To be honest, liquid hydrocarbons are a very good energy source when weight and volume is important, like aircraft. Battery-electric planes will likely become a thing for short range flights, but I'm having a hard time seeing how anything like the current level of long range flights would be compatible with a "zero carbon" society. Biofuels and synthetic fuels will allow a limited amount of long range flights though, so I don't think we'd need to give up on those entirely.