GRID · FIELD GUIDE
Where Crude Oil Becomes Fuel — How an Oil Refinery Works
Crude oil is a thick black soup you can't put in a car. So what actually happens inside a refinery to turn it into petrol, diesel and jet fuel — and why does it take those tall towers to do it?
Crude oil is one of the most valuable substances on Earth, and in its raw form almost completely useless. Straight from a well it's a thick, dark, foul-smelling liquid — a chaotic mixture of thousands of different hydrocarbon molecules, from light gases to heavy tars, all dissolved together, laced with sulphur and water and grit. You can't pour it into a car, a plane or a furnace. Everything that makes oil useful happens at a refinery, and this layer maps where that work is done.
Switch it on and a scatter of copper towers appears across the world. The key thing to notice is where they cluster, because it tells a truer story than most of the map's other layers. The pipelines and power-line layers lean heavily toward the United States and Europe — not because that's where the infrastructure really concentrates, but because that's where OpenStreetMap's volunteers have mapped most thoroughly. Refineries are different: they're vast, permanent, unmistakable landmarks, mapped well almost everywhere, so the clusters fall on the countries that genuinely refine the most oil — the US Gulf Coast, India, Russia, the Gulf states, China.
The towers are drawn at a single size, on purpose. There's no honest way to grade them: the data carries no figure for how much crude each refinery processes, and rather than guess, the map leaves size out and lets one warm colour mark each plant. So this layer answers where cleanly — where crude oil becomes the fuel that moves the world — and is upfront about the questions it can't answer from the data, like exactly how much each one makes. To see the rest of the chain, turn on the Pipelines layer: the crude flowing in, and the finished fuel flowing out.
Frequently asked questions
What is an oil refinery?
An oil refinery is a large industrial plant that turns crude oil into usable products. Crude oil pumped from the ground is a mixture of thousands of different hydrocarbons all jumbled together — too thick, too dirty and too variable to burn in an engine. A refinery separates that mixture into distinct streams and cleans and reshapes them into the things we actually use: petrol (gasoline), diesel, jet fuel (kerosene), heating oil, heavy fuel oil for ships, bitumen for roads, and the chemical feedstocks that become plastics. It's the bridge between an oilfield and a fuel pump. This map plots 728 of these refineries worldwide, drawn as the tall distillation towers that are their most recognisable feature.
How does a refinery separate crude oil?
The first and most important step is fractional distillation. The crude is heated to around 350–400 °C until most of it boils into vapour, and that vapour rises up a tall distillation column — the tower you see on this map. The column is cooler at the top than the bottom, so as the vapour climbs it cools, and each type of hydrocarbon condenses back into a liquid at the height matching its own boiling point. The lightest fractions (gases and petrol) stay vapour longest and are drawn off near the top; middle fractions (kerosene, diesel) condense in the middle; and the heaviest, tar-like fractions sink to the bottom. The plant then upgrades these raw cuts further — cracking heavy molecules into lighter, more valuable ones, and removing sulphur — but the tower doing that first split is why a refinery is drawn as a fractionating tower here.
Why doesn't this map size the refineries by how big they are?
Honesty about the data. On the wind and solar layers, every site is sized by its capacity in megawatts because that figure is recorded. For refineries, the underlying source (OpenStreetMap) carries no refining-capacity figure at all — a refinery's throughput in barrels per day is almost never tagged. Rather than invent a size, or draw every tower identically while implying they're all equal, this map does what the pipelines and LNG layers do: it leaves size out and lets one warm colour simply mark 'a refinery here.' So the map answers 'where are the world's refineries?' faithfully, without faking a 'how big?' it can't actually answer. The ranked country list counts refineries, not barrels — which is why a country with one enormous complex can rank below one with several smaller plants.
Where are the world's refineries?
Spread far more evenly than you might expect, and — unusually for an OpenStreetMap layer — genuinely global. Most OSM-based maps lean heavily toward the US and Europe simply because that's where mapping is most thorough, but refineries are huge, permanent landmarks that get mapped well everywhere, so this layer follows real geography instead. The United States leads on refinery count, concentrated on the Gulf Coast around Houston and Louisiana. Then come the giants of South Asia (India), the former Soviet bloc (Russia), the Gulf states (Saudi Arabia, Iraq, Iran), and East Asia (China) — the countries that actually refine the most oil. One honest gap: a few of the very largest refineries are tagged in OSM without a clear refinery name (Baytown in Texas, Yanbu and Ruwais on the Arabian Peninsula), so a handful of giants can be missing even where their country is well covered.
How do refineries fit with the pipelines and LNG terminals?
They're the midpoint of the whole hydrocarbon chain. Crude oil travels from oilfields to a refinery — overland through crude pipelines, or by tanker to a coastal one. The refinery turns it into finished products, which then leave by a separate set of products pipelines, or by ship and rail, to reach fuel depots, airports and petrol stations. Natural gas runs on its own parallel system: pipelines where it can reach, and LNG terminals where it has to cross an ocean as a frozen liquid. Switch on the Pipelines layer alongside this one and you can read the flow — crude in, products out — and switch on LNG Terminals to see the gas half of the same global energy trade.
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