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Nanotubes May Improve Solar Energy Harvesting
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."
oh yeah, and some nappy nanotubes also, you bet!
If you believe these guys:
http://www.trec-uk.org.uk/index.shtml
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
The proper headline should be "global warming solved for 3rd time this week".
nanotubes - what the nanonet is made of!
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.
So that's why they keep getting clogged so easily.
And I'm sure this is only 5 years away from commercial use, just like every other such announcement.
"It's the height of ridiculousness to say for those 9 lines you get hundreds of millions."
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.
Two wrongs don't make a right, but three lefts do.
"Hope", "may" and "unfortunately" all in one article.
It's like reading about Duke Nukem Forever.
biopowered.co.uk - catalytically cracking triglycerides for home automotive use since 2008. Just say no to big oil!
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!
Comment removed based on user account deletion
If you put a series of nanotubes ...
Do you get a Nanonet ?
Don't you know it is now both immoral and criminal to think beyond the next quarterly report?
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.
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.
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
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.
Do not try to read the dupe, thats impossible. Instead, only try to realize the truth
What truth?
There is no dupe
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.
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. And, as the article points out, we are on the way to doing
even better.s -selling-solar.html
--
Sprout Silicon Leaves: http://mdsolar.blogspot.com/2007/01/slashdot-user
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.
[Ego]out
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...
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
Two wrongs don't make a right, but three lefts do.
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.
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.
s -selling-solar.html
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-user
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 (the video is probably the best). Who knows, one of these breakthroughs if it works well could change a lot for us.
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.
---- Teach Peace. It's Cheaper Than War.
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 top out at about 21%. One can create multiple junction cells to capture different segments of the spectrum at higher efficiency. Consider this chart of maximum efficiency under lab conditions.
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.
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.
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.
You can't handle the truth.
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.
... 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 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
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.
"Ladies and gentlemen, my killbot features Lotus Notes and a machine gun. It is the finest available."
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.
VLC FOR MAC IS DYING! IF YOU DEVELOP, PLEASE SAVE IT!!
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) 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...)
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.
Slashdot "libertarians": Small government for me, big government for those I disagree with. -1, I disagree with you
But yes, I do think that some tax break should exist. California has a large subsidy but it isn't unlimited (first come, first serve).
Slashdot "libertarians": Small government for me, big government for those I disagree with. -1, I disagree with you
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.
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
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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