Budget airlines need to pay the same prices for airport space, jet fuel and labor as the big players do, said Mike Boyd of Boyd Group International, an aviation consulting firm.

Now the British government says that 22% of all jet fuel from UK aviation has to come from sustainable sources by 2040.

About 900 workers currently operate the refinery, which also produces diesel and jet fuel.

But SAFs’ share of the market is tiny, and they’re two to three times as expensive as jet fuel — basically kerosene — from refined oil.

Biofuels also draw criticism from many environmentalists because their supply chain still contributes carbon to the atmosphere, and much of what’s burned today is a mix of SAF and fossil jet fuel.