[refid]

Hello

I've read in book that a fuel cells need a constant supply of rectants. Im wondering in a hydrogen fuel cell H2 (g) and 02 (g) are  continously supply and the by products are H2O ( more complicated but trying to keep things simple). The question is if H20 is formed and electricity is produced couldn't the the some electrity produced be used the decompose the H20 to H2 and O2 gas to supply the cell?

Or the cell itself does not produce enough electricity to do both fuctions, power the car and break down H20?

[P]

Hello

I've read in book that a fuel cells need a constant supply of rectants. Im wondering in a hydrogen fuel cell H2 (g) and 02 (g) are continously supply and the by products are H2O ( more complicated but trying to keep things simple). The question is if H20 is formed and electricity is produced couldn't the the some electrity produced be used the decompose the H20 to H2 and O2 gas to supply the cell?

Or the cell itself does not produce enough electricity to do both fuctions, power the car and break down H20?

Nice idea, but,  it's like saying"I'll build a bicycle with a dynamo on it  -  the electricity generated from the dynamo can drive an electric motor to turn the wheels  -  if I just get it started then the thing will keep going forever"   -  problem is there is only a finite amount of energy in the system and some of it gets lost as heat though friction in the wheels and so on. With the fuel cell - the electricity produced will not be enough to claim back ALL of the H2 and O2 you started with, so gradually the cell will run flat.

[refid]

I see your point,but what if it was in a close system ( the engine compartment would be in a closed system wouldnt H2 explosive?)

[billnotgatez]

There is no free lunch

[Donaldson Tan]

The Second Law of Thermodynamics can be interpreted as: it is impossible to build a perpetual engine.

[Donaldson Tan]

hydrogen cannot be explosive if it is not in direct contact with oxygen.

H₂ -> 2H⁺ + 2e
O₂ + 2H₂O + 4e -> 4OH^-
Hydrogen gas is oxidised to cations in one compartment, while oxygen is reduced to anions in another compartment. The electrons from the redox process flows through the circuit and not through the chemical medium. Hydrogen and Oxygen gas are not in direct contact.

However, if there is a leak in the system, the fuel cell will become explosive, just like a leaking gasoline engine from the car.

[Bosnian_hero]

There is no perpetual engine, but I am researching something that is very interesting. If we could make low-diameter pipes (very low-diameter) and stick one end in water (any water source, river/lake/sea/glass/bathtub) and the other end in a higher altitude glass or anything else (a tank or any storage) the water would rise trough the pipe (like in plants, the walls of the pipe drag the water upways) and eventually exit on the other end, without using any energy by ourselves. Then if we release the water from that altitude on a turbine, we'll get electricity. Also if we make a small pump to speed up the water (it already goes by itself, just a small *push*), we could make a large scale perpetual hydro-plant for electricity production
I also guess that using earth's internal heat as energy for electricity, we could eventually have a perpetual engine (the electricity would convert into heat and light, which converts back into heat, so its basicly what we need, we all speak of energy production, while the real deal and term is energy conversion, which is what happens.

[Borek]

the water would rise trough the pipe (like in plants, the walls of the pipe drag the water upways) and eventually exit on the other end

Same force that pushes water up will prevent it from leaving the pipe on the other end. TANSTAAFL.

I also guess that using earth's internal heat as energy for electricity, we could eventually have a perpetual engine (the electricity would convert into heat and light, which converts back into heat, so its basicly what we need, we all speak of energy production, while the real deal and term is energy conversion, which is what happens.

All you can do is to disperse internal Earth heat into space using part of it on its way up.

[xiankai]

TANSTAAFL.

longest acronym i have ever seen. what is it. 

[P]

There Ain't No Such Thing As A Free Lunch?     

[Bosnian_hero]

the water would rise trough the pipe (like in plants, the walls of the pipe drag the water upways) and eventually exit on the other end

Same force that pushes water up will prevent it from leaving the pipe on the other end. TANSTAAFL.

I also guess that using earth's internal heat as energy for electricity, we could eventually have a perpetual engine (the electricity would convert into heat and light, which converts back into heat, so its basicly what we need, we all speak of energy production, while the real deal and term is energy conversion, which is what happens.

All you can do is to disperse internal Earth heat into space using part of it on its way up.

Thats why I added the *small* pump that will extract the water once it gets on top. I know that there isn't free lunch, but this is a very interesting concept.

[Borek]

Thats why I added the *small* pump that will extract the water once it gets on top. I know that there isn't free lunch, but this is a very interesting concept.

It won't work. Amount of work needed to release the water once it got high will be at least identical with its potential energy. I agree with you that the system is interesting, but I am looking at it from completely different perspective - thermodynamics tells us that such thing will not work. What is interesting is finding out WHY it will not work.

[billnotgatez]

<tongue in cheek on>
Well rule of thumb (a deep subject)

about 32 feet for water
at sea level

about 29.92 inches for mercury
at sea level

<tongue in cheek off>

I am obtuse today

[Borek]

about 32 feet for water
at sea level

about 29.92 inches for mercury
at sea level

Not sure if I understand what you are referring to. Or rather I am sure I have no idea what you are talking about

[billnotgatez]

Borek -
I probably should not have been so obtuse. I definitely did not want to give you angst. But, since this has degenerated into a discussion of "perpetual motion machines (sic)", I wanted to inspire some critical thinking. As you can see from the posts, there seems to be some "cherry picking" of concepts to arrive at a result. In many cases one item proven false in a paradigm will render the entire paradigm false, but one item true in a paradigm does not necessarily make it true.

In the spirit of my previous post and thinking about Wells I post the following link.

http://howthingswork.virginia.edu/water_distribution.html

By the way, it looks like I was off by 8 feet.