Aviation hub Singapore will require airlines departing from the city-state to use sustainable aviation fuel (SAF) from 2026 as part of industry plans to cut carbon emissions. But as the environment-friendly fuel is three to five times more expensive than conventional jet fuel, authorities will introduce a levy on tickets to help cushion costs. Aviation is responsible for between two and three percent of global CO2 emissions but it is one of the most difficult industries to decarbonise. SAFs are produced from renewable biomass and waste resources and can comprise up to 50 percent of jet fuel mixes.