Fuel Cells Video Lecture - NEET

fuel cells are based on it they use some
pretty clever chemistry and they're
based on the idea that hydrogen gas and
oxygen gas always come together to make
water whenever they can so h2 plus O 2
makes h2o hydrogen gas and water come
together to make water hi Piper gasps
knocking gasps come together make water
these guys will come together whenever
they have the opportunity and whenever
they have the opportunity they'll do so
very quickly will they'll do so a lot of
energy hydrogen and oxygen coming
together a little bit like the boys and
girls at summer camp we're going to try
really hard to break into each other's
dorms and come together form couples
let's build on that analogy to try to
understand how fuel cells actually
creating energy maybe in a car or in a
spacecraft or an airplane in a fuel cell
there there are sort of two different
tanks on one side we have one that
contains a lot of h2 hydrogen gas not -
gas is coming here okay
on the other side we have one that
contains a lot of a lot of o2 a lot of
oxygen so this like the boys dorm and
the girls dorm at summer camp all right
these guys want to come together really
badly but they can't because there's a
barrier in between just like any good
any good counselors would have set up at
camp there's a barrier that's going to
prevent these h2s we'll call these the
boys from coming over here so they want
it they want to come over here so badly
mix with the o2 form couples but they
can't because there's a sparing right
here separate so let's look at how they
do this well it turns out that this
barrier isn't quite as ominous as it
seems this barrier may be like a fence
at camp with big slats or that's a
little bit above the ground it's not
impervious to everything
positively-charged things can get
through the barrier negatively or
neutral things they can
get through so maybe it's sort of like a
fence that really short kids at Camp can
squeeze under but other kids can so in
order for hydrogen to be able to come
over here one thing happens right here
there's what's called a catalyst the
catalyst is put there because it takes
advantage of the fact that only positive
things get through the barrier now all
atoms all molecules are made up of
positive things protons and negative
things electrons so the catalysis place
there because scientists who designed
the fuel cell pretty much said a hot
positive things can pass through the
barrier negative things can so what
we'll do is we'll take the hydrogen and
we'll split it we'll split it into two
parts well split it into a positive part
that can pass through the barrier and
we'll split it into a negative part that
can't pass through the barrier so here's
the catalyst catalysts are often made of
of platinum so they're expensive because
people would just assume use that for
bling for grills or for cell phones or
whatever so that is one of the reasons
why fuel cells are so expensive here's
what happens in the catalyst h2 on its
way to get to the o2 passes through the
cattles catalyst splits it into two
pieces maybe giving the h2 sort of like
a really tiny kid and a bigger kid who
are both trying to squeeze into the
girls dorm they're like I order for us
to get over there we're going to have to
split up the little kid says okay we'll
split up you go around the long way and
I'll go around the short way because I'm
able to get on to the barrack so H+ gets
split into two parts it gets split into
two H plusses and there's a lot more h2
obviously here than just one molecule
and it gets split into two minuses which
are electrons now as I said before the
H+ they're like the skinny skinny small
little kit that can squeeze under the
barrier
so these H+ is by virtue of their
positive charge they can squeeze right
over and that's what this arrow
indicates they move there they're
squeezing up
and now they end up on the other side of
the bear but they're negatively-charged
buddies maybe the larger kids they were
teamed up with in order to achieve this
mission of breaking into the girls dorm
they're not so lucky
because they can't pass through this
barrier the blocks all positive charge
so imagine we have this big barrier
separating the boys dorm in the girls
dorm and if people are really ambitious
they'll be able to run all the way
around me like run into town and down a
street and then they come back out on
the other side of the barrier and that's
essentially what happens to you because
a positive because these negatively
charged electrons can't pass through the
barrier there instead given another
route around it's a long way around but
they'll still get there they'll still
get there eventually so here is the
route that these electrons are going to
take again they're taking a long way
through town with a long way through the
forest or the cornfield
whatever is separating these guys so H+
is obviously went right through these
immitis is on the other hand the
electrons I'm going to write this right
here so we can keep track of what they
are they're their electrons the
electrons can enter this pipe they can
flow through the pipe and then they end
up coming out on the other side right
here after they've made their trek
through the forest through the woods
they come out on the other side now on
the other side we have h pluses and
minuses they join back together it's
like the short guys and the big guys
team back up on the other side of the
barrier to then go break into the girls
dorm these guys two H's two electrons
come together to cancel each other's
charges out all them come together here
the Arabs all these four things are
going to come together and they're going
to make an H+ and h2 and that h2 just as
we said earlier once to combine with the
o2 the h2 and the o2 come together and
what do they create the h2
and the o2 come together to create water
so big deal why does this create energy
we have the h2s breaking up into two
pieces splitting up finding different
ways over the girls dorm eventually
connecting up with the o2 and forming
water big deal here's a big deal
think about this pipe that the electrons
are having to travel through in order to
get to the other side what sort of a
thing can electrons travel through well
it's not a pipe instead of a pipe what
this is is this is a wire because
electrons can flow through wires now
whenever we have electrons flowing
through wires we call that something
electrons flowing through wires is what
we call electricity electricity so these
guys moving through here are causing
electricity to flow H+ is move through
here but the e - is moving through here
are a moving current that is where the
energy from fuel cells comes from so
their electrical excitation
what we can do is we can take advantage
of the fact that the electrons are
moving through this water and for
example we could go ahead and we could
we could take this wire and we could
hook it up to a light bulb and we could
make that light bulb turn on could make
that light bulb go bright because the
current that's traveling through that
was positive electricity to happen now
at the same time if this were a car we
could go ahead and we could hook this up
to an electric motor that would cause
the wheels to spin so once again let's
look at the whole deal just to make sure
that this all makes sense a shoe over
here o - over here all they want to do
is combine it for water but that there's
a barrier between there that only
positively charged hydrogen can get
through so there's a catalyst that
breaks the h2 into its component parts
into positive H plusses negative
electrons H+ it can move right through
that barrier but the electrons can
instead the electrons off
flow through this wire to meet up with
the H+ on the other side to make water
when the electrons flow through this
wire they're creating electricity
they're generating electricity and that
electricity is used to power the motor
of a car this fuel cell is being used in
automobile now the final word is think
about what's getting created in an
automobile engine we're creating carbon
dioxide if it's perfectly efficient but
usually there's also soot there's a
whole variety of other components like
carbon monoxide sulfur dioxides and
other chemicals a fuel cell engine after
the h2 and the o2 have combined it
creates only water it creates creates
water here's a little here's a little
drop of water show you what's going on
so many people are really interested in
the idea of fuel cell cars because they
don't create any pollution they only
create water