TechStuff Tidbits: Fuel Cells and Catalysts

Some researchers in the UK made a breakthrough that could have a dramatic impact on the cost of fuel cell technology. But how do fuel cells work anyway, and what's holding us back from using them?

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Episode Transcript

Speaker 1 (00:04):
Welcome to Tech Stuff, a production from I Heart Radio. Hey,
they're in Welcome to Tech Stuff. I'm your host, John
than Strickland. I'm an executive producer with iHeart Radio. And
how the tech are you? You know? I read an
interesting article from the Imperial College in London about how

(00:26):
researchers at that college had developed an alternative catalyst for
technologies like fuel cells, potentially opening the door to making
that tech much more affordable, and I thought it might
be good to do a tech stuff tidbits about fuel cells,
specifically hydrogen fuel cells, and to talk about that specific

(00:48):
development with catalysts as well. So first, what the heck
is a fuel cell? Well, in some ways it's very
similar to a battery. Batteries and fuel cells both rely
upon chemical reactions that create an output of electricity. So
with batteries, you've got yourself a closed system, right. All

(01:09):
the chemicals are contained within the battery, and what's in
the battery stays in the battery unless you get a
battery leak, in which case you really need to take
care of that because battery acid can be nasty stuff.
But yeah, the chemical reactions inside the battery will eventually
slow down and ultimately stop as there will not be
enough reactive elements remaining in the battery for the reaction

(01:32):
to continue in the battery goes dead. Rechargeable batteries can
reverse those reactions, and recharging is really just the opposite
of discharging, So instead of having electric current flowing out
of the battery, you make electric current flow into the battery,
and this reverses those chemical reactions, so you end up

(01:53):
with the original reactive elements inside the battery. Eventually, even
rechargeable batteries go dead because you ever really reverse all
of the chemical reactions, some stuff ends up becoming alert,
and over time, more and more of those chemicals become inert,
until your battery just isn't putting up very much juice
and ultimately will be useless. But what about fuel cells, Well,

(02:18):
a fuel cell is different from a battery because you
refuel a fuel cell, you've got your reactive elements that
are inside the fuel cell and the reactions that they
go through release electricity. But in the process the fuel
is spent, it is converted into something else, and once
that happens, you have to add more fuel to the

(02:39):
fuel cell and the process can continue. But let's get
a little more detailed. So, the type of fuel cells
that we frequently talk about when we discuss stuff like
fuel cell powered vehicles, for example, are a type called
polymer electrolyte membrane fuel cells. Now, this is just one
of many different kinds of fuel cells. Uh, there are

(03:02):
a lot of different ones that are good for specific
types of applications. However, we're gonna focus on this because
it's the type that the average person might encounter should
fuel cell vehicles become more of a thing in the future.
And to be clear, they're a thing right now. There
are fuel cell vehicles out there, some of you might
even drive one, I don't know, but they're not common.

(03:24):
So with these fuel cells, you have several components. You've
got a polymer electrolyte membrane. That's what gives this type
of fuel cell its name. And let's break down what
that means. All right, So membrane, I think we pretty
much all have a handle on that, right, It's a
thin boundary between two things. And an electrolyte is a

(03:47):
material that contains ions. Ions are charged atoms, So you're
talking about atoms that either have more protons than they
have electrons, so they would be positively charged. Because protons
carry a positive charge, electrons carry and negative. If you
have the same number, then the opposite charges neutralize each other.
It's a neutrally charged atom. So an ion has to

(04:08):
have either more protons than electrons, or more electrons than
it has protons. In that case, you would have a
negatively charged ion. UM. A polymer is a long chain molecule.
Plastics are a type of polymer um, and there are
lots of naturally occurring polymers, including some naturally occurring plastics,

(04:29):
though we don't really think of natural plastics when we
use the word plastic. Now. I mentioned that the membrane
acts as a boundary, Well what is it a boundary for?
It acts as a barrier between the two sides of
the fuel cell. You can think of it as like
a gateway, if you will. So, on one side, which

(04:52):
is the cathode side of the fuel cell, you have oxygen.
On the other side, the anode side of the fuel cell,
you have of hydrogen. Hydrogen happens to be the most
plentiful element in our universe. However, it's also highly reactive.
It bonds with other elements readily, so readily. In fact,

(05:12):
that pretty much we only find hydrogen informs where it
has bonded with something else. So when hydrogen bonds with oxygen,
we get water H two O, you know, two hydrogen
atoms and an oxygen atom, and then things get all
splichy splashy. So in a fuel cell, the hydrogen quote

(05:35):
unquote wants to bond with the oxygen and form water.
But you've got this pesky membrane that acts kind of
like a bouncer in a club, and this bouncer doesn't
want any neutral glum hydrogen atoms coming in. You know,
a hydrogen atom. A standard hydrogen atom consists of a

(05:55):
single proton and a single electron. Well, that's positive neck
of charge cancels each other out. You've gotta neutrally charged atom.
The membranes like, sorry, we only want positive folks in here,
so you can't come in. And the bouncer definitely doesn't
want any negative nancies coming in, so no negativity. So
the only way it will let a hydrogen atom pass

(06:17):
through the membrane is if the hydrogen atom chucks it's
one electron and becomes a hydrogen ion, also known as
a proton. Because again, the hydrogen atom is it consists
of a single proton and a single electron. So if
a hydrogen atom gets rid of its electron, it is
a hydrogen ion. It's also a proton. Now, once it

(06:39):
is free of its electron, the hydrogen atom can just
waltz right on by the bouncer and pass over to
the oxygen side. We we will just call that club
oxygen on the other side of the membrane. But here's
the thing. Chucking an electron isn't so simple, right, Like,

(07:00):
typically we would have to pour energy into the system
to start stripping electrons away, because we would excite an
electron so that it would move further out from the
nucleus of the atom until you could make it go
do something. So, the hydrogen atom cannot just shed an
electron all by itself. It needs a catalyst. Now, if

(07:23):
you remember from your chemistry, a catalyst is something that
facilitates a chemical reaction. The catalyst itself isn't getting like,
it's not part of the reaction in the sense of
it is undergoing a change. It can increase the rate
of a chemical reaction without itself undergoing any significant or

(07:44):
permanent change, and We'll touch on the catalyst issue in
a moment, because that's the key of the research I
was talking about the beginning of the episode. So the hydrogen,
with the help of this catalyst, sheds an electron and
becomes a proton, a positively charged particle, and then it
can pass through the membrane. Now, electrons have a negative charge,

(08:08):
and negatively charged particles repel other negatively charged particles. We
know this right, Like charge repels like opposite charges attract,
So that means the electrons are attracted to the positively
charged particles that are on the other side of the membrane.
So the electrons quote unquote want to get through the

(08:29):
membrane and rejoin the positively charged hydrogen at ions aka
the protons on the other side. But that pesky bouncer
won't let the electrons through. It will not let that happen.
So the electrons are not on the guest list. They
aren't allowed inside. But if you were to provide a
pathway like a circuit for the electrons to pass through

(08:54):
so that they could ultimately rejoin the positively charged ions
that are on the other side, like, they may have
to go a much further distance and they might have
to do some work. Well, they're still gonna jump at
the chance. So this is how you make electrons go
and power something. You have electricity right the flow of electrons,
and then ultimately they can make their way over to

(09:16):
club oxygen. They're just going through like a side door
as opposed to the front door. And this is how
fuel cells supply electricity, although we you know, don't actually
use the analogy of a bouncer in a club. So
the electrons that have been shed by hydrogen will flow
into a circuit and ultimately join up with the oxygen
atoms and the hydrogen ions all over in club oxygen.

(09:40):
Once the electrons get there, well then they can zip
on over to those hydrogen ions, and you have hydrogen
atoms mixing with oxygen atoms, so you get water molecules.
This means that in one of these fuel cells, your
fuel consists of hydrogen and oxygen, your output is electricity,

(10:00):
and your waste is water vapor. And that's one of
the big reasons fuel cells come up in discussions of
green energy because they do not produce carbon dioxide or
carbon monoxide emissions, at least not if you're using pure
hydrogen as fuel. More on that in a bit, so
they just produce electricity and water. Like a car that's

(10:21):
powered by a fuel cell that's using pure oxygen and
pure hydrogen wouldn't give off any emissions other than water vapor.
All right, When we come back, I'll get into a
little more detail about some of the challenges of fuel
cells and explain why they aren't everywhere right now. But

(10:41):
first let's take a quick break. Okay, so fuel cells work.
There are fuel cell vehicles out there today, though there
are not a lot of them. So why aren't fuel
cells more popular? If all you need is the most

(11:03):
common element that's in the universe on one side, and
oxygen in the other, and if you can just essentially
scoop up oxygen from our atmosphere, why aren't we all
using fuel cell vehicles. There are a few big reasons,
and one is that fuel cells have an ideal operating temperature.
Your average polymer electro light membrane fuel cell best operates

(11:25):
it around eighty degrees celsius or a hundred seventy six
degrees fahrenheit, which is pretty toasty, and it means that
in really cold regions it could take a while to
warm up the fuel cell to a temperature that's high
enough to generate enough electricity to do whatever it is
you want to do. You might be familiar like batteries
don't operate as quickly in very cold temperatures, meaning you

(11:48):
get less electricity out of a battery. You get, uh,
electricity that may not be enough for you to do
whatever it is you need to do. If you've ever
picked up a flashlight that was sitting in a freezing
room and turn it on, you I be like wow
that the light is really weak from this, and then
over time, as the flash light warms up, the light
gets stronger. The same sort of thing can happen with

(12:09):
fuel cells. Like you, you could have a slower chemical
reaction at lower temperatures, and if it's slow enough, it
might not be enough to do what you need it
to do, like power and electric motor for example. Now,
for another reason why fuel cells aren't everywhere, Uh, they
deteriorate over time, so you do have to replace them occasionally.

(12:30):
And then we get to what's a really big drawback.
They are expensive, and they are expensive because of the catalyst.
See the typical catalyst used in these types of fuel
cells is made of platinum. That's a very rare, very
expensive metal. And even though you only need a relatively

(12:51):
small amount of platinum per fuel cell, that requirement really
drives up the price significantly. In fact, according to the
researchers that Imperial College London, about six of a fuel
cells cost comes from the platinum that's used for the catalyst.
That's why the work done by those researchers could be transformative.

(13:12):
The researchers were able to create a catalyst using iron
instead of platinum. Now, iron isn't scarce at all. The
Earth is lousy with the stuff. Iron is plentiful, and
if we could use iron as a catalyst material instead
of platinum, that would bring the price of fuel cells
way down. And let's talk a little bit about what

(13:34):
those researchers did. They took iron atoms and they embedded
singular iron atoms within a matrix of carbon, so they had,
you know, multiple iron atoms in the matrix total, but
they would in each atom was kind of its own
little individual part in that section of the matrix. This
is where we can talk about something that's really interesting

(13:56):
and it's also a little counterintuitive because we're familiar with
the way how iron works on moss. Meaning if you've
got a whole bunch of iron atoms together forming say
a chunk of iron, we know how iron will behave, right.
It's on this classic system. However, when you get down
to an individual iron atom, you're now diving down to

(14:17):
the nanoscale. Actually you're diving down to the atomic scale,
which is even smaller than the nano scale. Once you
start hitting the nanoscale, stuff starts to behave in an
entirely different way than the way we are used to
it on the macro scale, and it can in fact
be really bizarre um on the nano scale, even though
you're talking about unimaginable tiny particles, those particles have way

(14:41):
more surface area per unit of mass than what you
would find at the macro level, and that means that
more of the material can come into contact with other
stuff by unit of mass, and the materials behaviors can change.
One of those behaviors is that material reels can become
better catalysts at the nano scale or the atomic scale.

(15:06):
The researchers said that they're iron catalyst, and a carbon
matrix was able to perform as a good substitute for platinum,
and that it has performance that is quote unquote approaching platinum.
So it sounds as if the iron catalysts perhaps isn't
quite as effective as platinum, but the tradeoff in price
could more than make up for the decline in performance.

(15:29):
But performance is just one part of the issue. Another
one is durability. That's something that the researchers are working
on now, trying to make the iron solution as durable
as platinum catalysts. Otherwise you would have to replace the
catalyst more frequently, which would eat into the cost savings
of iron. Right if you have to replace it more

(15:50):
frequently than you would with a platinum catalyst, then the
benefits start to that that get that that span of
benefits begins to narrow, I guess, is what I'm trying
to say. Plus, it becomes a hassle if you have
to frequently get your fuel cells serviced or replaced. Now,
if the team can make the iron catalysts stability match

(16:11):
that of platinum, the breakthrough could lead to a revolution
and fuel cell technology. However, there is still one more
thing we have to talk about, and that's hydrogen itself. So,
as I mentioned, it's the most plentiful stuff in the universe,
but it also tends to bond with other elements really easily,
and that's the tricky bit. To get at hydrogen, we

(16:34):
typically have to exert energy to do it. We can't
just go and collect hydrogen pure hydrogen on its own.
It's almost always bonded to something else, So we have
to find a way to break those chemical bonds that
hold hydrogen to whatever it happens to be bonded with. Well,
when you start to look at fuel cells from an
energy ecosystem point of view, you have to start asking

(16:57):
tough questions like do you have to spend more energy
to get the hydrogen then you are getting out of
using it in a fuel cell? And how are you
getting at the hydrogen? Is it as efficient as it
can be? Is it environmentally friendly because some of the
ways we get hydrogen is definitely not environmentally friendly. In fact,

(17:19):
the primary way we get hydrogen is we collected as
a byproduct from natural gas processing and and natural gas
is a fossil fuel. So if we assume that that's
how we're gonna keep getting hydrogen, it means we're presuming
that we're going to continue to depend on fossil fuels,
and that is an issue, right. It means that we're

(17:40):
still doing something that itself is environmentally harmful. We can
use hydrogen without breaking those bonds in some forms of
hydrocarbon gases, but that would mean that we would actually
have emissions beyond just water vapor. It might include carbon
monoxide for example. So you know, you could have fuel

(18:01):
cells that use hydrogen that's in a mixture of something else,
like a hydrocarbon gas, but you have down downsides to
that as well. There are other ways we can get
hydrogen that don't involve fossil fuels. One way is just
to do what fuel cells do, but in reverse. So
remember with fuel cells, we take hydrogen and oxygen and
using that membrane and a catalyst, we get electricity and

(18:24):
water vapor as byproducts of the chemical reaction. But then
if you were to take water and pass an electrical
current through the water, you would break the molecular bonds
between hydrogen and oxygen and you would get O two
and H two gases. But again that means you have
to expend energy in order to release the hydrogen and oxygen.

(18:45):
If you're expending the same amount of energy as you
would be getting out of the fuel cells. You're not
really seeing a benefit here, really, you're just shifting where
the load is. One way to approach this is by
using renewable energy sources to create the electrical current you
need to break those molecular bonds in a process is
called electrolysis. Anyway, harvesting hydrogen presents its own big challenges. Yes,

(19:10):
the use of hydrogen and fuel cells is clean energy,
but getting at the hydrogen might not be so clean.
There's always a catch still. With the possibility of fuel
cells becoming more economically feasible, that could encourage more r
and d into how we can collect hydrogen in a
more environmentally conscious way. And who knows, maybe we'll get

(19:31):
that hydrogen economy that folks were talking about nearly twenty
years ago. And that's it. Protect Stuff Tidbits. Hope you
enjoyed this. I'll talk to you again really soon. Text
Stuff is an I Heart Radio production. For more podcasts
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(19:53):
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