Ethanol-Diesel Blend Fuels in Compression Ignition Engines

Ethanol-diesel blends represent a promising route to reduce carbon intensity and particulate emissions from compression ignition engines while utilising existing infrastructure. By incorporating ethanol – a renewable oxygenate – into conventional diesel, the physical properties of the fuel change markedly: viscosity and density decrease, volatility increases and cetane number may be moderated. These changes influence atomisation, ignition delay and combustion phasing, often leading to lower soot formation and reduced unburned hydrocarbon emissions but sometimes to higher nitric oxides. Engine calibration, including injection timing and pressure, must be optimised to reconcile the trade-offs between thermal efficiency, power output and exhaust composition. Recent advances have explored ternary blends, in which ethanol is combined with biodiesel or other co-solvents to improve stability and lubricity. Such formulations seek to maximise renewable content without compromising spray dynamics or increasing corrosion risk. Globally, regions with abundant feedstocks and existing diesel fleets view ethanol-diesel blends as a transitional pathway towards decarbonised transport, offering rapid deployment and compatibility with heavy-duty and agricultural machinery.

Research from Nature Portfolio

Recent studies have assessed ternary mixtures of waste-derived biodiesel, bioethanol and petroleum diesel in single-cylinder engines under full-load conditions. Physicochemical testing revealed that the addition of fish-oil biodiesel and ethanol reduced kinematic viscosity and flash point but lowered net calorific value. Combustion trials showed a modest decline in torque and thermal efficiency, accompanied by an increase in specific fuel consumption. Emissions measurements demonstrated substantial cuts in carbon monoxide and unburned hydrocarbons, with reductions exceeding 40–50 %, although nitrogen oxides rose by around 25–30 %. The work highlights the potential to tune blend ratios to achieve emission trade-offs and underscores the importance of optimising biodiesel and ethanol fractions to control NOx.

Ethanol-Diesel Blend Fuels in Compression Ignition Engines publication trend

The graph below shows the total number of articles in ethanol-diesel blend fuels in compression ignition engines across all publications each year (not limited to Nature Index journals).

Technical terms

Cetane number: A measure of a diesel fuel’s ignition quality, defined by the delay between injection and auto-ignition.

Brake specific fuel consumption (BSFC): The mass of fuel consumed per unit of brake power produced over time, indicating engine efficiency.

Brake thermal efficiency (BTE): The ratio of useful mechanical energy output (brake power) to the chemical energy input of the fuel.

Ignition delay: The interval, usually expressed in degrees of crank angle, between start of injection and the onset of combustion.

Oxygenated biofuel: A fuel containing oxygen in its molecular structure, which promotes more complete combustion and reduces soot formation.

References

1. Physical properties, engine performance, and exhaust emissions of waste fish oil biodiesel/bioethanol/diesel fuel blends. Scientific Reports (2023).
2. Experimental investigation of the influence of ethanol and biodiesel on common rail direct injection diesel Engine's combustion and emission characteristics. Case Studies in Thermal Engineering (2022).
3. Emission and Performance Evaluation of a Diesel Engine Using Addition of Ethanol to Diesel/Biodiesel Fuel Blend. Energies (2022).