A study on the heterogeneous fleet of alternative fuel vehicles: Reducing CO2 emissions by means of biodiesel fuel

•An extension of the heterogeneous Vehicle Routing Problem with synchronized visits is studied.•New aspects such as alternative fuel vehicles, biodiesel, and carbon emissions are investigated.•Three hybrid algorithms based on Artificial Bees Colony are proposed and compared.•Good computational performance is achieved for the investigated problem.•The benefits of a heterogeneous fleet in terms of saving consumption and emission is demonstrated.