Getting the Most from Sustainable Aviation Fuel

By Lloyd Ritter, Esq., Director, Green Capitol LLC

Special to The Digest

The aviation industry is currently responsible for less than 3% of total global carbon emissions, according to the International Energy Agency (IEA). But with air travel expected to increase by more than 60 percent (compared to pre-pandemic 2019 levels) by mid-century,[1] emissions will continue rising unless changes are made.

The U.S. Energy Information Administration (EIA) expects overall transportation carbon emissions will rise through 2050. Fuel consumption will increase because anticipated energy efficiency gains will not keep pace with increased travel, per EIA. Cost-effective, high-energy-density renewable fuels will remain an important option to decarbonize transportation – especially aviation – in the near-term.

Administration officials including Energy Secretary Jennifer Granholm and Agriculture Secretary Tom Vilsack as well as Rep. Julia Brownley (D-CA) are highlighting aviation as an important future market for advanced biofuels. Based on experience with the Renewable Fuel Standard, though, policy makers need to be clear that sustainable aviation fuels (SAF) will reduce carbon emissions. To incentivize those carbon reductions, federal policies must incorporate up-to-date, science-based assessments that assure stakeholders of sustainability.

Lifecycle inventory analysis is the best tool for evaluating the overall carbon impacts of biofuels. The field has evolved significantly since it was first used in federal policy in the 2007 Energy Independence and Security Act.

Lifecycle analysis started out simply counting carbon scores for each step of biofuel production and balancing them against the carbon uptake of the renewable biomass feedstock. Then, these analyses began to incorporate market-mediated impacts from biofuel processes, including impacts on food and animal feed availability and prices and land use changes. Initial estimates of indirect land use change in 2009 and 2010 made some biofuels look less favorable in comparison to a static snapshot of petroleum emissions.

A decade-and-a-half of studies built a more robust picture of biofuels’ market-mediated impacts, including indirect land use change. Lifecycle analysis continues to evolve to include not just carbon, but other sustainability measurements. The lifecycle analysis of any renewable fuel must consistently and accurately incorporate carbon changes and economic impacts throughout the production chain.

Evaluating overall sustainability requires more than just measuring carbon inputs and outputs. A full sustainability inventory can incorporate impacts on biodiversity, water use, soil health and local economies. Fuel production processes that utilize renewable sources of heat and power obviously should receive a better lifecycle carbon reduction score than those using fossil-based electricity. Those that recycle water, create new jobs, or support regenerative farming practices that are more sustainable should also be incentivized.

Argonne National Laboratories’ Greenhouse Gases, Regulated Emissions, and Energy Use in Transportation (GREET) model has been at the forefront of the evolution of lifecycle analysis. The model is updated annually to reflect current crop data, new feedstocks, and new technologies. It incorporates modeling for indirect land use change impacts and other market impacts, such as co-products, recycling of process inputs, and carbon sequestration.

Unfortunately, public policies like the RFS (managed by the Environmental Protection Agency) and the International Civil Aviation Organization’s (ICAO) Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA) have failed to keep up. Neither policy incorporates the sustainability analyses that are now a part of the GREET model.

Agricultural practices that minimize use of petroleum-based chemicals and fertilizers can help reduce the carbon intensity of the biomass inputs to a biofuel. Advanced tillage techniques can build soil carbon while reducing farmers’ fuel and chemical use. In many instances, biofuels can achieve net-zero emissions when renewable energy and regenerative agricultural practices are incorporated in their lifecycle. In RFS and CORSIA, agricultural practices are only considered as a carbon penalty.

Because advanced biofuels are the best option to decarbonize aviation, public policy and industry standards should incorporate the Argonne GREET model and keep pace with the evolution of lifecycle modeling. Failing to do something about transportation carbon emissions shouldn’t be an option, especially as petroleum becomes less sustainable over time. Policies supporting advanced biofuels should be clear, comprehensive, and science-based to ensure that carbon reductions are achieved and counted correctly from farm to fuel.

Lloyd Ritter is founder and managing partner at Green Capitol LLC based in Washington DC and a former Senior Counsel on Capitol Hill. Green Capitol is a boutique eco consultancy that specializes in helping businesses, trades, and non-profits build a cleaner world through meaningful public policy impact.

[1] U.S. Energy Information Administration’s Annual Energy Outlook 2021