Solar energy breakthrough

[mb]

Looks to me like the big plus with this is cheap catalysts on the electrolysis side of things. IIRC the energy available from the resulting hydrogen has historically been about half of the energy cost to separate it from water. Still leaves me the question about why we dont just capture the electricity from the solar panel into a battery and skip a couple of levels of efficiency loss.

Yes, I agree, a solar cell battery system is currently a more efficient way to do this. Improving the oxygen reaction efficiency makes it a closer competition and although I can't give you the actual numbers I'm pretty sure that the conventional solar cell/battery will still have an advantage.

I think that perhaps the more important point is that there are many other industrial applications many of which the public doesn't know about where this could improve efficiency and save millions of $ in energy costs long before the so-called "hydrogen economy" comes into existence, if indeed it ever comes into existence.

But a story suggesting that maybe, just maybe, in the future, we will use this to run our cars or heat our homes and perhaps give some relief on energy costs and reduce oil imports sells a lot better than one saying some chemical company is going to save $/year in energy costs starting a year or two from now because they now have a better catalyst.

MB

 

[harley]

Generally when clearly articulated facts are not in evidence, it means that the facts arent very good and dont contribute well to the general urgency to get everyone excited about something.

Looks to me like the big plus with this is cheap catalysts on the electrolysis side of things. IIRC the energy available from the resulting hydrogen has historically been about half of the energy cost to separate it from water. Still leaves me the question about why we dont just capture the electricity from the solar panel into a battery and skip a couple of levels of efficiency loss.

I agree about the lack of facts being annoying. However, in one of the articles I skimmed they made a point of saying that this new process was specifically more efficient than storing in batteries as far as dark-time usage was concerned. So I think the point of the discovery, completely missed by most talking heads, was for more efficient release of energy when the sun don't shine.

 

[cute fuzzy bunny]

Sure. But then you have to compress the hydrogen into a tank and pay for the electricity to run the compressor out of your efficiency (unless we all have a zeppelin in our back yards), and your equipment tally is now a solar array, an electrolysis machine, a hydrogen compressor, and something to burn the hydrogen and turn it into electricity or mechanical energy.

I could be way off, but that sounds like 40-50k worth of equipment after it hits volume production discount level. If you went to direct burn, add a new furnace, air conditioner, car, etc to the equation. A lot of those things carry 5-20 year average service lives...so a long adoption curve.

Maybe more reasonable to do this commercially where you'd have a few football fields worth of solar panels, a big separator, some humongous high pressure tanks and a generator that runs on hydrogen and feeds the power grid.

Still thinking there'd be some hard looks at the gas compression and storage costs and the generator costs vs batteries.

 

[mb]

I am a chemical engineer and I cannot figure out what this new advance does from the press release.

I agree with cfb on batteries.

Ed, I'm also a ChE and I've done a lot of work in the area of batteries, fuel cells, energy storage and conversion and electrochemistry.

A couple of mundane applications for a better oxygen catalyst that come to mind follow. I'm sure that there are others.

- Zinc/air batteries are used in hearing aids. A better catalyst for the air/oxygen electrode may enable lower cost and/or higher power and/or smaller zinc/air batteries. There are also several other types of metal/air batteries most of which have not advanced to commercialization, partially because of the oxygen electrode probems, that this could help improve.

- Adiponitrile, which is a precursor to nylon, is made by an electrosynthesis reduction reaction. I'm not sure about the oxidation reaction so I could be all wrong on this but the most obvious is oxygen evolution. If that is the case then a better oxygen catalyst should reduce energy costs for the nylon manufacturers.

MB

 

[NW-Bound]

MB may be able to help me here.

Only skimming the article, not knowledgeable about catalysts, I thought they were talking about directly getting hydrogen from sunlight, not by electrolysis. Yes?

If so, hydrogen gas can be accumulated and stored with higher energy density than the best battery technology so far, i.e. Lithium Ion. Yes?

I'd think plain photovoltaic panels for the forseable future will remain the only feasible home scale solar source. Other technologies appear to be more amenable for massive industrial plants to be economically feasible. Yes?

 

[mb]

I could be way off, but that sounds like 40-50k worth of equipment after it hits volume production discount level. .

No, no, no. You're costs are probably a couple of orders of magnitude to low. We're talking real man size equipment here. Not that little itty-bitty stuff that you guys use to make those computer chips. After all what sort of real man wants to spend his career making things smaller

Of course you did ER so maybe it wasn't a bad choice

But seriously there was a study that suggested (I was always a little sceptical myself of the results) that for really large quantities of energy over very large distances that it was cheaper to move it as hydrogen rather than electrical power. But I think that the key was really large quantities and long distances. You needed to get to the scale of the Alaska pipeline before it made any sense.

MB

 

[cute fuzzy bunny]

I'm not mb but I think I can help.

They're using the solar to power an electrolysis process to separate hydrogen from water. Solar as opposed to plugging something into the wall.

Sunlight has no hydrogen in it.

All they've done here is come up with something better and more efficient to do the water separation. Traditionally that was done with lots of platinum. This uses cheaper materials.

 

[cute fuzzy bunny]

No, no, no. You're costs are probably a couple of orders of magnitude to low. We're talking real man size equipment here. Not that little itty-bitty stuff that you guys use to make those computer chips. After all what sort of real man wants to spend his career making things smaller

Heyyy...dont make me come over there!

Its definitely an order of magnitude too low...we already read about the guy that spent $500k on it. I was thinking more in line with when you could go buy the system from sears.

I wonder if you'd have to have a "pool guy" come over and mix all the chemicals into the water that the hydrogen is extracted from...

 

[NW-Bound]

I'm not mb but I think I can help.

They're using the solar to power an electrolysis process to separate hydrogen from water. Solar as opposed to plugging something into the wall.

Sunlight has no hydrogen in it.

All they've done here is come up with something better and more efficient to do the water separation. Traditionally that was done with lots of platinum. This uses cheaper materials.

Hey, I am not a chemist, but I am not stupid. I may use the wrong words or not phrasing my questions correctly.

By electrolysis, I meant two electrodes in a solution with a current passing through it, you know, like high school stuff.

What I meant is this new process is not the same as using PV panels to get electricity, then using this electric power in the aforementioned elementary electrolysis.

Who said sun ray carries hydrogen in it?

Come on CFB, I was only teasing you about bacon. Don't be too sensitive, man.

 

[cute fuzzy bunny]

I am not stupid.

Good to have that cleared up

By electrolysis, I meant two electrodes in a solution with a current passing through it, you know, like high school stuff.

Thats exactly what this is. Two electrodes in a bucket of water.

From the article:

"In his experimental system, Nocera immerses an indium tin oxide electrode in water mixed with cobalt and potassium phosphate. He applies a voltage to the electrode, and cobalt, potassium, and phosphate accumulate on the electrode, forming the catalyst. The catalyst oxidizes the water to form oxygen gas and free hydrogen ions. At another electrode, this one coated with a platinum catalyst, hydrogen ions form hydrogen gas."

Who said sun ray carries hydrogen in it?

This?

"I thought they were talking about directly getting hydrogen from sunlight"

Come on CFB, I was only teasing you about bacon. Don't be too sensitive, man.

Bacon? Sensitive?

 

[NW-Bound]

I stopped reading after this sentence.

"Nocera's advance represents a key discovery in an effort by many chemical research groups to create artificial photosynthesis--mimicking how plants use sunlight to split water to make usable energy."

No electrodes there.

Did not see his electrode thinggy mentioned afterwards. So, I guess I do not know what this is all about. Some mumbo jumbo like cold fusion?

About sunray carrying hydrogen, I guess I have to be more careful with my wording, but it was all my fault.

 

[cute fuzzy bunny]

Did not see his electrode thinggy

You should have offered him some lite beer.

 

[HFWR]

Maybe some Hai-Karate, and a Nehru jacket...

 

[FIRE'd@51]

A hydrogen fuel cell has a theoretical voltage of 1.2V but usually operates at about 0.8V. That means a third of the energy is lost because of inefficiencies and a lot of that is because of the inefficiencies of the oxygen reaction.

Isn't the energy output proportional to the square of the voltage? So a loss of 1/3 of the output voltage would lead to a loss of 56% of the energy. Even a small increase in output voltage, say 0.1V, would reduce the energy loss to 44%. So an increase in output voltage of 12% would lead to an energy increase of 27% (56/44).

 

[mb]

Isn't the energy output proportional to the square of the voltage? So a loss of 1/3 of the output voltage would lead to a loss of 56% of the energy. Even a small increase in output voltage, say 0.1V, would reduce the energy loss to 44%. So an increase in output voltage of 12% would lead to an energy increase of 27% (56/44).

No, the V squared relationship is only for a capacitor, where: E = CV^2 / 2.

For a battery or fuel cell you have to go a step backwards to E = integral VI dt, and then integrate over the voltage-current curve which is different for each different chemistry.

MB

 

[mb]

CFB has it right on the device.

For the really techie minded or those with insomnia here is more detail.

You make one electrode from a semi-conductor material and immerse it in an aqueous electrolyte. The other electrode can be similar to those used in a fuel cell and is also immersed in the electrolyte.

You then shine light on the semi-conductor electrode and create conduction band/high energy electrons and/or holes. These then react directly with the water in the electrolyte, electrons being injected from the electrode into the electrolyte at one electrode where oxygen in created and removed from the other electrolyte where hydrogen is created.

Both electrodes have a catalyst layer coated on the surface to decrease the voltage loss needed to make the reactions go. The claim of the MIT group is that they have developed a better catalyst for the oxygen electrode which as you can see is only one subcomponent of the device.

The device is a way to convert solar energy directly into chemical energy in the form of hydrogen but although it sounds like a pretty cool thing I'm pretty sure that it is more efficient to first capture the solar energy with a conventional solar cell and then turn it into H2 in a separate electrolysis plant if you need hydrogen or use it directly as electrical power since that is probably the ultimate use anyway.

MB

 

[samclem]

Or, here's an idea: Instead of shining the light on a semi-conductor electrode, shine it on thousands of acres of farmland. Eat the crops produced. Turn the crop waste into methanol through very well established, mature processes.

Burn the methanol directly in vehicles. If you want, convert the methanol to gasoline through the process develpoed by Mobil many years ago and burn it in existing cars.

Entirely carbon neutral: The plants took the carbon out of the air during photosynthesis last year, now you are burning it and returning it to the atmosphere. That's as "carbon clean" as it is possible to get.

Ooops--sorry. No hydrogen to compress, figure out some way to transport, and needing a tank as big as a phone booth to get a reasonable range. Hydrogen is the ANSWER --I keep forgetting to start from that point.

Back to the regularly scheduled discussion . . .

 

[ls99]

Entirely carbon neutral: The plants took the carbon out of the air during photosynthesis last year, now you are burning it and returning it to the atmosphere. That's as "carbon clean" as it is possible to get.

Ooops--sorry. No hydrogen to compress, figure out some way to transport, and needing a tank as big as a phone booth to get a reasonable range. Hydrogen is the ANSWER --I keep forgetting to start from that point.

Back to the regularly scheduled discussion . . .

There you go, introducing well established and understood methods into a beautiful but un-necessary Hydrogen ANSWER.

 

[cute fuzzy bunny]

Hydrogen is the ANSWER --I keep forgetting to start from that point.

Yep, the laws of unintended consequences mates easily with starting at an answer and backing into the question, doesnt it?

I've been thinking about that whole idea of having a zeppelin in my back yard. That might be pretty cool. Drive that around instead of the car. Hang my tv antenna on it, bet it'd get good reception.

Wow, brain flash...we could all LIVE in hydrogen filled zeppelins that would fill the sky, solar panels mounted on top so you dont have that rainy day problem, and we could all migrate to parts of the world that were the sunniest. Sort of like boating but without the dry rot.

No problems with pollution either. Just throw everything over the side. I'm sure the folks that cant afford zeppelins wont mind too much.

 

[Ed_The_Gypsy]

mb,

You got me thinking. Maybe this process reduces the overvoltage. That's all I can think of.

 

[FIRE'd@51]

No, the V squared relationship is only for a capacitor, where: E = CV^2 / 2.

For a battery or fuel cell you have to go a step backwards to E = integral VI dt, and then integrate over the voltage-current curve which is different for each different chemistry.

MB,

I'm still confused on this point. If I have a "black box" with a constant output voltage of 1.2V and another with a constant output voltage of 0.8V, the 0.8V device will deliver 44% ( (2/3)^2 ) of the energy of the 1.2V device into the same resistive load over the same period of time, regardless of what's going on inside the "black box". In other words, the integral VI dt, is going on inside the box. Isn't all I care about the terminal voltage of the box (independent of whether the box is a battery, a fuel cell, or something else)?

 

[ERD50]

FIRE'd@51, you are correct that .8V applied to a resistive load will produce 44% of the energy that 1.2V will. I'm not a chemist, but I suspect that the voltage involved in electrolysis is not as simple as a resistive load.

Take this example - some cells (batteries) have a voltage of 1.5V, some 3.3V depending on chemistry. All else being equal, the 3.3V cell will produce more energy connected to the same R, but that alone does not make the 3.3V cell more efficient, it's just a different chemistry at a different operating point.

There may be some of this 'operating point' stuff going on with the catalyst, to some degree. Maybe the chemists can confirm/deny that explanation for us.

-ERD50