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They count the world's oil by its shadows
Countries guard their oil stockpiles. So data scientists started estimating them from space, by measuring the shadows inside floating-roof tanks. Here is how it works, what it found, and where it goes blind.
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Nobody knows exactly how much oil the world is holding. Countries guard their stockpiles, and official numbers arrive late, or not at all.
So a group of data scientists looked at the problem from space.
The tank that gives itself away
Much of the world's crude is stored in giant floating-roof tanks. The roof is not fixed: it floats on the oil itself, to stop vapour building up.
- When the tank is full, the roof sits near the top.
- As oil is drained, the roof sinks with it.
A sinking roof leaves a clue. Seen from above, the tank wall casts a crescent-shaped shadow onto the roof. The lower the roof, the bigger the crescent. A second shadow, on the ground outside the tank, gives its height. Put the two together and you can estimate how full the tank is, as Business Insider described Orbital Insight's method.
Teaching AI to read the shadows
Orbital Insight, a Goldman Sachs-backed startup, trained computer-vision models to find floating-roof tanks in satellite images, measure each shadow, and convert fill levels into barrels.
What it found:
| Market | Satellite AI count | Industry database | Gap |
|---|---|---|---|
| China (end-2014) | ~2,100 tanks, ~900M barrels capacity | ~500 tanks | about 4× |
| Saudi Arabia | 624 floating-roof tanks | 318 tanks | nearly 2× |
Sources: Satellite Today on China, Orbital Insight on Saudi Arabia. These are the company's own figures, from 2014–2017.
Clouds, nights and radar
Optical satellites need daylight and clear skies. That is a real problem over places like China, which is often under cloud.
The fix is radar (SAR). Radar satellites see through clouds, day or night, and can still detect the height of a floating roof. Ursa Space uses radar alone and says it covers more than 4,000 floating-roof tanks in China.
Where it goes blind
It isn't perfect:
- Underground caverns cannot be seen from orbit.
- Fixed-roof tanks hide their fill level.
- Estimates differ between providers. In 2017, Fortune showed firms tracking China's stocks with different methods reaching different numbers.
- Orbital's own comparison with official JODI data for Saudi Arabia tracked well at first, then diverged, partly because JODI also counts storage satellites cannot see.
Why it matters for traders
Oil prices react to inventory data. If you can estimate stockpiles before official reports, or where there are no reliable reports at all, you have an information edge.
Our reading: this is a textbook case of alternative data. The value is not one perfect number, but a faster, independent signal that you cross-check against everything else.
One of the world's most guarded numbers can now be estimated from orbit, by measuring the dark.
So, next time oil prices move, ask yourself: who saw the shadows first?
Narration in the video is an AI voice (ElevenLabs). The satellite tank-farm image is an AI-generated illustration, not a real location. Not investment advice.
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