Reducing aviation carbon emissions through U.S. sustainable aviation fuels

Dr Reyhaneh Shenassa, Chief Engineer at the Bioenergy Technologies Office (BETO), U.S. Department of Energy, explains how U.S. sustainable aviation fuels will reduce aviation carbon emissions

The U.S. Department of Energy Bioenergy Technologies Office leverages national laboratory research and development expertise to help build a sustainable aviation fuel economy.

The U.S. transportation sector accounts for 34% of the nation’s greenhouse gas (GHG) emissions, which is a significant driver of climate change. Transportation sector GHG emissions primarily stem from the combustion of petroleum products such as gasoline and diesel in cars, trucks, airplanes, ships, and trains.

Achieving the Biden-Harris administration’s goal of economy-wide net-zero emissions by 2050 in the transportation industry presents a challenge. It will require public and private cooperation using a targeted suite of technology solutions, including electric vehicles, and using hydrogen and sustainable liquid fuels.

Electrification of automobiles, light-duty and medium-duty trucks, and school and transit buses is underway, with support from the Biden-Harris administration Bipartisan Infrastructure Law and Inflation Reduction Act.

For the aviation industry, battery-powered aircraft for longer flights have technological and scalability hurdles to overcome. This is where renewable biofuel technology can assist in the decarbonization of the aviation industry.

BETO supports renewable carbon resource R&D to produce low-carbon biofuels

Renewable carbon resources are carbon-based resources that are frequently regenerated, either via photosynthesis (e.g., plant, algae biomass) or through regular generation of carbon-based waste (e.g., the non-recycled portion of municipal solid waste, biosolids, sludges, plastics, carbon dioxide, industrial waste gases). This contrasts with finite carbon resources, such as petroleum and coal, which take millennia to regenerate.

BETO estimates that over 1 billion dry tons of biomass could be available each year in the United States (U.S.), which is enough to produce 50–60 billion gallons of low-carbon biofuels, including renewable fuels for the aviation industry.

Sustainable aviation fuel can decarbonize the aviation industry

The combustion of petroleum-based fuels in the aviation industry releases vast amounts of carbon emissions that contribute to global warming.

In the U.S., jet fuel demand for domestic and international travel is predicted to increase by more than 40% by 2050. To avoid a carbon emissions surge, it is critical to improve airframe technology and operations, and most importantly, switch to sustainable aviation fuel (SAF).

Leveraging potential of corn ethanol industry to increase SAF volumes industry to increase SAF volumes

The existing corn ethanol industry has tremendous near-term potential to increase SAF production volumes through the alcohol-to-jet conversion pathway. Replacing gasoline with corn ethanol results in lower life cycle GHG emissions by 44%–52%, according to an Argonne National Laboratory study. Once corn ethanol is converted into SAF, the life cycle GHG emissions can be decreased by 21% for SAF from typical corn ethanol and by up to 56% if smart agricultural practices are considered.

Renewable ethanol can also be produced from agricultural residues such as corn stover resulting in SAF with even lower lifecycle GHG emissions. One example of such a promising BETO funded renewable ethanol project includes Sustainable Aviation Fuel From [i] Renewable Ethanol (SAFFiRE) pilot project, which brought together government and industry partners to help shift the aviation sector toward national SAF goals.

SAF made from renewable biomass and waste resources have the potential to deliver the performance of petroleum-based jet fuel but with a fraction of its carbon footprint, giving airlines solid footing for decoupling GHG emissions from flight.

To support this desire and spearhead SAF development, the U.S. government launched several whole-of-government funding initiatives.

Leveraging U.S. Government initiatives to support market for SAF

The U.S. government supports the market for SAF production, which aligns with the Biden-Harris administration goals to deliver an equitable, clean energy future, while placing the U.S. on a path to achieve net-zero emissions, economy-wide, by no later than 2050.

SAF Grand Challenge goal to supply SAF to meet 100% of aviation fuel demand by 2050

In 2021, the government-wide Sustainable Aviation Fuel Grand Challenge was launched. The U.S. Department of Energy (DOE) along with the U.S. Departments of Transportation and Agriculture, and other federal government agencies are working together to scale up new technologies to produce SAF on a commercial scale.

The SAF Grand Challenge will attempt to reduce the cost, enhance the sustainability, and expand production and use of SAF while:

• Achieving a minimum of a 50% reduction in life cycle GHG emissions compared to conventional fuel.
• Supplying 35 billion gallons of SAF annually by 2050, enough to meet 100% of aviation fuel demand.

DOE Energy Earthshot™ to focus on decarbonizing fuel

To significantly reduce the negative impacts of GHG emissions from carbon-based fuels and products critical to our way of life, DOE recently launched the Clean Fuels & Products Shot™. This Energy Earthshot™ builds upon the SAF Grand Challenge through the development of sustainable feedstocks and conversion technologies necessary to produce crucial fuels and carbon-based products in hard to decarbonize sectors.

BETO funding opportunity announcements to support SAF Grand Challenge

BETO has continued to focus on supporting R&D in accelerating the creation of sustainable fuels from domestic biomass and waste resources. One of the methods to support this includes funding opportunity announcements (FOA). Many of BETO’s FOAs have aligned with the goals of the SAF Grand Challenge.