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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Well at least we could retire the age or joke about plugging the toaster into a current bush on camping trips.
Article is flat-out wrong. (Score:5, Informative)
This statement "Millions of years have evolution has resulted in plants being the most efficient harvesters of solar energy on the planet" is flat out incorrect.
Plants come in at about 2% energy conversion efficiency. The best solar cells are over 35% conversion efficiency [gizmag.com].
Now, to be fair, plants aren't optimimized for energy conversion efficiency-- they are basically solar-powered engineering units that synthesize complex organic molecules and make self-replicating macromolecular structures out of little more than carbon dioxide and water, plus a few trace minerals... they are harvesting, mining, concentrating, and structural machines of amazing complexity. But "efficient energy conversion engines"-- no, not even close.
When the very first sentence of an article is factually incorrect, I have no interest in reading any more of it.
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Plants come in at about 2% energy conversion efficiency. The best solar cells are over 35% conversion efficiency [gizmag.com].
I think it depends on how you're counting. The 2% probably includes all photons hitting the leaf, which seems reasonable enough when comparing to a solar cell where nearly the entire surface is supposed to be converting photons to electricity. However, the individual proteins in plants that capture photons are indeed extraordinarily efficient. Nothing we can synthesize is as efficient on the nano-scale as Photosystems I and II - but of course since the plant is not made entirely of photosystems, the rela
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An other measure of efficiency would be to consider where the tool at hand is coming from. The solar panel comes from a big and expensive factory with all sorts of inputs, and the plant basically made itself.
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I think it depends on how you're counting. The 2% probably includes all photons hitting the leaf, which seems reasonable enough when comparing to a solar cell where nearly the entire surface is supposed to be converting photons to electricity. However, the individual proteins in plants that capture photons are indeed extraordinarily efficient.
No, actually they're not. Even if you're looking at the quantum efficiency of an individual photon absorption by a chlorophyll molecule, plant proteins aren't anywhere near as good as a decent solar cell, which will have very close to 100% quantum efficiency
I'm not sure where this myth that plants are extraordinarily efficient in energy conversion came from. They aren't. Energy conversion efficiency is not what they're optimized for. In evolution, "good enough" is good enough.
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Nothing we can synthesize is as efficient on the nano-scale as Photosystems I and II
Typical solar cells now have an internal quantum efficiency well over 90% across the whole visible spectrum and slightly into near IR. Even when factoring in reflectance and issues with getting light into that region, the external quantum efficiency is over 80% from middle of blue into near IR. Photosynthesis on the other hand, has an internal quantum yield of about 10% in the red and blue regions, and dips to about 5% around the green region.
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The fact that you work at NASA makes your comment rather sad since you should have a inquisitive mind and at the very least should ahev read the research paper before claiming it wasn't worth your time because you believe he misstated that plants are the "undisputed champions of solar power."
It makes you look like a douche bag.
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Plants take an amazing amount of energy to make. They require constant solar input and ground water to convert Carbon (from CO2, waste product O2) and Water (H2O) into sugars (CH2O) arranged as structure (cellulose), readily-available energy (simple sugars), and long-term storage (starches, i.e. potato). Initially a plant starts out as a seed containing a bunch of basic materials plus a bulk mass of energy (starch). Barley for example contains bulk mass starch and amylase; when wet, the amylase reacts wi
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Came to say this. 35% is hilariously lol though, the best solar cells are like 19%. The best plants are 10%-12% but those are VERY specialized and at peak (they need a lot of direct sun to hit 12%); 2% is the normal baseline, anything above that is very specialized.
You want 30%, use a polished metal parabolic reflector dish and a sterling engine.
The Potato Clock? (Score:5, Interesting)
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.
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How is this like a potato clock?
In that the potato is only electrolyte for a zinc copper battery.
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the potato doesn't act as the battery and electric engines were one of the first mass market car engines...
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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.
Photo synthesis is not all that efficient. (Score:3, Informative)
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Re:Photo synthesis is not all that efficient. (Score:5, Insightful)
OK, coming down further, plants do not use all the electrons, since they are trying to do an energy absorbing chemical reaction using that energy. Apples to solar cell comparisons show that photosynthesis is about 2% efficient in most plants, sugarcane reaches a peak of 7%.
But we can define cost efficiency to account for the cost of making it more efficient. If it is bio mass, that grows, replicates by itself and sustains itself, the cost of "manufacturing" the cell is practically zero. Cost of input energy is zero. Economically speaking bio mass, based on switch grass or algae must become cost efficient and competitive. It basically the interest on the cost of installation that determines economic viability of such projects. When other forms of renewable energy harvesting has such long history and hard data, this new fangled thing that has carbon nanotubes woven into leaf structure, is novel, interesting and might prove useful in a decade or two. But that is all that it is. A novelty. Nothing to get over excited about in the field of renewables.
The breakthrough we are all waiting for in renewables is not technical/scientific anymore. It is economic. Cheap natural gas is making coal too expensive. It is a good news bad news situation. Coal is not going to be economically viable soon. So powerplants grand fathered out of clean energy act which are steadfastly refusing to upgrade pollution control still burning coal all will switch to natural gas reducing pollution. But the bad news is, coal is replaced by even cheaper natural gas. The renewables must now beat even more cheap source of energy.
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Yeah we do not need any research into other energy forms. We have all we need.
It's kind of like doing research into the energy generation potential of pederasty via thermal generation from friction.
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Re:Photo synthesis is not all that efficient. (Score:4, Interesting)
Except they're apparently harvesting the photosynthetic structures from plants and then incorporating them in something resembling a dye-sensitized solar cell using some exotic carbon nanotube substrate. That's not self-assembling, and given the lack of any cellular repair mechanisms, probably not very long-lasting.
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True, but it's also incredibly cheap to produce.
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A thermodynamic engine, carnot engine has a theoretical maximum of 42%, not 57%.
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It depends on the temperature differential. The higher the difference the more efficient the engine.
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Ofc. But that does not change the theoretical maximum.
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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%.
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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?
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I have no idea where you got that number, or why you think that there even is any limit below 100%.
Do some reading: http://en.wikipedia.org/wiki/Heat_Engine#Efficiency [wikipedia.org] Note how the graphs for a Carnot Engine start at ~40% and go up to ~75% as the inlet temperature rises.
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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.
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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.
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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
Re:So now we're stealing energy from plants? (Score:5, Funny)
The Matrix: Vegan Edition.
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that's just great (Score:2)
when the Invid catch a whiff of this, don't say i didn't warn you.
Appropriate quote (Score:2)
"Treeborgs: trees, plus technology!"
Shrugs (Score:2)
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!
Ooh! I just love giving new meanings! (Score:1)
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? [kickstarter.com]
You could add LEDs in addition to the inherent luminescence and give new meaning to both Grow Lights, and OLED!
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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".
Linguistical conundrum foreseen (Score:2)
Double Benefit (Score:2)
So my lawn can power my house, and I won't need to mow since it has no energy to grow?
Not at all efficient (Score:5, Insightful)
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%.
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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%.
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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.
http://www.youtube.com/watch?v=l2pUD3N-SPI [youtube.com]
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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
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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
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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
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Cost effective PV cells need less than a year to repay their manufactoring costs. (And that includes aluminium frames for mounting them!) ... 30 years!
Your info is outdated since
Pracctical joke come true (Score:3)
English Laurel (Score:4, Funny)
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.
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Isn't there an obvious flaw? (Score:2)
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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.
The summary is wrong ofc ... or the article (Score:1)
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%
you guys (Score:1)
we've tried this (Score:1)
This article is bullshit (Score:1)
"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.
Real numbers (Score:3)
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.