Invisible Solar Nano Cells Promise Clean Energy

An anonymous reader writes "ZDNet is reporting that Harvard scientists have developed a silicon nanowire 200 hundred times thinner than a human hair that crank out up to 200 picowatts. Charles Leiber from Harvard University, who devised the technology with colleagues, is quoted: "An individual nanoelectronic device will indeed consume very little power, but to do something interesting will require many interconnected devices and thus the power requirement — even for nanosystems — can be a challenge". Conventional sources, he added, are "bulky, non-renewable and expensive" by comparison."

Comments

a side product of balding hair research

[rgaginol]

what's sad is that this was discovered in the attempt to create a more life like toupe;P

Re:a side product of balding hair research

[edwardpickman]

The really sad thing was it they didn't discover it in the 70s. A self powered neon toupe would have been huge among the middle aged disco fans.

Localizers

[56]

Anyone ever read Vernor Vinge's 'A Deepness in the Sky'? These things might be a great power source for the localizers he mentions.

An obvious question?

[Linker3000]

"...Charles Leiber and colleagues at Harvard University, have devised a 'silicon nanowire' that can convert light into electrical energy.... ...Two hundred billionths of a watt may not seem much, but at nanoscale it is enough to provide a steady output of electricity to run ultralow power electronics, including some that could be worn on -- or even inside -- the body. "

Erm, how bright is the inside of a body!?

Re:An obvious question?

[vbraga]

It depends on the type of body. Think of goatse. Sunshine can reach inside it. Well, almost the whole Sun.

(Yes, I'm ashamed of thinking this...)

Re:An obvious question?

[edwardpickman]

Erm, how bright is the inside of a body!?

It's being developed for people that live near Chernobyl. Kind of like the X Ray film that you just have to stand next to for five minutes and the lead lined shorts that are a fashionable item in Kiev.

Re:An obvious question?

[fishthegeek]

That depends. From my point of view there aren't any problems with light getting to the inside of a body.

Sincerely,
Hannibal Lecter

Re:An obvious question?

[Ungrounded Lightning]

Actually it's moderately transparent - unless you happen to be one of the subset of humanity that has a particularly dark skin pigment. (Even then it's pretty transparent except on the outer layer - not that it matters. B-( )

Hold your hand up to a lamp. Notice the light coming through it. Very diffused, but clearly quite a bit there.

Of course if you move the nanowires out to the skin level the transparency of the body - even with a heavily-pigmented skin - is no longer an issue.

However, given the enormous energy density of the body's processes there should be plenty of power to tap for "embedded systems". For medical sensors give me a sugar/oxygen fuel cell any day. (The body uses those. Though perhaps a different system might be better for straight electrical output.)

Meanwhile this sort of structure sounds like it would make a dandy textile if it were thickened up a bit, spun into thread, and somebody can figure out how to connect to it.

I Hate Science Reporting

[MBCook]

Virtually invisible to the naked eye, a single strand can crank out up to 200 picowatts.

I hate science reporting. It's also nice to know the editors aren't doing their jobs (ZDNet, I don't blame /.). What is a single strand? Is that 10mm long? 10cm? 1m? There is a big difference between those three. The summary just chops that sentence up worse. And why do they always use human hair as a comparison? Who's hair is that? Some people have very thin hair. For some people it is quite a bit thicker. If you are comparing it to the average, you should include that word. Also are we talking theoretical maximum or a practical estimation under normal daylight conditions?

It's great to know this generates 200 picowatts per something. How about comparing it to a normal production solar cell. I'm glad you can make it thin, but it must need some kind of support structure to survive, so how much thicker does it need to be so it is actually useful? After all, the silicon part of a solar cell is just a fraction of it's thickness.

Re:I Hate Science Reporting

[Planesdragon]

If you are comparing it to the average, you should include that word. No, they shouldn't.

In the case where a reasonable person would understand that "average" is meant, then "average" is just a useless word cluttering up the sentence. Its presence or omission is best left to the writer, subject to the needs of the surrounding text and the work as a whole.

Re:I Hate Science Reporting

[sumdumass]

Well, I too would like to know more about it. Like can it be woven into a yarn or thread and made into clothing? A 200 pico watts isn't much power but if it is 1 strand 10 centimeters long and something like 10 strands can be spun/woven into a single thread similar to wool and cotton that can be used to weave and overcoat, how much power would that be? Could it be possible to make cover for your hybrid electric car or even a soft top that is also a solar charger so the batteries are at full charge sitting in the parking lot waiting for you to get off work. Even a ball cap that can power your Ipod or Walkman would be great.

I mean the possibilities are endless depending on the properties of the stuff. It is made out is silicon it is small, and it produces power. It should be Usable in a lot of ways.

Re:I Hate Science Reporting

[Falstius]

As someone who teaches MEMs technology, I find myself frequently using the human hair comparison with new students. It is the closet thing to a microstructure that people have daily physical experience with, and helps give a feeling of scale. A 200 micron wide bridge is an abstract number until you understand it is about 1 to 4 hair-widths (depending on whose hair). Its not nearly as meaningless of a unit as LOCs (Libraries of Congress). If you have a better suggestion for a comparison, I'd love to hear it.

Your point about leaving off the length is a good one. Science journalists don't seem to understand enough about what they're covering to know which points are important or which claims are plausible.

Re:I Hate Science Reporting

[fractoid]

The article also contains this gem:

Incoming light generates electrons in the outer shell, which are then swept into the second layer and the inner core along micropores. Nice to see that they're actually generating electrons instead of just moving them around like most of those lazy-ass photovoltaics. I hope they generate positrons at the same time to balance out the overall charge of the universe...

Re:I Hate Science Reporting

[jellomizer]

Well the Human Hair Anology is just so a person has some basic reference for small things. Giving exact size for the general audence is a waist, if you are more interested read the sciencetific papers. 200 times the size of a human hair even if they have corse hair is still unobservably small. Small enough to be wove into fabric without feeling it (like wires) or placed in the body without feeling it. Some Bacteria could use it as swords to fight of other bactera.

I wonder

[Dr. Eggman]

Any biologists out there who wishes to inform me of how this solar cell compares in efficiency and equivalent energy production for photosynthesis. I understand that they're are two very different forms of energy (storage medium may be a better comparison) but I would be interested as I have thought that perhaps natural evolution had already long ago derived the most efficient ways of recovering energy to drive its organisms. I wonder if the real future of small scale generators/batteries lies with organic synthesis of energy through genetically modified organism with some medium transforming the resulting chemical energy into electrical energy (not unlike a battery but with it's own complications necessary for dealing in the organic compounds) rather than straight up developing life-facsimiles.

Then again maybe I'm just rambling on after approaching the 40th consecutive waking hour... It'd be nice to know.

Re:I wonder

[StikyPad]

I have thought that perhaps natural evolution had already long ago derived the most efficient ways of recovering energy to drive its organisms.

Not usually true. Plants and animals have plenty of other concerns, such as the efficient storage thereof, combating predators, reproducing, etc., any one of which could take precedence over obtaining energy. Is fat the most economical storage medium? It's pretty good, but other factors come into play: it's not toxic to the body, it's pliable, which permits relatively free movement, it's a good insulator, and it provides protection to bones and internal organs (any of which may or may not be an evolutionary side effect). Natural selection is about favoring the most competitive in a particular environment, and obtaining the most energy, while ignoring other factors, is not always the best strategy. A design that extracts more energy from sunlight than pine needles might be more prone to wind damage, pests, molds, fungus, etc. Even if an organism is more efficient at extracting energy than its competitors, that's no guarantee that its the *most* efficient possible design, just that it was good enough.

Additionally, what we're primarily concerned with is electromagnetic energy. There are always losses in any conversion, and if we convert the sunlight into chemical energy, then back into electromagnetic energy, we're guaranteeing more losses than if we can harness/store the sunlight directly. That's why it's often more efficient to use net metering rather than off-grid battery storage alone. Many people opt to include batteries in their solar systems, but that's typically for the purpose of grid independence and/or backup power. Of course there are losses inherent in converting DC to AC, so that must be considered as well. Overall, the more directly you can transfer the power from the source to the load, the more efficient that transition will be.

I'm not a biologist, but I did stay at a Holiday Inn last night.

Re:I wonder

[commando_jim]

I had a graduate professor (in bioengineering/nanotechnology) who claimed that the light absorptive complexes in plant cells (chloroplasts) were on the order of 95% efficient(I've forgotten the exact number) in certain wavelengths. (not green since that all gets reflected for you to see the nice green color of the leaf)

Unfortunately comparing the efficiency of plants to this wire thing isn't that simple. Chloroplasts have lots of internal complexes(Thylakoid disks) full of organized protein structures that convert light to electricity as one hugely efficient electron transfer system. To compare a plant leaf to this wire we'd need to know how the wire performs in densities similar to the thylakoid disk density in a plant leaf. We'd also need to know things like whether these wires get more or less efficient with packing, what the peak achievable packing density is, and what kind of alignment restrictions we have regarding the incoming photons.

Simply put: the 0.2nW quoted here is probably not a useful number when considering systems aggregating the production of many of these things.

Disclaimer: although I had relevant class work my degrees focus in biomechanics not biochemistry or nanotechnology.

Wait a minute, I'm confused

[shlashdot]

Where is the promise that this will be commercialized in a few years and we can paint our houses with it? What kind of solar article is this?

Hey....

[DoofusOfDeath]

"Invisible" "Solar" "Nano" "Cells" ... "Clean Energy"

I WON SLASHDOT BINGO!!!

TFA was for Dora the Explorer club, and not /.

[viking80]

I think this article was meant for Dora the Explorer club, and not /.

The journalist is either completely clueless or trying to make it comprehensible for kindergarten. The result is so wrong and incomprehensible that it is worthless: ...The cable itself looks, like the cables used to hook up cable television networks...But the similarity stops there...Incoming light generates electrons in the outer shell, which are then swept into the second layer and the inner core along micropores. These "holes", as they are called, carry an equal, but opposite, charge as electrons, which means that the two particles move in opposite directions in the presence of an electric field.

200 hundred?

[Nullav]

Curious, does that mean 20,000, or is it just redundant moonspeak? I've heard people say things like 'a thousand million', but never for such small numbers.

A furry battery charger?

[Anaerin]

Let's see, we've got nanowire that's "Thinner than a human hair", and generates 200 picowatts of electricity. So, if we use these things tethered at one end and free to sway loose at the other, we have a mat of electric-generating "fur". Fuzzy satellites? Implant into the human scalp (To cover those bald spots) and you could power your cybernetic implants. Self-powering Electro-Luminescent wire (Charges when off)?

Weave these things into a cloth, and we could have spaceships with a power-generating solar sail. Or sailboats that generate the power for their electronics (And/or onboard electric motors) with their sails. Or electric cars with power-generating soft-tops. Heck, weave a cloth of these things and embed it in epoxy resin and you've got power-generating carbon-fiber-like body panels. Just paint the inside and use a clear laquer on the outside.

Clothing that powers your wearable PC? In fact, what's to stop this being used as a low-current power conductor to start off with?

The possibilities are (almost) endless...

Re:Definition of PicoWatt

[marcosdumay]

1 pico watt is still 1.6e8 eV/s. See, a huge number. A hypotetical nano-assembly powered by that could ionize near 6.5e7 hydrogen atoms per second, and, while 250nm is a bit big for such application, you could still put 4e6 such machines in a centimeter, leading to 26e13 atoms/(s cm).

Of course, everything depends on how long is the cell. You got 10cm from nowhere, it would even be hard to make it that long. If you are right about the length, it is useless. But if its length is 4 times bigger than the width, you'd get 1e6 such things on a centimeter, getting 26e19 atoms/(s cm^2), what is 26 mols every 10.000 seconds on a square centimeter, or 26 mols every second on a square meter.

As I said, everything depends on the length. But if I had to speculate its length, I'd say that is quite an impressive cell. Not useless.