Self-Assembling Photovoltaic Cells

dhj writes "MIT scientists have developed a self-assembling photovoltaic cell in a petri dish. Phospholipids (think cell membranes) form disks which act as the structural support for light responsive molecules. Carbon nanotubes help to align the disks and conduct electricity generated by the system with 40% efficiency. The assembly process is reversible using surfactants to break up the phospholipids. When filters are used to remove the surfactants the system reassembles with no loss of efficiency even over multiple assembly/disassembly cycles. The results were published September 5th in Nature Chemistry."

Comments

Like this story from before?

[PCPackrat]

http://science.slashdot.org/story/10/09/07/0424217/Self-Assembling-Photovoltaic-Tech-From-MIT

Re:Like this story from before?

[Required Snark]

Yes. The story was disassembled into it's component letters and then reassembled to harvest more Slashdot trolls. Recycling at it's most efficient.

Re:Like this story from before?

[beakerMeep]

To be fair, the article on MIT's site is dated "September 7, 2010."

Naturally the only logical conclusion for the dupe is that MIT News hired some Slashdot editors.

Re:Like this story from before?

[snookerhog]

it starts with self assembling Slashdot entries. Before you know it, the self assembling photovoltaic overlords are installing themselves on your roof.

Re:Like this story from before?

[Genda]

Go ahead, mock Slashdot!!! Do you have any idea just how much it costs to bring a story from 09/19/2010 through a wormhole to 09/07/2010??? You should be getting down on your knees and thanking your robotic overlords that Slashdot spares no expense (not even space and time) to get you the latest news!

Re:Like this story from before?

[el3mentary]

Dude...you need to get out more.

Re:Like this story from before?

[Anonymous Coward]

It seems to have added extraneous apostrophes in the process. Check your code. It's means "it is".

Re:Like this story from before?

[Anonymous Coward]

The exce'ss apostrophe's are their on porpoise. They have been found to attract troll's more affectively.

Re:Like this story from before?

[Jeremi]

Dude...you need to get out more.

Don't bother... I've been there. Way overrated IMO.

Re:Like this story from before?

[causality]

To be fair, the article on MIT's site is dated "September 7, 2010." Naturally the only logical conclusion for the dupe is that MIT News hired some Slashdot editors.

That's not possible. The grammar of MIT's articles is far too good. It doesn't contain spelling errors that a basic spellchecker would have fixed. It doesn't have links to stories that are behind a paywall when freely accessible ones are also available. It doesn't needlessly link to someone's blog when articles a bit closer to the primary source are readily available. If it has the occasional blatant factual error that the slightest and most basic fact-checking would have corrected, this remains to be demonstrated.

To reiterate, there's no possibility that MIT News has hired some Slashdot editors. They probably list "ability and willingness to run a quick automated spellchecker" and "familiarity with English grammar" as requirements for their editors. They have little incentive to engage in the other practices I listed.

Incidentally, it's not an instance of a "grammar nazi" when you expect paid professionals who call themselves "editors" to either correctly and consistently use basic spelling and grammar or, failing that, call themselves something other than "editors." Maybe "reposters" would be a good title. The standard and the expectations are higher for "editors" who draw a wage. It's not the same situation as the Slashdot users who post for leisure and are nit-picked over issues of grammar.

Re:Like this story from before?

[derGoldstein]

Last time Slashdot recycled a story was on the 10th.
If this is what's going to happen from now on, then I'lll start recycling my posts:

"Slashdot has become so big that the left hand doesn't know what the right hand is doing, and neither hand actually READS Slashdot..."
(originally posted on Friday September 10, @04:20AM)

Oh joy. *Another* photovoltaic breakthrough

[gestalt_n_pepper]

To be tossed in the same boxes as "may lead to a cure for obesity" or "may lead to breakthrough in cancer treatment."

Wake me when I can buy it at Wal-Mart, and if there's a penny stock or investment opportunity, I'm not interested.

Re:Oh joy. *Another* photovoltaic breakthrough

[JWSmythe]

Ditto.

    Anyone can make any sort of wild "forward looking statement". I may have designed a zero emissions perpetual motion power generator. If I can get enough hits to my site, and persuade enough investors, I'll make a fortune!

    Come visit my site today! We'll all be rich!

    I'm still waiting for flying cars, obediant robots to clean the house, distant places to live or visit, green energy, world peace, and a few other things. World of tomorrow my ass. When I was a kid, they kept telling us about how by the year 2000 everything would be so different. Ya. I have gray hair, no flying car, and moon weekend home. Tell your grandchildren that all the lies of things coming in the year 2100 are lies! Lies! The cake is a lie!

    ({snicker})

Re:Oh joy. *Another* photovoltaic breakthrough

[Lennie]

I prefer climate change, instead of global warming. Climate change doesn't add to the confusion. But it was "colder in winter this year", etc.

Another recycled story?

[WSOGMM]

Ok, it's our job to recycle the conversation. I'll start with the first comment from the last article (but recycled into a new comment): Call me when I can pick it up at Lowe's.

Re:Another recycled story?

[suomynonAyletamitlU]

OiouooeeeoeaioIaieioeoeaaieueeioaeoe ktsrjbtrcclthcnvrstnllstrtwththfrstcmmntfrmthlstrtclbtrccldntnwcmmnt yy ,'.'():

aeeIaiiuale CllmwhncnpcktptLws '.

Would it kill you to organize your recycling? You don't even have to alphabetize it, just separate the vowels and consonants from the garbage, to make our lives easier. And we don't recycle y's, either, you can just throw those away.

40%!

[ebonum]

One of the problems with solar that no one seems to talk about is the system is limited by the size of the southern facing roof on a house. In the case of desert power generation, a large amount of land is required. If solar cells can make the leap from 12% efficiency to 40%, this will change everything. Your roof installation will be able to produce a much more meaningful amount of power especially in the context of trying to run air conditioning during day light hours. More importantly, the same applies for many malls, warehouses, factories, etc. At 12% efficiency, the roof of a mall is simply too small to generate enough power to be off the grid during the day. The amount of land required per MegaWatt will drop considerably. At 40% efficiency solar starts to become a much more viable option.

Re:40%!

[DFJA]

One thing that is worth remembering is that plants have an energy conversion efficiency of about 1%, if I remember correctly. So although 12% may seem low it is still a lot better than nature achieves. This is worth bearing in mind when you see fields of oil seed rape or other energy crops being grown - it would be far more efficient to cover the land area with photovoltaics. You could even grow sheep in the gaps between the panels.

Re:40%!

[sunspot42]

Nobody needs to go "off the grid" for solar to become viable. It all comes down to $ per kw/h. Even if solar can only meet 10-20% of your needs, if you can recoup your investment in a reasonable timeframe, solar is viable.

If you live in Phoenix and have a $200 a month light bill, a hypothetical $2,500 solar array that saves you just $40 a month but which lasts for 20 years looks like a pretty good deal - it'll pay for itself 3 times over. Unlike, say, a $2,500 3D television. And of course there's the network effect - if everybody installs one of the things, demand for electricity declines by 10-20% - as does the price - meaning you could all be saving a lot more than just $40 a month. That'll also spill over into the cost you pay for locally-produced goods and services.

Re:40%!

[MarkvW]

That's true, but plants turn carbon from the air into a solid. If my solar panels could manufacture carbon fiber bicycles, I'd be really happy.

Re:40%!

[cheater512]

Actually photosynthesis tops out at 25% efficiency.
11% using the sun's spectrum.

It all depends on where you want to measure the efficiency.

Re:40%!

[physburn]

Don't know where you get the 12% number from. Sun Power solar cells are already 22% efficient, while the average commercial solar cells are 17 or 18% efficient.

---

Solar Power Feed @ Feed Distiller

Re:40%!

[Peach Rings]

demand for electricity declines by 10-20% - as does the price - meaning you could all be saving a lot more than just $40 a month

I wonder though if it's possible for energy costs to go down. It might be like bandwidth, where once the ISP has invested in the architecture to support a certain throughput it doesn't really cost them much to run it at full capacity and they don't save any money by turning things off and letting fiber go dark.

Hydroelectric and nuclear power aren't ever going to be turned down, and it makes no sense to do so because it saves no money. Oil is sort of the same thing: x barrels of oil gush out of the seafloor monthly, and it's a constant flow. All the infrastructure and support for a certain amount of power going to the grid is almost completely paid for.. if people don't use it, it's not saving the energy companies any money and prices won't budge.

Re:40%!

[Black Gold Alchemist]

FYI, at 20 percent efficiency in California, here's the math. One watt-peak = 2 kWh/year. One house = 11040 kWh /year, thus = 5520 watts peak.
At 1 kW/m^2 (100 percent), you get 5.5 m^2, which means 2.3 meters (7.7 feet) on a side.
At 40 percent, you get 13.7 m^2 = 3.7 meters (12 feet) on a side.
At 20 percent you get 27.6 m^2 = 5.5 meters (17.23 feet) on a side.
At 10 percent you get 55.2 m^2 = 7.4 (24.3 feet) meters on a side.

Re:40%!

[JWSmythe]

    Actually, you hit on something that must be adjusted for solar to work. Modern structures are rarely insulated enough. That insulation can be natural (semi-subterranean homes), or artificial (like XPS, EPS, and fiberglass). On a few occasions, I've had opportunities to look inside residential walls. Rarely are the walls insulated well. They're insulated well enough to pass inspection, and meet the bare minimum of the building codes. For example, I was replacing the wall around a tub/shower. On the outside wall, there was only about 3/4" encapsulated fiberglass behind the concrete block wall. I guess that was enough to pass inspection at the time. The person who owns the house noted that in the summer, the A/C couldn't keep up. All you had to do was touch any of the interior walls. You could feel the outside heat on the exterior facing walls (from inside) and even the interior walls (not facing outside). The heat from the attic was heating the interior walls too.

    As long as it is acceptable to build houses as cheaply as possible, we will continue using more power than is required. So yes, solar can be way too expensive to supply even the power to just cool the house.

    There are some very interesting projects that people have done for alternative methods of cooling homes. While you may be able to hack something together from your local big-box hardware store, you'll never see a full kit nor instructions on doing it there. The building codes in your are may expressly forbid some. I know plenty of people who live in planned communities, where they are not allowed by deed restrictions, to put up solar panels, windmills, or even change the construction of their roof (a white roof reflects more solar energy than a black shingle roof).

Re:40%!

[elashish14]

Where are you getting this 12% efficiency factor from? That may be a decent figure for thin-film solar cells, but single-crystal silicon solar cells (the highest manufacturable efficiency) are well past 20% right now. And I don't believe the article at all when it says 40% power efficiency. Even the most advanced multijunction cells barely eek past 40% efficiency (and I think that's only due to the light being highly concentrated - >100x).

What they probably meant is that the quantum efficiency is 40%, especially since it's impossible for any solar cell to exceed 86% within the detailed balance limit. 40% is nothing special compared to existing technology, though it's surprisingly high for a novel technology like this.

Re:40%!

[celle]

"At 20 percent you get 27.6 m^2 = 5.5 meters (17.23 feet) on a side.
At 10 percent you get 55.2 m^2 = 7.4 (24.3 feet) meters on a side."

Ok, who owns/rents/whatever a house that's less than 25 feet per side in this day and age?

Re:40%!

[sunspot42]

Hydroelectric and nuclear power aren't ever going to be turned down,

Not entirely true, as someone has already noted. Hydro especially can be turned "up and down" as demand dictates. We burn very little oil for electricity - it's too expensive for that. We do burn a lot of coal though, and if solar were capable of supplying just 10-20% of our energy needs, it would certainly put a dent in the cost of coal-generated power.

Re:40%!

[sunspot42]

Who cares? Use solar where it's economical. Use something else in Lansing.

Re:40%!

[sunspot42]

Let's assume I can sell you a very very cheap solar cell that runs at 2% efficiency. In this case, you will quickly recoup your investment, but you aren't producing much power. Do you plan to make your roof 5 to 10 times as large?

No, but if they're cheap enough at just 2% efficiency to pay for themselves quickly, it might make sense to cover the sides of buildings with them, as well as parking garages, covered parking spaces, the sides of freeways, etc. So in aggregate you could end up generating just as much power as you might with more expensive, more efficient cells, just by carpeting every exposed surface with them.

However, most cells these days are in the 10% and up efficiency range, and growing more efficient (and cheaper) with each passing year. So your hypothetical seems kinda unlikely.

Re:40%!

[sunspot42]

Negative. You're assuming that if power use decreases by 10-20%, the cost of power will decrease. It will not. The power company will charge more for less.

That's not true. The cost of power in many places in the US (and elsewhere, I'd imagine) varies during the course of the day depending on demand. So when demand is low power is cheap, but when demand is high (in the sunbelt, on hot sunny days), the price of power skyrockets, sometimes to ten times or more what it costs when demand is low.

Solar cells have the unique property of generating maximum power just at the time when utility rates peak in the sunbelt. So looking at the average cost of power and comparing that to the cost of power generated by a solar cell doesn't begin to tell the whole story. Look at the peak cost of power and see how much of that a solar installation will shave off of your electric bill. And of course, thanks to the network effect, if everyone starts installing these things, the peak cost of electricity across the sunbelt will implode. Either way, consumers win. The power companies could try to jack up the cost a little, but they aren't going to be able to jack it up tenfold.

Also, $200/mo light bill?! Maybe for AC in Phoenix... but that's a lot of lights. :)

We were paying $200 a month in Phoenix to cool a 4 bedroom home 25 years ago. I'd imagine it's substantially more expensive today, especially when you factor in all the electronic, power sucking gizmos in the average home of 2010, from massive HD sets to power-guzzling desktop computers. My Core 2 box and its two LCD monitors consumes about 5 times as much electricity as my old Atari 800XL, 1050 disk drive and Amdek Color I monitor did back when I lived in Phoenix 25 years ago.

Re:40%!

[zrbyte]

40% is just the efficiency of the individual molecules in converting photons to electric charge. The overall efficiency of the device must be abysmal. The real breakthrough here lies in the fact that these guys can disassemble and reassemble the component light harvesting molecules of the device. This is important since photovoltaic devices using organic molecules are prone to degradation during irradiation by sunlight (see: http://en.wikipedia.org/wiki/Polymer_solar_cell).

Re:40%!

[baegucb]

Speaking from experience, when demand for a utility goes down 10-20%, the utility company will try to raise rates 10-20% based on the fact that they have had a drop in revenue, but still have the same costs.

Re:40%!

[Abstrackt]

Do you have any good links on this regard? I'm quite interested in this. I've been looking at (though not building yet) distillation refrigerators using solar heat as fuel.

I'm not sure if this is exactly what you're looking for, but I've done a lot of research on building a passive house in a climate with extreme temperature variations and the following links made good starting points:

http://en.wikipedia.org/wiki/Passive_solar_building_design
http://en.wikipedia.org/wiki/Superinsulation
http://en.wikipedia.org/wiki/Ground-coupled_heat_exchanger
GreenBuildingTalk forums

Other options include designing the overhang of your house to be long enough to block most of the sun during the summer when it's higher but short enough to allow most of all of the sun through in the winter when it's lower, planting leafy trees with a lot of little branches near windows (the leaves block light during the summer and the small branches allow it through during the winter), and one that I cannot stress enough: the better your insulation is the more comfortable you'll be.

In my current house the biggest change came from putting in triple-pane argon-filled windows. We could only afford to do half the house at a time and the half of the house with new windows was much more pleasant to be in both during the summer and the winter.

Re:40%!

[Mindcontrolled]

If you want to be real efficient, I guess you gotta take some clues from the usual "Passive House" concepts. Now, passive house in it's original form is more geared towards temperate to cold climates, but the key element should be the same in a hot climate, namely controlling the ventilation in the house tightly and insulating as good as possible. Exchange humidity and heat between incoming and outgoing air using ERV, cool the incoming air in a second stage with an air-to-ground heat exchanger and in a third stage with a solar driven absorption heat pump. Combine that with passive measures like painting the roof white or planting stuff on it, and providing ample shade for the sun side, and you should be set.