Biofuels have long been touted as a carbon-neutral alternative to fossil fuels, doing for the world’s planes, ships and automobiles what windfarms and solar panels are doing for its electricity grids. With the transport sector accounting for almost one fifth of Australia’s total carbon emissions, green biofuels could be an important ingredient of the zero emissions future envisioned by the Paris climate agreement. On paper, biofuels seem the ideal replacement for fossil fuels, which drive