Fusion's Third-Plus Share Held All Summer. Now Comes the Harder Season.

COPENHAGEN — Fusion carried better than a third of the reconnected grid through the whole of the northern summer without a single system-wide fault — the quiet, unglamorous achievement Aurora Fusion Works keeps insisting is the point. Cooling load is the great summer test, the hours when a hemisphere runs its compressors at once, and the baseload fleet met it. But engineers gathered here this week were already looking past the win to the harder season. Heat, not cool, is the temperate north's autumn and winter problem, and heating demand does not peak in tidy afternoon spikes the way cooling does; it grinds, all night, for months. "Summer we survived. Winter we have to plan," said one grid operator. "Different curve, longer test, less margin." The build-out that spent the warm months proving it could keep the cold air flowing now turns to prove it can keep the warm air flowing too — the same reactors, a harder duty cycle, and a hemisphere about to ask for heat the way it just asked for chill.