Because kerosene can be used so cheaply, alternatives are neglected
1. Kerosene’s characteristics are unmatched.
It has the highest energy density (thrust to weight ratio) and chemical stability. It’s low freezing point allows efficient flights in cold air at high altitudes whilst it is very safe to use. A burning match doesn’t ignite a puddle of kerosene when it is thrown into..
2. Hydrogen is much more hazardous and cumbersome.
Airbus has stopped it’s 2004 study on hydrogen aircraft long ago and recently it’s E-Fan project. Airbus and Rolls-Royce cancel E-Fan X hybrid-electric CRYOPLANE Flugzeuge mit Wasserstoffantrieb Dr. Reinhard Faaß Airbus Deutschland GmbH
3. It is predicted, that Biofuel and Power to Fuel options will be very costly.
Short or long term availability is doubtful. Please see page III/IV of: Utrecht University 2017, Renewable Jet Fuel in the European Union, Scenarios and Preconditions for Renewable Jet Fuel Deployment towards 2030, and Financial Times, Greener biofuels battle for take-off to cut aviation emissions
4. 100% electric flights are only feasible for shorter flights. Electricity will never reach the flexibility and operational efficiency of fluid powered aircraft. Fuel powered airplanes get lighter when burning their fuel. This considerably increases their efficiency, whilst battery powered aircraft have to carry always it’s full weight.