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Power Earth Science Technology

Plug Into a Plant: a New Approach To Clean Energy Harvesting 80

cylonlover writes "Millions of years have evolution has resulted in plants being the most efficient harvesters of solar energy on the planet. Much research is underway into ways to artificially mimic photosynthesis in devices like artificial leaves, but researchers at the University of Georgia are working on a different approach that gives new meaning to the term 'power plant.' Their technology harvests energy generated through photosynthesis before the plants can make use of it (abstract), allowing the energy to instead be used to run low-powered electrical devices."
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Plug Into a Plant: a New Approach To Clean Energy Harvesting

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  • The Potato Clock? (Score:5, Interesting)

    by jellomizer ( 103300 ) on Friday May 10, 2013 @09:34AM (#43684213)

    It sounds like a new approach to the Potato clock.

    However I would like to point out the trade off. If you are going to produce energy with plants, (Sound green and all) but you will probably need to strip forests to give enough sunlight, as well as irrigation. For these plants that will not grow too much, because most of their energy is being taken away. You are better off growing switchgrass or other material to produce energy.

    • by h4rr4r ( 612664 )

      How is this like a potato clock?
      In that the potato is only electrolyte for a zinc copper battery.

      • by thaylin ( 555395 )
        Because it uses a plant to generate electricity.. Notice how he said a new approach, kinda like the electric engine was a new approach on the car engine.
        • by gl4ss ( 559668 )

          the potato doesn't act as the battery and electric engines were one of the first mass market car engines...

    • by AmiMoJo ( 196126 ) *

      You wouldn't use them for large scale power generation. TFA even says that. Where this technology could be really useful is things like sensor networks or other low power applications that need to run for a long, long time and are expensive to go out and replace the batteries in.

  • by 140Mandak262Jamuna ( 970587 ) on Friday May 10, 2013 @09:34AM (#43684219) Journal
    From what I understand the efficiency of photosynthesis used by the plants is quite poor. Just about 2% or so. Even the chemistry used in photosynthesis has a theoretical maximum of 25%. Compare that to theoretical maximum efficiency of ideal Carnot engines at around 57% for typical gas engine source/sink temperatures and the 38%(? not very sure of this number, too lazy to look up) or so theoretical maximum efficiency for windmills.
    • Windmill theoretical max is 59.3%. Not 38%.
    • Photosynthesis isn't very efficient, but it is very convenient. If you want the maximum possible conversion rate from solar energy, it's a terrible choice. If, however, you want something that can be cheaply deployed, then something that can self-assemble from light, water, atmospheric carbon dioxide, and a few trace nutrients is quite attractive in comparison to photovoltaics.
    • by Hentes ( 2461350 )

      True, but it's also incredibly cheap to produce.

    • A thermodynamic engine, carnot engine has a theoretical maximum of 42%, not 57%.

      • It depends on the temperature differential. The higher the difference the more efficient the engine.

        • Ofc. But that does not change the theoretical maximum.

          • The formula for efficiency for an ideal carnot engine is 1 - Tc/Th, with Tc and Th in K. So if you have a cold side of 0K, your efficiency is 100%.

            • Then perhaps we have a different definition of efficiency? A thermo dynamic process can not transform more than 42% of its thermal energy in any other form of energy.

              Is that not the carnot limit?

              • I have no idea where you got that number, or why you think that there even is any limit below 100%.
                Do some reading: [] Note how the graphs for a Carnot Engine start at ~40% and go up to ~75% as the inlet temperature rises.

                • Yepp, you are right. Already did that reading :)
                  My number came from the "wrong remembered" efficiency of ordinary power plants or combustion engines (due to theor typical temperature range).I somehow forgot that there is a general formular.
                  Thanx for pointing that out.

    • Wind mills are ofc close to 100% efficient ... sigh, where do those strange numbers come from? In practice - however - they likely only yield 85%.
      Note: a windmill is a mechanical beast, forget your thermodynamics bias.

    • by J'raxis ( 248192 )

      Do those efficiency numbers take everything into account, or is that just the efficiency of the fuel input to energy output?

      That is, I'd rather have a 2%-efficient power source that I could just plant in my back yard and forget about, than a 57%-efficient one that I'm constantly buying fuel for, periodically maintaining, and so on. Maybe it'll take half an acre of these "power plants" to give you the same amount of energy as one engine---but if that's half an acre of trees that grow on their own, unassisted

  • when the Invid catch a whiff of this, don't say i didn't warn you.

  • "Treeborgs: trees, plus technology!"

  • Millions of years have evolution has resulted in plants being the most efficient harvesters of solar energy on the planet. Much research is underway into ways to artificially mimic photosynthesis in devices like artificial leaves, but researchers at the University of Georgia are working on a different approach that gives new meaning to the term 'power plant.' Their technology harvests energy generated through photosynthesis before the plants can make use of it

    Shrugs, throws another log on the fire!

  • Electricity producing plants gives new meaning to the term "green energy", too!

    Like any other seedlings I imagine you'd have to cultivate the plants in controlled environments for maximum yield -- Gives new meaning to "harvesting energy".
    With these plants making our energy wouldn't the 'greenhouse effect' actually be good for us?

    What if you combined this technology with those Glowing Plants? []
    You could add LEDs in addition to the inherent luminescence and give new meaning to both Grow Lights, and OLED!

    • Too bad such a concept will never work.

      Plants evolved to support themselves, not to generate tons of energy.
      Even crappy solar cells are more efficient than any plant out there, add an LED light source and you're still probably something like 10 times more efficient than the plant-based solution.

      Too bad people fall for stuff if it's "plant-based" or "natural".

  • "You guys are off the grid with all computing work load ?" "Yeah, we bought a century-old, 1000-acre forest and are running our data centre off it." "How much power does it leave in the forest ?" "Nearly none. 99 percent of the power leaves the trees." "Have the trees any leaves left ?" "No, we chose for an eco-rightist approach..."
  • So my lawn can power my house, and I won't need to mow since it has no energy to grow?

  • by cjameshuff ( 624879 ) on Friday May 10, 2013 @10:07AM (#43684535) Homepage

    Plants are nowhere near "the most efficient harvesters of solar energy on the planet". The most efficient plants, such as sugar cane, reach around 8%, on par with the very lowest efficiency photovoltaic modules. More typical efficiences are 0.1% to 2%.

    • This. I've seen yew quoted as 10%, but I think that's a maximum in ideal conditions. Typical solar PV is around 15%, with more specialised (read expensive) panels better than 40%.

      • Yes, that's in line with the numbers I've seen. If your goal is to convert solar radiation into electricity, you're much better off with off-the-shelf PV cells. But a more intriguing effort is underway to create a nano-scale matrix that can split water much more efficiently, offering the potential to produce liquid fuel directly. []

    • From TFA:

      Plants are the undisputed champions of solar power. After billions of years of evolution, most of them operate at nearly 100 percent quantum efficiency, meaning that for every photon of sunlight a plant captures, it produces an equal number of electrons. Converting even a fraction of this into electricity would improve upon the efficiency seen with solar panels, which generally operate at efficiency levels between 12 and 17 percent.

      Maybe the previously stated efficiencies for plants were calculated when extracting sugars? This process tries to capture the electrons before sugar is made. Obviously the 'quantum efficiency' isn't what they'll harvest, but I would think they could get a reasonably large percentage.

      While the overall efficiency of this system is yet to be determined, it probably has a much lower embedded energy (i.e. the energy that went into producing it) than PV. This system seems to use a carbon-nanotube back

      • The "nearly 100 percent quantum efficiency" apparently refers to the fact that almost all of the energy of light of the appropriate wavelengths that is absorbed directly by a chlorophyll molecule ends up going into freeing electrons. The problem is that most of the light is of unusable or suboptimal wavelengths, a huge part of the remainder is reflected or absorbed by other things, and not all the freed electrons actually get put to useful work.

        And they don't have anything that reproduces, they just use ext

    • In terms of efficiency per square area, no they're not the most efficient.

      In terms of efficiency per energy/money invested, yes they are the most efficient. So efficient that they're net positive and self-replicating. Trees can shed their leaves every year and still have a substantial net energy gain. The most cost-effective PV cells need 5-7 years to pay back their manufacturing costs.

      And that's really what matters. Tesearch PV cells with 40% efficiency per square area aren't used commercially be
      • Cost effective PV cells need less than a year to repay their manufactoring costs. (And that includes aluminium frames for mounting them!)
        Your info is outdated since ... 30 years!

  • by Errol backfiring ( 1280012 ) on Friday May 10, 2013 @10:13AM (#43684589) Journal
    When I was camping in a forest, I saw somebody who had mounted a wall socket on a tree, put his shaving mirror on top of it, and plugged his (rechargable) electric razor into it and shaved himself, so it looked like the razor was powered by the tree.
  • by PPH ( 736903 ) on Friday May 10, 2013 @10:16AM (#43684611)

    I have an English laurel hedge. I'd plug into it except it has one of those big British style receptacles and I've lost my adapter.

  • I mean, grabbing the energy the plant 'produces' by photosynthesis. I don't suppose the plant was going to do anything important with that energy? like sustaining it's own life?
    • They grind the plants up, extract the thylakoids from the chloroplasts in the plant's cells, and somehow bind them onto a base electrode covered in carbon nanotubes (it's not clear where the other electrode is). So no, the plant is not going to be doing anything with the energy produced. It's also not going to be doing any repair or replacement work on those extracted bits of cellular machinery, or reproducing, etc.

  • Plants are by far not the most efficient energy harvesters.

    The amount of light energy transformed into sugar or what ever is far below 10%.

    Cheap solar cells are at 20% and the best are over 40%

  • Stop confusing peoples feel good stories with facts...
  • if plant photosynthesis were enough, we'd... just burn them. we know how that ends though: deforestation, desertification, and tapping into paleo-photosynthesis. clearly anything that is going to be relevant to modern society needs to have better conversion efficiencies.
  • "Millions of years have evolution has resulted in plants being the most efficient harvesters of solar energy on the planet"

    Nope, humans are the most efficient solar energy harvesters. Plants have a shitty 3-9% efficiency range, our solar panels go much higher.

  • by jklovanc ( 1603149 ) on Friday May 10, 2013 @01:20PM (#43686771)

    The only vaguely relevant number in this article is the following quote;

    The researchers say that small-scale experiments of this system have yielded a maximum current density that is two orders of magnitude larger than previously reported for similar systems.

    Even that is meaningless as there is no basis for comparison. One hundred times a few milliamps at a few microvolts is still not much power.

    I just love the following quote;

    If we are able to leverage technologies like genetic engineering to enhance stability of the plant photosynthetic machineries, I'm very hopeful that this technology will be competitive to traditional solar panels in the future.

    It sounds like they are having issues keeping the thing from breaking down. Considering that the process interrupts the plant's ability to make food for itself longevity might be an issue.

    As with many other "scientific breakthroughs" this looks like another "Give me more money for research" announcement.

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