Consider the following materials:
- 1.Agricultural residues
- 2.Corn grain
- 3.Wastewater treatment sludge
- 4.Wood mill waste
Which of the above can be used as feedstock for producing Sustainable Aviation Fuel?
Answer & explanation
Answer: (c) 1, 2, 3 and 4
Sustainable Aviation Fuel is made from renewable, non-petroleum feedstocks, and the US Department of Energy's list of them names all four materials: agricultural residues, corn grain, wet waste such as wastewater treatment sludge, and wood mill waste.
- ✓ 1. Agricultural residues are named on the DOE list of SAF feedstocks. They are a typical waste-based biomass source.
- ✓ 2. Corn grain is also on the list. It is a starch crop, which is why it feeds ethanol-based routes to jet fuel. ICAO's India study notes that maize supplies part of India's ethanol, and that ethanol can be turned into jet fuel by the alcohol-to-jet route.
- ✓ 3. Wet wastes, specifically manures and wastewater treatment sludge, are listed as feedstocks. ICAO's India study also mentions sewage sludge as a wet waste that can be turned into biocrude for SAF.
- ✓ 4. Wood mill waste is on the list. ICAO's India study lists sawdust and bark from sawmills among forest-based SAF feedstocks.
Remember · SAF feedstocks are broad: crops such as corn, crop and forest residues, wood mill waste, municipal solid waste, wet waste such as sludge, and fats, oils and greases.
Sources
- US Department of Energy (BETO), Sustainable Aviation Fuel: Reducing Emissions from Commercial Flight ↗ “These resources include corn grain; oil seeds; algae; other fats, oils, and greases; agricultural residues; forest harvesting residues; wood mill waste; municipal solid waste streams; wet wastes (manures, wastewater treatment sludge); and dedicated energy crops.”
- US Department of Energy, Alternative Fuels Data Center: Sustainable Aviation Fuel ↗ “SAF can be produced from non-petroleum-based renewable feedstocks including, but not limited to, the food and yard waste portion of municipal solid waste, woody biomass, fats/greases/oils, and other feedstocks.”
- ICAO (ACT-SAF), Feasibility Study on the Use of Sustainable Aviation Fuels in India (copy of the ICAO PDF) ↗ “Other types of residues include sawdust and bark generated at sawmills, tall oil, and black liquor from kraft pulping. … through hydrothermal liquefaction of wet wastes such as sewage sludge. … Sugarcane provides most ethanol production, with the remainder from food grains such as maize and surplus rice stocks determined by the Food Corporation of India.”
Question and answer: UPSC's official GS Paper I (2024, Series A) — paper ↗ · answer key ↗. Explanation: Minimalist IAS, checked 30 Sept 2026 (how we verify). ·