Intra-simulative ecological assessment of logistics networks: Benefits, concepts, and tool enhancement
Proceedings Title: Proceedings of the 2012 Winter Simulation Conference (WSC)
Ecology and resource efficiency have achieved high relevance in industry, not only due to their economic effects. Thus, logistics planning is required to contribute to "green" initiatives. However, it still lacks appropriate methods and tools. Simulation represents a well-accepted method in logistics planning, for it can handle dynamics, stochastic effects and a high degree of complexity. In the context of ecological planning, dynamics play an important role as demand peaks are compensated by
... re compensated by usually inefficient supporting processes, such as express transportation. OTD-NET is known as an innovative supply chain simulator and is extended by the ecological transportation assessment. This enables the evaluation of green KPIs and -due to the intra-simulative approach -logistics decisions based on ecological balances. In this paper we describe the state-of-the-art on ecological assessment, discuss requirements for its integration into simulation, and explain an implementation approach as well as its benefits by means of a use case. 978-1-4673-4780-8/12/$31.00 ©2012 IEEE 3156 978-1-4673-4782-2/12/$31.00 ©2012 IEEE Cirullies, Schwede, and Toth the transportation sector was already intended. Since 2/2/2009 the EU directive 2008/101/EG has encompassed also air traffic. Counteractive measures can be divided into technological and organizational approaches. Technological improvements include innovations such as hybrid engines or SkySails (the equipment of cargo ships with sails, cf. http://www.skysails.info), whereas organizational activities refer to logistics planning, e.g. decisions on transport disposition or network node locations. Logistics planning is part of the Supply Chain Management (SCM), which consists of three hierarchic levels: Supply Chain Design (SCD), Planning (SCP), and Execution (SCE). The top level is SCD, which comprises strategic, long-term decisions. Thus, it provides the maximum potential for ecological improvements and is focused in this paper. Yet, SCD decisions are still made exclusively on a cost and logistics performance base (Hellingrath et al. 2008, p. 460). Energy-related and environmental criteria play only a subordinate role in the network design (Horváth & Partners 2012) and are balanced -if at all -in a subsequent stage. Due to the expected increasing ecological and, thus, financial relevance of SCD, the classic targets of "costs" and "performance" have to be extended through the inclusion the "ecology" dimension. However, analyses of the German Logistics Association (Bundesvereinigung Logistik, BVL) show that in logistics concepts, tools, and research results are missing in practice (Straube and Pfohl 2008). Simulation is a common method to support SCD as it allows detailed analyses of highly complex logistics systems considering dynamics and stochastic effects. In order to integrate ecology completely into the SCD planning process, environment based decision making within simulation studies, e.g. transport disposition, has to be enabled. In order to provide a decision basis, an intra-simulative ecological assessment approach is required, as the results must be available at simulation runtime. Therefore, Fraunhofer Institute for Material Flow and Logistics (IML) extended a well-established logistics network simulation tool to include ecological targets. The new features for the intra-simulative assessment necessitated the modification of the whole tool environment. Accordingly, the aim of this paper is to derive specific requirements for this intra-simulative ecological assessment approach, to present the necessary extensions of a particular simulation tool, and to lineout the concept for an environment-based logistics decision mechanism. The requirements are derived and described in section 2. Then, in section 3, the methodology for emission and energy demand calculations is presented. Its integration into the simulation tool and the resulting benefits are explained in section 4 in the context of a use case. Finally, section 5 summarizes the paper and presents critical remarks as well as an outlook on further research.