Sometimes something dangerous can also be  life saving.

This is anhydrous ammonia.

It's   critical to putting food on your table, both as a  fertilizer and as a refrigerant.

50% of the food   that you eat is directly thanks to ammonia.

And  without it, the world population would starve.

This means that there's lots of it moving around  the world by truck train and even pipeline.

So sometimes accidents happen.

In 1976, a truck  carrying in anhydrous ammonia crashed in Houston,   killing seven people and injuring 200 more.

In 2002 a train derailment sent a cloud of  anhydrous ammonia over Minot, North Dakota,   killing one person and injuring at least 95  others.

And in 2019, a mechanical failure on a   farm tractor towing, anhydrous ammonia released a  cloud of gas that sent 83 people to the hospital.

And those are just the headline-making  accidents: between 1996 and 2011 there   were over 900 accidents at places that store  anhydrous ammonia resulting in 19 deaths.

You're probably familiar with household ammonia in  things like glass cleaner at the molecular level.

Ammonia is a nitrogen with three hydrogen stuck to  it, and it's normally found solubilized in water.

It's typically about 90 to 95% water and five to  10% ammonia in your typical household ammonia.

But in anhydrous ammonia, that ratio is very  different.

Usually about 99.98% ammonia, and just   a little bit of water.

And that first part of the  name gives it away.

Anhydrous means without water.

At room temperature, it exists as a gas  though.

It can be pressurized into a liquid,   which is how it's usually transported.

Since  you can store a lot of it in a small space   that makes it easier and safer to transport by  pipelines, trained cars and trucks, to farmers   across the country who use it as fertilizer.

Nitrogen is incredibly important for plant growth.

Plants use it to make everything from  amino acids to the chlorophyll that they   need for photosynthesis.

Nitrogen serves an  important structural role because it can form   bonds with weird angles.

Each nitrogen atom has  five valence electrons, three of them like to   form bonds.

And two of them often hang out  in a pair and participate in hydrogen bonds.

So you can get really cool structures for things  like amino acids and the bends in DNA helices.

And then you can stick things together with  those hydrogen bonds.

It's a win-win for   chemical synthesis.

But plants can't use the  nitrogen gas or dinitrogen that's in the air.

That's because of those three valence  electrons that we talked about before   in dinitrogen.

Those electrons form bonds with  each other, making a super stable triple bond   that plants just don't have a way to break apart  and use.

So instead of getting nitrogen directly   from the inert dinitrogen in the air, plants  typically get it by way of bacteria in the soil.

The bacteria are able to break the dinitrogen  down and combine it with hydrogen and create   ammonia that the plants can use to make all  of those proteins in chlorophyll and nucleic   acids that they need.

This process of  turning inert dinitrogen into other   more reactive and useful nitrogen containing  molecules is called fixation.

The nitrogen   fixation abilities of bacteria end up being  a big rate limiting step for food production.

So if you are a farmer and you wanna grow more  crops than the bacteria on your land can support,   you've gotta get more bioavailable  ammonia from somewhere.

This is why back in the 19th century wars were  fought over islands of guano used for fertilizer.

Guano.

That sounds so  familiar.

It’s bat droppings.

It was one of the only ways to  get a rich source of nitrogen.

And without that nitrogen, they couldn't  produce enough crops to feed everyone.

There were real worries about running out of  food.

They solved those worries with poop.

But in the early 1900s, German chemists, Fritz  Haber and Carl Bosch developed a process that   could artificially fix nitrogen and hydrogen to  create usable ammonia.

So how does that work?

First, you gotta make hydrogen gas.

You can do this with a process called   natural gas or steam reformation.

You mix methane  and steam at super high pressures with a catalyst   and you get out hydrogen, carbon monoxide, and  carbon dioxide.

Then you combine nitrogen from   the air with the hydrogen gas and a catalyst  under high pressure at a moderate temperature   of 500 degrees Celsius.

And bam, you get anhydrous  ammonia farmers use that anhydrous ammonia to   grow food.

They can inject it straight into the  ground as a liquid where it will rapidly expand,   turn into a gas and ideally get stuck in the  damp soil due to its water loving nature.

This way farmers can cut out the bacteria  middlemen when trying to feed their crops.

This process made the manufacturing  of ammonia for fertilizer possible.

Without it, we wouldn't be able to grow the huge  amount of crops that we need to feed the world.

Once the Haber Bosch process was implemented on  a large scale, the increase in food production   allowed the world's population to rise from 1.6  billion to 6 billion during the 20th century.

That is huge.

In the US, most of our  anhydrous ammonia is made on the Gulf coast   and piped across large agricultural  areas via a huge pipeline, but it's   also transported by train cards and trucks  and stored in facilities across the country.

In 2020, the US produced 14 million metric tons  of the stuff.

To put that into perspective, an   average African elephant weighs about six metric  tons.

So that's over 2.3 million elephants worth,   and it isn't just used fertilizer.

It's a really  important chemical precursor for everything from   plastics to pesticides to explosives.

It's  also often used as a refrigerant in big   industrial cooling systems like warehouses and  factories.

It's more efficient than commonly used   hydrocarbons and many technicians actually prefer  to work with it because you can smell a leak   quickly giving you more time to get away  or solve the problem than other odorless   refrigerants.

Anhydrous ammonia has also been  suggested as a potential way to transport large   amounts of hydrogen to support fuel cell  cars.

Talked about that in another video.

So this all sounds great, but in order to  use this stuff, we have to actually move   it from the industrial plants where it's made  to the farms and facilities where it's used.

And by virtue of the fact that we're moving  so much of it, there's a chance that things   could go wrong if it isn't stored properly,  or if it ends up in a train or car crash.

When anhydrous ammonia leaks from a high pressure  container, one of two things could have happened.

In the first scenario, ammonia leaking  from a high pressure source will often   cool down as it expands and turns from a liquid  into a gas.

This cold vapor can be dense causing   it to stay close to the ground, but usually warm  surrounding air can mix into it, heating it up   so that it's buoyant and lighter than air.

And then it can drift upwards and disperse   away.

But if the pressurized liquid ammonia  leaks out through a small hole in the tank,   it can aerosolize the ammonia creating tiny  droplets stuck in a cloud of vapor.

This aerosol   is just like the tiny hairspray droplets sprayed  from a can.

That gets stuck in a cloud of gas.

Oh.

The liquid ammonia droplets make the aerosol  cloud heavy.

And it takes a lot of energy.All   of those droplets up the aerosol that forms  is also pretty stable.

So there's not a lot   of chance for warmer surrounding air to mix in.

This means the cloud stays cool and dense for a   long time giving it its distinctive creeping  shape rather than just dissipating quickly.

The very first thing to know about an ammonia  leak is that if you can see a cloud, you should   absolutely not enter it.

Your body is mostly water  and ammonia is really good at dissolving in water.

When ammonia and water mix, you get ammonium  hydroxide and ammonia reacts with moisture,   absolutely anywhere.

It can find it on your body,  your eyes, nose, mouth, and especially your lungs.

The resulting ammonium hydroxide burns through  your tissue, and breaks down your cell membranes   in a process known as saponification.

When  you inhale it, it can burn the moist inner   surfaces of your nose and throat eventually  leading to respiratory distress or failure.

Once ammonia gets into your lungs  and on your mucus membranes,   much of the medical care you get is based  on just allowing your body to rebuild.

Doctors can decontaminate you with a lot of  water and assist your breathing and try and   rehydrate you, keeping you alive so that  your body can repair, but that's about it.

So this small version of the ammonia fountain  experiment can show how even a small amount of   ammonia gas can quickly turn a watery solution  basic.

So first I'm gonna fill this pipette bulb   with ammonia gas.

I'm gonna do that by placing on  top of another pipette bulb filled with household   ammonia and warming it up gently.

I can then take  my ammonia gas filled pipette and dip it into a   flask filled with water and a pH indicator.

When  I draw just a tiny bit of water up into the bulb,   you can see that the pH indicator rapidly turns  blue indicating that the pH is very alkaline.

So are we all in danger of an anhydrous  ammonia accident all the time?

No.

And anhydrous ammonia is moved  and stored around the country a lot,   but if properly contained and transported, it's  not dangerous.

The kinds of accidents that make   the headlines are typically tragedies, but also  aren't caused by the ammonia itself.

Trained   derailments and car crashes can happen no matter  what's being transported.

To keep everyone safe,   the containers used to transport anhydrous ammonia  are rugged, reinforced and checked regularly.

Since it boils at negative 33 degrees Celsius, the  containers have to be able to handle pressures of   up to 250 PSI to make sure that it stays  liquid.

Even when outside temperatures   reach 37 degrees Celsius, they also can't be made  out of copper or zinc alloys as the ammonia will   react with them and eat straight through the  container.

And you've gotta test the tanks   regularly to keep everyone safe, but with proper  testing precautions in PPE anhydrous ammonia   continues to move around the world safely every  day.

We would all be a lot hungrier without it.