A green routing problem: optimising CO2 emissions and costs from a bi-fuel vehicle fleet

Abstract

Road transportation is a big contributor to the existing CO2 emissions, among other greenhouse gases (GHGs) and air pollutants. The amount of emitted pollutants by a vehicle depends on the amount of fuel consumed and the type of fuel utilised. Moreover, the fuel consumption level is dependent on distance, load, speed, road gradient, driving pattern and many more factors. This paper extends vehicle routing problem (VRP) literature by developing a new variant as a green routing problem (GRP) which deals with optimising CO2 emissions and costs from a bi-fuel vehicle fleet, which runs on both the main fuel and the cleaner alternative fuel. The modelling approach deals with not only the fuel consumption level, but also with the optimised utilisation of the alternative fuel of the vehicle. To analyse environmental and economic performance of the GRP, two extensions as P-GRP and CB-GRP were developed and implemented in an Iranian case study, with a bi-fuel (gasoline/CNG) fleet. Results of the case study and computational experiments suggest a possible reduction in CO2 emissions by up to 27.38% and in costs by up to 18.76%, when compared with CVRP with a simple distance minimisation objective, using the conventional gasoline as the fuel.