Emission characteristics and efficiency assessment of biomass-derived syngas in a spark-ignition generator compared to LPG and gasoline

• Syngas C showed best efficiency (14.54 %) and lowest CO (0.512 %) and HC (15 ppm). • Syngas B gave better low-load output but declined in efficiency at higher loads. • Syngas A had the worst performance, with CO at 2.112 % and HC at 62 ppm. • Gasoline and LPG emitted more CO (9.56 %, 6.11 %) and HC (up to 443 ppm). • Biomass-derived syngas is suitable for clean, low- to medium-load power generation. This study investigates the performance and emission characteristics of biomass gasification-derived syngas under various loads in comparison to Liquefied Petroleum Gas (LPG) and gasoline in a spark-ignition, single-cylinder generator. In the experiment, syngas A (4.11 % CH 4 , 9.83 % H 2 , 25.04 % CO, 12.01 % CO 2 , 49.01 % N 2 ), syngas B (2.88 % CH 4 , 18.19 % H 2 , 21.73 % CO, 6.07 % CO 2 , 51.13 % N 2 ), and syngas C (5.96 % CH 4 , 18.79 % H 2 , 28.85 % CO, 8.12 % CO 2 , 38.28 % N 2 ) were used to represent the real biomass gasification-derived syngas. Engine speed, thermal efficiency, and emissions of CO, CO₂, and HC under variable electrical loads (0–400 W) were analysed. Syngas C delivered the highest lower heating value (7444.13 kJ/kg) and demonstrated superior performance among syngas variants, achieving up to 14.54 % efficiency at 400 W, with CO and HC emissions as low as 0.512 % vol and 15 ppm, respectively. Syngas B performed better at lighter loads due to its high H₂ content, but its efficiency declined with increasing load. In contrast, Syngas A recorded the poorest performance and emissions, including peak CO of 2.112 % and HC of 62 ppm at 200 W. Among the tested fuels, gasoline and LPG exhibited higher CO emissions, reaching 9.56 % and 6.11 % respectively, along with higher HC emissions, particularly for LPG, which reached up to 443 ppm at 0 W load. Despite their lower energy density, syngas fuels, especially Syngas C, showed potential for decentralised, low-to-medium load power generation due to their cleaner emission profile and adequate efficiency.