Why Can't Fuel Cells Simply Use Water to Generate Hydrogen?

[Red Ninja]

I was wondering if you could recommend an article that would explain a concept to me. That is: the drawback of fuel cells, reportedly, is that hydrogen is not readily available. However, I am wondering why it is that if the original idea of fuel cells came from reversing the concept that hydrogen could be separated from water, why can't fuel cells take water, separate the hydrogen, separate the electrons and then merge them all back together at the other end of the circuit? Basically borrowing the hydrogen electrons for a minute and then returning them back to the water?

 

[Cliff_J]

Why not take a battery, use electricity from it and then return it back to the battery? There are always losses in a system, usually larger than the net output.

If you search around a bit, there have been a few good threads about this in the last couple months with a few links to good websites. Would be worth the effort to search this forum a bit.

Cliff

 

[russ_watters]

However, I am wondering why it is that if the original idea of fuel cells came from reversing the concept that hydrogen could be separated from water, why can't fuel cells take water, separate the hydrogen, separate the electrons and then merge them all back together at the other end of the circuit? Basically borrowing the hydrogen electrons for a minute and then returning them back to the water?

Splitting water: 2H20+ENERGY->2H2+O2

Burning hydrogen: 2H2+O2->2H2O+ENERGY

As you can see, the reactions are mirror images of each other: the energy is exactly the same in each.

 

[anggoro_nuswantoro]

Splitting water: 2H20+ENERGY->2H2+O2

Burning hydrogen: 2H2+O2->2H2O+ENERGY

As you can see, the reactions are mirror images of each other: the energy is exactly the same in each.

The energy used to split water is the same to the energy produced in the burning process. But, the total amount of energy NEEDED to split water into hydrogen + oxygen is a lot bigger then the energy can be USED when we burn the hydrogen.

We have losses in the power plant, transmission grid, chemical reactor in which we split the water, etc.

In the other end, there is losses in the burning process etc.

 

[chroot]

You can certainly electrolyze water to produce hydrogen, which can then be used in fuel cells. The problem, of course, is where do you get the energy to electrolyze the water?

- Warren