What is crude oil?

0:46 Welcome to Science is Not Boring by kidopoly.com. I'm Mira. And I'm Finn. A big hello to eight-year-old Bodie in Surrey, England, who loves science and asked for an entire episode all about petrol and crude oil. And a huge hello to Reed in Melbourne, Australia, listening on all his car trips after moving from New York City.

1:11 If you haven't already, tap follow wherever you're listening so you never miss an episode. So, Bodie wants to know about petrol. Wait, what is petrol actually made of? Just some kind of squished rock? Oh Finn, it is so much wilder than that. Imagine a black, gooey liquid made from billions of dead sea creatures that lived a hundred million years ago, during the time of the dinosaurs.

1:40 Wait, dead sea creatures are powering the cars we drive today. Yes, and we use it for almost everything. Right now, the world is gulping down nearly a hundred million giant barrels of this ancient goo every single day. A hundred million barrels? Every single day? That is an unbelievable amount of goo!

2:04 It really is! Today we're diving deep underground to discover exactly where crude oil comes from, how we manage to pump it out of the earth, and how it powers almost our entire world. And how we turn it into petrol for Reed's epic car trips. Okay, so start from the beginning. You said ancient sea creatures, like giant megalodon sharks or massive squid?

2:28 Actually, we have to think way, way smaller. We're talking about microscopic seaplankton, tiny algae, and microscopic bacteria. Plankton? Like those tiny green specks floating in the ocean. They made all this oil. That's it! During ancient periods like the Jurassic and Cretaceous, between 66 million and 201 million years ago, our oceans were completely packed with these tiny creatures.

2:58 So what happened to them? Did they all die at once from an asteroid? They just lived their normal lives, and when they died naturally, they slowly sank all the way down to the dark seabed. That must have been a lot of dead plankton piling up, like a creepy underwater blizzard. Mountains of it. But down on the ocean floor, there was almost zero oxygen in the water.

3:20 Why does it matter if there was no oxygen? Because without oxygen, normal bacteria couldn't eat them, so they didn't just rot away. Instead, they got buried under heavy, heavy layers of mud, sand, and silt. Like a giant muddy blanket trapping them at the very bottom of the sea. Exactly. And over millions of years, as continents shifted, those layers of sediment got thousands of feet thick and incredibly heavy.

3:48 So the entire weight of the ocean floor was just squishing them down. Yes, immense crushing pressure. And as they got pushed deeper and deeper into the Earth's crust, things started to get really, really hot. How hot are we talking? Like an oven baking a pizza. Exactly like an earth-sized pressure cooker.

4:08 The temperatures deep underground reach between 50 and 150 degrees Celsius. Whoa, that is way hotter than boiling water. So what did that heat do to the squished plankton? It slowly cooked their remains. The intense heat and pressure changed their chemistry, turning them into a waxy substance called kerogen, and finally into dark, thick, liquid, crude oil.

4:36 Wait, so where is it now? Is there just a giant underground lake of oil sloshing around? Not quite. The crude oil actually squeezed up into porous rocks, like sandstone and limestone, acting a lot like water trapped inside a hard rock sponge. A rock sponge? So how do scientists even find it if it's trapped inside solid rock?

4:59 They use seismology. Geologists shoot massive sound waves into the ground and measure the echoes that bounce back to map where the oil is hidden. Like giant underground sonar? That is brilliant! And to get it out, massive metal rigs have to drill thousands of feet into the ground. Some oil wells go down 30,000 feet.

5:22 30,000 feet? That is deeper than Mount Everest is tall. How does a drill even survive that? The drill bits are studded with industrial diamonds so they can chew through the solid rock without breaking. But wouldn't the spinning drill get super hot from all that friction? It would! That's why engineers pump thick, special mud down the hole just to cool the drill bit off.

5:46 Drilling deeper than Everist with diamond bits just to pump up ancient plankton goo. Science is wild. It gets even wilder. Because when that black, sticky crude oil finally pumps up to the surface, it isn't actually ready to use yet. Why not? Can't you just put it straight into a car or a tractor? No way!

6:09 Raw crude oil is a messy mixture of hundreds of different chemicals. It would completely ruin an engine. Oh, so it has to be cleaned first. Exactly. We send it to a giant chemical factory called an oil refinery. They process the crude in a massive 50-meter tall machine called a distillation tower. 50 metres tall?

6:33 That's like a 15-story building just for cooking oil. Spot on! They blast the crude oil in a furnace until it reaches an incredible 350 to 400 degrees Celsius. 400 degrees? That would instantly melt plastic. What does it do to the oil? It vaporizes it. Most of the oil turns into hot gas and vapours that rise up the giant tower, just like steam rising from a boiling kettle.

7:03 Wait, so the heavy liquid turns into a floating cloud of oil gas? Yes, and this is called fractional distillation. As the vapours rise, the tower gets cooler near the top. So they turn back into liquids when they cool down. Exactly. The lightest, fastest vapours go all the way to the very top before turning liquid.

7:25 That's where we get the light petrol for cars. What about the middle of the tower? The middle layers catch slightly heavier liquids, like kerosene, which becomes jet fuel to fly massive aeroplanes across the world. And what about the bottom where it's hottest? What gets stuck down there? The thickest, heaviest sludge of all.

7:44 It's called bitumen or asphalt, and we literally use it to pave our roads and highways. So let me get this straight. Everything from the fuel in airplanes to the actual sticky black roads we drive on comes from this cook's plankton. Yep, and that's what even half of it. Crude oil is broken down into special chemicals called petrochemicals, which are used to make plastics.

8:09 Plastics? So like water bottles and toys. Exactly! Plus ingredients for medicines, synthetic clothes, crayons, and even toothpaste. Wait, my toothpaste and my toothbrush are related to ancient sea plankton. They sure are. That's why crude oil is so important to modern human life. Today, the world uses nearly 100 million barrels of oil every single day.

8:37 How big is one of those barrels? One barrel holds exactly 42 gallons, or about 159 litres. So the world is burning over 15 billion litres of oil daily. That's enough liquid to fill 6,000 Olympic swimming pools every single day. It's an unbelievable amount. But Finn, there's a really big catch to using all this ancient oil.

9:02 I knew there was a catch. What is it? Burning all that oil releases greenhouse gases into the atmosphere. It traps the sun's heat and makes our planet's climate too hot. Oh, climate change! Is that why everyone is racing to build electric cars and massive wind turbines? Exactly! Scientists are working around the clock to build clean, renewable energy so we can eventually stop burning the oil.

9:27 That makes total sense. We should let the ancient plankton rest in their underground rock sponges. Well said, Finn. And here's one last wild fact. Crude oil isn't always black. Depending on its chemicals, it can be dark brown, yellow, or even bright green. Alright, Finn, time for the quiz. Are you ready?

9:48 Okay, my brain is completely fuelled up. Let's do this. First question. What tiny microscopic creatures sank to the seabed millions of years ago to eventually become crude oil? Next one. Geologists use giant sound waves to find oil. But what do they use on their drill bits to chew through solid rock?

10:16 Question three. What temperature in Celsius do refineries heat the crude oil to in those 50 meter distillation towers? Here's number four. How many barrels of oil does the whole world use every single day? Last question. What is the name of the heavy, thick sludge at the bottom of the tower that we use to pave roads?

10:49 Great job! Let's see how you did. The first answer is it was microscopic sea plankton and tiny algae. For question two, they use industrial diamonds on the drill bits to chew through the rock. Number three, the answer is they blast the crude oil up to 350 to 400 degrees Celsius. Question four. The world uses nearly 100 million barrels of oil daily.

11:20 And the final answer is it's called bitumen or asphalt and it makes our highways. Whoa! I am never going to look at a road, a plastic toy, or a car the exact same way again. It really is incredible how a tiny, invisible sea creature from millions of years ago is completely powering our world today. I bet Bodie and Reel are going to be thinking about ancient squished plankton every time they get in a car now.

11:50 I hope so. And if you learn something mind-blowing today, please leave us a five-star review. Yeah, give us five stars if you were completely shocked that your toothbrush is related to ancient plankton. Just scroll down and tap the stars. And be sure to tap follow wherever you're listening, so our next adventure pops right up.

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12:35 Bye, everyone.