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Not too long ago, the estimated number of people on this planet
hopped over eight billion.
I feel like we should all get a cake for that.
Like, it feels like a tremendous occurrence.
And to make all of that cake, 8 billion of them,
we’re going to need a very important ingredient.
Ammonia.
Which is not what you were expecting me to say probably,
because it’s not an ingredient in the cake.
But it is a crucial ingredient in many fertilizers.
In one year, the global agricultural industry uses
about 144 million metric tons of the stuff.
So it helps keep human civilization fed, which is nice, but making all that ammonia
has its downsides, like, for example, its huge carbon footprint.
Luckily, scientists are on the hunt for a way to make ammonia production greener.
Over the past century, humanity has relied on one major method
to get its ammonia fix.
It’s called the Haber-Bosch process, and it pumps out a bunch of ammonia
a lot faster than nature would make on its own.
Each molecule of ammonia needs one nitrogen and three hydrogen atoms.
And the Haber-Bosch process creates those molecules by smushing a bunch of
nitrogen and hydrogen gas molecules together at high temperature and pressure.
And I mean high temperature and pressure.
Between 450 and 650 degrees Celsius, and 200 to 400 times
the atmosphere’s pressure at sea level.
So the Haber-Bosch process requires a lot of energy to maintain that environment.
And these days, the majority of that energy is created by burning fossil fuels.
But that is not the only connection ammonia has to the climate crisis.
See, the process can get its nitrogen gas from pretty much anywhere you look.
It’s nearly 80% of the air around you.
But hydrogen?
Well, that actually has to come from breaking up molecules of methane…
which has a big juicy carbon atom in the center.
And after the methane molecules get broken up,
that carbon is free to bind with oxygen and make carbon dioxide.
So in total, modern ammonia production is responsible
for over 1% of global CO2 emissions.
That might sound like a small percentage,
but we’re still talking more than 400 million tons a year.
With an increasing population, humanity is going to need
even more ammonia at its disposal.
So we need to tackle its carbon footprint.
Right now, the dream is to leave the Haber-Bosch process behind entirely,
and produce ammonia using a completely different method.
One of the more promising techniques is called
the electrochemical nitrogen reduction reaction.
Which is an absolute mouthful, so we’ll just call it the ENRR.
Unlike Haber-Bosch, the ENRR process can be done at room temperature
and pressure, meaning it uses way less energy.
And until all our energy is made from renewable resources,
the less we use to make our ammonia, the better.
The setup looks a lot like a battery, but it works in reverse.
You have a container filled with an electrolyte solution.
A fluid with some kind of acid, base, or salt
all dissolved up in it so an electric charges can flow through.
Then, two rods are placed into that solution on either side of a membrane
that protons, otherwise known as hydrogen nuclei, can pass through.
They don’t actually have to be rod-shaped,
but we’ll stick with that image for simplicity’s sake.
Those rods are each coated in a substance called a catalyst, which makes chemical
reactions happen at either end when you run electricity through the whole system.
Instead of using chemical reactions to generate electric power like a battery,
these ENRR machines use electricity to make the chemical reactions go.
And the most important reaction
is still bonding hydrogen with nitrogen to make ammonia.
But instead of sourcing hydrogen from carbon-containing methane,
ENRR relies on water.
Good ol’ H2O.
First, water molecules in the electrolyte solution react with the catalyst coating
one rod and get split into hydrogen nuclei, free-floating electrons, and oxygen gas.
The electric current directs the hydrogen across the membrane.
Meanwhile, the electrons have to get to the other side using a separate wire.
Over at the other rod, nitrogen gas is pumped in.
By reacting with that catalyst, each nitrogen molecule gets broken apart,
freeing up the nitrogen atoms to make a new friend.
Actually, three friends.
So if the hydrogen can get to that rod fast enough, they can use up some of those
electrons to help them react with the nitrogen and make that precious ammonia.
Unfortunately, the type of electrolyte often messes this reaction up.
Water-based electrolytes are incredibly inefficient at creating ammonia
because the water molecules tend to steal the electrons for themselves.
There’s a much more efficient alternative out there, but it’s incredibly goopy.
Just as you would have a hard time walking through jelly,
the hydrogen ions slow down as they travel from one rod to the other.
So while the ENRR process definitely does produce ammonia on small scales,
it can’t currently create enough of it fast enough
to reduce humanity’s reliance on Haber-Bosch.
But researchers are working on it, experimenting
with both different electrolytes and different catalysts.
If they can make this work, the results could not just help
bake over eight billion slices of celebratory cake.
Ammonia could also help deliver those slices of cake around the world.
Because it could become an alternative source of energy.
See, ammonia is actually pretty energy dense.
It’s one of the reasons why fertilizer is often used in improvised explosives.
One liter of ammonia releases as much energy as roughly one third
of a liter of gasoline, but without any of the associated carbon emissions.
But before you dream about a future where we power our bakeries
and cars with green ammonia,
it’s worth noting that ammonia can be hazardous, both to people and animal life.
Ammonia is still a pollutant, and it can cause environmental problems
if it enters waterways.
So it’s not necessarily the solution to all of our energy problems.
But figuring out how to make ammonia cheaply, efficiently, and cleanly
is an important step to a greener, and maybe more delicious, future.
Okay, so ammonia can’t create a solution.
But a solution can create ammonia.
I’m talking about chemistry!
And you can learn all about that stuff with Brilliant’s course:
“The Chemical Reaction.”
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through this Brilliant course because it starts off with the basics.
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And by the end, you’re working with moles like a champ.
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