Influence of eco-friendly diesel fuel additives on fuel properties, engine performance and exhaust emissions

Diesel fuel used in transport, marine applications, and stationary power systems is vulnerable to storage-related degradation, especially in the presence of bio-components, which creates a need for environmentally benign additives that preserve fuel quality without compromising engine operation. This study investigates the effect of four eco-friendly diesel additives—liquid Effective Microorganisms EM(F), ceramic EM carriers EM(C), silver solution (SS), and colloidal nanosilver (CNS)—on fuel properties, engine performance, and exhaust emissions. Fuel blends were prepared at additive concentrations of 1, 2, and 5% v/v for physicochemical analyses, while engine tests were performed for selected blends at 2 and 5% using an SW 680/1 direct-injection diesel engine operating at 20 and 30 kW. The novelty of the study lies in the integrated assessment of environmentally oriented additives as potential alternatives to conventional fuel-treatment agents through combined evaluation of ignition quality, density, distillation characteristics, low-temperature behavior, corrosion tendency, fuel consumption, thermal efficiency, and exhaust emissions. The results showed that the additives did not adversely affect compliance with the evaluated EN 590 fuel-quality requirements (e.g., density, distillation, copper corrosion, cetane number, CFPP) and caused only negligible changes in density and volatility-related properties. At the same time, selected additives improved ignition quality, with the cetane number increasing from 54.73 for neat diesel to 55.83–55.97 for ceramic EM blends and to 55.70–55.83 for silver-solution blends at lower concentrations. Engine tests demonstrated reduced brake specific fuel consumption, from 421 to 408 g/kWh at 20 kW and from 366 to 358 g/kWh at 30 kW, together with an increase in brake thermal efficiency from 20.1 to 20.7% and from 23.1 to 23.7%, respectively. Simultaneously, reductions in NO x , CO, and CO 2 emissions were observed without deterioration of engine power output. These findings indicate that eco-friendly additives show potential to improve diesel-engine energetic performance while maintaining short-term fuel stability and physicochemical compatibility, which supports their further investigation for sustainable fuel management.