How Much Nuclear Energy the World Makes — A Record Year, and the Year Solar Overtook It

There is a number that captures a strange double truth about nuclear power in 2025: the world's reactors generated more electricity than they ever have, and in the very same year they were overtaken by solar. This counter shows the world's nuclear output as a running daily total, and like the electricity, renewables and carbon counters beside it, it wears an est. badge — understanding why is the key to reading it honestly.

The number, and the record

In 2025, the world's nuclear reactors generated 2,812 terawatt-hours of electricity, according to Ember's Global Electricity Review 2026 — an all-time high. That was:

• about 8.9 per cent of all the world's electricity — roughly a tenth;
• roughly 89 megawatt-hours every second, spread evenly across the year;
• an increase of about 35 terawatt-hours over the year, driven mainly by new reactors in China, with higher output in France and Japan.

So the headline most people heard in 2025 — that nuclear was overtaken by solar — sits right next to a record. Both are true. Nuclear's own output reached its highest level ever; it was simply passed by a source climbing far faster.

A record, and an overtaking, in the same year

Solar grew by a record 636 terawatt-hours in 2025 — more new generation than any other source has ever added in a single year — and that surge was enough to push solar past nuclear globally for the first time. Both solar and wind are expected to overtake nuclear outright in 2026. The reason nuclear can set a record and lose its place at the same time is simple: the whole electricity pie is growing faster than the nuclear slice. Nuclear's output crept up about 1.3 per cent, but total generation grew faster, so nuclear's share of the mix actually slipped to about 8.9 per cent — a 45-year low — even as its raw terawatt-hours hit a record.

How it sits next to the electricity counter

Running beside this one is a counter for all the world's electricity — about 31,750 terawatt-hours a year, ticking at roughly 1,006 megawatt-hours a second. This nuclear counter ticks at about 89 megawatt-hours a second, which is close to a tenth of that. That is not a coincidence: it is the same total, with the nuclear slice pulled out. Beside it, the renewables counter ticks at about a third of the electricity rate. Watch the three together and you can feel the shape of the world's power: renewables about a third, nuclear about a tenth, and the rest still fossil.

Low-carbon, but not renewable

Nuclear produces electricity with very little direct carbon dioxide, which makes it low-carbon — but it is not renewable, because it runs on mined uranium rather than a naturally replenished flow like sun, wind or water. That is why it has its own counter and is not folded into the renewables figure. Together, though, they are a meaningful pair: renewables (about a third of the mix) plus nuclear (about a tenth) make low-carbon sources more than 40 per cent of the world's electricity.

Where the figure comes from

The number is assembled, not read off a single meter. Ember, an independent energy think tank, pulls together national figures from sources like the US Energy Information Administration, Eurostat, the Energy Institute, the UN and national statistics offices, reconciles them onto a common basis, and publishes a free global dataset each year. Its 2,812-terawatt-hour all-time high for 2025 is corroborated independently by Carbon Brief, which cites the identical figure — which is what makes it a hard number rather than a guess.

Why it says "est."

There is no live meter on every reactor on the planet. What we do is take Ember's most recent verified annual figure and spread it evenly across the seconds of the year, then show how much has built up since midnight UTC. Nuclear is actually one of the steadiest sources — reactors tend to run flat out around the clock — so an even average fits it more closely than it fits solar or wind. But it is still an honest yearly average made visible, not a live feed, and the est. badge says exactly that.

See the fleet behind it

A single figure hides the few hundred reactors making it. Open the power stations in Grid and the world's power plants appear on the map, coloured by the fuel they run on and sized by capacity — nuclear stations among the giant hydro dams, sprawling solar farms and the rest. This counter is the world's nuclear power as one ticking figure; Grid is the fleet that generates it, country by country.