Has anyone got a sense of what the issues are with moving to bio fuels/ liquid methane for aircraft? It looks as if it's going to have to be at least a medium

Has anyone got a sense of what the issues are with moving to bio fuels/ liquid methane for aircraft? It looks as if it's going to have to be at least a medium term solution, I havent really heard much talk about them though. Is that just because they aren't sexy compared to electric planes?