
'Major discovery' from MIT primed to unleash solar revolution - nreece
http://web.mit.edu/newsoffice/2008/oxygen-0731.html
======
ars
OK, I tried. I really tried to give them the benefit of the doubt - I mean
it's mit.edu, but seriously what they wrote there and what I know of physics
have little to do with one another.

I fell like I'm missing a joke somewhere.

First off: what does electrolysis have to do with photosynthesis? If you want
to store energy it's just as important with wind, or any other.

Second: photosynthesis and photovoltaics are not the same thing. They seem to
confuse them quite a bit. And on top of that, this seems to have nothing to do
with either of them - it's all about electrolysis.

Third: "Currently available electrolyzers, which split water with electricity
and are often used industrially, are not suited for artificial photosynthesis
because they are very expensive and require a highly basic (non-benign)
environment that has little to do with the conditions under which
photosynthesis operates."

Has so many errors I don't even know where to start.

a: electrolysis does not require a basic environment, it requires a salty one.

b: again mixing up photosynthesis and photovoltaics

c: there is no such a thing as artificial photosynthesis. Only plants know how
to make hydrocarbons from water CO2 and light.

If someone actually did manage to create artificial photosynthesis that would
be massive. Which is what I hoped to read about here, and then I didn't.

Fourth: they start off saying something about advances in solar power, and
well? Where was the advance? All I see is something about electrolysis.

Fifth: "[plants] storing energy for use when the sun doesn't shine." Most
plants don't actually do that. They don't store energy, they make
hydrocarbons, which are not an energy source for them, they are the final
product. (For us the hydrocarbon is energy storage.) There is the CAM
photosynthesis cycle used by pineapples, which does actually store energy for
later. But the only reason the pineapple does that is so that it doesn't dry
out during the hot day, so rather it collects it's CO2 at night. This does not
seem to apply here.

Someone: please tell me if I missed something massive, but this really looks
like the kind of nonsense energy inventions you read about all the time. But,
but, but it's on mit.edu!

~~~
ztravis
You are correct about your first point - the connection with photosynthesis is
shaky at best. This research describes a new electrocatalyst for the
production of oxygen. The source of electrical energy for driving this
production could be solar cells, but that would be just one potential use.

The paper does focus on photosynthesis, however, because the Nocera's lab
works on "artificial photosynthesis," a field largely devoted to understanding
the electrochemical processes of photosynthesis and mimicking them in man-made
systems. For the most part, "artificial photosynthesis" focuses not on carbon
fixation but on the transformation of light to electrochemical energy (via
electron/proton transfer). This is the process that Nocera's research is
replicating, and likely why he focuses on using solar cells as the source of
energy, to parallel a plant's use of solar energy as a route to energy
storage/O2 production.

Finally, I think some of your scientific analysis needs correction:

Electrolysis (in its simplest form) doesn't require any solute - it can be
performed, very slowly, in pure water. Adding salt (say, NaCl), as you
mention, speeds up the rate greatly. However, in doing so, the reaction
changes - you'll evolve hydrogen as before, but at the anode you'll evolve
chlorine gas, not oxygen. You can't use electrolysis alone to produce oxygen
gas or as a route to storing energy. One alternative to this is to use an
electrocatalyst, but currently, (as the article mentions), the only available
catalysts require expensive metals or very basic environments (or both). This
article is on the discovery of a new catalyst that will allow for the
production of oxygen via catalyzed electrolysis at neutral pH and with a
cheap, abundant catalyst (cobalt).

Also, if we're looking at the same quote: "storing energy for use when the sun
doesn't shine," the article is talking about humans storing energy, not
plants. Even so, plants do store energy for when the sun doesn't shine. They
metabolize hydrocarbons into ATP via mitochondria, just like we do - so
glucose and other products of photosynthesis are indeed forms of stored
energy.

I think a lot of the confusion stems from the fact that we're reading a
popular article and not the actual research - these articles tend to pick up
on terms like artificial photosynthesis, energy production, and solar energy
and run with them.

~~~
ars
Thanks for the clarifications.

>artificial photosynthesis" focuses not on carbon fixation but on the
transformation of light to electrochemical energy (via electron/proton
transfer).

Then why call it photosynthesis? It's not, it's photovoltaics. If you want
photosynthesis you have have to fix carbon, or you're making a mockery of the
term. And if you are making hydrogen directly, then call it photolysing.

Either way you are not synthesizing anything.

I didn't realize that chlorine is preferred to O2, but what does it matter? I
don't want O2, I want H2, and once all the chlorine is gone, won't the sodium
hydroxide work just as well as NaCl? Or is that what you mean by 'very basic
environment'?

They should rewrite that article and omit any mention of solar, just say they
invented a new cheaper way to electrolyze water. Applications include storing
energy from solar or wind for when the sun isn't shining.

Doesn't the above paragraph make a lot more sense than the parent article?

~~~
ztravis
To be honest, I don't know why it's called artificial photosynthesis versus
photovoltaics - perhaps it is because this research looks to the actual
chemical systems involved in photosynthesis as models for man-made systems (as
opposed to trying to develop light-converting systems ab initio). In any case,
"artificial photosynthesis" is commonly used to refer to research both on
hydrolysis via solar energy and carbon fixation into organic compounds, both
of which are fundamental to photosynthesis as a whole.

I was wrong about the chlorine production, actually - it only occurs at high
concentrations of salt. Otherwise (or with different solutes), you can produce
oxygen. Still, I believe that this reaction is not efficient enough to be
feasible as an energy source. Overall, you do want the hydrogen, but you also
need an oxidant to, for example, run a fuel cell. I think there are hydrogen-
chlorine fuel cells, but I imagine it would be easier and more practical to
run a hydrogen-oxygen cell instead to avoid using chlorine gas/producing HCl.
In any case, it boils down to developing catalysts to improve the rate and
efficiency of this electrolysis (by lowering overpotentials).

I agree with you that your paragraph makes a lot more sense than the parent
article. It's annoying how these press releases make things seem much more
revolutionary than they really are.

------
stanley
Decentralization of energy production will be revolutionary.

This particular article, on the other hand, makes no mention of the economic
factors involved in the said processes. To top it off, there's been a sway of
"amazing solar discoveries" recently and we'd be lucky to see a handful of
them actually make it into the real world. That said, I'll believe it when I
see it.

~~~
d0mine
Regarding economics factors:

 _Requiring nothing but abundant, non-toxic natural materials, this discovery
could unlock the most potent, carbon-free energy source of all: the sun._
</quote>

 _Now we can split the water (H2 + O2) in a cheap efficient and highly
manufacturing way_ </quote>
<http://www.sciencemag.org/cgi/content/full/sci;1162018/DC2>

Though It requires Platinum at the moment (Pt is not a cheap earth-abundant
material).

~~~
berryg
In the podcast (<http://www.sciencemag.org/cgi/content/full/sci;1162018/DC2>)
Nocera explains the process perfectly. This "missing link" in electolysis has
been the production of O2. Now this is possible. And now a closed loop of
water splitting and water production is possible for the first time
apparently. So, this could indeed be a possible way to store energy for times
when there is no sun or wind available to produce electricity. Nocera also
mentions that there are already alternatives for Pt for the hydrogen
production and they are going to test them.

However, indeed nothing is said on the efficiency of the whole process and
thus the economics of this process. How large a system do you need for a
household and what would it cost? Hopefully we will get answers soon.

Still you need photovoltaic cells or windmills to produce electricity for your
house, your car, etc. And you need extra electricity to produce H2 and O2 for
times when there is no sun or wind. PV cells still cost a lot and still are
not efficient enough (thus take up too much space). So, there are still other
missing links to solve to really start a electricity revolution.

~~~
ars
Hu? electolysis makes O2 just fine.

~~~
orib
Not without large amounts of waste energy. This energy cost makes electrolysis
impractical for efficient energy storage.

If you could reduce the amount of energy required to electrolyze water, then
it would make an extremely good energy storage vehicle. That's exactly what
this research is about.

~~~
ars
Releasing or not releasing O2 has nothing whatsoever to do with waste energy.
It's _impossible_ to electrolyze water without releasing O2.

It's great to try to make it more efficient, but this research doesn't
actually do that, it just makes the equipment cheaper, but at the same
efficiency.

And besides electrolysis is a terrible way to store energy because storing
hydrogen is impractical (it leaks right though metal). Plus there are
unavoidable inefficiencies.

------
shimon
The desire to store generated energy for use at a different time isn't limited
to solar cells or other day-only sources. A similar problem is posed by the
fact that conventional power stations have a fixed maximum throughput, but
demand is much higher during the day.

To balance the load and maximize revenue, a number of power producers employ a
decidedly low-tech way to store energy: every night, they pump a lake of water
up a mountain, and during the day they drain it through hydroelectric
generators.

Really! I shit you not: <http://en.wikipedia.org/wiki/Pumped-
storage_hydroelectricity>

~~~
wallflower
Also, the economics work because the demand for power (to pump) is much lower
at night than during the day. So that they aren't eating into their customer's
electricity consumption.

------
nazgulnarsil
its not just electricity. decentralization is going to be the major hurdle of
the 21st century. we may even get to the point of one world government before
we realize how stupid and inefficient it is.

------
fizx
According to wikipedia, electrolysis is currently around 65% efficient, with a
theoretical cap somewhere around 90%. So this could help, but it's not going
to be an order of magnitude improvement.

Also, storing large quantities of (I assume pressurized) gas has got to be
expensive. The nice thing about liquids is that you can store them in a vat,
or a dammed up canyon.

I didn't rtfa, its probably cool tech, but hardly a revolution. Good luck
guys.

~~~
pmorici
That was my question too. I had always thought electrolysis was a non starter
for large scale production because of the inefficiencies involved.

Even th article seems to focus on how they invented non-toxic catalysts. It
mentions nothing about improving the efficiency of the reaction.

------
ericb
Anyone notice after a couple years of reading digg, reddit, hacker news, even
CNN, that these breakthroughs we are continually excited about don't seem to
go anywhere? I know things take time time, but I keep waiting for just one of
these breakthroughs to make it to the real world, and I can't think of any so
far where I read about it, and now it is here.

------
danteembermage
What's not clear to me from the article is, if the cheap easy catalyst makes
oxygen gas from water, what's left over before we get the platinum involved,
perhaps a bunch of hydrogen ions in solution? Something like 6xH20 -> O2 +
2xH30 or 2xH20 -> O2 + 2H+

~~~
ars
What? You can't make oxygen gas and hydrogen ions at the same time. If you
make oxygen gas you also make hydrogen gas. Which is not a big deal,
electrolysis is not new.

Not sure what the platinum has to do with it though.

~~~
orib
Who says you're making necessarily making oxygen gas? I don't know the details
of current industrial processes, but you can easily free hydrogen by
displacing it with something that binds more tightly (eg, Sodium: 2H2O + 2Na
=> H2 + 2NaOH) and produce free hydrogen gas with sodium hydroxide waste. I
suspect that a similar sort of process is happening currently when water is
hydrolyzed with a "catalyst" in current processes.

Platinum is often used in catalysts. It works by providing an alternative
reaction pathway that takes less energy to fuel the reaction. An analogy is
that instead of rolling a rock up a hill to get it from point A to point B,
the catalyst provides access to a tunnel through the hill.

~~~
ars
If you're reacting sodium to water to get hydrogen you're not exactly
electrolyzing water now are you?

The same is true with current processes, if your catalyst is being used up to
bind oxygen then a: it's not a catalyst it's a reactant, and b: well don't,
and c: you're not electrolyzing water, you're doing some more complicated
reaction.

So emitting O2 from electrolysis is not even the slightest bit new. That part
of the article was basically nonsense.

------
tlrobinson
So what's the catch? If there is none, then this could be huge.

------
strayLolCat
So now they know how to efficiently store Hydrogen as gas ?

------
chrisconley
awesome stuff though Kocera seems to be drinking a little too much of his own
koolaid

