[api]

You could probably fill a 737 with biodiesel today and fly it. A jet will run on anything combustible within the right ignition temperature, density, and viscosity ranges and diesel is not far from kerosene aka jet fuel.

I mean, you could probably almost run a jet turbine on bacon grease if you kept it warm to keep it from solidifying. Some military stuff is intentionally made to be as “flex fuel” as possible in case you are cut off from official supply lines and have to do something like gas up a plane with road diesel of unknown quality.

You wouldn’t just do things like that with a million dollar plane since it might be bad for the engine but if the engine were tuned for it it’d be fine.