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Photovoltaic Cell from Plant Proteins 36

TheSync writes "FuturePundit has a story about work at MIT to develop a photovoltaic cell from spinach chloroplast proteins to generate electricity. These cells convert 12% of the light energy into electricity, and researchers hope to reach 20% efficiency, better than commercial silicon solar cells."
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Photovoltaic Cell from Plant Proteins

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  • Plants have this amazing ability to turn sunlight into usable energy. They're even quite good at it in the shade.

    And now a scientist has worked out how to do it as well using plant protiens. Wow.

    I'm frankly amazed this didn't come much sooner. Especially with the genetic technologies they're playing with these days.
    • Actually, I read somewhere that only about 1% of solar energy actually gets converted to something useful inside a plant. Silicon cells are much more efficient, they just happen to cost more than plants.

      • So the combination of silicon production abilities, and plant-cell growth efficiency, and a little of Moore and more... might give us extremely more powerful, much cheaper to produce, solar cells.

        Hope so, anyway. I'd much rather be invading a country for their spinach than their oil.
    • I'm frankly amazed this didn't come much sooner.
      You should read up on physical-/biochemistry sometime. It's really damn hard. Here is one project. []

      There are certainly more.

    • I bet if you compared plants to silicon the plants would win on a TCO (total cost of ownership) basis. Silicon solar cells are far from cheap to produce not to mention all the chemicals used in their production are far from earth friendly.
    • In fact it did. Similar cells were demonstrated about a decade ago at the Swiss Federal Institute of Technology in Lausanne, Switzerland. A company has been launched ( to sell the product, but guess what, it doesn't catch on. People still think silicon is better...
  • by simonecaldana ( 561857 ) on Saturday July 03, 2004 @05:59PM (#9602044) Homepage
    1) Develop spinach based photovoltaic cells
    2) Use Popeye in the logo
    3) Profit!
    • no, no... 3) get bought out by large oil company looking for their green image before the technology becomes profitable. Oil company then makes profit from the technology. BP and Shell are buying their way into solar big...
  • Wow, can you imagine giant cultivating ships for spinich for conversion into solar cell arrays? Would the first ship be called the USS Popeye? The companion ship the "Olive Oil"?
  • Which efficiency? (Score:3, Informative)

    by Markus Registrada ( 642224 ) on Saturday July 03, 2004 @06:46PM (#9602377)
    The only measure of efficiency that matters much is peak Watts per dollar cost. Of course that's variable, increasing along the learning curve as the manufacturing process improves, so you have to guess where it will end up. The absolute energetic efficiency (joules of electrical energy out per joules of electromagnetic energy in only needs to be above maybe 10%.
    • The only measure of efficiency that matters much is peak Watts per dollar cost. ... in a really super-narrow view of the world, sure.

      There are other things that matter besides cost... like size and weight. If a space-based satellite needs 1 KW of power, and you're comparing solutions that are 10% efficient and dirt cheap, and 100% efficient and 100X more expensive, you'd probably choose the 100% efficient version, as it's 10X smaller and 10X less weight.

      Of course, you might say this does turn into cost
  • by samjam ( 256347 ) on Saturday July 03, 2004 @06:57PM (#9602434) Homepage Journal
    Well.... spinach, eh?

    They'll be bio-hackers trying to crack the genetic drm; or taking illegal cuttings to try and increase the power they get without paying more money to the patent licensee.

    Or maybe high-level UV will mutate the plant to become profific and it will spread like triffids and overpower the grid.

    I really want to be able to grow more power when I need it, and if I have too much I can eat some, for kicks.

  • Only 20%? (Score:5, Informative)

    by Kevin Burtch ( 13372 ) on Saturday July 03, 2004 @07:47PM (#9602731)

    What about this []?

    And it's nothing compared to this []!

  • by manganese4 ( 726568 ) on Saturday July 03, 2004 @08:18PM (#9602902)
    I just read the article in Nano letters. The reported 12% efficiency was not for Spinach proteins. The authors simply demonstrate that Spinahc PSI proteins can be interated into a working device but report no statement of efficiency.

    Instead the authors extracted the distinctly different photosynthetic proteins from Rb. sphaeroides. Also, it is not clear if the author's efficiency calculation take into account the inherent loss of energy due to using excitation energy higher than the energy of the charge separated state of the RC. Or if they are simply comparing photons in and number of electrons out.
  • Oxidation issues (Score:5, Informative)

    by cagle_.25 ( 715952 ) on Saturday July 03, 2004 @09:50PM (#9603258) Journal
    From the article ...
    My take on chlorophyll-photovoltaic cells is that they will be feasible some day but it is hard to say when. Their potential advantage over more conventional biomass approaches to energy is that thay would not need to be tended to the way plants in fields or in vats must be. Their potential advantage over more conventional silicon photovoltaic cells is that they may some day be much cheaper to make. But one question that arises is whether the proteins in the chloroplasts can be treated to be made stable for long periods of time.
    This is a non-trivial concern. The electron generation can probably occur by multiple pathways, only some of which are reversible. As a result, the proteins become oxidized over time, and lose potency. Some of the links in the article hinted at this problem.
    • Not to say that oxidation wouldn't be a problem too but when their concerns about protein stability are probably more about whether it can maintain the proper active shape or fold and whether it can avoid being chewed up by the many organisms and proteases out there.
    • Although not clear in the actual paper, the oxidation potentials of the special pair in PSI and Rb. spaeroides is roughly 0.5 V vs S.H.E. On the other hand, the reduction potential of the FeS complex of PSI is almost 1 V. Luckily, proteins are most resilliant to high reduction potential than high oxidation potential.

      In higher plants under full sunlight, the PSI complexes can function for days without need for replacement by the plant. In fact, under full light conditions the plant actually will incre
  • That's misleading (Score:5, Informative)

    by durandual ( 687371 ) on Sunday July 04, 2004 @12:00AM (#9603822)
    to say that 20% efficient is better than silicon solar cells is simply misleading... how many people will think that that means it's more efficient than solar cells thinking that silicon is the most efficient. For example the galium arsenide solar cells are anywhere from 22-27% efficient.

    What you probably should have said wast that it was more efficient than some types of solar cells. The batch of 27% efficiency solar cells that my group just rejected are a heck of a lot more efficient than spinach ever will be at 20%... be careful you accurately present comparison information in a none misleading method. Thanks!
    • Re:That's misleading (Score:1, Interesting)

      by Anonymous Coward
      It's even more misleading. There are two different measures of efficiency here. The first is quantum efficiency, i.e., electrons out per photon in. The second is conversion efficiency in terms of electric power per illumination power. The "spinach cell" is claimed to have 12% quantum efficiency. The silicon cell has 20% power conversion efficiency but its quantum efficiency is very close to 100% at certain wavelengths. I'd estimate the spinach cell to have a power conversion efficency well below 1%.
  • If it use chlorophyll I guess it quite literally is green, in colour :-)

    I'm green with envy...

  • by rpiquepa ( 644694 ) on Sunday July 04, 2004 @01:40PM (#9606840) Homepage
    This was the subject of a column I published on my blog [] a week ago. You'll find references to recent articles by Nature, Science News Online and the research paper published by Nano Letters.
  • you get current flow (Score:2, Informative)

    by zogger ( 617870 )
    just by having two different conducting metals trouching, and applying any sort of heat.(picky physics majors feel free to correct my terminology and description if this is wrong, just looking for a ball park term for casual conversational purposes here). It's called a thermocouple.

    Back when I used to work on a dairy, the farmer had a kerosene lamp that ran a table top radio! He got this gizmo when he was in the navy in ww2 and doing one of the murmansk lend-lease runs to the soviets. He bought it in a

    • by Anonymous Coward
      Most of these alternative things are great, but they are not cheap out of the pocket. Of course, we start talking about externalized costs, etc. Sure, geoheatpumps are great, but they are very expensive (most of the labor is in digging the hole or trenches for the heat exchange pipes), compared to even a high-end conventional heat pump.

      Same goes for composting toilets, external water heaters/boilers/furnaces, etc.

      Plus, tricky things like environmental air quality, what to do with the compost from the comp
  • I already have a greenish complexion according to people. I now have a dream. I want to be a deep green quasi-autotroph nudist.
  • So with the lower efficiency of this plant-based photovoltaic conversion, you'd have to have some REALLY BIG plants to get significant amounts of power.... and what would they do with this capability?

    Why, use it to drive out competing plants, of course. Or maybe cross-fertilize with Venus flytraps and stun/fry small animals as food in order to spread into areas with poor soil. Maybe a good niche would be as a desert plant, lurking around watering holes.

    Yes, I know the Slaver sunflowers used mirrors, no
  • plants will have to license the technology from these guys! :-)

"If the code and the comments disagree, then both are probably wrong." -- Norm Schryer