Power and Nuclear

From coal-fired steam to solar, nuclear reactors, and Space Age fusion. How each power tier works and when to step up to the next.

Every machine in your factory needs power, and Factorio gives you a clear progression of ways to make it. You start by burning coal for steam, move to pollution-free solar as you scale, step up to nuclear when your demand outgrows what solar can comfortably cover, and in Space Age reach fusion on Aquilo. Each tier trades setup complexity for output and cleanliness, and because pollution drives biter attacks and evolution, your choice of power is also a choice about how hard the natives hit you. Sizing power correctly is one of the steady background tasks of a run.

Steam, the starting power

Early power is steam. You burn coal in boilers to heat water, then feed that steam to steam engines that produce electricity. It is cheap, simple, and the right call for the first hours, but it pollutes, and pollution is what musters biters and raises evolution. Steam stays useful well beyond the early game as a backup or for remote outposts, but its pollution cost is the reason most players look to cleaner options as their factory grows.

Solar, the clean middle

Solar panels paired with accumulators provide pollution-free power. Panels generate during the day and accumulators store a charge to carry the factory through the night, so a solar setup is sized as a ratio of panels to accumulators that covers a full day-night cycle. Solar’s appeal is that it produces zero pollution, which directly slows biter attacks and evolution. Its cost is footprint: a large factory on solar needs a large field of panels, which is why many players run solar alongside nuclear rather than relying on either alone.

Nuclear power

Nuclear uses uranium fuel cells in reactors to make heat, which heat exchangers turn into steam for steam turbines. Two numbers anchor the design. One fuel cell burns in exactly 200 seconds, and adjacent reactors give a neighbor bonus, so reactors placed side by side produce more heat per cell than the same reactors standing alone. That neighbor bonus is why nuclear builds cluster reactors in a row or block. Nuclear delivers far more power per footprint than solar and runs clean once built, at the cost of a more involved setup and the uranium supply chain behind it.

Reactors give a neighbor bonus, so two reactors side by side beat two standing apart. Plan the reactor block before you place the first one, because the layout is what determines your output per fuel cell.

Fusion, the Space Age endgame

Space Age adds fusion power on Aquilo. The sources describe it running on a 4:28 reactor-to-generator ratio and delivering gigawatts from near-free fuel at a very slow burn, paired with a cryogenic-plant cooling loop. Fusion is an Aquilo technology and part of why that planet demands so much prior infrastructure: you need the cryogenic plants and integrated heating in place before fusion power makes sense. Treat the exact cooling-loop numbers beyond that 4:28 ratio as something to verify against a current source rather than memorize.

Watch out for

Staying on coal steam too long. Its pollution feeds biter attacks and pushes evolution up, so the cleaner tiers pay for themselves in fewer attacks.
Undersizing accumulators on a solar build, which leaves the factory dark at night.
Placing reactors without planning the block. Ignoring the neighbor bonus wastes a large share of a nuclear build’s potential.