When you get to the size of airliners, though – so much money, time and effort has gone into designing, producing and operating the existing airliner fleet that

When you get to the size of airliners, though – so much money, time and effort has gone into designing, producing and operating the existing airliner fleet that it makes sense to invest in biofuels rather than completely new airliners: https://en.wikipedia.org/wiki/Aviation_biofuel#Economics https://en.wikipedia.org/wiki/Aviation_biofuel#Economics