Thermal coal prices reached their highest level in more than 18 months over the weekend, with benchmark Newcastle futures trading above $150 a tonne as European and Asian utilities rushed to lock in winter supplies. The surge followed a spike in oil and gas prices linked to disruption in the Strait of Hormuz.

The rally reflects a scramble by power generators to hedge against a costly heating season. Higher crude and liquefied natural gas prices have made coal-fired generation economically competitive again, reversing years of decline across Europe, according to S&P Global Commodity Insights.

Germany, Poland and several Asian importers, including India and Indonesian domestic buyers, have increased procurement in recent sessions, trading desks at Trafigura and Glencore reported. Utilities that had scaled back coal plants are now restarting mothballed units to guarantee baseload capacity through the colder months.

The shift complicates European Union climate commitments and threatens to raise carbon emissions this winter. The International Energy Agency warned earlier this year that a supply shock could temporarily reverse the structural decline in coal demand across advanced economies.

"When gas becomes unaffordable, coal is the fuel of last resort, and that is exactly where we are heading into this winter," said a senior analyst at Rystad Energy in Oslo.