Energy implications in a two-stage production system with controllable production rates

Nowadays, it is an essential commitment for firms to reduce energy consumption and therewith energy costs, which frequently account for a large part of the manufacturing costs. This work analyzes a system where a single product is manufactured on a machine and delivered to the subsequent production stage in batch shipments. The production rate at each stage may be varied within given limits. Energy consumption at each stage is strictly related to the production rate set according to a given function that depends on the specific characteristics of the production process. Energy consumption is assumed to occur both during production and during the idle state of the machines. The aim of this work is to propose an analytical model of this system and to minimize the total costs of producing and storing the product, including energy costs. The results of the paper indicate that energy-related costs can be reduced significantly if energy consumption is considered in planning the production process.