- Physics world. - Hello and welcome to the
Physics World Weekly Podcast. I'm Hamish Johnston. In this episode, I'm in conversation with a researcher who's developing
graphene based materials that are designed to play crucial roles in a hydrogen economy. Hydrogen can be used
as a carbon-free source of energy in a wide range of applications, including home heating,
transportation, and industry. However, there's significant challenges that must be overcome to ensure the safe and efficient storage and transportation of the gas
to talk about these challenges and how they can be overcome. I'm joined down the line from
the UK's Cranfield University by Christophe ksal, who is Professor of Composites Engineering there. Hi, Christophe, welcome to the podcast. - Hello, Hamish. It's a
pleasure to join you today. - Great. I'm, I'm really interested in, in talking about hydrogen because it's something that
hydrogen energy is something that I've, I've been
fascinated with, so I, I'm really looking forward
to this conversation. So, so Christophe, what are
the main challenges involved in the safe and efficient storage and transportation of hydrogen? - We are all excited about hydrogen, and it's back on the table, so to say, because, uh, as you know, uh, uh, the world was looking into
hydrogen many years ago. Um, but, uh, it's sort of now is back on. Um, and, uh, the biggest
problem that I think I am, uh, looking
at with hydrogen is because of this, of its intrinsic size, hydrogen is a tiny, small molecule. And when we are dealing with
hydrogen, um, in situations where we need to store
it, as you said, and, and transport it, uh, we have
to use materials, obviously, materials, uh, that, uh,
build the structure, the, the build, the vessel that we
are going to, to move it about and keep it, keep it also on
site, uh, somewhat safely. Um, so because it is a tiny molecule, it can diffuse literally
into any material. It will go through the material, and this is what will then
cause damage to the material. So, uh, hence we have
got concerns of safety because of the deterioration
of the materials that are used to store hydrogen and move about hydrogen. - And so, and so the hydrogen gas, it, it, it can actually damage a vessel, um, through chemical processes. Is that right? - In, in fact, um, there, there
is different type of damage that you could have in materials,
depending also what sort of materials of, of vessels
we are going to use. So you could, uh, maybe classify
those into two categories. Uh, we've got metallics,
metallic storage, metallic, uh, containers, uh, for
example, steel or aluminum. And you have got the composite structures. Um, so when you use metallic systems, uh, you have got this typical issue of, uh, of embrittlement. So you've got steel
embrittlement with hydrogen. That means that the hydrogen
goes into the lattice of the, of the material of, of the
method that we are using. And it slowly is damaging it. It's slowly causing cracking
to that, uh, to that structure of that metallic system. You've got, you've got
slightly different, um, issues with composite materials. And, uh, in this case you've
got, uh, typically a aligner. Aligner is, uh, is a, is a
film, is a coating that is, um, covering the inside of your,
uh, let's say storage tank, a carbon fiber, glass fiber
storage tank, uh, and hydrogen and gain going, um, uh,
is, is able to penetrate, diffuse through that liner. And when you, uh, fill
up the tank and empty it, and you do it many times, you
may have different, again, problems with this polymeric
coating the liner in terms of buckling or, or any other me mechanical
damage that, that may, may be caused by, by this process. So different issues,
different material issues. Uh, but there are, again, no matter whether you look at metallics or whether you look at
composites, polymers, you have got challenges to face. - And, and are these, are
these problems, uh, I mean, I would imagine when you
are, when you're storing and transporting natural
gas, for example, there are challenges there and challenges, I'm guessing that we've overcome. But are, is it a different
problem with hydrogen? Is, is hydrogen more difficult
to deal with than, um, than a traditional fuel like natural gas? - So natural gas is again,
um, going back to the size of the molecules because I think it's, you
know, the easiest to, to, to really understand the problem. And, um, natural gas, typically
you, you have got methane as part of natural gas
is much bigger molecule. Uh, you don't have really these
sort of diffusion problems. Uh, what, um, what we are facing, um, uh, what the, the challenges we are facing with natural gas are the impurities. So for example, you've
got hydrogen sulfates that this one will go in and corrode, for example, the,
um, the steel pipelines that, you know, are used to
transport natural gas. Um, when you now, uh,
bring hydrogen on board and, you know, you introduce
hydrogen into a pipeline, you are likely to have, uh,
also impurities in there. You may have, um, uh, po
possibly also presence of, of hydrogen sulfate as
well, uh, uh, uh, you know, as part of, of the, of the infrastructure that we might be still dealing with. Um, and hydrogen is, uh, going to diffuse into the lattice
and causing an additional or rather enhanced, uh, degradation or corrosion of metallic systems. And this is what we are, um,
mostly concerned about that, uh, you know, it's not only the, the hydrogen is causing the,
um, the, the, the local damage to the, to to dose materials, those traditional materials like steel, but it is actually accelerating, um, maybe diffusion or, uh, penetration of other impurities that will further damage
that metallic system. - Right. I see. And, and so, uh, uh, some of your research is focused on developing new graphene based materials and polymers, um, for use in,
in these hydrogen systems. Can, can you describe these materials? What role does graphene
play in their design? - Graphene is really an exciting material. Uh, it is, uh, part of
a class of materials that we call 2D materials, and there are a lot of other 2D materials out there that are coming up. Uh, my colleagues, uh, uh, all around the world are super
excited about, you know, researching 2D materials, but
we are looking at graphing because, um, it is, uh, actually quite simple material
is made out of carbon. So graphene is consisting
only of carbon atoms. It has got, um, a
molecular layer thickness. So this is a single layer, uh, thin sheet of basic carbon atoms
assembled in a hexagonal, uh, pattern, uh, structure. And because it's made
out of, uh, carbon only, we can understand it very well in terms of how it's going to behave. But it's super powerful because, you know, these carbon
atoms are super compacted. Um, when you start looking
at the, um, environment of hydrogen, uh, you know,
again, hydrogen, um, being, uh, such a small molecule,
uh, you have to deal with a material that is, uh,
powerful enough to handle, uh, molecules like hydrogen and graphene particularly,
you know, is that powerful because of its crystal? You know, the, the arrangements of carbon atoms within
graphene are, uh, superb. So you've got, you know, a
molecular, uh, crystal basically, you know, a single layer crystal. Uh, so you've got densely
packed carbon structure that can now deal with
a molecule, a small, tiny molecule like hydrogen. What I find also exciting
about graphene is that, um, there are different ways
of obviously making those, those new materials that
are coming up to the world. But, um, we are looking also
at, uh, sustainable ways of making graphene. Uh, we are actually, uh, looking at making graphene on
a very significant scale using greenhouse gas greenhouse gases. So, so this is basically
fugitive gases like methane or C two that are going
to enter the atmosphere. Instead, we are diverting
all of these gases as feedstock to make graphene from them. So we are basically, um, reaching out to this high performance
material graphene, uh, but at the same time, it's actually going to be produced from the waste
and fugitive gasses that otherwise will end up in the atmosphere. So this is, this is the
excitement that really I wanted to share as well with you today. - And, and so how does the
graphene act as a barrier? Is, is it, is, I mean, is c
can it be thought of as a, as as a physical barrier in the sense that the carbon atoms are
packed so tightly together that the, the hydrogen molecule molecules can't squeeze through? Or, or does the hydrogen
actually react with the graphene and, and create a, a layer that, um, that itself is impervious or, or maybe it's a bit of both,
um, or, or neither ? - So at this moment, we are looking at this physical barrier, which you described, and, and that's, you know, precisely
what a tightly packed, um, material like graphene
will, will offer you. When you look at hydrogen,
the, you know, the, the best barrier for hydrogen
is a material that is, that has got high crystallinity as well. So for example, if you look
at, uh, polymers, uh, we, the material that performs
very well is polyethylene. Uh, for example, for hydrogen
pipelines, we will be using, uh, a material called
PE 100, which is, um, which is a high crystallinity,
uh, polyethylene. So you've got these
tightly packed, um, uh, atoms within the material that
will act as a barrier for, uh, a barrier for hydrogen. And therefore, if you're
dealing with material like graph in here with, again,
tight Deepak atomic structure, it does act as a molecular filter. So it seems to be perfect
sort of material really to deal with any future
challenges around hydrogen, but it doesn't stop just there. Um, I think you have already
put, uh, an interesting, uh, direction forward here, which
is, you know, looking at, uh, interaction between hydrogen and graphene. And to be honest, this is
what we are going to, uh, to explore even further. Uh, we are doing this
at a very, very, um, um, initial level, but I think
the interaction with graphene between graphene and hydrogen
will give us this additional enhancement of, um, the barrier performance coming from graphene as well. - And Christophe, you, you mentioned, um, uh, hydrogen pipelines. I think you've developed
a new paint, um, for hydrogen pipelines. Um, at, at what stage is
this, uh, development at? Is, is, is this paint
being used in commercial hydrogen distribution systems? - So in, in Cranfield, um,
we are dealing with, um, uh, large number of industries. Um, and this particular
development was our partnership with, uh, national Grid, or what's now it's called National Gas because National Gas has
separated from National Grid. Um, and we have been working
with, uh, national Gas, uh, on this project, um, uh,
for almost two years. And, um, the, the project
basically was looking at, at an upgrade to the
existing pipeline that, uh, we have in uk and I think
there are almost 8,000 kilometers of pipeline within the UK and, um, national Grid, uh, and National Gas is very keen to, uh, to upgrade the whole infrastructure to make it suitable for hydrogen. Uh, there are, there have, there have been announcements
earlier this week around this, and we know that national
gas is going to, to put, uh, hydrogen into the grid already. So this is super exciting. Um, but the vision is to move towards a, a complete a hundred percent
hydrogen infrastructure and, uh, it's, um, it's super impressive what National Gas is doing because there is a very clear plan of when this is going to happen. So it's not, if it's going to happen, it's just when this is
happen, it's going to happen. And, um, national Gas is
already testing a smaller infrastructure, um, preparing
for this large deployment of two kilometers long UK backbone that will connect the north and the South. Uh, and by 2030, I believe
the plan is to connect with these massive, um,
hydrogen infrastructure that exists already in Europe. Um, so where, where do we come from? Come, uh, in, into this picture is, uh, we are looking at the upgrades
to, to, to this existing, uh, steel pipelines. These are, you know, large
huge dia the pipelines that are already, um, in operation. So basically they are, um, on the ground or under the ground. And the biggest challenge
at the moment is to, um, make the underground pipes
suitable for, for such a gas. Um, there was actually a
question, you know, um, uh, put forward from National Gas
to say, actually, do we need to upgrade this pipeline because, um, we are not dealing
with thin, uh, materials. You know, this is a very
thick, very big, you know, pipeline, uh, made out of steel. Um, there are different grades of steel of course there as well. But, um, we are dealing with,
with, uh, with a large lump of steel, you know, uh,
forming the pipeline. Um, and uh, on the surface it looks like
we actually might be still okay to simply just put hydrogen
through the network. But of course, national gas is
looking at safety, you know, we are looking at super,
we are preparing for, for, for the environment, for the situation that we absolutely need to be safe when introducing hydrogen. And, and therefore, uh, they want to possibly look at the options, how to, um, maybe upgrade these existing
pipeline infrastructure with something that, um,
will not be too expensive. You know, it cannot destroy
the environment again. So we, you know, we don't want
to sort of create a project that suddenly we are
transitioning into hydrogen. We have to dig out all of these
pipelines from the ground, you know, it's going to be,
again, massive, massive amount of carbon footprint behind. No, what we want to do is we
want to find cheap solution that will upgrade the existing system, and we have been exploring
coatings, so how do we deploy, um, a coating into the existing pipelines? Uh, there are methods of doing this. So, uh, the, uh, the, the
machine, the, the machinery that is used to service
existing pipelines are, are called pigs. Uh, you know, it's basically a, a vessel that goes into a pipeline
is, is being, uh, pushed through the pipeline and it can clean it because obviously you've
got variety of debris and co deposits and so on. So we can quite easily use
this, this vessel called, called the, the, the pig,
um, to go into the pipeline and retrospectively deploy air coating that would particularly
be suitable to, um, prevent any damage deterioration
from coming up hydrogen. And, uh, we have indeed developed, uh, coatings using graphene. We, we, we, we were looking
specifically at graphene because this is the best material that we can deploy in a coating. Uh, you know, with this crystal
structure, as we discussed, you know, with the capabilities
to deal with hydrogen, um, we have developed coatings
that currently are, are at TRL level four. They really perform, uh,
impressively, uh, in terms of stopping hydrogen from
diffusing through them and getting to steel. Um, and currently we are
at the process of, um, identifying manufacturers of these paints. But on one, on the other
side, we have got national gas that obviously, you know, he's looking for exactly solutions like this to adopt. But what is important, what is absolutely
critical is whatever we do around hydrogen, it has
to be low cost net zero or, uh, or better than net zero situation, because we do not want to
create an environment, you know, that looks clean and
exciting like hydrogen, but actually behind we are polluting more. - Yeah. Wow. Wow. That, I mean, that it sounds like a big project and yeah, I, I hope that
goes very well for you. Um, you, you're also working
with the aircraft maker Airbus to develop a, a cryogenic
storage system for hydrogen C. Can you talk a bit about that project? - Airbus is, um, super impressive. Uh, if you look at, you know, hydrogen, because they have made some, um, really great statement, you know, transitioning basically the aviation, uh, from current fossil fuels
to, to hydrogen, um, the others are looking at stuff
sustainable aviation fuel, and that's basically,
it's just a fuel, uh, that burns produces against CO2. But, uh, hopefully it's made sustainably, hopefully it's made with
lower carbon footprint, but it's still emitting
CO2 hydrogen aviation. Uh, you know, pushing hydro, putting, pushing hydrogen into aviation
means really, you know, you do not have any CO2 emissions. And, and this is why, you
know, I'm super impressive with our bus making, obviously
these massive sort of, um, uh, steps forward. So again, um, at Cranfield with our, um, with our, you know, um, uh,
commitment to support industry, and we have got a
longstanding, uh, partnership with Airbus at Crown Field, and we are also supporting
Airbus on this, uh, program. So, uh, creating a hydrogen
aircraft is not simply, uh, you know, making, uh, the
hydrogen a little bit tighter, uh, making the existing kerosene storage tanks a bit,
um, uh, less permeable to, to hydrogen. That's not going to to work really, uh, going into a hydrogen aircraft
means designing the entire aircraft from scratch, bearing
in mind that you have got, uh, you know, this fuel, new fuel that you have to deal with. So I think it is, uh, it is an amazing, um, uh, development, uh, innovation within, uh, aviation. So I, I, I see it as, you
know, it's not just simply creating hydrogen, hydrogen aircraft, but this is a major innovation
within the aerospace. - And is the, is is the
challenge in, in aviation to, to get the hydrogen fuel into a state, um, of a very high energy density so you can get enough hydrogen on a plane to take it across the Atlantic. I I, is that where the challenge is? And, and the, the, the
cryogenics are you, is the plan to use liquid hydrogen rather
than GS hydrogen to get that, to get the density? - So if you look at GS
hydrogen of, uh, if, if you look at Gaius, um, uh, uh, storage of hydrogen, as you
pointed out, uh, Hamish that's the issues we are
facing is this energy density, right, that we have got. And we can still deal with
gaius hydrogen storage, uh, for aircraft, but we'll be
looking at maybe island hopping, you know, short dis very
short distances right here. Uh, so really to make, uh,
to transition hydrogen into, uh, aerospace, we need
to go for liquid hydrogen because you absolutely need
that, uh, storage density. And we know that's, you
know, that's possible. If, if we are, we are
dealing with liquid hydrogen, we can indeed look at, you know,
uh, cross atlantic flights, you know, long hold flights, that is absolutely not a problem. But you need to deal
with cryogenic hydrogen. And that is, that is a new, uh, uh, level of challenges that we are facing. Again, everywhere you look
at it's about materials and it's, you know, to me, uh,
being a material scientist, it's again, super exciting times because, uh, it's not about
traditional materials. It's not about steel,
aluminum, carbon fiber. We have to look at completely
new generation of storage. So, um, you know, we are
familiar with, uh, four types of tanks that we are, we are dealing with the type four, it's the, the latest composite tank type
five is just removing liner, but again, coming up, but here we are looking at
type six, type of tongue type, um, that we need to create because we need to reduce the weight. Uh, we need to deal with extremely low temperatures
minus 253 degrees Celsius. But most importantly,
especially for aerospace is that safety, uh, the safety aspect that we need to deal with. And, um, uh, we are looking at at least
three levels of safety. So you've got the, the basic
level where you make sure that you keep your hydrogen, uh, the, uh, cryo, uh, temperature. Of course you've got a
secondary level, uh, you know, what happens if this turns off and you need to have
materials without, uh, the, uh, energy input. So that means, you know,
passive materials that will keep that environment for a period
of time that will allow for the aircraft to land, you know, at the near nearby airport,
if there's an issue and you've got a third layer
of safety, uh, means that, you know, if something really happens that is uncontrollable, uh,
you know, how do you drop off that fuel or that, that
sort of entire tank that you have got on board,
you know, somewhere, um, into the Atlantic Ocean, for example. You know, how do you drop it and how do you manage to
have enough fumes to, uh, safely land aircraft? So that's all exciting, that's
all, you know, uh, possible. We are not looking at,
uh, you know, something that is very much into the future. That's something that we
can do, uh, already now or we can start doing now. And of course, we, we are on
a trajectory by I think 2030 to 2035 to really have a system flying. - Okay. And, you know, I think a lot of our listeners will have,
will, will be familiar with using liquid nitrogen in the lab. Um, I'm guessing that liquid hydrogen and liquid nitrogen are
two different things. Is it much, is it much more work to, to make hydrogen a liquid and to, and to keep it as a liquid? Because, you know, with
nitrogen, it, it seems fairly straightforward, but I'm guessing that's
not the case with hydrogen. - So, uh, yes, it is
definitely another level down. Um, you know, going to
minus 200 degrees, again, there are lots of materials that can deal with this temperature, you know, the liquid nitrogen, basic temperature. We, we are familiar with this, and it feels like, oh, we are only going to go an additional minus 53 degrees, but that additional minus 53
is, is really a, you know, a step down, quite a
significant step down. Um, so there are not, um, uh, the, the, there are
certain sort of limitations that you have got in terms
of even, um, you know, depressurizing a system
like this, you know, bringing it it up maybe for servicing, which you, you would have to do. Um, so it is quite another sort of level down. Um, uh, and that sort of in
involves, you know, materials, but also, um, the servicing
of a system like it, we, we have been dealing with
cryo tanks, you know, for, uh, liquid hydrogen and there
are companies that are doing liquid hydrogen, um,
you know, management, storage and transportation, um,
uh, some big companies. But, uh, if we are up in the air, that's a completely different environment. So on the ground, yes,
that is done now, you know, we know how to do it, uh, but up in the air at, uh,
you know, uh, 30 kilometers above the ground, that's an,
that's really a, you know, a different, uh, environment to deal with. - I see. And, and in terms
of energy density, the, the, the energy density of, of
liquid hydrogen, is, would that be on par with aviation
fuel or, or would it be greater or would it be a bit less? - So, uh, if we compare, um, a liquified hydrogen, um, we, uh, would be able to get a higher energy density from, from the hydrogen than
an the aviation fuel. Um, obviously, you know, that's because of, uh, of the liquid
state, uh, of the density that, that we can reach with hydrogen. Um, and, um, if you
compare the, uh, density, uh, of, um, uh, the, the, the
liquified form of hydrogen, uh, you are going to, uh, to,
uh, to expect a higher, uh, energy density, uh, out
from it than you would from existing fuels that we are deploying. Um, but, uh, there are also an additional
maybe obviously benefits of it, not, not to mention obviously
that we have got no CO2 uh, emissions coming out,
but also, uh, in terms of how the hydrogen will burn as well. So, you know, and, and obviously you have
two options in here, which you don't have
with existing, uh, fuels. You can burn hydrogen or
you can use fuel cells. So you, you may have, you know, no, really no onboard combustion
taking place, so to say. So, uh, so I think there
are, are the, the, the, these are the additional benefits that you may have different ways of really extracting the energy out from
hydro, from liquid hydrogen. - Oh, that's really interesting. I mean, that sounds like
another fascinating project. Um, I, from my final
question, I just wanted to get your take on
what, what is your view on a hydrogen economy? Do you, do you think
that hydrogen will become a mainstream fuel in the future? Or, or perhaps will it
be a specialist fuel for aviation, for example? - So, uh, we know that for aviation there are going to be
two streams, uh, at least for the next sort of mid
to, um, short to mid time. And that's the staff that is coming in because obviously, you know, we, we can see some decarb
decarbonization potential from staff, uh, and then the hydrogen
will obviously enter the, the, the, the reals of, uh, of aviation. And, uh, at the end of
the day, uh, I think hydrogen, uh, will win
in aviation as a fuel. Uh, as long as we can
demonstrate that we can really make the hydrogen, uh, all,
uh, at the low carbon level. 'cause that's ultimately
what we are after, right? It's not about surface, it's not about hydrogen is about low carbon footprint of where we are going. So we, we have to
absolutely make sure that the cryogenic systems, the,
uh, production of hydrogen, that is all going to be lower
carbon footprint overall. And, um, I'm stressing this
always to all my colleagues, um, within industry that the,
the first thing that you need to do is to do a proper
carbon footprint analysis in whichever direction you are going. Uh, are we going to see
hydrogen on, um, on a big scale? Uh, I think there is an, there
is a very clear opportunity for the hydrogen in the future. There is a place for it. I, I'm not sure whether it
will become the main sort of source of energy and fuel. I think we need to, we need
to think smart, we need to, we need to combine things. You know, you've, you've got
solar, you've got wind, um, you have got, um, energy coming, uh, from nuclear sources. Um, uh, there, there's fusion coming up. So I think there will be a mix of things, uh, in, in the future. We shouldn't just put
all our, you know, cars and investment into one area. But I do believe that hydrogen
will play an important role, uh, decarbonizing heavy
industry, for example, uh, capturing, uh, the, um,
sustainable, uh, green energy when we cannot use it. So for example, there is
this, this, this discussion, you know, why do we even,
you know, need hydrogen, we can just simply use
straightaway electricity. And that's brilliant. You know, if we can use the green
electricity for heating homes, for running, um, uh, plans, that's, that's what we should do. This is the lowest carbon
future, uh, for, for doing, for running the, the,
the, the future world. But that is not necessarily
going to be possible always. And this is where, where
hydrogen beautifully comes in. But again, the most
important is to be able to make this hydrogen at the lowest carbon footprint we can have. We can possibly have it. And the good news is that there is great
support from UK government because there is the low carbon, uh, hydrogen standards already there. We have the number, we have
the protocols, you know, uh, how we should quantify the low carbon footprint, uh, of hydrogen. So everything is out there. Um, and we just simply
have to follow this and uh, and yes, use hydrogen wherever that's, that makes sense. And that's, you know, wherever
that's is a smart decision to do, but at the lowest
carbon footprint possible. - Well, that's great, Christophe, thanks. Thanks for talking
about your research and, and talking about
hydrogen in general as a, as a fuel for, for the future. And, uh, thanks for coming on the podcast. - It's a pleasure. Thank
you very much, Hamish. - I am afraid that's all the time we have for this week's podcast. Thanks to Christophe Al
for joining me today. And a special thanks to
our producer Fred Isles. We'll be back again next week, but in the meantime, do
check out the latest episode of the Physics World's Stories podcast host Andrew Gluster is in conversation with the astrophysicist and author Emma Chapman about the history of radio astronomy. Chapman, who is at the UK's
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