The Role of Advanced Biofuels and E-fuels

The global transportation sector is undergoing decarbonization, with electric vehicles, low-carbon fuels, advanced biofuels, e-fuels, renewable diesel, and sustainable aviation fuel gaining popularity.

FREMONT, CA: The global transportation sector contributes to greenhouse gas emissions, responsible for approximately 25 percent of energy-related CO2 emissions worldwide. Consequently, decarbonizing transport has become a critical priority. Several solutions are emerging, including electric vehicles (EVs) and low-carbon fuels such as hydrogen, methanol, and ammonia. Advanced biofuels and e-fuels also offer promising opportunities to reduce the carbon footprint in transport sectors where electrification faces significant hurdles, particularly in aviation, shipping, and heavy-duty road transport.

A key advantage of sustainable hydrocarbon fuels is their drop-in capability, allowing them to be used in existing engines and infrastructure without substantial modifications. This feature is precious for sectors like aviation and shipping, where transitioning to alternative propulsion systems is complex, costly, and time-intensive.

First-generation biofuels, such as bioethanol and biodiesel from food crops like corn, sugarcane, and vegetable oils, have traditionally dominated the sustainable fuel market. However, concerns over their competition with food production, lifecycle emissions, and land use drive regions to pursue more advanced alternatives. Second-generation biofuels, which utilize lignocellulosic biomass, agricultural residues, and non-food crops, are gaining traction for their enhanced sustainability and minimal impact on food resources. Meanwhile, third and fourth-generation biofuels leverage microalgae and other microorganisms, holding future potential despite current production challenges.

E-fuels, also called power-to-liquid (PtL) fuels, represent another promising advancement in sustainable fuel technology. Created by combining green hydrogen (produced via water electrolysis using renewable energy) with captured CO₂, e-fuels could enable carbon-neutral energy solutions. Examples include e-methane, e-methanol, and liquid e-fuels like e-gasoline, e-diesel, and e-kerosene (e-SAF for aviation). While market activity remains robust for second-generation biofuels, e-fuels are quickly gaining momentum due to their theoretically unlimited feedstock sources, potential for carbon neutrality, and support from regulatory bodies and major corporations.

Renewable diesel, or hydrotreated vegetable oil (HVO) or green diesel, is a direct alternative to conventional fossil diesel. It is primarily produced through the hydroprocessed esters and fatty acids (HEFA) pathway, which involves the hydrotreatment and upgrading feedstocks such as vegetable oils, animal fats, and waste oils. The HEFA process also serves as the principal method for producing sustainable aviation fuel (SAF), an essential solution for reducing carbon emissions in the aviation sector. SAF is a drop-in replacement for conventional jet fuel (Jet A-1), allowing seamless integration with existing aircraft engines.

While other production pathways for SAF and renewable diesel are emerging—such as gasification followed by Fischer-Tropsch (FT) synthesis, alcohol-to-jet processes, and power-to-liquids (e-fuels)—these technologies are anticipated to have limited commercial uptake through 2035. HEFA processes are expected to retain dominance due to their scalability, efficiency, and compatibility with the current refining infrastructure. Additionally, all processes generate valuable by-products, including lighter fractions such as propane, butane, and naphtha, which can be utilized across various industries, enhancing the economic viability of renewable diesel and SAF production.

The sustainable fuel market is expected to grow significantly, with global renewable diesel and SAF production capacity exceeding 57 million tonnes annually by 2035. This growth is driven by policy developments, reduced carbon emissions from vehicle fleet operators and airlines, and the emergence of new production technologies.