Why Alternative Fuels Matter
Alternative fuels are technical levers to reduce the carbon intensity of energy used in freight transport. As one of the five levers identified in Kaya’s equation for freight, decarbonizing the energy source itself is among the most impactful long-term strategies.
Various paths are being explored across different transport modes. Here we focus on the most mature solutions for international freight transport.
Key Alternative Fuel Options
🌿 Biofuels
Derived from organic matter (vegetable oils, waste fats, agricultural residues), biofuels can be blended with or replace conventional fossil fuels. They are among the most commercially available alternatives today.
- Biodiesel (FAME/HVO) — Used in road freight; HVO (Hydrotreated Vegetable Oil) is a “drop-in” replacement for diesel
- Bio-methanol & bio-ethanol — Gaining traction in maritime shipping as dual-fuel vessels become available
- Waste-based biofuels — Preferred as they avoid competition with food production
🔥 LNG (Liquefied Natural Gas)
LNG is widely adopted in maritime shipping as a transition fuel. It reduces SOx and particulate emissions significantly but offers only modest CO₂ reductions (10–20% on a WtW basis). A key concern is methane slip — unburned methane escaping during combustion — which can partially negate the CO₂ benefits given methane’s high global warming potential.
✈️ SAF (Sustainable Aviation Fuel)
SAF is the leading decarbonization lever for air freight. Produced from waste oils, agricultural residues, or synthesized from captured CO₂ and green hydrogen, SAF can reduce lifecycle emissions by up to 80% compared to conventional jet fuel.
- Compatible with existing aircraft engines (as a blend, typically up to 50%)
- Currently represents less than 1% of global aviation fuel but rapidly growing
- Regulatory mandates (EU ReFuelEU) are driving adoption
⚡ Electrification
Battery-electric trucks are becoming viable for short-to-medium distance road freight (up to 300–500 km). For longer distances, battery weight and charging infrastructure remain challenges, though rapid progress is being made.
💧 Green Hydrogen & Ammonia
Produced from renewable electricity via electrolysis, green hydrogen (and its derivative, green ammonia) represents a promising long-term solution for maritime and heavy-duty road transport. However, production costs, infrastructure, and energy efficiency challenges mean widespread adoption is still years away.
🌬️ Wind-Assisted Propulsion
For maritime transport, technologies like rotor sails, rigid wing sails, and kite systems can reduce fuel consumption by 5–30% depending on route and conditions. These are increasingly being retrofitted on existing vessels.
🔑 Key Takeaways
No single alternative fuel will solve freight decarbonization alone. The optimal mix depends on the transport mode, route, and timeline. Biofuels and SAF are the most commercially ready today, while hydrogen and electrification hold promise for the longer term. The key is to start acting now with available solutions while supporting the development of next-generation technologies.
Explore More
Return to the full curriculum on the Academy homepage, or revisit the foundations: Climate Change, GHG Accounting, and Freight Environmental Impact.