Research examines biofuel crops for emissions impact

To determine the true sustainability of sustainable aviation fuel (SAF) researchers have examined the environmental impact of six different types of crops proposed for the production of sustainable aviation biofuels.

These crops – proposed by the Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA) – are soybeans, maize (corn), switchgrass, miscanthus, jatropha, and reed canary grass. The authors used spatial data with global coverage to calculate the Direct Land Use Change (DLUC) emissions for each of them.

Neus Escobar, a researcher in the Integrated Biosphere Futures Research Group of the IIASA Biodiversity and Natural Resources Program in Vienna said: ‘Direct land use change emissions occur when land is converted to grow crops for biofuels, which can reduce the amount of carbon stored in the soil and vegetation. Understanding these emissions is crucial for determining whether sustainable aviation fuels genuinely reduce greenhouse gases compared to traditional fossil fuels.’

Biofuels are very much to the fore as a means of reducing carbon emissions from aviation, but large-scale biofuel production can be problematic to the extent that the negatives outweigh the positives. An example of this is the use of palm oil which the European Commission has said will be phased-out by 2030. 

The new study aimed to provide information for policymakers and biofuel producers, enabling them to make informed decisions about which crops to use and where to grow them to maximise environmental benefits.

The research found that soybeans crops were responsible for the most DLUC emissions, while jatropha and miscanthus had the lowest, although this depended to an extent on where they were grown. The higher yields of miscanthus and switchgrass mean they have the greatest production potential if grown in agricultural areas.

Escobar explained: ‘We found that where the crops are grown is just as important as what is grown. Some areas have better conditions for producing low-carbon fuels, like having soil and climate that support high crop yields and low carbon loss. This means that choosing the right locations for growing these crops can help ensure that sustainable aviation fuels are truly sustainable. 

‘Our study identifies areas that meet and don’t meet CORSIA’s sustainability criteria for reducing greenhouse gases and conserving land and biodiversity. This can help policymakers determine where targeted interventions are needed to promote the raw materials with the lowest environmental impact and highest greenhouse gas savings in each location. We also suggested improvements for CORSIA to better reflect diverse crop production possibilities and help biofuel producers identify raw materials and agricultural practices that meet CORSIA’s requirements for sustainable fuel production.’

The full report can be read here