
MIT's artificial leaf is ten times more efficient than the real thing (Wired UK) - stretchwithme
http://www.wired.co.uk/news/archive/2011-03/28/artificial-leaf
======
pbsurf
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."

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corin_
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_.

~~~
jbri
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.

~~~
corin_
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 use them in third world
countries, when they could instead use solar panels.

So, based on those two facts, surely anyone who would be using solar panels
ought to look to be using this product in the next few years? (And, depending
on how much better than traditional solar panels it is, possibly more
people/companies would want to use it than are willing to use solar power
right now.)

~~~
berntb
>>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, there will be some other solar variant
soon.

<http://en.wikipedia.org/wiki/Grid_parity>

It seems to go faster than this prediction from 2009:
<http://news.bbc.co.uk/2/hi/8386460.stm>

(Kurzweil argued in 2008 that solar energy will take over
[http://www.livescience.com/4824-solar-power-rule-20-years-
fu...](http://www.livescience.com/4824-solar-power-rule-20-years-
futurists.html) )

~~~
ars
BTW one reason that Grid Parity is a moving target is that one of the input
costs to making solar power is energy. When energy (hydrocarbon fuel) becomes
more expensive, instead of making solar power cheaper in comparison, it has no
real effect.

Instead, regular power becomes more expensive, which makes building solar
power also more expensive, and the net result is a wash.

~~~
DannoHung
That seems weird. That would imply that the lifetime energy capture of a solar
panel is roughly equivalent to the creation and installation energy cost.

~~~
randallsquared
Doesn't seem weird at all, I think. Solar just barely passed breakeven in the
last decade, unless you factor in subsidies. I notice that for a random zip
code in Maine, <http://bpsolar.cleanpowerestimator.com/bpsolar.htm> shows that
absent federal and state subsidies, you'll save only about $4600 over 25 years
with their default settings. It's phrased as saving $36K, though, due to
subsidies and interesting presentation. :) But BP Solar really wants you to
buy solar panels, of course.

------
dctoedt
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).

<\pedantry>

[1] <http://en.wikipedia.org/wiki/Photosynthesis>

[2] <http://en.wikipedia.org/wiki/Photodissociation>

~~~
serichsen
I agree. Photosynthesis would be to split carbon dioxide, release oxygen, and
use the carbon to _sythesize_ some organic compound.

------
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).

~~~
thehotdon
Engineering beats evolution, every time.

~~~
photophotoplasm
Horses for courses, and all that.

~~~
thehotdon
Well, it's not just a difference in optimization goals; it's a difference in
methodology.

Evolution optimizes by using heuristics and stochastic search--piling crap on
top of crap, and obfuscating into oblivion.

Engineering optimizes by finding elegant mathematical solutions.

Sorry, getting off-topic. I guess I'm just bitter about not being a robot.

~~~
wladimir
Evolution "optimizes" for a lot more constraints. It needs to be self-healing,
and work for a long time without any outside maintenance and monitoring. It
collects its own energy, and competes with (unpredictable) other organisms for
nutrients and sunlight.

Good luck engineering a system like that. Elegant mathematical solutions are
great, but only exist for limited, well-defined problems.

------
bad_user

        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.

~~~
ginkgo
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.

------
steamboiler
On a lighter note, this is what Dilbert/Dogbert have to say on new "green"
breakthroughs.

<http://dilbert.com/fast/2011-03-29/>

------
grammaton
"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?

------
gacek
Lets wait until this has some peer-revied tests and they can claim a certain
output in KWh for a sunny day in California or some region of Africa.

------
rbanffy
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.

------
naz
By what definition of efficiency? I'm sure a leaf costs much less energy to
produce than one of these.

------
viggity
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.

------
alantrrs
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...](http://www.energiaadebate.com/Articulos/noviembre2007/imagenesnov/Solis.pdf)

~~~
mikexstudios
No, it's not Melanin. It's a cobalt oxide complex.

------
mhb
How are these reconciled? Optimism?:

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
The previous artificial leaf and the current one are different things.

~~~
mhb
But 45 hours and one day aren't that different.

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

~~~
mhb
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?

~~~
jedsmith
"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.

