Problem with hydrogen is that:
(1) impossibly difficult to store it on an aircraft.
(2) You need to expend energy to separate it from water in the first place.
RR Dart Engines have been run on soya oil.
The real issue as alluded to above is that it gels and clogs fuel lines above -40 celsius. The FAA specs for jet fuel require viscosity down to -40C and biofuels so far can't do that economically.
Yes you can add anti gelling agents, but not economically so.
Rape seed oil and sunflower seed oil seem the best anti-gelling bets.
Algae can be grown at prodigious rates from city sewerage to produce ethanol.
The point really ought to be why fuss over adapting biofuels for aviation ?
Aviation accounts for only 2% of carbon emissions whilst private motor cars account for around 30%.
If you can reduce carbon emission from private motor cars by just 23% you will halt increases in global emission. If you halve carbon emissions by private motor cars then you will reverse the growth in global carbon emissions so why not concentrate on the possible rather than the impossible.
Few private motor vehicles need fuel to resist gelling above -40C.