The "Leaf": Generates Electricity

[3113]

Since it looks like Nuclear power is on its way out...

A team of scientists at the Massachusetts Institute of Technology has developed what it describes as the first practical artificial leaf.

The device, made from silicon, electronics and catalysts, is the same size and shape as a playing card, but thinner.

It splits water into its two components, hydrogen and oxygen. These are then stored in a fuel cell and used later to generate electricity.

Full story here.

Probably not so easy, quick, cheap and surefire as we need or want it to be at this point, but hey, "one small step..." and all that.

 

[TxRad]

What next. Potato batteries?

 

[3113]

What next. Potato batteries?

http://www.ee.washington.edu/images/events/2000/potato_battery.jpg

Can it charge an iPhone?

 

[stephen55]

Hydrogen and oxygen combine to form water and a fair amount of energy. Put enough hydrogen and oxygen into fuel tanks and you can get a Saturn-V rocket, (which weighed about as much as a modern Destroyer naval ship) off the ground and into orbit. Well, at least the very top part into orbit...

All that energy that comes from burning hydrogen and oxygen...you need every bit of it and then some to get water to go back to hydrogen and oxygen.

The second law of thermodynamics says "There ain't no such thing as a free lunch."

Yes, you can use solar energy to get hydrogen and oxygen from water. That doesn't mean that it is cost effective, much less energy effective. Using solar energy to directly produce electricity, even at 10% efficiency, might be a lot more useful than using solar energy to produce H2 and O2 at 70% efficiency, when burning the stuff to produce electricity in a cell is only 10% efficient.

10%> 10%x70%....(7%)

It's that damned second law of thermodynamics. Power is good. Waste heat is useless.

Hydrogen/oxygen fuel cells are the cat's ass in Apollo space craft. For supplying electricity to the masses, they suck.

 

[Zeb_Carter]

Uh! Burning Hydrogen produces energy. In the form of heat. Enclose the burning in a small space such as a piston cylinder and the expanding gases will move the piston, but they also produce a lot of heat. The end product of all that commotion is water.

In a fixed setting that heat can be trapped and used for other purposes. So you have a win / win system. Use H2 and O to power a generator, trap the heat in a sink of some kind, whether it be water or some medium, and use it to heat homes, office building, blast furnaces.

In an automobile the heat is thrown away, but the power can be used to move the car.

And if built properly, the by product - water - can be trapped and reused.

 

[stephen55]

Zeb....

Methinks you confuse heat with entropy.

Heat can be used.

If you can come up with a use for entropy...you can rule the world.

Knock yourself out.

 

[Zeb_Carter]

Zeb....

Methinks you confuse heat with entropy.

Heat can be used.

If you can come up with a use for entropy...you can rule the world.

Knock yourself out.

Nope. When something burns it produces energy...that energy is most usually in the form of heat. When confined to a small space that heat can be used to produce kinetic energy, in the form of its expansion either by by moving say a piston or being directed so the whole object itself is moved. As in a rocket.

Entropy...which definition are you referring too?

 

[Weird Harold]

Yes, you can use solar energy to get hydrogen and oxygen from water. That doesn't mean that it is cost effective, much less energy effective. Using solar energy to directly produce electricity, even at 10% efficiency, might be a lot more useful than using solar energy to produce H2 and O2 at 70% efficiency, when burning the stuff to produce electricity in a cell is only 10% efficient.

Who cares how efficient the entire cycle is when H2 can be stored and used on demand, unlike direct solar generation of power.

7% of the solar energy falling on the oceans at the equator is enough to power all of civilization and liquify the H2 and transport the LH2 to where civilization prefers to hang out for use, too.

 

[TxRad]

Nope. When something burns it produces energy...that energy is most usually in the form of heat. When confined to a small space that heat can be used to produce kinetic energy, in the form of its expansion either by by moving say a piston or being directed so the whole object itself is moved. As in a rocket.

Entropy...which definition are you referring too?

The problem with hydrogen is that it explodes instead of burning. It's such a fine line that even in rockets it has to be precisely controlled.

 

[stephen55]

Who cares how efficient the entire cycle is when H2 can be stored and used on demand, unlike direct solar generation of power.

7% of the solar energy falling on the oceans at the equator is enough to power all of civilization and liquify the H2 and transport the LH2 to where civilization prefers to hang out for use, too.

One of my favorite fishing lodges has a solar system for electricity. During the day, when we're usually out fishing, the system is working away. At night, we use the electricity for lighting. My guess is that somewhere in the system is what are usually called batteries.

 

[Zeb_Carter]

The problem with hydrogen is that it explodes instead of burning. It's such a fine line that even in rockets it has to be precisely controlled.

So does gasoline vapor...what's your point?

Mine being hydrogen burns "clean" or explodes "clean", which ever you prefer.

 

[TxRad]

So does gasoline vapor...what's your point?

Mine being hydrogen burns "clean" or explodes "clean", which ever you prefer.

The difference is the power of that explosion. Gasoline does not explode, it is a controlled burn. Hydrogen is very hard to control as a burn. It wants to explode. There is a great deal of difference.

I've worked on all kinds of gasoline and alcohol race cars and one hydrogen powered land speed record car. The difference in fuel control is staggering to say the least. Without computer help it just doesn't happen safely. In the hands of the general public hydrogen fuel would be a bunch of mini bombs looking for a place to happen.

 

[stephen55]

Nope. When something burns it produces energy...that energy is most usually in the form of heat. When confined to a small space that heat can be used to produce kinetic energy, in the form of its expansion either by by moving say a piston or being directed so the whole object itself is moved. As in a rocket.

Entropy...which definition are you referring too?

I'm referring to the classical thermodynamics sense of entropy, as defined by the German scientist Rudolf Clausius. That is, entropy as a measure of how much of the energy of a system is potentially available to do work and how much of it is potentially manifest as heat.

As my high school physics teacher put it..."Heat, cannot of itself, pass from one body to a hotter body..."

Or as Lord Kelvin put it...

No process is possible in which the sole result is the absorption of heat from a reservoir and its complete conversion into work.


You can run hydrogen and oxygen through a fuel cell and get electricity. It's clean energy as the only by-product is pure water (and some heat). It's wonderful...no CO2 or any other noxious pollutants.

It would be the salvation of the planet, except for that crummy old second law of thermodynamics.

2(H2) + O2 ----> 2(H2O) + heat (energy) ...it's an exothermic reaction.

In order to get a hydrogen fuel cell to run, you have to feed it hydrogen. If you want to get your hydrogen from water...

2(H2O) + heat (energy) -----> 2(H2) + O2 ...it's an endothermic reaction.

The second law of thermodynamics says that the amount of useful energy you get out of burning hydrogen and oxygen to water is less than the amount of energy you have to put into water to get out hydrogen and oxygen in the first place. If it wasn't so, then you would have a perpetual motion machine.

You can run a hydrogen fuel cell until the cows come home, but in the running, all you're doing is increasing entropy and losing useful energy.

If the energy you put into the water comes from solar energy then it just might make economic sense. If the power you get from a hydrogen cell is worth more money than what it cost you to run the entire system, including producing the hydrogen, then you'd have something that would make money. What it wouldn't do is make energy, at least in terms of more energy than it took to run the system. Like every other system, you get out less energy than you put in.

 

[Weird Harold]

One of my favorite fishing lodges has a solar system for electricity. During the day, when we're usually out fishing, the system is working away. At night, we use the electricity for lighting. My guess is that somewhere in the system is what are usually called batteries.

Collecting Solar Energy where it is most plentiful -- at the equator -- and transporting it to where civilization needs in -- mostly around 40N Lat -- isn't going to happen with batteries or transmission lines. It could happen with LH2 cracked from seawater and who cares how much 'sunshine' is wasted in packaging and transporting the energy as long as sufficient energy reaches civilization in a useable form?

 

[stephen55]

Collecting Solar Energy where it is most plentiful -- at the equator -- and transporting it to where civilization needs in -- mostly around 40N Lat -- isn't going to happen with batteries or transmission lines. It could happen with LH2 cracked from seawater and who cares how much 'sunshine' is wasted in packaging and transporting the energy as long as sufficient energy reaches civilization in a useable form?

No argument on solar from me...

Despite what a few people around here believe, the world is running out of petroleum and the supply of natural gas, while large, is not infinite. It too, will disappear in time. Coal is ugly stuff and when burned, gives off nasties. (When I'm in the mood for a good belly laugh, I go to the website of Peabody Energy (once Peabody Coal) and read about how they get green energy from coal.)

http://www.peabodyenergy.com/Stewardship/CleanGeneration.asp

Nuclear is going through a bad phase right now but it will continue to be a major source of energy. If the boffins can get nuclear fusion to work, other than in a thermo-nuclear weapon, it will change everything. Forty years ago, it was forty years away. Today it's still forty years away...

Solar is going to get bigger and better, if only because there is no alternative. Hydro is about tapped out. Wind, geo-thermal and tidal are all going to remain minor players. So, it looks like solar is going to have to step up to the plate. As for using tropical solar to get hydrogen from water and then shipping the hydrogen as liquid to the world, it could work. Natural gas is already transported in bulk as liquid, so why not hydrogen?

Until the supply of natural gas gets low, however, simple economics will dictate that the natural gas will be used first.

Then, things will get very interesting...

 

[Zeb_Carter]

I'm referring to the classical thermodynamics sense of entropy, as defined by the German scientist Rudolf Clausius. That is, entropy as a measure of how much of the energy of a system is potentially available to do work and how much of it is potentially manifest as heat.

As my high school physics teacher put it..."Heat, cannot of itself, pass from one body to a hotter body..."

Or as Lord Kelvin put it...

No process is possible in which the sole result is the absorption of heat from a reservoir and its complete conversion into work.


You can run hydrogen and oxygen through a fuel cell and get electricity. It's clean energy as the only by-product is pure water (and some heat). It's wonderful...no CO2 or any other noxious pollutants.

It would be the salvation of the planet, except for that crummy old second law of thermodynamics.

2(H2) + O2 ----> 2(H2O) + heat (energy) ...it's an exothermic reaction.

In order to get a hydrogen fuel cell to run, you have to feed it hydrogen. If you want to get your hydrogen from water...

2(H2O) + heat (energy) -----> 2(H2) + O2 ...it's an endothermic reaction.

The second law of thermodynamics says that the amount of useful energy you get out of burning hydrogen and oxygen to water is less than the amount of energy you have to put into water to get out hydrogen and oxygen in the first place. If it wasn't so, then you would have a perpetual motion machine.

You can run a hydrogen fuel cell until the cows come home, but in the running, all you're doing is increasing entropy and losing useful energy.

If the energy you put into the water comes from solar energy then it just might make economic sense. If the power you get from a hydrogen cell is worth more money than what it cost you to run the entire system, including producing the hydrogen, then you'd have something that would make money. What it wouldn't do is make energy, at least in terms of more energy than it took to run the system. Like every other system, you get out less energy than you put in.

I still don't get your point...sunshine is free. Silicon is mostly free. Who cares if you lose 90% of the energy to produce the other 10%...the energy you use is free. What's the problem?

Every minute 100% the sun shines on my solar cells, I will be producing hydrogen. Do I care if 90% of that sunshine is wasted? Not a bit. I'm making hydrogen with the other 10%, day in and day out.

Now all YOU have to do is come up with a transportation system.

 

[Zeb_Carter]

The difference is the power of that explosion. Gasoline does not explode, it is a controlled burn. Hydrogen is very hard to control as a burn. It wants to explode. There is a great deal of difference.

I've worked on all kinds of gasoline and alcohol race cars and one hydrogen powered land speed record car. The difference in fuel control is staggering to say the least. Without computer help it just doesn't happen safely. In the hands of the general public hydrogen fuel would be a bunch of mini bombs looking for a place to happen.

And a gallon of Gasoline produces 115,400 net BTU's, while the equivalent Hydrogen only produces 130 net BTU's.

Butane rate is 60 ft/sec.
Acetylene 330 ft/sec.
Hydrogen (H2) 680 ft/sec.

While I couldn't find a specific propagation rate of gasoline vapors, they do use butane to slow down it's burn rate.

 

[TxRad]

I still don't get your point...sunshine is free. Silicon is mostly free. Who cares if you lose 90% of the energy to produce the other 10%...the energy you use is free. What's the problem?

Every minute 100% the sun shines on my solar cells, I will be producing hydrogen. Do I care if 90% of that sunshine is wasted? Not a bit. I'm making hydrogen with the other 10%, day in and day out.

Now all YOU have to do is come up with a transportation system.

The transportation is already there. Liquid Hydrogen is transported every day somewhere.

As for your 90% loss and using the 10%, have you thought far enough ahead to realize how large a sun array you would need at those numbers. Get real and quit arguing just for the sake of arguing.

Stephen corrected you and yes you were wrong on your first statement so pull up you bigboy pants and admit it. You keep making an ass out of yourself just so you can argue. What's the point in that.

 

[Zeb_Carter]

The transportation is already there. Liquid Hydrogen is transported every day somewhere.

As for your 90% loss and using the 10%, have you thought far enough ahead to realize how large a sun array you would need at those numbers. Get real and quit arguing just for the sake of arguing.

Stephen corrected you and yes you were wrong on your first statement so pull up you bigboy pants and admit it. You keep making an ass out of yourself just so you can argue. What's the point in that.

Hey Tex...fuck you asshole.

 

[TxRad]

Hey Tex...fuck you asshole.

About what I expected from you at this point.

 

[trysail]

http://www.world-nuclear-news.org/newsarticle.aspx?id=28907


Putin suggests Germans replace nuclear with firewood

01 December 2010
Russian prime minister Vladimir Putin has told German businessmen that they may have to rely on Russian firewood for heating if they do not want to construct new nuclear power plants or bring in Russian gas supplies. At a business conference organized in Berlin by the German newspaper Sueddeutsche Zeitung, Putin recognised that "the German public does not like the nuclear power industry for some reason." He continued: "But I cannot understand what fuel you will take for heating. You do not want gas, you do not develop the nuclear power industry, so you will heat with firewood?" Putin then noted, "You will have to go to Siberia to buy the firewood there," as Europeans "do not even have firewood."