Advanced biofuels (SAF, renewable diesel & biomethane)

Advanced biofuels convert waste oils, crops and lignocellulosic residues into drop-in fuels that cut lifecycle CO2 by 50–90% versus fossil equivalents while needing no engine or infrastructure changes. Sustainable aviation fuel (SAF) is the demand spike: global SAF output reached about 1.5 Mt in 2024 — roughly 1.9 billion litres, yet still only 0.53% of jet fuel — and IATA projects demand near 6 Mt in 2025 and 20 Mt by 2030, rising to about 358 Mt by 2050 when SAF is expected to deliver 65% of aviation’s emissions cuts. Three conversion routes dominate: hydroprocessing of fats and oils (HEFA), alcohol-to-jet (ATJ), and anaerobic digestion to biomethane. The synergy is feedstock flexibility plus refinery reuse: the same waste-lipid stream can swing between renewable diesel and SAF as price and mandate demand shift.

Key directions of advanced biofuels:

1. HEFA renewable diesel and SAF (Hydroprocessed Esters & Fatty Acids): waste cooking oil, tallow and vegetable oils hydroprocessed into diesel and jet — the dominant pathway today, with waste-oil routes near 20 gCO2e/MJ.
2. Alcohol-to-jet SAF (Alcohol-to-Jet): ethanol or isobutanol dehydrated, oligomerized and hydrogenated into jet-range paraffins, fully blend-compatible with Jet A-1.
3. Bioethanol as fuel and platform (Bioethanol): corn, sugarcane and cellulosic sugars fermented to ethanol for E15+ blends and as ATJ feedstock.
4. Biomethane and biogas (Biomethane): municipal and agricultural residues digested to biogas, then upgraded to grid-injection renewable natural gas.

Sectoral value chain#

[feedstock] ──> [pretreatment] ──> [conversion] ──> [upgrading]
                                  │
                          (H2 + catalysis)
                                  │
                                  ▼
[SAF + diesel + RNG] <─── [certification] <─────┘

Value chain levels#

Cross-cutting technologies of the sector:

• HEFA hydroprocessing (HEFA Hydroprocessing): catalytic deoxygenation of fats with hydrogen.
• Alcohol-to-jet catalysis (Alcohol-to-Jet Catalysis): dehydration–oligomerization–hydrogenation of alcohols.
• Carbon capture and sequestration (Carbon Capture & Sequestration): Class VI sequestration cutting pathway carbon intensity.

The stack rests on three conversion platforms, each matched to a feedstock class.

1. HEFA hydroprocessing (HEFA Hydroprocessing):
   • waste fats and oils plus hydrogen yield renewable diesel and SAF at 50–90% lower lifecycle CO2.
   • Neste co-processes SAF in existing refineries, reaching about 3.3 Mt/yr of renewable capacity.
2. Alcohol-to-jet catalysis (Alcohol-to-Jet):
   • ethanol or isobutanol is dehydrated, oligomerized and hydrogenated into Jet A-1-compatible fuel.
   • LanzaJet’s Freedom Pines became the first commercial ethanol-to-SAF plant in 2025; Praj licenses the Axens Jetanol pathway.
3. Anaerobic digestion and biomethane (Biomethane):
   • municipal and agricultural residues are digested to biogas, then upgraded to grid-injection RNG.
   • Verbio runs circular biomethane biorefineries on regional biomass.