Dhaka, April 29 -- The Iran war has blown European airlines' plans well off course. While curtailed flights to the Middle East have a limited impact on carriers like IAG and Air France-KLM that fly more west than east, a near-doubling of jet fuel prices - and potential shortages unless the Strait of Hormuz reopens - could whack their earnings. What the conflict has done is markedly shrink the relative cost of so-called sustainable aviation fuel (SAF) from a pre-war level that was almost three times that of its fossil-based counterpart. ‌Yet to really change the game, it needs to fall a lot more.

Compared to other sectors, decarbonising aviation is tricky. Batteries weigh too much to be practical in large jets, while liquid hydrogen...