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

Soulskill posted about a year ago | from the it's-not-easy-being-green dept.

Power 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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"Artificially mimic" (0)

Anonymous Coward | about a year ago | (#43684207)

As opposed to naturally mimic?

Re:"Artificially mimic" (1)

Big Hairy Ian (1155547) | about a year ago | (#43684651)

Ahh woodwork finally adapts plug-in and play :)

Re:"Artificially mimic" (1)

icebike (68054) | about a year ago | (#43685245)

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. (4, Informative)

Geoffrey.landis (926948) | about a year ago | (#43685449)

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.

Re:Article is flat-out wrong. (2)

the gnat (153162) | about a year ago | (#43685653)

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 relative efficiency rate appears to be less.

Re:Article is flat-out wrong. (2)

Blaskowicz (634489) | about a year ago | (#43685879)

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.

Re:Article is flat-out wrong. (2)

Geoffrey.landis (926948) | about a year ago | (#43685937)

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.

Re:Article is flat-out wrong. (1)

bluefoxlucid (723572) | about a year ago | (#43687995)

It came from that animals eat plants and get big and strong and they only retain 10% of the energy, so plants must be fucking awesome. The planet isn't covered with animal bodies, though; it's a giant mass of plant coverage, right down to algae in the sea. Plants are a collection grid for mobile harvesters.

Re:Article is flat-out wrong. (2, Informative)

Anonymous Coward | about a year ago | (#43686439)

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.

Re:Article is flat-out wrong. (0)

Anonymous Coward | about a year ago | (#43686755)

And the plant survives how?

Re:Article is flat-out wrong. (1)

oh_my_080980980 (773867) | about a year ago | (#43686889)

RTFA: "meaning that for every photon of sunlight a plant captures, it produces an equal number of electrons."

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.

Re:Article is flat-out wrong. (-1)

Anonymous Coward | about a year ago | (#43687029)

TFA is WRONG, douche bag.

Re:Article is flat-out wrong. (0)

Anonymous Coward | about a year ago | (#43686971)

Thank you! I had just come to post the same thing. I hate when people just throw around terminology without understanding what it means.

Re:Article is flat-out wrong. (0)

Anonymous Coward | about a year ago | (#43687621)

Plants come in at about 2% energy conversion efficiency. The best solar cells are over 35% conversion efficiency

How much energy (and infrastructure, and energy to make and support that infrastructure) does it take to make a new plant versus making a new solar cell? How much energy does it take to maintain, repair, and replace existing plants vs solar cells?

That 35% figure is pure Hollywood accounting.

Re:Article is flat-out wrong. (2)

bluefoxlucid (723572) | about a year ago | (#43688079)

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 with the starch to produce maltose, which provides the energy fuel to produce a plant capable of collecting a small amount of energy from sunlight. The plant then expends most of its resources manufacturing structure to grow and collect more energy. After it's grown enough, it expends a large amount of its own energy to produce seeds.

Plants cannot provide energy required for locomotion; some can produce tension by slow processes, such as by osmotic pressure or by generating chemicals and structures that respond to the chemicals to give one fast-twitch that takes up of 24 hours to reset (if they can ever reset--lots of one-shotters out there). Some plants are also under energy pressure due to predators stealing the structural and energy resources the plant has produced.

Plants primarily move by producing small seeds with little enough mass to float on the wind. This means the entire construction process must begin again to move one plant from one place to another--a maple seed must float on the wind several miles, then grow an entire tree. Plants accomplish this growth using only local resources, because they are expending all of their energy growing rather than driving trucks. The majority resources are water and air--redwoods are comprised of dense plant cellulose fiber, which is constructed by using carbon from CO2 and hydrogen and oxygen from H2O. All other components of plants are trace, comprising very little percentage of the mass, derived from the environment as well.

Solar panels are solid sheets of refined glass and other compounds. No energy is wasted constructing a massive redwood body to act as a substrate for a few sheets; instead, energy is wasted constructing solid silicon-based substrate at high concentrations. A plant attempting to achieve these high concentrations would require millions of years and an ungodly amount of energy expenditure.

Plants expend a lot of energy to use a lot of space to produce very little usable energy.

Re:Article is flat-out wrong. (0)

bluefoxlucid (723572) | about a year ago | (#43687971)

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? (4, Interesting)

jellomizer (103300) | about a year ago | (#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.

Re:The Potato Clock? (1)

h4rr4r (612664) | about a year ago | (#43684385)

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

Re:The Potato Clock? (1)

thaylin (555395) | about a year ago | (#43684507)

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.

Re:The Potato Clock? (0)

Anonymous Coward | about a year ago | (#43684679)

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.

The electric engine hasn't been a new approach for car engines since the 1880's.

Re:The Potato Clock? (1)

gl4ss (559668) | about a year ago | (#43685091)

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

Re:The Potato Clock? (0)

Anonymous Coward | about a year ago | (#43686507)

... and plants were one of the first sources of energy for humans in the forms of fuel for fire and as food for livestock.

Re:The Potato Clock? (0)

Anonymous Coward | about a year ago | (#43684587)

I was just wondering if the research credited Cave Johnson and someone called GLaDOS. I hear they have a particular fondness of potato power.

Re:The Potato Clock? (1)

AmiMoJo (196126) | about a year ago | (#43687229)

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. (2, Informative)

140Mandak262Jamuna (970587) | about a year ago | (#43684219)

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.

Re:Photo synthesis is not all that efficient. (2)

140Mandak262Jamuna (970587) | about a year ago | (#43684301)

Windmill theoretical max is 59.3%. Not 38%.

Re:Photo synthesis is not all that efficient. (0)

Anonymous Coward | about a year ago | (#43684415)

Yeah we do not need any research into other energy forms. We have all we need. /sarcasm

Our society is built on energy usage. We need more and more of it, not less. We need oil, gas, solar, wind, hydro, nuke, chemical, etc... We need to figure out ways to get rid of the waste heat and waste of some of the chemical reactions at some point. We need more research into this. Not less. Even knowing the 'what a carnot engine is' you should see that? Someone researched that. Someone spent the time to figure it out. We need research like that as we need more energy.

Yeah maybe it is poor. But what if I cover the roofs of all the buildings in Manhattan with these plants? Oh 'but it is just a few megawatts'. So? Thats less megawatts needed by resources we have a finite amount of.

Re:Photo synthesis is not all that efficient. (5, Insightful)

140Mandak262Jamuna (970587) | about a year ago | (#43684649)

We clearly don't have all we need. I was just pointing to the fact "evolution has achieved the maximum efficiency" is a false statement. Usually they will play with the definition, and it is a warning sign. In this case they define "perfection" as the ability of the plants to emit an elector for each photon captured. But leaves and structures do not capture all the photons. They reflect most of it, not unlike solar cells. But in solar cell we define efficiency as the energy delivered to the wire to the solar energy incident on that surface.

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.

Re:Photo synthesis is not all that efficient. (1)

bluefoxlucid (723572) | about a year ago | (#43688109)

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.

Re:Photo synthesis is not all that efficient. (0)

Anonymous Coward | about a year ago | (#43684483)

The Betz limit for flow machine efficiency is 16/27 efficiency, 59.26%

I agree that photosynthesis is not efficient, but you proceed to compare photosynthesis to a bunch of other stuff that doesn't have to work off of the same resource. Your efficiency numbers are meaningless and have no relationship to how advanced the technology is. A carnot engine does not work off of sunlight and produces work, not electricity. A windmill does not work off of sunlight and produces work, not electricity - you have to append a generator efficiency as well to even get the same output. The proper comparison is to something that uses the same resource - solar PV, or solar thermal with electricity generation.

To my knowledge the better solar panels out there are around 13% efficient in their conversion of sunlight to electricity.

Re:Photo synthesis is not all that efficient. (2)

TheRaven64 (641858) | about a year ago | (#43684575)

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.

Re:Photo synthesis is not all that efficient. (3, Interesting)

cjameshuff (624879) | about a year ago | (#43684653)

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.

Re:Photo synthesis is not all that efficient. (1)

Hentes (2461350) | about a year ago | (#43684605)

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

Re:Photo synthesis is not all that efficient. (1)

angel'o'sphere (80593) | about a year ago | (#43684967)

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

Re:Photo synthesis is not all that efficient. (2)

jkflying (2190798) | about a year ago | (#43685427)

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

Re:Photo synthesis is not all that efficient. (1)

angel'o'sphere (80593) | about a year ago | (#43689831)

Ofc. But that does not change the theoretical maximum.

Re:Photo synthesis is not all that efficient. (0)

Anonymous Coward | about a year ago | (#43689905)

Actually, it does change the theoretical maximum, as the theoretical maximum is not a single number but a function of the cold and hot reservoir temperatures. The theoretical efficiency can arbitrarily approach an efficiency of one if you have a high enough hot temperature and low enough cold temperature. And in particular, it is really easy to make an engine that runs at temperatures that give a theoretical maximum higher than 42%.

Re:Photo synthesis is not all that efficient. (1)

jkflying (2190798) | about a year ago | (#43694665)

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%.

Re:Photo synthesis is not all that efficient. (1)

angel'o'sphere (80593) | about a year ago | (#43697291)

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?

Re:Photo synthesis is not all that efficient. (1)

jkflying (2190798) | about a year ago | (#43708235)

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.

Re:Photo synthesis is not all that efficient. (1)

angel'o'sphere (80593) | about a year ago | (#43710771)

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.

Re:Photo synthesis is not all that efficient. (2)

angel'o'sphere (80593) | about a year ago | (#43684985)

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.

Parent is flat out wrong (0)

Anonymous Coward | about a year ago | (#43686625)

Yes, a windmill is a mechanical beast, but you are the one trying to introduce a thermodynamics bias, as that is not what other people are talking about. Read up on Betz' law that covers the theoretical maximum kinetic energy that can be extracted from wind by an open turbine. This is not near 100%, because otherwise the output of the wind turbine would need to have near zero wind velocity and would amount to a bunch of stagnant air blocking any more air from incoming. And even taking into account this theoretical maximum, most wind turbines reach less than 80% of the theoretical maximum at optimal conditions, and that theoretical maximum is only 59% of the kinetic energy of wind that flows through the turbine. So now, they are not close to 100% efficient at extracting energy from wind.

Re:Photo synthesis is not all that efficient. (1)

J'raxis (248192) | about a year ago | (#43685177)

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, just like natural plants, isn't it more efficient on the whole than a mechanical engine?

So now we're stealing energy from plants? (0)

Anonymous Coward | about a year ago | (#43684275)

It's a good thing plants aren't sentient.

Re:So now we're stealing energy from plants? (4, Funny)

ArcadeMan (2766669) | about a year ago | (#43684427)

The Matrix: Vegan Edition.

Re:So now we're stealing energy from plants? (2)

Hazelfield (1557317) | about a year ago | (#43686461)

That would be a rare example of a sequel that actually makes more sense than the original.

Re:So now we're stealing energy from plants? (1)

slash.jit (2893213) | about a year ago | (#43687479)

So true... I never thought of that until I saw that comment :)

that's just great (1)

hamburger lady (218108) | about a year ago | (#43684295)

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

Appropriate quote (1)

ThunderBird89 (1293256) | about a year ago | (#43684355)

"Treeborgs: trees, plus technology!"

Re:Appropriate quote (0)

Anonymous Coward | about a year ago | (#43686621)

Be careful treeborgs are a slippery slope to techno-druids. And you don't want to deal with a techno-druid and his pet laser-bear.

Shrugs (1)

Chrisq (894406) | about a year ago | (#43684367)

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! (0)

VortexCortex (1117377) | about a year ago | (#43684377)

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!

It's just too bad that no one I know would use this tech, everyone in my address book is an asshole -- It's a regular Dicktionary... or is that an example of Dickshunnery?
OMFG! Two New Meanings for one word!

Re:Ooh! I just love giving new meanings! (1)

ericloewe (2129490) | about a year ago | (#43685077)

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".

Millions of years have evolution has resulted? (0)

Anonymous Coward | about a year ago | (#43684411)

Millions of years of evolution has resulted

FTFY.

Linguistical conundrum foreseen (1)

vikingpower (768921) | about a year ago | (#43684419)

"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..."

The Rise of the Planet of the Plants (0)

TheRealHocusLocus (2319802) | about a year ago | (#43684441)

Yeah, and if Monsanto holds the patent the plant power cells will die off after one generation and we will have re-invented disposable batteries. But this has all happened before.

[citation [wikipedia.org] "a disease killed the world's cats and dogs, leaving humans with no pets. To replace them, humans began keeping plants as household pets. Realizing the plants' capacity to supply the energy to charge cell phones by subverting the mechanism of photosynthesis, humans trained them to perform simple electrical tasks. By 2020, American culture is based on plant slave labor."

Plug into an atom instead. Then run wires to it. Million to one ratio of energy density compared to any chemical (combustion or otherwise) process. Then we will also avoid the cultivation of these energy producing plants which would naturally be really ugly. And would after neural evolution and social resentment, turn on their masters and bury the Statue of Liberty on a beach.

"...the most efficient harvesters..." (0)

Anonymous Coward | about a year ago | (#43684445)

They are not.

If you compare the harvested energy (per a certain area) from solar panels to plants you will see that solar panels collect much more energy over a year.

Double Benefit (1)

NEDHead (1651195) | about a year ago | (#43684461)

So my lawn can power my house, and I won't need to mow since it has no energy to grow?

Re:Double Benefit (0)

Anonymous Coward | about a year ago | (#43685073)

Triple benefit.

You can still yell at the kids to get off of it.

Not at all efficient (4, Insightful)

cjameshuff (624879) | about a year ago | (#43684535)

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%.

Re:Not at all efficient (1)

DeathToBill (601486) | about a year ago | (#43684767)

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%.

Re:Not at all efficient (1)

taiwanjohn (103839) | about a year ago | (#43685211)

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]

Re:Not at all efficient (1)

MiniMike (234881) | about a year ago | (#43685187)

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 backing, no silicon in it.

Also, how many PV panels reproduce? (Answer: none that I'd want.)

Re:Not at all efficient (1)

cjameshuff (624879) | about a year ago | (#43686207)

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 extracted plant bits as the active material in another type of PV panel. One that requires a large area carbon nanotube based substrate.

Re:Not at all efficient (0)

Anonymous Coward | about a year ago | (#43686715)

The quantum yield of photosynthesis, working out how many useful chemical reactions the plants can actually drive per photon is less than 10%. It isn't just about quantum efficiency, as the quantum efficiency of reactions in a solar cell are over 95%, except solar cells don't have as much problems in the green or near IR regions as chlorophyll does...

Re:Not at all efficient (0)

Anonymous Coward | about a year ago | (#43685603)

The most efficient plants, such as sugar cane, reach around 8%, on par with the very lowest efficiency photovoltaic modules.

On the other hand, plants are quite cheap and self-replicating. And the hippies are less likely to revolt.

Re:Not at all efficient (1)

Solandri (704621) | about a year ago | (#43688075)

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 because they suck by this measure.

Re:Not at all efficient (1)

angel'o'sphere (80593) | about a year ago | (#43694147)

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!

Pracctical joke come true (2)

Errol backfiring (1280012) | about a year ago | (#43684589)

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.

English Laurel (3, Funny)

PPH (736903) | about a year ago | (#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.

Evolution of Plants (0)

Anonymous Coward | about a year ago | (#43684655)

Perhaps the OP can point out the data backing up his sweeping statement that the plants of millions of years ago were not the most efficient harvesters of solar energy on the planet. Back then, what was and what DNA changes have resulted in them now becoming the most efficient harvesters?

Re:Evolution of Plants (1)

DeathGrippe (2906227) | about a year ago | (#43684863)

The original poster didn't make that comment - it's a direct quote from whoever wrote the article in gizmag. Also, plants have been evolving for BILLIONS of years, not "millions."

Isn't there an obvious flaw? (1)

fisted (2295862) | about a year ago | (#43684953)

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?

Re:Isn't there an obvious flaw? (2)

cjameshuff (624879) | about a year ago | (#43688193)

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 (0)

angel'o'sphere (80593) | about a year ago | (#43684961)

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 (1)

Frontier Owner (2616587) | about a year ago | (#43685095)

Stop confusing peoples feel good stories with facts...

we've tried this (1)

shirikodama (2670887) | about a year ago | (#43685725)

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.

This article is bullshit (0)

Khyber (864651) | about a year ago | (#43685805)

"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 (2)

jklovanc (1603149) | about a year ago | (#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.

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