Its been suggested that the oil companies are keen on hydrogen (you separate the it from the carbon in oil) but realistically it will come from electrolysis. The trouble is that we don't have enough renewable fuel for the existing grid and would need far more for electric cars and huge electrolysis plants. That's a lot of wind farms and photoelectric cells. Its interesting that going back to my childhood (half a century ago) the future was nuclear power, the power being used to create hydrogen which would be burnt in aircraft. Back then the problem was seen as lack of oil and no one had thought of global warming, but it was still felt that new sources of energy would be required. We know that technology advances, the question is how fast and crucially in which areas. Look at an episode of Thunderbirds (mid 60s). The (actually very perceptive) writers missed the rise in computers, algorithms, internet, mobile telephony for all (nor just a few selected International Rescue agents), etc but seemed to think that we would have rather more nuclear powered devices masses of supersonic commercial aircraft and so on. If we look back to today in thirty or fifty years how accurate will our predictions to the future look?
Its amazing how much technology come about because of the space race in the 60s. The Saturn V used cryogenic storage - for a few hours, it couldn't be used later in the mission and if launches were delayed the fuel was allowed to bubble off, rather wastefully - but maybe it was assumed that cryogenic storage would advance. If we announced the equivilant to the Apollo programme for sustainable fuels where would we get?
My view is that the future is biofuel derived from algae (seaweed) which will cost a lot more than jet fuel does today but partially offset by more efficient aircraft making aviation affordable. Oil refineries may disappear to be replaced by large algae processing plants, but the actual fuel distribution network will be similar to today's. I may of course be wrong as to which technology works which is why I fully support the development of hydrogen and electric powered aircraft - and any other promising new technology that comes along. Lets hope that one of them achieves a breakthrough.