The key to carbon neutrality is the massive electrification of our way of life.
This means powering not just our homes and cars but every sector of the world economy
with carbon-free electricity.
But there’s a problem.
You see, not all sectors of our economy CAN be electrified, and in those cases, we usually
need to burn fuel to produce thermal energy.
This calls for clean, carbon-free fuel to burn but, where do we find it?
For Japan, the answer is hydrogen.
But not just any hydrogen…
Red Hydrogen produced with nuclear energy.
I’m Ricky, and this is Two Bit da Vinci.
When you think of Japan and nuclear power, I’ll wager that hydrogen isn’t the next
thing to pop into your head.
Yet Japan is a world leader both in hydrogen technology and nuclear energy production,
and recently they tied both expertise together in a technological breakthrough that has been
decades in the making.
Japan has been one of the strongest proponents of hydrogen adoption in the international
scene, working to create hydrogen supply chains and developing the hydrogen fuel cell electric
vehicle industry.
They house the world’s largest green hydrogen plant, the Fukushima Hydrogen Energy Research
Field (FH2R) [1].
However, clean hydrogen produced from renewable sources is very expensive and unlikely to
be a cost-effective alternative in the next several decades, so Japan’s energy policy
regarding hydrogen seems somewhat like a gamble [2].
Even Elon Musk once joked that hydrogen-powered vehicles ran on fools’ cells…
instead of fuel cells…
get it?
Regardless, “...establishing elemental technologies for hydrogen production…” is still one
of Japan’s core Green Growth Strategies to reach carbon neutrality by 2050, something
the government confirmed just last year.
Now… we’ve covered hydrogen before on this channel (links in the description), so
I won’t go too deep into the pros and cons here, but hydrogen has plenty going for it.
After nuclear energy, hydrogen has the highest specific energy density of any known fuel,
packing 33.3 kWh/kg, which is three times more punch in the same amount of mass as the
best fossil fuels.
Additionally, we can burn hydrogen to generate heat and use a fuel cell to generate electricity,
in both cases releasing nothing more than water vapor, so it’s carbon-free.
On the flip side, being a gas, hydrogen has very poor volumetric energy density, so we
have to compress it at very high pressures to make it practical.
This brings all sorts of problems that go from storage and transportation to safety
issues, none of which are trivial, and which have helped make batteries and not hydrogen,
the key technology for the EV industry.
But why does Japan seem so hell-bent on pursuing hydrogen, and how does this affect you and
me?
The main reason is that Japan is a very small island with few resources but with a big appetite
for energy.
This makes energy security a BIG DEAL in Japan, especially after the oil crisis of
the 70s.
So, they’ve been pushing hydrogen technology as a more sustainable and reliable option
ever since.
They also turned to nuclear energy, by the way!
In fact, nuclear energy is at the core
of today’s topic, and not because of
what you’re probably thinking.
But we’ll get back
to that in a minute.
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The second and equally important reason is that many heavy industries like steel, heavy
transportation, the chemical industry, and even in the aerospace industry CAN NOT run
on electricity alone and require burning some form of fuel, where hydrogen is the perfect
replacement for fossil fuels.
This makes hydrogen imperative to reach our global carbon neutrality goals.
Take steel making, for example, which accounts for roughly 8-9% of our total worldwide greenhouse
gas emissions [3].
A Swedish company called H2GS, as in hydrogen green steel, will use hydrogen instead of
coal to produce steel and is set to start operations in 2024, producing five million
tons of high-quality steel per year with 95% fewer carbon emissions than traditional steel
mills [4].
Additionally, if used in the heavy transportation sectors, hydrogen could help cut down as much
as 13-14% of our total carbon emissions [5,6].
Image Source [6]
Image Source [5] So, clean hydrogen could help us cut down
almost a quarter of the world’s emissions, which is a huge step forward toward carbon
neutrality.
But There’s a catch.
Notice how I said “clean” hydrogen and not simply hydrogen?
The problem is that, though hydrogen itself burns cleanly, hydrogen is only as clean as
the energy and processes we use to make it.
And the sad truth is that 90% of the world’s hydrogen, including the one Japan, mostly
uses is made by burning fossil fuels.
As it turns out, even if we captured those emissions, producing what we call blue hydrogen,
this hydrogen’s carbon footprint is actually worse than just burning fossil fuels, to begin
with [7].
So, how can Japan use dirty hydrogen and then have the nerve to say that it’s all with
the aim to decarbonize by 2050?
As you may have already guessed, there’s still more to unpack.
In essence, Japan needs a stable hydrogen supply chain to keep its hydrogen industry
growing until they find an economically viable alternative.
And that they did!
Ok, so, the first thing that comes to mind when putting Japan and nuclear energy together
is the nuclear disaster at Fukushima Daiichi Nuclear Power Plant.
The disaster caused the meltdown and explosion of the reactor, releasing tons of radioactive
material into the atmosphere, displacing hundreds of thousands of Japanese residents, and unleashing
a worldwide anti-nuclear energy movement.
The aftermath affected all of us.
In the United States, nuclear has been declining ever since, with 26 of the 96 operational
nuclear reactors either scheduled to or already being decommissioned and only two reactors
currently under construction.
Japan closed down all its nuclear reactors and was forced to go back to coal and oil
to cover the energy gap.
Image Source [8] However, the energy crisis caused by the war
in Ukraine caused oil and gas prices to skyrocket, making the Japanese reconsider, and now, nuclear
is making a big comeback in Japan thanks to a cutting-edge nuclear reactor called the
High-Temperature Gas-Cooled Reactor or HTGR for short, and the implications are huge!
We’ve been testing HTGRs since 1964, but only as small-scale experimental reactors
or pilot plants.
Image Source [9]
Yet HTGRs are “almost” the holy grail of nuclear energy.
They could prove to be the solution to cut down a significant portion of our carbon emissions
and make hydrogen a real game-changer that could rival lithium-ion in some market segments.
But what exactly is a High-Temperature Gas-cooled Nuclear Reactor and how is it different from
all the others we have today?
To answer that, let’s put our engineering hats on and do a nose dive into the nuclear
reactor…
well, not literally, but… you know what I mean.
Nuclear energy is pretty straightforward.
All current reactors use fission energy from the breakup of heavy atoms like uranium or
plutonium to generate heat.
We use that heat directly or we use it to boil water and drive steam turbines and generate
electricity.
This reaction needs a neutron to start but releases three other neutrons, which leads
to a sustained chain reaction that constantly produces heat and power.
It’s crazy hard to maintain and control this chain reaction without it running away
and blowing to smithereens.
The big problem is heat, so we need to drain it out as fast as possible to avoid the core
from melting.
The vast majority of the 440 operational reactors worldwide are light water reactors that use
liquid water as coolant.
But in the case of the HTGR, the coolant isn’t water, it’s a gas!
A gas?
As in, air-cooled?
Now that I think about it, the HTGR is the VW Beatle of nuclear power plants!
Anyway, using gas as the coolant has many challenges because gases have very low thermal
conductivities (in the range of 0.01 to 0.03 W/m.K at room temperature) [10] an order of
magnitude lower than liquid water’s (0.598 W/m.K), and also low specific heats.
For example, air has a specific heat of only 1.005 J/g.K, which is a fourth of liquid water’s
4.186 J/g.K.
This means that gases absorb heat at a slower rate than water, and can hold less heat for
the same temperature difference, making them less effective as coolants in general.
But Japan’s new HTGR reactor isn’t cooled by air.
They chose helium, which has an unusually large thermal conductivity of 0.15 W/m.K [10]
and a specific heat at room temperature that is actually greater than water’s.
While still not as good as water at cooling the core, using helium has other more important
advantages:
We can heat helium to much higher temperatures than liquid water and since it’s an inert
gas, it won’t corrode the piping.
This allows us to operate the nuclear reactor at over 1,800 °F (approx. 1,000 °C) compared
to light water reactors that barely reach 600 °F (315 °C).
This temperature opens a world of opportunities in terms of what we could use HTGRs for, besides
generating electricity, including many heavy industries.
Image Source [11] With adequate coupling technology, we could
use this heat directly to power heavy industrial processes like iron making, oil refining,
and even the petrochemical industry.
In comes hydrogen So, to summarize, HTGRs are amazing.
But what does this all have to do with hydrogen?
The answer is EVERYTHING!
Notice that several of the potential applications of HTGR heat have to do with hydrogen production.
In the first place, HTGR heat is enough to drive the steam reforming process used to
make hydrogen from methane and other components of natural gas.
This means we can use HTGR heat to produce hydrogen without burning fossil fuels.
However, because gas reforming still produces carbon monoxide and dioxide as by-products
of the chemical reactions, hydrogen’s carbon footprint is only reduced by about 40% [9].
But there are two other hydrogen production technologies that require high temperatures
but that don’t generate any carbon emissions at all, making the resulting hydrogen completely
clean.
Those are high-temperature steam electrolysis (HTSE) and thermo-chemical cycles like the
thermochemical water-splitting iodine-sulfur (IS) process.
This is exactly where Japan’s potentially genius plan comes in.
They’re the first in the world to attempt coupling an operational HTGR called Hight-Temperature
Engineering Test Reactor or HTTR, with a thermochemical cycle hydrogen production plant.
The HTTR test reactor achieved its first criticality on November 10th, 1998, and started operating
at its full 30 megawatts of thermal power on April 19th, 2004.
It was then successfully run for 50 consecutive days in 2010 at full power, with an outlet
helium coolant temperature of 1,742 °F (950 °C).
Everything was shut down and put on hold after the 2011 Fukushima disaster.
But ten years later, after passing all the new safety standards, the reactor was restarted
on July 30th, 2021, and has been operating at full power ever since.
With the HTTR in full swing, things start falling into place for Japan’s strategy
for carbon neutrality by 2050.
On February 8th this year, Mitsubishi Heavy Industries was commissioned to spearhead the
nation's biggest bet on hydrogen to date: the construction of the first-ever large-scale
hydrogen production plant coupled to direct heat drawn from the HTTR nuclear reactor.
The plant will use a new way to produce hydrogen using a two-step thermochemical cycle called
the iodine-sulfur or IS cycle.
In essence, this runs two separate chemical reactions that produce hydrogen and oxygen
and a third one that consumes water and regenerates the fuel for the first two reactions.
So, the only input is water and the only outputs are hydrogen and oxygen.
Fun fact, many mistakingly refer to hydrogen produced this way as pink hydrogen, but it’s
actually called red hydrogen, as it’s a form of high-temperature catalytic splitting
of water that uses nuclear heat as a source of energy [12].
But why is this game-changing?
The significance of Japan’s test reactor for all of us is three-fold.
It’ll be the first time ever we manage to produce large quantities of totally clean
hydrogen in a constant, reliable, and economical way, with costs far below green hydrogen.
This could seriously change the game in the quest for carbon neutrality worldwide, as
it could be the answer heavy industries were looking for to decarbonize their operations,
something renewables just haven’t been able to pull off.
Secondly, these reactors can be built right next to industries anywhere, since they don’t
require vast amounts of nearby running water.
So, we could see heavy industries moving further away from power grids and closer to raw materials,
lowering operational costs and further cutting down carbon emissions due to less transportation.
HTTR Safety The third benefit is related to safety.
Or, did you think that I was about to cut the video short without addressing something
as important and meaningful for nuclear energy?
Hydrogen and carbon emissions aside, I have to say that the biggest and most significant
benefit of Japan’s HTTR reactor is how it fixes one of the biggest and most notorious
flaws of nuclear energy: the risk of a nuclear meltdown!
These new reactors have a series of inherent safety features that make a nuclear meltdown
almost impossible, and it starts with the fuel.
HTTR uses Tri-structural isotropic fuel or TRISO fuel.
This is made of tiny ceramic kernels with 6% uranium oxide covered with four layers
of highly resistant ceramics.
Image Source [13]
This encapsulation traps all the radioactive waste inside it and makes it almost impossible
for this waste to be released into the atmosphere even in case of an accident.
But the best part is that these ceramics are incredibly heat resistant and require temperatures
of several thousand degrees Fahrenheit to decompose making a meltdown almost impossible.
Additionally, its high thermal conductivity coupled with a high heat capacity helps the
TRISO fuel lose heat passively to the surroundings very quickly, which means that even in the
unlikely case that there was no active cooling (like what happened in Fukushima) the reactor
wouldn’t melt down.
You’re probably going like…
Yeah right!
Prove it!
I get it!
I felt the same way!
Most Japanese did, in fact.
But you wanna know what Japan did?
They proved it!
As in, they simulated catastrophic failure of the cooling system and control rods in
an experiment while the reactor was opperating at full capacity.
Spoiler alert!
It didn’t blow up!
In fact, it never even got close to the safety limits.
The reactor fuel initially reached a scorching 2,400 °F (1,320 °C) and then slowly cooled
passively to 2,372 °F (1,300 °C).
This would’ve been doomsday in any other nuclear reactor, yet the reactor survived
unscathed and is still opperating today.
The test’s results suggest that we could have Hommer Simpson running the reactor and
we’d be fine.
Jokes aside, though, we have a safety margin of at least one full week without human intervention
and without risk of meltdown or radioactive contamination.
Not bad at all!
If you’re thinking, “that’s in Japan!
What does this have to do with me?”
Well, a lot!
This success is unprecedented and it could mean the return of nuclear power worldwide
in all its glory, bringing clean hydrogen along for the ride.
Not everything is perfect But of course, there’s always a tradeoff.
First of all, though HTGRs almost completely solve safety, they still produce as much nuclear
waste as all the old technologies do.
So, we still have to ask ourselves how are we going to manage all that waste for the
next couple of thousand years.
Furthermore, we don’t know if this technology will scale as they predict.
But, we have our fingers crossed!
It’s encouraging to think that most of the remaining challenges are related to design-specific
details and coupling technology [13] and we can almost surely overcome these with clever
engineering as we always have, proving, once again, that the future is going to be awesome!