Energy recovery has been found to be a promising approach for disposal of polymer waste such as expanded polystyrene (EPS) which entraps large volume of air. Biodiesel known as an advantageous alternative fuel possesses bio-solvent attributes and is feasible to be used for energy recovery from EPS. In this study, maximum EPS dissolution value in biodiesel was calculated and a homogenous fuel composition was achieved. At the second phase, several biodiesel-diesel blends (B5) containing various percentages of EPS were tested in a DI diesel engine. Statistical analyses showed that addition of a limited amount of EPS led to a significant emission reduction, NOx in particular, while engine performance criteria remained stable. It was found that B5 blend containing 50 g EPS/L biodiesel was found highly advantageous on both level of performance and emissions. Despite a 3.6% reduction in brake power, a significant decrease in brake specific fuel consumption (8.5%) and increase in brake thermal efficiency (9.8%) were observed at maximum rated power and speed operation condition of the engine when the new fuel was injected. Furthermore, sustainable reductions of CO, CO2, NOx, and soot as the major exhaust emissions were achieved. (c) 2012 Elsevier Ltd. All rights reserved.