Every day, 45,000 planes fly across the United States, carrying some 1.7 million passengers. Aviation dominates a frequent traveler’s individual contribution to climate change, and yet it is one of the most challenging sectors to decarbonize.

The United States is the largest contributor to aviation carbon dioxide emissions in the world and is responsible for more than a quarter of all carbon dioxide emitted from flying.

But what if we could make all U.S. air travel nearly emissions free? What if we could replace carbon-intensive jet fossil fuels with a cleaner alternative: biojet fuels derived from rain-fed grass grown in the U.S.?

New research published today in the journal Nature Sustainability shows a pathway toward full decarbonization of U.S. aviation fuel use by substituting conventional jet fuel with sustainably produced biofuels.

The study, led by a team of Arizona State University researchers, found that planting the grass miscanthus on 23.2 million hectares of existing marginal agricultural lands — land that often lies fallow or is poor in soil quality — across the United States would provide enough biomass feedstock to meet the liquid fuel demands of the U.S. aviation sector fully from biofuels, an amount expected to reach 30 billion gallons per year by 2040.

In the study, the researchers used an integrated framework of land assessments, hydro-climate modeling, ecosystem modeling and economic modeling to assess where and under what conditions across the United States energy crops used for biojet fuels could be grown sustainably using criteria that evaluate both environmental and economic performance.

The criteria were extensive. The team first identified and assessed where optimal marginal agriculture lands already existed in the U.S. They then assessed whether one could grow the right energy crops on the land without using additional water.

The team then analyzed whether growing energy-crop feedstocks on these lands would have detrimental effects on the surrounding climate or soil moisture and predicted the potential productivity of yields of two different grasses — miscanthus and switchgrass — as suitable biomass-energy feedstocks. Finally, the team quantified the amount and the cost of biojet fuel that would be produced and distributed nationwide at scale. https://www.nature.com/articles/s41893-022-00990-w