Environmental hedging point policies for collaborative unreliable manufacturing systems with variant emitting level technologies

As the main cause of environmental problems, GHG emissions generated by industrial activities are necessary to be reduced. In order to meet strict environmental regulations and make production cleaner, a large number of enterprises operating with high-emitting machines (HEMs) are gradually investing in low-emitting machines (LEMs) instead of undertaking costly replacements of all their HEMs. Recently, in a stochastic dynamic context, a control policy was developed to control such systems in which the HEM and LEM are not operating simultaneously (NOS). In this paper, as an extension to this base policy, we start by proposing a more efficient control policy for NOS systems. Our main objective is to develop new cost-effective and environmentally friendly control policy for the enterprises aiming to gradually invest in the LEM and help the manager to synchronize HEM and LEM together. So, we develop two new additional policies in which both HEM and LEM can operate simultaneously (OS) to increase the availability of the entire system and simultaneously reduce inventory, backlog and emissions generated. To determine the optimal parameters of these control policies, simulation modelling, an experimental approach, and response surface methodology are applied. Finally, several experiments are conducted to carry out comparisons between the policies based on a wide range of cost and system parameters. The results show that the new developed control policies for OS systems bring significant cost savings and GHG emission reductions as compared to the NOS systems. (C) 2019 Elsevier Ltd. All rights reserved.