amount of electrical energy out of the solar cell from any of these photons.

However, the red, blue, and UV photons have significantly different energies due to their different wavelengths. The UV photon, though more energetic, will produce the same electrical energy output as the less energetic red photon. If you were to shine only red light on the solar cell, it would make quite efficient use of them. Unfortunately, red is only one component of the solar spectrum. The solar cell makes poor use of the higher-energy photons in the solar spectrum, and thus has a seemingly poor light-->electricity conversion efficiency.

If everything else went perfectly, the solid state physics at work limit the maximum efficiency for silicon solar cells to about 25%. Good cells mass-produced today [sunpowercorp.com] top out at about 21% [sunpowercorp.com] . One can create multiple junction cells to capture different segments of the spectrum at higher efficiency. Consider this chart [wikipedia.org] of maximum efficiency under lab conditions.

Re:A different problem with photovoltaics (2, Interesting)

pmosh (1092661) | more than 7 years ago | (#18858311)

True, traditional photovoltaics get the same energy out of every color photon as long as it has enough energy to clear the bandgap. The rest of that energy is lost to vibrations in the semiconductor as heat instead of electrical energy. BUT - here's another area where nanostructured devices might help, because it takes much longer for an energetic electron to emit those vibrations in a structure on the quantum scale (i.e., nanometer scale). These energetic electrons can sometimes be collected at their high energy or kick up another electron across the bandgap through Auger recombination. This has been demonstrated a few times for nanometer-sized semiconductor particles called quantum dots and is called "hot electron capture" or "multiple exciton generation" in the scientific literature.


What I'm trying to say is that nanorod structures have the potential of increasing the maximum efficiency because they might be able to collect those higher energy photons and pull out more electricity than a conventional photovoltaic cell.

Hopefully this will be practical someday...the multijunction cells are just way too expensive how they are currently made.

Heating (1, Interesting)

BlueParrot (965239) | more than 7 years ago | (#18858225)

Here we go again. Let me sum arise it. -The cheapest, most efficient AND easiest way to collect solar energy is as heat. -If this was cheap enough, people would use solar heating all over the place. -Solar heating remains of limited popularity -If solar heating is not competitive with other energy sources, despite a dramatically lower price than photovoltaics, and despite better efficiencies than are even theoretically possible with photovoltaics, then photovoltaics, which will inevitably be less efficient, more expensive, and less durable, is not going to be competitive. EVER. The ONLY way solar energy can become competitive is for the price of other forms of energy generation to sky-rocket. Whereas this may be true for fossil fuels, nuclear, wind, hydro, geothermal and biomass are not set to become more expensive any time soon. On the contrary, developments in reactor technology is set to make nuclear costs comparable to gas ( and that includes waste disposal and decommissioning ). Wind power is seeing improvements as we speak. Geothermal is not set to get any more expensive, and biomass is already competitive with fossil fuels. Solar simply doesn't stand a chance. Even if solar cell's were as cost efficient as solar heat collectors, they would still lose out compared to the alternatives. Solar cells are good for remote applications where you can't stick a power plant, like in an orbiting satellite. For pretty much everything else they are rubbish.

Re:Heating (0)

Anonymous Coward | more than 7 years ago | (#18860793)

> Here we go again. Let me sum arise it.
> -The cheapest, most efficient AND easiest way to collect solar energy is as heat.

This is correct. However, the cheapest way to mine carbon is in the form coal.
Yet, people don`t dangle lumps of coal round their necks, they prefer diamonds ;-)

The problem is that the times and place where heat is plentiful from solar power does not coincide with the time and place where such heat is greatly appeciated.

Where this does coincide, thermal solar power is a great success, e.g. for heating pools or greenhouses.

But you will have a hard time selling a solar heating installation to a home owner in Anchorage.

Heat (or, more exactly, heat potential differencies) are the least useful form of energy, because they are hard to convert into other forms of energy, but all other forms of energy can be easily converted to heat.

Furthermore, with solar energy, it is relatively easy to generate small heat potential differences (have the sun shine on a black slab), but very hard to generate large differences (use lenses or mirrors that need to be cleaned and moved, works only in clear skies).

Unfortunately, Carnot's cycle dictates that converting small heat potential differences to other forms of energy is terribly inefficient.

Therefore, 15 percent efficiency for solar electricity generation does not sound too bad after all - if the collectors can be produced fairly cheaply.

Currently, solar panels are an add-on to existing roofs. Once they are produced in sufficient quantities and standardized sizes, they should not be too much more expensive than a conventional roof with excellent insulation properties. Also, you could integrate warm-water-generation into the panels.

Re:Heating (0)

Anonymous Coward | more than 7 years ago | (#18863465)

This depends on the PV. There are models and ideas out there that break the single crystal model limit of ~40%, and hit numbers close to ~60%.

Re:Heating (1)

dbIII (701233) | more than 7 years ago | (#18864877)

I live in Australia and I see a lot of solar panels. Navigation beacons have them. Ten year old mobile phone repeater towers have them. Electronic signs parked by the side of the road with text on them telling you about roadworks or whatever have them. Give it a few years and low end laptops will have them since all it takes is for the power requirements to drop - remember pocket calculators used to plug into the wall too. As to the other comments - yes I agree that nuclear genorated electicity that is worth using for civilian purposes may be around the corner if future prototypes perform as expected - but the article was about a solar advancement that has real, practical appications but should never be assumed to be the universal cure for everything by people that want to argue against it.

worth the price? (0)

Anonymous Coward | more than 7 years ago | (#18858619)

i don't think this is a great solution... if we need to use nanotechnologies, then there are better ideas. I read somewhere of a project that used nanotecs to generate power by movement. they claimed that 1 hectar of those micro-motors could produce 162 mw... sorry, can't find the link.
anyway...
solar panels (speaking for Italy here) are quite expensive if you compare them to their life and how much they give in therm of power.
here in Italy, you can sell energy at 0.1 euros/kwatt, and now you can add the o.3 euros/watt the government gives you on environmental-friendly structures. given that, you pay your solar panel in approximately 5 years. that would have been 15 years without government moneys. a solar panel lives 20 years.
well, i think we can see the problem. too expensive.
nanotechnologies have better usage in project like the one i illustrated.

Nanotubes May Improve Internet Experience (1)

roman_mir (125474) | more than 7 years ago | (#18858851)

Today the Internet is built with tubes. This takes lots of land, the large tubes require lots of materials, it is difficult to pull a tube to everyone's appartment. Where the normal tubes fail in efficiency, cost, benefit and where they plainly cannot be used the Nanotubes will come to the rescue! Nanotubes don't need as much space as normal tubes, you can use existing infrastructure, for example power lines and sewage pipes to pull the nanotubes right on the surface of the wires or the pipes. Nanotubes are basically invisible, so they can be put right on top of the paint in a building and you won't even know they are there. It is much cheaper to do it that way, it also requires less initial design work. Nanotubes can be bent, you can have a nanotube being pulled behind you and noone will be the wiser. Nanotubes can be part of your clothes. Nanotubes require less materials for production, they are more treehugger friendly and besides they are just way more cool.

Vote for me in the next election, I would require nanotubes for everyone!

Nanotube, the more comfortable and cooler experience than the pipe.

"tremendous amounts of nanotubes" (1)

plasmacutter (901737) | more than 7 years ago | (#18860329)

but remember nanotubes are too small for a single nanotube to carry an entire internet to you before tomorrow morning, so you need a tremendous amount of nanotubes, tremendous amounts of nanotubes.

Film and AgX (1)

purduephotog (218304) | more than 7 years ago | (#18861837)

I tend to post alot about film because it's something I know. Which is why this is another humorous topic because Film has been dealing with this problem for years!

When a photon strikes a grain of Silver Halide (AgX, where X is chloride or bromide) it knocks an electron free. This is really a poor process, so people coat the grains with sensitizing dye that increases the area available and helps to shunt the electron (http://en.wikipedia.org/wiki/Cyanine [wikipedia.org] ) into the crystal structure. The fastest grains were the T-Grains- they were very flat, large surface area and thin- but hard to make.

So it's very interesting to me to see a company touting the dye problem... maybe Kodak ought to pull out some of those useless dye colours and get them into Solar Cells...

(The fastest film was TMZ3200, with a nominal speed of 800, but could easily be pushed to 6400 ISO or higher. I know I personally shot in some crappy lighting conditions at 12500 and higher...)

interesting development (1)

kma221 (1093985) | more than 7 years ago | (#18897321)

thats great once i was interested in a solar energy product but there are big hassals in a developing country to cope with but that sounds very interesting since the cells right now are converting only 11-22% of sunlight into energy

If the biggest problem for solar (1)

GreyFlcn (963950) | more than 7 years ago | (#18953185)

If the biggest problem for solar is PRICE.
Then why are they suggesting we use nanotubes, which cost thousands of dollars per teaspoon?

Might be great for spacecraft, but absolutely worthless for conventional use.

The four big technologies for PV solar are:
1. Thinfilm CIGS semiconductor panels
2. Quantum Dots (Which allow for up to 7 electrons to be created from 1 photon)
3. Concentrating PV Solar (Using Mirrors)
4. Titanium Dioxide Organic Dyes

Re:If the biggest problem for solar (1)

qmeg (1096701) | more than 7 years ago | (#18972521)

The four major PV technologies are in fact 1. Si 2. CdTe thin film 3. CIGS thin film 4. III-V multijunction One could do concentrating PV for 1 and 4. TiO2 dye sensitized solar cell has around 10% lab efficiency and low cost, but generally unstable, thus, not in production. One of the nanowire solar cells is a proposal to improve such solar cell by replacing dye with a semiconductor shell. Quantum Dots (Which allow for up to 7 electrons to be created from 1 photon): not even reaching 1 % efficiency so far (anything can get that efficiency). Buy 1 get 6 free sounds good, but you cannot take home even one (they are all traped in the dot, and disappear within a few hundred ps, ~ 10^(-10) second. People have suggested to have dots connected by molecules, so the electrons could get out. However, when they are connected, they are not "dots" any more.
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