"In the long run, we'd like to power the world:" Nanotech and solar energy

March 13, 2006 1:57 PM

Nanocrystal technology shows promise for cheaper, more efficient solar energy generation [more inside]
posted by expialidocious (21 comments total)

For those who want to read the formulas etc, there are published papers behind the cheaper [bugmenot] and more efficient [pdf] articles. And for the less technically-inclined, here's two more news articles on the first topic.
posted by expialidocious at 1:57 PM on March 13, 2006

i still don't know why every roof top doesn't have some solar panels on top...it, along with wind, are the perfect energy sources.

nano's really impractical tho, for now--can't they just improve how the current ones work and lobby for tax breaks so more people will get them? (it worked for hybrid cars, no?)
posted by amberglow at 2:49 PM on March 13, 2006

Hmm. I'm guessing, like me, you saw this on the cover of SFGate this morning and were sorely disappointing with the lack of details in the article. Thanks for the follow-up, but there's still not much news, is there? According to the SFgate article, they're trying to use nano techniques to create miniaturized solar panels, but they're 10-20 years off, at best.
posted by mrgrimm at 3:06 PM on March 13, 2006

Oh yeah, MI ... Bummer. That Science article looks good, but it's subscription only.
posted by mrgrimm at 3:07 PM on March 13, 2006

More information re nanocrystal technology and other forms of energy, including a controversial resource.
posted by nickyskye at 3:07 PM on March 13, 2006

The resulting films, which were about 1,000 times thinner than a human hair, displayed efficiencies for converting sunlight to electricity of about 3 percent. This is comparable to the conversion efficiencies of the best organic solar cells, but still substantially lower than conventional silicon solar cell thin films.

3% isn't a whole lot. Most solar energy systems sold today are around 15% (total overall effiency). While this is good in that it is cheap and doesn't require tons of energy to create, but its no replacement for the power grid yet.

3% efficency is 30W per square meter. So to just power my computer (which uses 150W at idle, 220W under load) would require 7.3 square meters, or about 80 sqft. A conventional silicon solar panel would need 1.5 square meters to generate 225W, or 16 sqft.

However if this tech were to get to 15%, or even 10% efficiency for a cheap price ($50/sqft), in places like the desert southwest, it could reduce the amount of power needed drastically.
posted by SirOmega at 3:15 PM on March 13, 2006

the technique is great and very very promising.

but i think it will never be big in the short run as it is decentralized by nature and the big companies (although looking seriously for alternatives) are weary about that aspect.
posted by Substrata at 3:22 PM on March 13, 2006

There are three main thrusts in solar cell research these days-

1) High efficiency (often quite expensive and only suited for very particular applications, with efficiencies of 35-40%)

2) Low cost (generally, organic cells which can be "painted" onto a surface, with efficiencies of <= 5%)

3) Improvements in the midrange. Commercially available cells are in the 10-20% range and of moderate cost.

This technology has the potential to affect all three, but it's clearly not yet ready for prime time. Right now, it's physics and chemistry with potential applications, but there is a lot to work out before it makes great solar cells, and I think the 60% efficiency numbers are probably pretty unrealistic.

Also, don't be put-off by the term "nanotechnology," which doesn't necessarily mean high cost.
posted by JMOZ at 4:34 PM on March 13, 2006

What struck me, and why I put the post together, were the possible combinations of the cheap and durable (inorganic nanocrystals don't need a clean room for manufacture) from the first article with the efficient (impact ionization, or cue ball effect) from the second. And since Los Alamos and Lawrence Berkeley labs are both at least partly managed by UC Berkeley... you'd think there might be some cross-pollination there. Or maybe that's too much to expect.
posted by expialidocious at 4:51 PM on March 13, 2006

i still don't know why every roof top doesn't have some solar panels on top...it, along with wind, are the perfect energy sources.

Eventually they may, but at the moment, there are problems. First, solar panels can be pricy. Secondly, they don't really produce much power at the moment. Also, they can be a bit heavy. A roofer once told me that he recommends against solar panels; a lot of them are heavy enough that over the course of the years they cause more wear and tear on your roof than if you just had shingles, so there's often roof damage in the long term. Another thing that needs to be improved is, ironically enough, environmental issues. Many of the consumer grade solar panels are made with some fairly toxic stuff, so disposing of broken panels is a non-trivial issue. Of course, it's important to note that all these things are problems that could and probably will be solved with more research.
posted by unreason at 4:55 PM on March 13, 2006

Actually, unreason, most of the consumer units available are silicon (either polycrystalline or amorphous) and are relatively nontoxic.
posted by JMOZ at 4:58 PM on March 13, 2006

Actually, unreason, most of the consumer units available are silicon (either polycrystalline or amorphous) and are relatively nontoxic.
posted by JMOZ at 7:58 PM EST on March 13 [!]

Oh, are they? maybe it's the high grade ones that are toxic, I forget. Anyway, that's one more thing in its favor I guess.
posted by unreason at 5:30 PM on March 13, 2006

and for cities tho? My apartment bldg--every single apartment building could have them, no? Every single office building too. Even it just heated the water or something small like that, that would help.
posted by amberglow at 6:15 PM on March 13, 2006

If you can "paint" this stuff onto any surface, remember that you don't just have to paint the roof, although that's the surface that will get the most light. You can also paint it on all south-facing wall surfaces, and even east and west facing will get you some power in morning and afternoon. I suppose during daylight hours even PV stuff facing north will generate some small amount of current, just from ambient light.

If you make the stuff cheap enough you can cover pretty much everything with it. Pretty much everything out there is covered with some form of paint or coating.
posted by zoogleplex at 6:20 PM on March 13, 2006

amberglow, I think gardens and trees are a much better use of large flat-roofed buildings.

I totally agree on the general point though. We need a serious push for decentralized generation and demand metering. The technical issues are completely solved, as far as I can tell.
posted by Chuckles at 7:51 PM on March 13, 2006

unreason: A roofer once told me that he recommends against solar panels; a lot of them are heavy enough that over the course of the years they cause more wear and tear on your roof than if you just had shingles, so there's often roof damage in the long term.

This sounds very 'unreasonable'. Roof covering needs periodic replacement, but the structure hardly ever 'wears out'. When it does, it is because the covering material has failed and allowed water intrusion. Regardless, if the weight was a structural issue, you could easily design new construction with 10% stronger roofs to take care of the problem.
posted by Chuckles at 7:55 PM on March 13, 2006

This sounds very 'unreasonable'.

I really can't provide much background on this claim; I just heard it from a roofer a few years ago. I don't even remember clearly what his reasoning was, just that there are problems with your roof over time if you have solar cells.

Regardless, if the weight was a structural issue, you could easily design new construction with 10% stronger roofs to take care of the problem.

You could, but builders generally don't. Home builders generally aren't willing to spend a lot on roof improvements that are not visible initially and won't enable a higher sale price for the house.

I'd like to note that with this and other problems I'm not saying that solar cells are a bad ideas. I'm just listing these problems as a sign that a little more research is necessary.
posted by unreason at 6:18 AM on March 14, 2006

Regardless, if the weight was a structural issue, you could easily design new construction with 10% stronger roofs to take care of the problem.

You could, but builders generally don't. Home builders generally aren't willing to spend a lot on roof improvements that are not visible initially and won't enable a higher sale price for the house.

The key of course is to make them. Not necessarily the stronger roof thing but it is possible to make builders take into account renewable sources of energy when constructing new properties and to deny planning permission where this does not happen. (Obviously planning regimes will vary from place to place.) In the UK, the London boroughs have started doing this, insisting that new developments have to include provision of renewable energy sources up to 10% of energy needs for their proposed building. There is a lot of hope it will act to push forward new technologies in domestic settings. More info here.
posted by biffa at 8:41 AM on March 15, 2006

doesn't it also make good sense, extreme-weatherwise, to build a sturdier roof?
posted by amberglow at 7:27 PM on March 15, 2006

Groovy nano hippiecrystal solar technology. Story at 11.
posted by muppetboy at 7:45 PM on March 15, 2006

doesn't it also make good sense, extreme-weatherwise, to build a sturdier roof?

Lots of places don't have much in the way of extreme weather to no demand for sturdier building. Builders aim to minimise costs to maximise profits and build to minimum spec unless they see a real demand from customers.
posted by biffa at 2:30 AM on March 16, 2006