Assessing the environmental sustainability of biofuels

•Not all approaches to produce liquid biofuels will provide sustainable alternatives to fossil fuels.•True sustainability requires a holistic consideration of the environment, economy, and wider society.•Life cycle assessment (LCA) is a quantitative approach to estimating the environmental sustainability of biofuels.•Plant scientists can contribute to biofuel LCAs by establishing robust data for energy crop productivity, and improving models of land use.

Biofuels vary in their potential to reduce greenhouse gas emissions when displacing fossil fuels. Savings depend primarily on the crop used for biofuel production, and on the effect that expanding its cultivation has on land use. Evidence-based policies should be used to ensure that maximal sustainability benefits result from the development of biofuels.