things like drag imply energy will be needed to transport people. The only solution that seriously tries to make some gains there is the hyperloop. I have doubt

things like drag imply energy will be needed to transport people. The only solution that seriously tries to make some gains there is the hyperloop. I have doubts about the biofuels for the simple reason that fields which produce them can probably be used to produce food as well. Also whether they are CO2 neutral is questionable as they typically store less carbon when the plants are small after harvest, compared to permanent forests or algae. Increasing populations imply the food will be seen as more vital. maybe if we crack the energy puzzle in a space efficient matter hydrogen can be used in planes and the like eventually.