- Hydrogen. The simplest of elements.
One little proton hanging around,
often it's, it's own best friend; H2.
It also gets along with oxygen
and that's water and you drink it.
So how in the heck can it power a car?
We're talking about hydrogen fuel cells!
(upbeat dissonant music)
Look, even if you think the Earth isn't very old
and petroleum based fuels are somehow
a sort of regenerative blood of the land
like that guy in the comments.
We know that what your car farts,
isn't great for the planet or its inhabitants.
What if we could use a fuel, get energy out of it,
and its only waste was say... water?
That's a hydrogen fuel cell powered car!
First things first; a car that runs on hydrogen
is an electric vehicle.
Wanna learn how most of those work?
Check out the video.
A hydrogen fuel cell takes the energy
from combining hydrogen and oxygen and creates
an electric current.
But its different than the big lithium
and iron batteries in the bellies of these Tesla's.
Hydrogen fuel cells actually complete a chemical reaction
in which the hydrogen is combined with the oxygen
in the environment and discarded as water.
The concept of a fuel cell like this was first
demonstrated by Humphry Davy in 1801.
But the invention of the first working fuel cell is credited
to William Grove; chemist, lawyer, and physicist.
Grove's experiments with what he called
a gas voltaic battery proved,
in 1842, that an electric current could be produced
by an electrochemical reaction between hydrogen and oxygen
over a platinum catalyst.
So, how does it work?
Well first, you might be thinking, "Bart, how can I trust
that hydrogen and oxygen makes water and that there's
a lot of energy to be had when that happens?"
Well, I'm glad you asked.
This is kinda the opposite with what happens in a fuel cell,
we gonna take water and split it up.
Thanks to the electric current, we're separating the bonds
between the hydrogen and the oxygen.
I'm trying to collect the hydrogen in this tube.
The oxygen more than likely is just bonding
with the metal in the metal of the other screw.
Thanks Philippe. That was a sincere thanks,
it wasn't like a sarcastic like you screwed something up
you didn't screw anything up.
So we just gonna wait till this test tube fills.
Science is a lonely game. We got about 15 milliliters.
So we got a little bit more than 10 milliliters
of hydrogen in here, and hydrogen
is lighter than air so it goes up
(pop)
Pretty cool!
Well that's kind of what happens in a fuel cell;
two hydrogens combine with an oxygen
but its not exactly the same, so lets get in there.
It works because hydrogen, the most prolific element
in the universe is also, the simplest.
Here's the fuel cell in a hydrogen powered electric vehicle
its got a few main parts, we'll go over them
then we'll watch it in action to see
how they tie together to power your car.
First, lets look at the anode.
The anode; the negative post of the fuel cell,
has several jobs. First it conducts the electrons.
We'll see how that happens in a minute.
And second, it has channels etched into it that disperses
the hydrogen equally over the surface of the catalyst.
The catalyst basically means something
that makes another thing happen.
The cathode, the positive post of the fuel cell,
has channels etched in it to distribute the oxygen
to the surface of the catalyst, it also conducts
the electrons back from the external circuit
to the catalyst where they can recombine
with the hydrogen ions and oxygen
and form that sweet, sweet water of life; water.
The electrolyte is the proton exchange membrane
this specially treated material,
which looks something like an ordinary kitchen plastic wrap
only conducts positively charged ions.
The membrane blocks electrons.
The catalyst is a special material that facilitates
the reaction of oxygen and hydrogen.
It's usually made up of platinum, nanoparticles
and very thinly coated onto carbon paper or cloth.
The catalyst is rough and porous so the maximum surface area
of the platinum can be exposed to the hydrogen or oxygen.
The platinum coated side of the catalyst faces
the proton exchange membrane or PEM,
that's that thing that doesn't let electrons through.
So now lets get things moving.
The membrane allows the protons to pass through it
virtually unimpeded, while the electrons are blocked.
The hydrogen hits the catalyst and splits up.
A single hydrogen molecule is a proton
so the protons, hydrogens, get to pass through
the membrane directly to the cathode side
while the electrons are forced to travel through
an external circuit. Neither the proton nor the electrons
like being charged, they wanna be neutral. Like the Swiss.
Hey, why are the most neutral countries
make the least neutral cheeses?
So the electrons travel from the anode
to the cathode and this is what drives the electric motors,
and lights, and dashboards, and all the other stuff
that makes driving, driving.
And we cover that in our electric cars video.
Meanwhile on the cathode side of a fuel cell,
oxygen gas, O2, is being forced through the catalyst
where it splits into two oxygen atoms.
Each of these atoms of these atoms
has a strong negative charge. This negative charge attracts
two hydrogen ions through the membrane
where they get their electrons back and combine
with an oxygen atom making water.
This circle will keep running
for as long as there's supplies of hydrogen and oxygen.
And since there's plenty of oxygen in the air,
the only limiting factor is how much hydrogen
there is in the tank and all it pumps out is water.
No NOx, no carbon monoxide, no hydrocarbons.
And another benefit is you can fill up your hydrogen tank
as quickly as a gas tank,
eliminating the time it takes
to charge modern conventional electric vehicles.
People are like, "Yeah but hydrogens dangerous."
Guys, we're using gasoline now;
you're driving around with gasoline in your car...
So, why aren't we using it all the time?
Well one reason is people are reluctant to get
a hydrogen fuel cell EV 'cause
there's nowhere to fill it up.
Some states are funding initiative
but that's a long way off, also we're still looking for
good ways to get it.
The way I got hydrogen earlier was using electrolysis
it doesn't make much sense to use electricity
to get hydrogen to make electricity, does it?
But we can use the Sun and there's chemists pioneering
ways to efficiently unlock the most common element
in the universe, that's hydrogen.
Go on, to chemistry and save the world!
Hydrogen fuel cells.
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Don't tell my wife I'm playing with hydrogen, she worries.