Why Hydrogen is the Only Fuel for Fuel Cells

[Imparcticle]

My chemistry book says it is impossible to use anything but hydrogen in a fuel cell, but does not say why. does anyone know why?

 

[Entropy]

Thats just how the engine works. Just like your car engine will only run on gasoline, that's what its designed to run on.

 

[Imparcticle]

my friend wants to know if its possible to make a fuel cell that runs on nitrogen and oxygen. Is that possible?

 

[chroot]

Your book is wrong. There exist a whole class of fuel cells that can run on other hydrocarbon fuels. So-called direct methanol and direct ethanol fuel cells can operate from methanol and ethanol.

Fuel cells are really just devices with semipermeable membranes that are permeable to protons (hydrogen ions) but not to electrons. It doesn't matter where these protons come from, either molecular hydrogen or some other hydogen-containing compound.

Nitrogen and oxygen, of course, contain no hydrogen. They cannot be used in a fuel cell. I should also note that oxygen is used in all fuel cells as the "hydrogen acceptor." Nitrogen itself is an inert gas and has no relevance to fuel cells. Even more importantly, such a fuel cell would actually produce very toxic NOx compounds as exhaust. That's not exactly the direction we'd like to see energy production going.

- Warren

 

[Entropy]

Hmm... I though it could only run on hydrogen and oxygen. Neat.

 

[chroot]

http://www.cfdrc.com/applications/fuelcells/dmfc.html

- Warren

 

[shrumeo]

don't forget phosphate FCs, carbonate FCs, and solid oxide FCs

http://www.chuden.co.jp/english/corporation/press/pre2000/pre0911.html
http://www1.elsevier.com/vj/fuelcell/show/latest_toc.htt

 

[LURCH]

Correct me if I'm mistaken here, but don't all these different types fo fuel cells just extract the Hydrogen from these fuels, and then run on Hydrogen and Oxygen?

 

[Imparcticle]

actually produce very toxic NOx

why is it toxic? what makes a gas inert?

 

[russ_watters]

Correct me if I'm mistaken here, but don't all these different types fo fuel cells just extract the Hydrogen from these fuels, and then run on Hydrogen and Oxygen?

That was my interpretation of Imparticle's chemistry book. It may be an oversimplification the way its written, but it is technically true.

 

[russ_watters]

why is it toxic?

"Toxic" just means "poisonous." I'm not sure if you are looking for how exactly it effects the body, but I'm pretty sure they displace oxygen.

what makes a gas inert?

Inert means non-reactive. Oxygen likes to burn, so its not inert. Nitrogen doesn't react with much of anything (when in diatomic gas form), so it is. There are varying derees though...

 

[Imparcticle]

how does nitrogen occur naturally? (monoatomic?)

Inert means non-reactive. Oxygen likes to burn, so its not inert. Nitrogen doesn't react with much of anything (when in diatomic gas form), so it is. There are varying derees though...

BUT what makes it inert? i know what inert means, I just don't know what makes gases inert. Does it have something to do with the electron orbits?

 

[shrumeo]

nitrogen is about 3/4 of the atmosphere, more or less, and it is diatomic

yes, in effect, all the other fuel cells mentioned use hydrogen but react it with something other than diatomic oxygen

here is a better description http://fuelcells.si.edu/basics.htm

 

[russ_watters]

BUT what makes it inert? i know what inert means, I just don't know what makes gases inert. Does it have something to do with the electron orbits?

Yes, chemical reactions are all about electrons. IIRC, the "noble gases" are the most inert because they have their outer shells completely filled, meaning they have no spaces to accept electrons, nor extra electrons to give. I'm not sure about the electron config of nitrogen (not a noble gas).

 

[Tiiba]

As I understand, nitrogen is inert because the triple covalent bond (?) that it's usually in already is so strong. You can get it to react with something else (that's where you get ammonium and TNT), but it's hard.