The future of flying might depend on used cooking oil, plants and green electricity. Sustainable aviation fuels, known as SAF, are made from less carbon-intensive processes and renewable sources. Airlines are touting them as the key to decarbonising flying.

The aviation industry has pledged to move from 2.5% of all global CO2 emissions to net zero by 2050 – with these alternative fuels being the cornerstone of the strategy. However, there’s little SAF actually being produced, it, and it’s much more expensive than fossil fuels. Can the technologies really take off?

Climate Question host Graihagh Jackson investigates, with reporting from the BBC's Monica Miller in Malaysia and Singapore.

Presenter: Graihagh JacksonProducer: Osman IqbalResearcher: Octavia WoodwardEditor: Simon WattsSound engineer: Tom Brignell