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MIT's artificial leaf is ten times more efficient than the real thing (Wired UK)

wired.co.uk

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Re: MIT's artificial leaf is ten times more efficient than the real thing (Wired UK)

#21

Post by tesseract »

corin_ wrote: post #6
jbri wrote: post #4

Earlier quoted context omitted.

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.

Solar panels are already good enough that they are used in developed countries such as USA and UK. Are they perfect? No, they cost too much, and they don't generate enough electricity, but they are used none-the-less. By the sound of it, this new creation would be more efficient, either in price, electricity generation, or both, than traditional solar panels - if that wasn't the case, why on earth would any project u…

I don't see, in the linked article, a comparison of the efficiency of this device to that of existing solar panels (which are quite a bit more efficient than natural leaves).

Re: MIT's artificial leaf is ten times more efficient than the real thing (Wired UK)

#22

Post by BoppreH »

corin_ wrote: post #16
pshapiro wrote: post #5

Earlier quoted context omitted.

I think the point is that it can use that small amount of energy to break the hydrogen bond in the water, releasing more energy than was used. Edit: Apparently I made a mistake. See the correction, which I was the first to upvote.

Pisses me off that comments like the one I'm replying to get downvoted. He expressed his understanding of the science, if he's wrong then by all means explain why and upvote those who have explained why - but don't downvote just because somebody made a mistake, it's surely better to have the discussion than for nobody to bring it up.

I won't upvote GP because it contains a factual error and you can't upvote only parts of a comment. If it was edited to include a note about the mistake, thus dismissing the error, I'm sure it'll get get some votes.

Re: MIT's artificial leaf is ten times more efficient than the real thing (Wired UK)

#23

Post by corin_ »

BoppreH wrote: post #22
corin_ wrote: post #16

Earlier quoted context omitted.

Pisses me off that comments like the one I'm replying to get downvoted. He expressed his understanding of the science, if he's wrong then by all means explain why and upvote those who have explained why - but don't downvote just because somebody made a mistake, it's surely better to have the discussion than for nobody to bring it up.

I won't upvote GP because it contains a factual error and you can't upvote only parts of a comment. If it was edited to include a note about the mistake, thus dismissing the error, I'm sure it'll get get some votes.

I'm not saying upvote incorrect comments, but there is a place inbetween punishing and rewarding.

Re: MIT's artificial leaf is ten times more efficient than the real thing (Wired UK)

#24

Post by jedsmith »

mhb wrote: post #19
MaysonL wrote: post #14

Earlier quoted context omitted.

Being at ~100% after 45 hours and at 0% after 24 hours are quite different.

Since you're intent on belaboring the point, it doesn't claim that one is at ~100% and the other was at 0%. More significantly, if the assertion is that one is more stable, don't you think it would be more compelling to demonstrate its operation for, say, a month? Or did they build this one leaf 45 hours before issuing a press release?

"Lifespan" implies that at the end of the period, the old leaf died. There would be no other reason to use the word. The submitted article also mentions 45 hours without a drop in activity, implying 100% at the end of 45 hours for the new leaf without any kind of assertion about a lifespan for the new leaf. The linked ACS release doesn't discuss this, either.

Grant him the point. Truthfully, you're splitting hairs, and it really isn't worth arguing about, especially since this entire thing seems dubious without proof.

Re: MIT's artificial leaf is ten times more efficient than the real thing (Wired UK)

#25

Post by runningdogx »

jbri wrote: post #8
pshapiro wrote: post #5

Earlier quoted context omitted.

I think the point is that it can use that small amount of energy to break the hydrogen bond in the water, releasing more energy than was used. Edit: Apparently I made a mistake. See the correction, which I was the first to upvote.

Breaking bonds does not release energy. Bonds are the way the are because they are (locally) the lowest-energy configuration for the atoms that are taking part. You need to put energy in to get out of a low-energy configuration. The device appears to use water->hydrogen as an energy storage mechanism, to solve (at some efficiency cost) the issue of energy demand generally being out of sync with the supply from the su…

Since most reactions do not end up with all the constituent atoms as free ions, the real question is how the sum of bond energies of the reaction product(s) compares to the sum of bond energies of the starting molecule(s).

In the case of water, 2 H20 -> 2 H2 + O2 is endothermic, but reactions do not have to be endothermic, or else chemistry would be very boring and cold.

Re: MIT's artificial leaf is ten times more efficient than the real thing (Wired UK)

#26

Post by photophotoplasm »

> 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).

Re: MIT's artificial leaf is ten times more efficient than the real thing (Wired UK)

#27

Post by ikono »

doyoulikeworms wrote: post #17
ikono wrote: post #9

Earlier quoted context omitted.

"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.

In fact, the framing of the performance characteristics of this this artificial leads me to believe that the selling point is their ease of manufacture. That is, they are less efficient than traditional solar cells, but cheaper/easier to make. Just a guess, though. Would love to see actual figures.

I think more specifically, the battery is cheap. It's the size of a refrigerator and provides very little power (a few AA batteries?) but it uses water instead of lithium.

All that said, if they can find a comercial use for it in it's current form, they may be able to improve the standard of living for a lot of people while funding the research needed to bring it to the developed world.

Re: MIT's artificial leaf is ten times more efficient than the real thing (Wired UK)

#28

Post by michaelchisari »

BoppreH wrote: post #22
corin_ wrote: post #16

Earlier quoted context omitted.

Pisses me off that comments like the one I'm replying to get downvoted. He expressed his understanding of the science, if he's wrong then by all means explain why and upvote those who have explained why - but don't downvote just because somebody made a mistake, it's surely better to have the discussion than for nobody to bring it up.

I won't upvote GP because it contains a factual error and you can't upvote only parts of a comment. If it was edited to include a note about the mistake, thus dismissing the error, I'm sure it'll get get some votes.

you can't upvote only parts of a comment

Well, that's an interesting UI idea...

Re: MIT's artificial leaf is ten times more efficient than the real thing (Wired UK)

#29

Post by puredemo »

berntb wrote: post #20
corin_ wrote: post #6

Earlier quoted context omitted.

Solar panels are already good enough that they are used in developed countries such as USA and UK. Are they perfect? No, they cost too much, and they don't generate enough electricity, but they are used none-the-less. By the sound of it, this new creation would be more efficient, either in price, electricity generation, or both, than traditional solar panels - if that wasn't the case, why on earth would any project u…

>>Solar panels are already good enough that they are used in developed countries such as USA and UK. Are they perfect? No, they cost too much, and they don't generate enough electricity, but they are used none-the-less. Does no one follow energy news, except for oil prices and the Polywell project?! :-) Many estimates talk about soon reaching "grid parity" in large parts of the world. If this leaf isn't good enough,…

Where do you get your energy news from?

Re: MIT's artificial leaf is ten times more efficient than the real thing (Wired UK)

#30

Post by johnny22 »

photophotoplasm wrote: post #26

> 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).

yes, if the plant sucks up too much power it might get too hot and lose too much of the often more scarce water.

or something like that anyways..

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