The used frying oil, the organic remains of our kitchen or the leftover branches of a pruning. They all have something in common: at first glance they may seem like waste, waste that we must get rid of because it has already finished its life cycle. Nothing is further from reality. And it is that these residues can be used to generate renewable fuels, capable of moving car engines, airplanes and even rockets. They are also one of the main solutions to reduce the net CO2 emissions generated by the mobility sector and to build a more sustainable model.