Duplicating MIT's artificial photosynthesis breakthrough

[James Arthur]

Not only do thay ignore the hydrogen storage problem, they seem to
think you can hop on over to Ace Hardware and pick up a convenient
fuel cell system.

John

Scientists aren't engineers.

--James Arthur

 

[Bill Ghrist]

James Arthur wrote:
....

Sure. He misspoke. Or was misquoted. He meant apply PV output
to his electrolysis cell, and make gasses.

IOW, take an already inefficient source, toss away perhaps
2/3rds of that output to make something that you'll later
burn, tossing away yet another 50-60%.

12% x .5 x .5 = 3%. I'd be pleasantly surprised if the
thing's overall efficiency exceeded 2%.

Cheers,
James Arthur

Whether that is accurate or not, it misses the main point, which is the
question of how you use solar energy when then sun goes down (or the
equivalent: how you use wind energy when the wind stops blowing). Solar
and wind will remain minor contributors to our energy supply until we
have an inexpensive means of addressing that issue. Storing some of the
energy for later use is one obvious approach. Efficiency is only one
factor in the expense of storing energy. The lower the capital and
operating costs are (as well as the environmental impact, if you include
that as a "cost"), the less efficiency is required in order to be
economically feasible. Whether the MIT discovery will eventually lead
to a cost effective solution is unknown at this point, but its potential
contribution appears to be the lowering of capital costs more than any
increase in efficiency. I don't have access to the Nature paper,
however, so it is a bit difficult to tell from the (as others have
noted) rather poorly written press releases.

Regards,
Bill Ghrist

 

[HarryD]

A lot of energy breakthroughs devolve to bad calorimetry.

John

Is this not the same school that discovered Resonate Energy Tunneling
(Marin Soljacic from the Massachusetts Institute of Technology).
Big hat, no cattle!
Harry

 

[James Arthur]

James Arthur wrote:
...

Whether that is accurate or not, it misses the main point, which is the
question of how you use solar energy when then sun goes down (or the
equivalent: how you use wind energy when the wind stops blowing). Solar
and wind will remain minor contributors to our energy supply until we
have an inexpensive means of addressing that issue. Storing some of the
energy for later use is one obvious approach. Efficiency is only one
factor in the expense of storing energy. The lower the capital and
operating costs are (as well as the environmental impact, if you include
that as a "cost"), the less efficiency is required in order to be
economically feasible. Whether the MIT discovery will eventually lead
to a cost effective solution is unknown at this point, but its potential
contribution appears to be the lowering of capital costs more than any
increase in efficiency. I don't have access to the Nature paper,
however, so it is a bit difficult to tell from the (as others have
noted) rather poorly written press releases.

Regards,
Bill Ghrist

If it's 2% efficient, it's not economic.

Photovoltaic systems (including inverters, installation,
wiring, battery, backup, etc.) aren't economic to the
consumer above about $3/watt, or about $1.50-2.00/watt
for the panels all by themselves. That's about 1/3rd
the current price.

With this new-fangled innovation you'd have to quadruple
your PV array, plus buy and maintain storage and
generation-from-gas facilities to make up for the storage
losses. These increase your system cost perhaps 6- to
10-fold. More for a fuel cell.

If you're going to use a very expensive power source,
you can't afford to waste 3/4 of it.

Cheers,
James Arthur

 

[Eeyore]

A lot of energy breakthroughs devolve to bad calorimetry.

John

Interesting you should say that.

I'm convinced that the supposed efficiency of the 'water car' as promoted by
Meyer was based on incorrect readings of pulse waveforms by primitive meters.

Graham

 

[whit3rd]

When I first heard about this, I thought they had come up with a cheap
method to directly split water with sun light. Unfortunately that is NOT the
case.

No, FORTUNATELY that is not the case. To directly split water
to H2 gas and O2 gas would make an explosive gas mixture at
the active site. With separated electrodes, one can collect
H2 gas bubbling from one electrode, and collect (or discard)
the O2 gas from the other electrode.

The 'use' of the catalyst doesn't use it up, so expense is low.
Mainly, efficiency of the electrolysis is higher than with untreated
electrodes, which is important if you want to scale the process
up. It's extremely important if you want to scale
the process 'way up'

It's disadvantageous, however, to form small bubbles (the
surface tension makes a high back-pressure which translates
to gas generation inefficiency). It would be good to find some way
around that step entirely.

 

[Sevenhundred Elves]

No, FORTUNATELY that is not the case. To directly split water
to H2 gas and O2 gas would make an explosive gas mixture at
the active site. With separated electrodes, one can collect
H2 gas bubbling from one electrode, and collect (or discard)
the O2 gas from the other electrode.

The 'use' of the catalyst doesn't use it up, so expense is low.
Mainly, efficiency of the electrolysis is higher than with untreated
electrodes, which is important if you want to scale the process
up. It's extremely important if you want to scale
the process 'way up'

It's disadvantageous, however, to form small bubbles (the
surface tension makes a high back-pressure which translates
to gas generation inefficiency). It would be good to find some way
around that step entirely.

Then the vanadium redox flow battery seems to be a better way of
storing electric energy. Energy density is low, so those batteries are
useless for powering vehicles, but since they can be built very large,
they seem ideally suited for fields of wind generators, solar panels
and such.

Quoting the Wikipedia,

http://en.wikipedia.org/wiki/Vanadium_redox_battery

: Currently installed vanadium batteries include:
:
: * A 1.5MW UPS system in a semiconductor fabrication plant in Japan
:
: * A 275 kW output balancer in use on a wind power project in the Tomari Wind Hills of Hokkaido
:
: * A 200 kW, 800kWh output leveler in use at the Huxley Hill Wind Farm on King Island, Tasmania
:
: * A 250 kW, 2MWh load leveler in use at Castle Valley, Utah
:
: * A 12 MWh flow battery is also to be installed at the Sorne Hill wind farm, Donegal, Ireland

This is proven technology, currently in use (except for the projected
last one). I think the numbers above speak for themselves.

S.

 

[Rob Dekker]

Could this be duplicated by anyone with basic electronics knowledge
and the right metals?

From the article:

The new catalyst works at room temperature, in neutral pH water, and
it's easy to set up, Nocera said. "That's why I know this is going to
work. It's so easy to implement," he said.

http://web.mit.edu/newsoffice/2008/oxygen-0731.html

Seems that everyone agrees that Nocera presents a lot of fluff and very little beef.
There is now even a $25 price set on a translation in plain English of what on Earth he is talking about :

http://infiniflux.blogspot.com/2008/07/daniel-noceras-big-secret-paper.html

Note the responses. It seems that his 'idea' has nothing to do with storing anything (let alone storing solar energy).
It is simply electrolysis, as we already suspected, but it seems to be a pretty efficient form of electrolysis.

Wikipedia (with references) reports :
The efficiency is a measure of what fraction of electrical energy used is actually contained within the hydrogen. Some of the
electrical energy is converted to heat, a useless by-product. Some reports quote efficiencies between 50% and 70%[1] This efficiency
is based on the Lower Heating Value of Hydrogen. The Lower Heating Value of Hydrogen is total thermal energy released when hydrogen
is combusted minus the latent heat of vaporisation of the water. This does not represent the total amount of energy within the
hydrogen, hence the efficiency is lower than a more strict definition. Other reports quote the theoretical maximum efficiency of
electrolysis as being between 80% and 94%.[2]

So it seems that at best he could have increased efficiency a few dozen percent, but he uses rare and expensive metals (Cobalt and
Platinum).
And too bad he says nothing about storing Hydrogen. Which is off course where the real magic should happen.

Maybe enough for a nich-market startup, but certainly useless as a way to 'store' solar energy on a large scale as he 'claims'.

Rob

 

[Eeyore]

Could this be duplicated by anyone with basic electronics knowledge
and the right metals?

From the article:

The new catalyst works at room temperature, in neutral pH water, and
it's easy to set up, Nocera said. "That's why I know this is going to
work. It's so easy to implement," he said.

http://web.mit.edu/newsoffice/2008/oxygen-0731.html

Seems that everyone agrees that Nocera presents a lot of fluff and very little beef.
There is now even a $25 price set on a translation in plain English of what on Earth he is talking about :

http://infiniflux.blogspot.com/2008/07/daniel-noceras-big-secret-paper.html

Note the responses. It seems that his 'idea' has nothing to do with storing anything (let alone storing solar energy).
It is simply electrolysis, as we already suspected, but it seems to be a pretty efficient form of electrolysis.

Wikipedia (with references) reports :
The efficiency is a measure of what fraction of electrical energy used is actually contained within the hydrogen. Some of the
electrical energy is converted to heat, a useless by-product. Some reports quote efficiencies between 50% and 70%[1] This efficiency
is based on the Lower Heating Value of Hydrogen. The Lower Heating Value of Hydrogen is total thermal energy released when hydrogen
is combusted minus the latent heat of vaporisation of the water. This does not represent the total amount of energy within the
hydrogen, hence the efficiency is lower than a more strict definition. Other reports quote the theoretical maximum efficiency of
electrolysis as being between 80% and 94%.[2]

So it seems that at best he could have increased efficiency a few dozen percent, but he uses rare and expensive metals (Cobalt and
Platinum).
And too bad he says nothing about storing Hydrogen. Which is off course where the real magic should happen.

Maybe enough for a nich-market startup, but certainly useless as a way to 'store' solar energy on a large scale as he 'claims'.

It's a drop in the ocean.

Seeing as how the 'hydrogen economy' is so farcical in the first place a couple of 10% improvement isn't going to help much.

Incidentally, seen what highly pressurised gas bottles can do recently ?

Graham

 

[Eeyore]

Following up my own post is bad form, but I have just found the least
garbled summary of their invention so far online at EE Times:

http://www.eetimes.com/showArticle.jhtml?articleID=209900956&cid=NL_eet

The claimed efficiency is "almost 100%" (sic). I'd be much happier if
they actually gave a number. I thought thermodynamics set a limit
somewhat lower than that. Have I missed something?

Interesting. The electrolysis may approach 100% but the solar cells are still
only around 15% and H2 fuel cells ~ 50%.

No cigar I'm afraid.

Graham

 

[James Arthur]

Interesting. The electrolysis may approach 100% but the solar cells are still
only around 15% and H2 fuel cells ~ 50%.

No cigar I'm afraid.

Graham

Nearly 100% efficient electrolysis would be a step, and that's
what R. Colin "neural-networks" Johnson wrote, but that's NOT
what the guy said. He said:

"In fact, with our catalyst almost 100 percent of the
/current/ used for electrolysis goes into making oxygen and
hydrogen." (emphasis added)

AIUI, this doesn't count I^2 * R drop.

Cheers,
James Arthur

 

[James Arthur]

As clear as mud. However, a quick search of patents filed did reveal
some other interesting (but I would guess still rather unstable real
photosynthetic mimics that can crack water using light). It seems the
state of the art ones last about 4 hours in sunlight at present.

http://appft1.uspto.gov/netacgi/nph...alt&OS=Nocera+AND+cobalt&RS=Nocera+AND+cobalt


That is a real system with photons in hydrogen out. And they do
reference Nocera's work indirectly. I could not find anything relating
to this recent paper.

It certainly looks that way. I asked my tame electrochemist
(non-industrial) to attempt a translation of the gibberish MIT press
release. Their comments were as follows:

Benign reaction conditions and neutral pH would be cute if it was
coupled with high efficiency and high current capacity.

It is possible that they have found something that works better and has
lower cell overpotential (less waste heat, better efficiency).

The invention/discovery relates to the oxygen electrode and electrolyte
allowing it to be made from a much cheaper material without corroding.

It looks like electrolysis and still seems to use platinum for the
hydrogen electrode.

They also said that the Henry Drefus Professor of Energy at MIT might
reasonably be expected to know what he was talking about and that
something has gone horribly wrong in the press office. The paper was
after all published in Science and presumably survived peer review. I
haven't had a chance to chase down a copy yet.


Be fair lets assume his convertion is at least as good as present state
of the art and a decent fuel cell for the reverse process.

That's fair enough--I was hasty. But let's be sure we add in
the cost of state of the art too, if we use it.

12% x 0.7 x 0.7 = 6% which is about as good as the best photosynthesis
(although at a combined cost of at least $5000 / per installed kW
excluding the cost of the electrolysis kit, gas compressor and storage).
It would be even better efficiency with one of the fuel cells that heat
domestic hot water with its waste heat.

Incidentally the "humble" lead acid battery would also manage about 70%
storage efficiency.

Or LiIon cells, which claim high-90's storage efficiency.

I have removed sci.electronics.basics and added sci.chem to the cross
posting list in the hope that a few of the regulars there will chime in.
A contribution from someone working on state of the art industrial
electrolysis cells would be most welcome.

The MIT press release that requires translation out of gibberish is at:

http://web.mit.edu/newsoffice/2008/oxygen-0731.html

Thanks for any enlightenment.

Cheers,
James Arthur

 

[Rob Dekker]

Nearly 100% efficient electrolysis would be a step, and that's
what R. Colin "neural-networks" Johnson wrote, but that's NOT
what the guy said. He said:

"In fact, with our catalyst almost 100 percent of the
/current/ used for electrolysis goes into making oxygen and
hydrogen." (emphasis added)

AIUI, this doesn't count I^2 * R drop.

Cheers,
James Arthur

He claims that "almost 100 percent of the current used for electrolysis goes
into making oxygen and hydrogen".
Let's assume 95% goes to creating hydrogen/oxygen.

We don't know the losses unless we know the overpotential. And that is here
:
It appears that he arranged the electrides so that he could do electrolysis
60mV above the thermodynamic value (1.29V vs. 1.23). This is the
"overpotential", and that would mean 60mV goes to losses.
60mV over 1.23 is 5% losses on the voltage side. This 60 mV is responsible
for moving the electrons (or ions) through the solution.

So 95% of the voltage and 95% of the current go to forming hydrogen and
oxygen. That is a power efficiency of 90%.

Currently, Norsk Hydro Electrolysers (NHE) (a leading producer of alkaline
electrolysers) has electrolysers that have an efficiency of over 80%. These
are widely used in Norway, where electricity from hydro plants is fairly
abundant and cheap.

So Nocera has found an electrolysis method that is 10% better than what is
industry standard practice. That's it.
Nothing was said about the current density (at this 60mV overpotential) yet.
If current density is really low, the practical use of the electrolyser is
deminishing.

10% improvement of electrolysis efficiency. Is this a big thing ? Maybe in
the electrolysis market (5% of the hydrogen market). But only if the extra
expense of rare metals can be validated. And 10% of a 5% of a already very
small market is not a whole lot.....

Either way, it certainly has nothing to do with storing solar energy or
anything else that he claims. In fact, I am very disappointed and almost
shocked by what this scientist has to say. Very vague, and very
unsubstantial. Very un-scientific.

By the way, there is a prize if you can explain in plain English what he is
saying.
http://infiniflux.blogspot.com/2008/07/daniel-noceras-big-secret-paper.html

I really hope that he shows his face and explains himself what on Earth he
actually did accomplish.

Rob

 

[Eeyore]

He claims that "almost 100 percent of the current used for electrolysis goes
into making oxygen and hydrogen".
Let's assume 95% goes to creating hydrogen/oxygen.

We don't know the losses unless we know the overpotential. And that is here
:
It appears that he arranged the electrides so that he could do electrolysis
60mV above the thermodynamic value (1.29V vs. 1.23). This is the
"overpotential", and that would mean 60mV goes to losses.
60mV over 1.23 is 5% losses on the voltage side. This 60 mV is responsible
for moving the electrons (or ions) through the solution.

So 95% of the voltage and 95% of the current go to forming hydrogen and
oxygen. That is a power efficiency of 90%.

Currently, Norsk Hydro Electrolysers (NHE) (a leading producer of alkaline
electrolysers) has electrolysers that have an efficiency of over 80%. These
are widely used in Norway, where electricity from hydro plants is fairly
abundant and cheap.

So Nocera has found an electrolysis method that is 10% better than what is
industry standard practice. That's it.
Nothing was said about the current density (at this 60mV overpotential) yet.
If current density is really low, the practical use of the electrolyser is
deminishing.

10% improvement of electrolysis efficiency. Is this a big thing ? Maybe in
the electrolysis market (5% of the hydrogen market). But only if the extra
expense of rare metals can be validated. And 10% of a 5% of a already very
small market is not a whole lot.....

Either way, it certainly has nothing to do with storing solar energy or
anything else that he claims. In fact, I am very disappointed and almost
shocked by what this scientist has to say. Very vague, and very
unsubstantial. Very un-scientific.

Nicely explained.

Graham

 

[Eeyore]

Power efficiency would be 95% @ the stated current density.
Voltage loss would increase as current denisty increases, but that
would still be a linear relationship.

How do we know that for a fact ?

Graham

 

[Ian Gay]

How do we know that for a fact ?

It isn't. Overvoltage will increase with current density, so the product
of overvoltage and current will increase faster than linearly.

 

[Rob Dekker]

......

Incorrect, 100% of the current goes into the reaction..
Electrons/Ions still accomplish work on a 1 to 1 basis.

I don't think you can make that assumption immediately.
Below 1.23 V, NONE of the electrons can cause ionization, so I think it is premature to assume that 100% of the electrons cause
ionization at 1.29 V.
I used 95% based on Nocera's "almost 100%" claim.

Power efficiency would be 95% @ the stated current density.

I doubt that. It's probably safer to say that with 60 mV overpotential, that the power efficiency must be BELOW 95%.
I think it's close to 90% overall.

Voltage loss would increase as current denisty increases, but that
would still be a linear relationship.

AFAIK, it's the other way around : as Voltage (overpotential) increases, the current density increases.
Unfortunately, overpotential is by definition a loss, so you want to keep that as low as possible.
Also, the increased current density that would result from increased overpotential could further reduce efficiency if the electrodes
'saturate' (due to bubble forming etc).

Long story short : Nocera should at least report current density at 60 mV overpotential, and preferably a graph showing efficiency
of production of H2/O2 w.r.t. current density and overpotential.

Rob

 

[Eeyore]

It isn't. Overvoltage will increase with current density, so the product
of overvoltage and current will increase faster than linearly.

Thank you. I thought it sounded over simplistic.

Graham

 

[z]

He claims that "almost 100 percent of the current used for electrolysis goes
into making oxygen and hydrogen".
Let's assume 95% goes to creating hydrogen/oxygen.

We don't know the losses unless we know the overpotential. And that is here
:
It appears that he arranged the electrides so that he could do electrolysis
60mV above the thermodynamic value (1.29V vs. 1.23). This is the
"overpotential", and that would mean 60mV goes to losses.
60mV over 1.23 is 5% losses on the voltage side. This 60 mV is responsible
for moving the electrons (or ions) through the solution.

So 95% of the voltage and 95% of the current go to forming hydrogen and
oxygen. That is a power efficiency of 90%.

Currently, Norsk Hydro Electrolysers (NHE) (a leading producer of alkaline
electrolysers) has electrolysers that have an efficiency of over 80%. These
are widely used in Norway, where electricity from hydro plants is fairly
abundant and cheap.

So Nocera has found an electrolysis method that is 10% better than what is
industry standard practice. That's it.
Nothing was said about the current density (at this 60mV overpotential) yet.
If current density is really low, the practical use of the electrolyser is
deminishing.

10% improvement of electrolysis efficiency. Is this a big thing ? Maybe in
the electrolysis market (5% of the hydrogen market). But only if the extra
expense of rare metals can be validated. And 10% of a 5% of a already very
small market is not a whole lot.....

Either way, it certainly has nothing to do with storing solar energy or
anything else that he claims. In fact, I am very disappointed and almost
shocked by what this scientist has to say. Very vague, and very
unsubstantial. Very un-scientific.

By the way, there is a prize if you can explain in plain English what he is
saying.http://infiniflux.blogspot.com/2008/07/daniel-noceras-big-secret-pape...

I really hope that he shows his face and explains himself what on Earth he
actually did accomplish.

Rob- Hide quoted text -

- Show quoted text -

it's not like the infrastructure for replacing batteries with H2 and
fuel cells is in place and just waiting to benefit from small
incremental increases in efficiency. give us something that will
charge cell phone and laptop batteries 10% more efficiently and you'll
make a dent in things.

 

[JosephKK]

Not only that but it could be "duplicated" by the original discoverers
of electrolysis of water over 250 years ago - shortly after the first
primitive batteries were invented by Volta.

Not invented by Volta, used by the ancient Egyptians 2500 years ago.
Do bother to learn your science history properly, please.