Cloud storage has a real energy cost, but it is smaller per file than most people imagine and larger in aggregate than most people notice. The number that matters is duration, not volume: a gigabyte kept for a year costs far more energy than a gigabyte sent once, which is why deleting what you will never open is the one step with real leverage.
What is actually known
Start with the one figure that is well sourced. The International Energy Agency's Energy and AI report (April 2025) estimates that data centres used around 415 TWh of electricity in 2024 — about 1.5% of the world's electricity — and projects that roughly to double by 2030, largely because of AI.
So: real, growing, and still a small slice of the total. Beyond that, be careful.
What survives that uncertainty is not a number but a ratio — and the ratio is what you can act on.
Why duration is the variable that matters
A file being sent uses network equipment for a few minutes. A file being stored uses energy continuously — drives powered, cooling running — for as long as it exists.
A year is about 525,600 minutes. Even if storage draws far less power per second than a transfer does, keeping a file for a year outweighs sending it once, and the gap grows every year you keep it.
Two things follow, and both feel wrong at first:
- A service that deletes your file after a week can be greener per file than one keeping it forever on renewable power. Duration multiplies whatever the energy source is.
- Compression barely matters. A file 20% smaller saves 20%. Deleting it saves all of it.
Replication multiplies it
Most large cloud storage keeps several copies, often across regions, so that "we will not lose your data" is true. Three copies is three times the storage footprint.
That is a genuine engineering trade, not waste. But the durability you are sold has a continuous energy cost, and not every folder of holiday photos needs it at the highest grade.
Dark data is the actual problem
The uncomfortable part is not that storage costs energy. It is how much of what is stored is never opened again.
Industry surveys consistently suggest a large share of stored business data is never read after it is written. The exact proportion depends on who counts and how, and the methods are usually loose — but nobody who has audited their own storage disputes the direction.
For creative work it is stark. A photographer keeps every frame, including the eleven near-identical ones. An editor keeps every export of every cut. None of it is opened again, and all of it is powered for years. That is the whole case for deleting.
What to do about it, in order of effect
- Delete what you will not use. Cull footage and frames before archiving, not after. This is most of it.
- Set a retention rule and follow it. Working files deserve a shorter life than deliverables. How to choose the periods.
- Find the copies nobody asked for. Backup, sync and archive often hold the same folder three times.
- Prefer providers with short defaults and honest disclosure. A smaller effect, still worth ten minutes: how to check a green claim, and what to look for in a file service.
- Compress when it is free. Not worth agonising over.
For sending specifically, a default that expires does the work for you:
Keeping perspective
For one person, storage is a small part of a footprint. Flights, heating, driving and making new devices dwarf it. Anyone telling you that deleting emails is meaningful climate action is overselling, and that framing does harm by making climate action look trivial.
Where it does matter:
- At organisational scale, where petabytes of never-read data cost real money and energy, and nobody owns the decision to delete.
- As a cost discipline, because storage is one of the few places where the environmental answer and the financial answer are the same.
- As risk reduction, because data you deleted cannot leak — and keeping personal data with no purpose is what data protection law already says not to do.
That three-way alignment is rare, and it is the reason to bother.
Disclosure
I run Yungle. It is hosted at Hetzner in Germany on hydropower, keeps one primary copy rather than three regional replicas, and backs up nightly to EU-jurisdiction storage at a second provider. What the site claims about its footprint — and what it deliberately does not — is on the sustainability page.