Renewable diesel and SAF: Impact on the biosphere
Clean at the tailpipe, but what happens upstream?
What this tab covers Effects on human, animal, plant, fungal and microbial life and on whole ecosystems: in the short term (construction and early years), medium term (operating life) and long term (decommissioning and legacy).The fuels burn more cleanly than fossil fuels in use, so impacts lie upstream: land-use change for crop oils, competition for scarce waste oils, and biomass harvesting for gasification routes.
Fossil jet fuel reference value (ICAO) 89 g CO2eq/MJ7 Lowest ICAO default value (municipal waste FT) 5.2 g CO2eq/MJ7 Highest ICAO default value (palm oil HEFA, no biogas capture) 96.6 g CO2eq/MJ7 SAF share of jet fuel (2025) 0.6%6Effects over time
| Life affected | Short term | Medium term | Long term |
|---|---|---|---|
| Humans6 | Little evidence of effect in the sources reviewed. | Higher fuel costs: the 2025 SAF premium cost airlines about USD 2.9 billion for 1.9 Mt of fuel. | Little evidence of effect in the sources reviewed. |
| Animals7 | Habitat loss where land is cleared for oil crops; not quantified in the sources reviewed. | Little quantified evidence in the sources reviewed. | Little quantified evidence in the sources reviewed. |
| Plants7 | Natural vegetation may be cleared where crop oils expand. | ICAO estimates indirect land-use change of 36.6 g CO2eq/MJ for palm oil SAF and 20.7-23.9 for soybean and rapeseed. | Camelina grown in rotation has negative land-use change (-11.5 g CO2eq/MJ). |
| Fungi and soil life7 | Little evidence of effect in the sources reviewed. | Little evidence of effect in the sources reviewed. | Little evidence of effect in the sources reviewed. |
| Ecosystems57 | Feedstock demand: fats and oils are already in high demand, and growth would need an extra 125 Mt of feedstock in the IEA accelerated case. | Waste and residue routes cut life-cycle emissions by about 84-94% against fossil jet (calculated from 5.2-13.9 against 89 g CO2eq/MJ). | Palm oil SAF from mills without biogas capture (96.6 g CO2eq/MJ) can exceed fossil jet. |
How the effects are reduced
Choosing wastes, residues and rotation crops avoids most land-use change; ICAO and the EU apply sustainability criteria and give these feedstocks lower default values. Capturing biogas at palm oil mills cuts palm HEFA from 96.6 to 74.0 g CO2eq/MJ. Low-carbon hydrogen would cut emissions from the hydrotreating step. Expanding gasification and alcohol routes broadens feedstock beyond scarce oils.
Sources
- Renewables 2025: Renewable transport International Energy Agency, 2025
- SAF Production Growth Rate is Slowing Down, Essential to Correct Course Ahead of e-SAF Mandates (press release, 9 December 2025) IATA, 2025
- CORSIA Default Life Cycle Emissions Values for CORSIA Eligible Fuels (ICAO document 06) International Civil Aviation Organization, 2025