دانلود رایگان ترجمه مقاله روش سلسله مراتبی برای برآورد مبادله انرژی در زنجیره های تامین (نشریه الزویر 2013)

یک رویکرد سلسله مراتبی برای ارزیابی موازنه های انرژی در زنجیره های تامین

A hierarchical approach for evaluating energy trade-offs in supply chains

Abstract

Supply chain design and operational decisions may impact the energy needed to keep the products flowing through to the customers. It is a challenge to determine the energy consumption and even more challenging to understand the impact of design and operational decisions on the energy consumption along the supply chain. This paper presents a hierarchical simulation based approach for estimating the energy consumption to keep the products flowing through a supply chain. System dynamics simulation is used at a high abstraction level to understand the major factors that may affect the energy consumption. Discrete event simulation is then used to delve down in detail for evaluating the critical stages in the supply chain. A case study for a closed loop supply chain of forklift brakes is used as an example of application of the approach.

1 Introduction

A number of progressive companies are making conscious efforts for reducing environmental impact of their operations. These companies obtain a competitive advantage towards customers in addition to making a contribution to a more sustainable future. An example from food and service industry is provided by the award winning restaurant in Sweden called MAX. They reported that their efforts for evaluating and improving their product value chain led to a reduction of their CO2-emmisions by 44% between 2007 and 2008 (MAX, 2008). Market research shows that 13 times more customers relate the MAX brand to environmental friendly products compared to their main competitor. MAX’s sustainability manager states that the latter figure is not the result of an increase in traditional marketing, but derives solely from communication of their products’ environmental footprint.

Matthews et al. (2008) highlight the importance of determining the carbon footprint across the supply chain and across the life-cycle. They recommend that the firms consider the life-cycle footprints from the outset, and “allow the largest sources of carbon emissions along the supply chain to be targeted first and most cost-effectively.” Hertwich and Peters (2009) stress that indirect impacts in the supply chain are more important than the direct impacts in the household in their analysis of carbon footprint of nations. Weber and Matthews (2008) show that about 30% of the carbon footprint of U.S. household consumption is outside the country, that is, the impact is in the international supply chains. These articles stress the importance of consideration of carbon footprint of the entire supply chain, in particular, the importance of including the international parts of supply chain.

A large contributor to the carbon footprint of a supply chain is the energy consumed in manufacturing and logistics. Ngai et al. (2012) identify control and reduction of unnecessary energy and utility consumption as one of the major ways to reduce greenhouse gases. This paper focuses on the energy consumption across a supply chain and presents an approach for evaluating options for reduction efforts and trade-offs related to energy use.

Calculation of energy use and emissions for a product across the supply chain can be challenging since almost all nodes and links across the supply chain serve multiple products. The energy use and emissions from manufacturing and logistics facilities may need to be allocated to determine the amounts for a specific product. Use of engineering models has been recommended to separately estimate the energy use for each product to avoid allocation (WRI/WBCSD, 2011). This paper presents an approach that uses engineering models, specifically simulation models of different paradigms, to calculate energy use for selected products across their supply chain.

The presented approach helps identify the largest consumers of energy along the supply chain at the outset using system dynamics modeling and then explore cost effective strategies for the largest consumers using discrete event simulation. Furthermore following the recommendations in the above mentioned literature, our proposed approach includes consideration of the entire supply chain including international segments if present as part of the configuration alternative.

The next section provides background information on different simulation paradigms and on hierarchical levels in supply chain. Section 3 briefly reviews related work. The proposed approach is presented in Section 4 followed by a case study in Section 5 for demonstrating the application of the approach. Sections 6 and 7 describe the implementation of key steps of the approach for the case study. Section 8 concludes the paper and includes potential future work.