How does a fuel cell work?

Hydrogen gas or H2 is a gas that contains a lot of chemical energy. If you ignite it, it will react with the oxygen in the air and release its energy by means of an explosion. And the only waste product is water. That`s right, no CO2, no toxic gasses, just a bit of innocent water.

And of course, uncontrolled explosions are great fun, but how do we properly use hydrogen as a fuel? To power machines and vehicles for example? Well, in order to do that, we use a device called a fuel cell. A hydrogen fuel cell is a device that takes hydrogen and oxygen and uses those to create electricity. But how exactly does a fuel cell work? Let`s find out.

Right here you can see my schematic drawing of a hydrogen fuel cell. On the left side you can see there is an anode, and on the right side there is the cathode. The anode and the cathode are hollow areas in which gas can be put. So, inside the anode this is where the hydrogen gas goes and the oxygen goes into the cathode. In between them, you will find a catalyst which is the green layer in this drawing and an electrolyte. So, let`s see what happens when this system is turned on.

So, we have got hydrogen in the anode and oxygen in the cathode. Now, the hydrogen inside the anode wants to go over to the other side and meet up with the oxygen then react with it to form water. But there is a problem, it cannot get to the other side because there is something in between them: the electrolyte.

The electrolyte is a material that only lets positively charged things get through it. Hydrogen is not positive. You see, hydrogen atoms consist out of one proton and one electron; one positive particle and one negative particle, which makes the overall particle neutral. So, the hydrogen in our system is neutral and not positive. So, it cannot get through the electrolyte. There is, however, a solution, which is the green layer in this drawing. This is the catalyst.

Now, what the catalyst does in this case is splitting off the electrons from the protons. So, the electrons of the hydrogen atoms are removed from their protons. Now, we have got a bunch of protons and electrons. The protons also known as H+ can get right through the electrolyte because they are positive and they can meet with the oxygen on the other side. But you see there is a problem, you see these are just protons, they are not really hydrogen anymore. So, they can`t react with this oxygen and form water.

In order to do that, the electrons that are still on the other side must be transported over to the cathode first. And clever people might have noticed that I just used the words electrons and transported. And transporting or moving electrons; there is a name for that: electricity.

That`s right. Moving electrons is what we call electricity. So, we can simply connect a wire like this and then the electrons will simply be able to flow right through that wire to the other side. And then, they will meet up with the protons and they will react with the oxygen to form water, which can leave the system.

And now what we`ve got is an electric current running through a wire, which we can then use to power a lightbulb, a motor, whatever. This is the power output of the fuel cell. Now despite the fact that the fuel cell is such a clever invention, it does have some drawbacks.

First of all, it gets really hot when it is in operation and this can lead to the fuel cell potentially damaging itself if it isn`t cooled properly.

Another disadvantage of a fuel cell is that it is very, very expensive. See, remember that catalyst we talked about, that green layer? Well, that is actually made out of platinum, which is of course a very expensive material. But anyway, now you know exactly how a fuel cell works. I hope you have enjoyed this video and of course thank you for watching.