Commercial airlines worldwide burn over 450 billion litres of jet fuel every year, and that number is projected to more than double by 2050. This is completely unsustainable, so a solution must be found. A collaboration of US researchers has come up with a 100% sustainable aviation fuel that may enable the airline industry to cut its carbon emissions significantly. The fuel is based on lignin, which is a lavishly abundant natural material that is found in the rigid parts of a plant’s cell wall. The molecular structure of lignin is excellent for creating fuel, but previous efforts to develop it failed because it was very difficult to break it down. However, this new research appears to have overcome those difficulties, and sustainable plant-based jet fuel may be on the horizon.