Study shows full decarbonization of U.S. aviation sector is within grasp
The study found that planting the grass miscanthus on 23.2 million hectares of existing marginal agricultural lands – land that often lays 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/year by 2040. Credit: ASU

Planes carry 1.7 million passengers every day in the US. One of the most challenging sectors to decarbonize is aviation, which dominates a frequent traveler's contribution to climate change.

The United States is responsible for more than a quarter of all carbon dioxide emissions from flying.

Is it possible to make all US air travel emissions free?

biojet fuels derived from rain-fed grass grown in the U.S. would be a cleaner alternative to fossil fuels.

A new research shows a path to full decarbonization of the U.S. aviation fuel use.

The study, led by a team of Arizona State University researchers, found that planting the grass miscanthus on 21.2 million hectares of marginal agricultural lands in the US would provide enough fuel to meet liquid fuel demands.

The study shows that it is possible for the United States to decarbonize the fuel used by commercial aviation without having to wait for the technology to be invented.

If we want to get to net zero greenhouse gas emissions, we need to deal with emissions from air travel which are expected to grow under a business-as-usual scenario. Liquid fuel sources for aviation are key to this.

Integrating science and expertise.

In the study, the researchers used an integrated framework of land assessments, hydro-climate modeling, ecosystems modeling, and economic modeling to assess where and under what conditions across the United States, energy crops used for biojet fuels could be grown sustainable.

There was a lot of criteria to consider. The team first looked at where optimal marginal agriculture lands were in the U.S.

The team analyzed whether growing energy crop feedstocks on these lands would have detrimental effects on the surrounding environment and predicted the potential productivity of two different grasses,miscanthus and switchgrass. The amount and cost of biojet fuel was quantified by the team.

The current way we produce sustainable jet fuel is very land inefficient and not on a large scale according to an author on the study. There are very limited ways that aviation could become low carbon emitting with a low climate impact and this is one way we've shown that is doable and can get the aviation industry to be carbon neutral through agriculture.

The integrated systems perspective was important to the study. In the past, research around the potential of biofuels has mostly consisted of isolated assessments that have not been well-integrated, for example, overlooking key data on how the altering crop cover affects the surrounding climate

"When you plant crops over strategically designed areas, the planting of these crops has an impact on the climate," said co-corresponding author of the study and associate professor in the School of Geographical Sciences and Urban Planning. There are implications for local to regional scale climate if there is an increase or decrease in the amount of vegetation.

The research team took the hydroclimate model's outputs to inform their model. Farmers were evaluated on the economic feasibility of growing these grasses.

There are real world solutions.

Economic sense is needed for any alternative energy pathway solutions.

The researchers benchmarked the financial returns of the existing uses for the lands they identified, some already are used for growing corn, soy, or various other crops, and others are being used as pasture

Miscanthus or switchgrass needed to be more profitable to replace the land that is currently being used.

Uludere Aragon said that the lands they identified were owned and operated by real people. The opportunity cost of alternative land uses is the main influence on the cost-effective potential of abiodiesel.

Biojet fuels derived from miscanthus can meet the 30 billion gallons/year target at an average cost of $4.10/gallon.

The team thought it was reasonable to consider biojet's potential to cut emissions. Jet fuel prices have varied from $2 to $5/gallon due to changes in supply and demand, but are within the range of possibilities.

There is a template for the future.

It is important for the scientific community to bridge disciplines in order to find further solutions to the Earth's climate crisis, according to the researchers. The researchers emphasize how important realistic solutions are.

The research was a culmination of eight years of modeling work and collaboration. The expert skills of a spectrum of domains are needed to address the issues of sustainable living.

People's decisions on the ground are driven by economics. When these decisions are aligned with desirable environmental outcomes, it's crucial to find the right circumstances.

There is more information on sustainable land use and biojet fuels. The article can be found at

Journal information: Nature Sustainability