Glycerol carbonate as a dual-function renewable additive for ethanol–gasoline blends: Improving miscibility, efficiency, and emissions

Ethanol is widely regarded as a promising biofuel for spark ignition engines due to its renewable nature and high oxygen content. However, its practical application in gasoline blends is often constrained by issues such as poor miscibility, phase separation, low vapor pressure, and reduced energy density. This study investigates glycerol carbonate (GC), a renewable, biodegradable compound synthesized from glycerol and urea, as a dual-function additive to enhance the stability and combustion efficiency of ethanol-gasoline blends. GC was blended into E40 fuel (40 % ethanol and 60 % gasoline) at concentrations ranging from 1 % to 4 %. Its effects on fuel properties, engine performance, and emissions were evaluated using a single-cylinder SI engine. The results demonstrated that GC significantly improved fuel miscibility, increased density and viscosity, and raised the flash point, thereby enhancing both fuel safety and handling. Combustion analysis revealed smoother pressure curves and more controlled heat release with the addition of GC, resulting in improved brake thermal efficiency (up to 14 %) and reduced brake-specific fuel consumption. Emission measurements showed substantial reductions in carbon monoxide and unburned hydrocarbons. However, an increase in nitrogen oxides was observed at higher GC concentrations. These findings highlight the potential of GC as a bio-based additive that addresses key limitations of ethanol-gasoline fuels while promoting cleaner and more efficient engine operation. The study offers valuable insights into the formulation of advanced biofuel blends and supports the integration of GC into future sustainable fuel strategies.