Unless this work differs completely from Nocera's previous work, the device relies on a conventional solar cell (with sub 20% efficiency if made from silicon as suggested in the press release) to provide current for electrolysis of water. Nocera's group focuses on developing low-cost, durable catalysts for electrolysis that can work efficiently at neutral pH. This would allow electrical energy (from solar or other sources) to be stored as hydrogen gas.
However, there are other ways to store solar energy once it is converted to electrical energy or chemical energy. The bigger impediment to large scale adoption of solar is the high cost and low efficiency of initially capturing the energy in each photon. Unfortunately, Nocera's interesting work does not address this much greater challenge.
Also, why was the device tested for only 45 hours? It would have taken more than two days just to prepare the talk he gave. This almost certainly means that the efficiency started dropping and the experiment was stopped.
Anyone interested in this topic should check out the work of Michael Gratzel and others on photoelectrochemical cells, which are more deserving of the label "artificial leaf."
If this is as good as it seems to be, why is the focus purely on the third world? Unless I'm missing something, this could bring cheap and extremely environmentally friendly energy to developed countries too.
If it's purely a case of "they need this more than we do", why not either just license out the technology to companies who can use it, or develop it themselves for developed countries. Either way, they could take the money raised through that side and use it to help bring the technology to third world countries. I can't see any downside of pushing to get this kind of technology widely used everywhere.
"With a single gallon of water, Nocera says, the chip could produce enough electricity to power a house in a developing country for an entire day."
I think a house in a developing country is key. They say the chip is 10x more efficient than a natural leaf. I don't think 10 leaves produce a whole lot of power...
I'm curious how it compares to a traditional photovoltaic solar cell.
Earth receives about 1.3 to 1.4 kW per square meter from the sun (and that's before the atmosphere absorbs and reflects a huge chunk of that) - which is effectively an upper bound on the energy that can be produced by any solar power source. A playing-card sized device is going to take more than a day to produce a day's worth of electricity for a current developed-world lifestyle, even if it were 100% efficient.
I would wager it's also an issue of corporate politics.
If these leaves are capable of creating a sustainable in-house power generator, you will have no more need to buy electricity from your local provider. (Or at least in significantly reduced quantities). This obviously won't sit well with them.
Consider then that it's these companies which have the expertise to develop and commercialize a technique like this. You need to keep them on your friendly side when you are about to market. Going for those locations which are not paying customers anyway, is a safe move from an economic p.o.v. At least until said corporation can figure out a way to monetize the new product in a way that does not reduce their profit.
A better use for this technology in the west would probably be inside of a powerplant, because generating power from hydrogen is probably cheaper in a large scale power plant than using a fuel cell.
My guess it's pretty hard to deploy new technologies inside of powerplants. It takes years of testing, larger sums of money, and very long sales cycles.
So it makes more sense to develop a grid-less version for the developing world, that would serve both as a commercial product and as a proof of concept for the technology, and would take much less time and money to deploy.
Is "photosynthesis"[1] the correct term? Seems to me that "photolysis"[2] would be closer (although readers would get the gist of the former more quickly).
> MIT's artificial leaf is ten times more efficient than the real thing
This doesn't surprise me, to be honest. Organisms have evolved to be fit enough to survive, and efficiency above a certain level might not affect an organisms fitness (or might even affect it negatively).
Was it input solar energy to O2 output? to H2 output?
Was it input solar energy to electricity output - trees doesn't directly produce it, so what thermal efficiency coefficient they applied to calculate conversion, if it is the case?
Provide every house on the planet with an artificial
leaf and we could satisfy our 14 terrawatt need with
just one gallon of water a day.
One gallon of water a day, in case we are talking about freshwater, is waaaay to much.
In case you haven't noticed, there are regions in this world with a freshwater deficiency (precisely those third world countries which would benefit from something like this), and one gallon of water per day is enough for 3, even 4 people to drink per day.
The article doesn't make it clear if this can function with salt-water, which would be more difficult. And if it cannot, this is not bio-friendly or cheap for that matter.
The US and other western nations would make up for it quickly. According to http://www.sustainablebusiness.com/index.cfm/go/news.display... we currently use 200 Billion gallons of water per day for the current Coal/Nuclear system. There's around 115 million households in the us so one gallon per house per day would be exponentially better.
Maybe it's possible to make this a closed circuit by channeling the "burnt" water back into the solar cell. This way, the daily water consumption could be brought down to (almost) zero.
I guess that this would need distilled water anyway.
This fact concerned me, especially when they suggested using this in India. 80% of Indians currently rely on a finite subterranean water supply. When this runs out, this will pose a very serious humanitarian problem. I'm hoping the technology they mention can be used or adapted to use sea water.
"Nocera's leaf is stable -- operating continuously for at least 45 hours without a drop in activity in preliminary tests -- and made of widely available, inexpensive materials -- like silicon, electronics and chemical catalysts."
So semiconductor grade Silicon is readily available and easily manufactured in a third world country? Or will they have to buy the finished product from first world countries? If they do, where do they get the money? Unless they can build it themselves - and it doesn't sound like they can - how will it help them?
Is it my impression or this device produces energy and water? It apparently works with seawater and, since its exhaust is hydrogen and oxygen that will be recombined in a fuel cell, the end result will be solar power and desalinated water.
I believe this alone is almost more interesting than the power output.
Seemingly every other month, someone comes out with a "solar power breakthrough". This has been happening for the past 30 years and they never seem to follow through. I believe it when I see it for sale at walmart.
I'm guessing the substance he is using is Melanin.
I've already heard of something like this. Mexican scientist, Dr. Arturo Solis Herrera, when studying the properties of melanin, discovered that this substance is to the human body, what chlorophyll is to plants. He achieved alternative energy generation using self-renewing photoelectrochemical cells which separate water into hydrogen and oxygen and then bring the atoms together again. Check it out!!! http://www.energiaadebate.com/Articulos/noviembre2007/imagen...
[+] [-] pbsurf|15 years ago|reply
However, there are other ways to store solar energy once it is converted to electrical energy or chemical energy. The bigger impediment to large scale adoption of solar is the high cost and low efficiency of initially capturing the energy in each photon. Unfortunately, Nocera's interesting work does not address this much greater challenge.
Also, why was the device tested for only 45 hours? It would have taken more than two days just to prepare the talk he gave. This almost certainly means that the efficiency started dropping and the experiment was stopped.
Anyone interested in this topic should check out the work of Michael Gratzel and others on photoelectrochemical cells, which are more deserving of the label "artificial leaf."
[+] [-] corin_|15 years ago|reply
If it's purely a case of "they need this more than we do", why not either just license out the technology to companies who can use it, or develop it themselves for developed countries. Either way, they could take the money raised through that side and use it to help bring the technology to third world countries. I can't see any downside of pushing to get this kind of technology widely used everywhere.
[+] [-] ikono|15 years ago|reply
I think a house in a developing country is key. They say the chip is 10x more efficient than a natural leaf. I don't think 10 leaves produce a whole lot of power...
I'm curious how it compares to a traditional photovoltaic solar cell.
[+] [-] jbri|15 years ago|reply
[+] [-] exch|15 years ago|reply
Consider then that it's these companies which have the expertise to develop and commercialize a technique like this. You need to keep them on your friendly side when you are about to market. Going for those locations which are not paying customers anyway, is a safe move from an economic p.o.v. At least until said corporation can figure out a way to monetize the new product in a way that does not reduce their profit.
[+] [-] luckyfish|15 years ago|reply
My guess it's pretty hard to deploy new technologies inside of powerplants. It takes years of testing, larger sums of money, and very long sales cycles.
So it makes more sense to develop a grid-less version for the developing world, that would serve both as a commercial product and as a proof of concept for the technology, and would take much less time and money to deploy.
[+] [-] bshep|15 years ago|reply
[+] [-] dctoedt|15 years ago|reply
<\pedantry>
[1] http://en.wikipedia.org/wiki/Photosynthesis
[2] http://en.wikipedia.org/wiki/Photodissociation
[+] [-] serichsen|15 years ago|reply
[+] [-] photophotoplasm|15 years ago|reply
This doesn't surprise me, to be honest. Organisms have evolved to be fit enough to survive, and efficiency above a certain level might not affect an organisms fitness (or might even affect it negatively).
[+] [-] VladRussian|15 years ago|reply
Was it input solar energy to O2 output? to H2 output?
Was it input solar energy to electricity output - trees doesn't directly produce it, so what thermal efficiency coefficient they applied to calculate conversion, if it is the case?
...
[+] [-] johnny22|15 years ago|reply
or something like that anyways..
[+] [-] thehotdon|15 years ago|reply
[+] [-] bad_user|15 years ago|reply
In case you haven't noticed, there are regions in this world with a freshwater deficiency (precisely those third world countries which would benefit from something like this), and one gallon of water per day is enough for 3, even 4 people to drink per day.
The article doesn't make it clear if this can function with salt-water, which would be more difficult. And if it cannot, this is not bio-friendly or cheap for that matter.
[+] [-] wriq|15 years ago|reply
[+] [-] ginkgo|15 years ago|reply
I guess that this would need distilled water anyway.
[+] [-] jsmcgd|15 years ago|reply
[+] [-] Natsu|15 years ago|reply
I wonder if there's any reason why it couldn't use saltwater? I guess it's possible that the salts would cause trouble or clog things up, but...
[+] [-] patrickgzill|15 years ago|reply
[+] [-] steamboiler|15 years ago|reply
http://dilbert.com/fast/2011-03-29/
[+] [-] grammaton|15 years ago|reply
So semiconductor grade Silicon is readily available and easily manufactured in a third world country? Or will they have to buy the finished product from first world countries? If they do, where do they get the money? Unless they can build it themselves - and it doesn't sound like they can - how will it help them?
[+] [-] gacek|15 years ago|reply
[+] [-] rbanffy|15 years ago|reply
I believe this alone is almost more interesting than the power output.
[+] [-] naz|15 years ago|reply
[+] [-] viggity|15 years ago|reply
[+] [-] alantrrs|15 years ago|reply
[+] [-] mikexstudios|15 years ago|reply
[+] [-] mhb|15 years ago|reply
Re: previous artificial leaf: It was also highly unstable, and had a lifespan of barely one day.
and
Nocera's leaf is stable -- operating continuously for at least 45 hours without a drop in activity in preliminary tests
[+] [-] stretchwithme|15 years ago|reply