HAMMERFEST, Norway — For a quarter-century, energy executives were tantalized by vast quantities of natural gas in one of the world’s least hospitable places — 90 miles off Norway’s northern coast, beneath the Arctic Ocean.

Bitter winds and frequent snowstorms lash the region. The sun disappears for two months a year. No oil company knew how to operate in such a harsh environment.

But Norway has finally solved the problem. The other day, on an island just offshore, a giant yellow flame illuminated the sky here. It was just a temporary flare for excess gas, but it signaled a new era in energy production.

Across the bay from this small fishing town, where reindeer wander the streets, one of the world’s most advanced natural gas plants is coming to life.