A Novel Life Cycle-based Principal Component Analysis Framework for Eco-efficiency Analysis: Case of the United States Manufacturing and Transportation Nexus

Abstract

In this study, the relationship between the U.S. manufacturing and transportation industries was studied from economic and environmental life cycle sustainability perspective. The main objectives were 1) to quantify the life cycle impacts of national freight transportation activities that were triggered by the U.S. manufacturing industries and supply chains, a.k.a. manufacturing transportation nexus, and 2) assess the transportation-focused sustainability performance of manufacturing sectors based on eco-efficiency. Three environmental impact categories were focused, namely: greenhouse gas (GHG) emissions, energy use, and water withdrawals along with the economic outputs. To achieve the goals, a novel integrated methodology that consists of Economic Input–Output Life-Cycle Assessment (EIO-LCA) and Principal Component Analysis (PCA) was utilized. The scope of the study consists of 276 U.S manufacturing sectors' economic and environmental impacts associated with four transportation modes including air, rail, truck, and water transportation. Based on EIO-LCA results, food manufacturing sector was found to be responsible for the highest environmental impacts and economic output with a share of over 20% for GHG emissions, energy use, and water withdrawals and about 12% for economic output. Motor vehicle manufacturing and motor vehicle body, trailer and parts manufacturing were found to have the second and third largest share of environmental impacts and economic output, respectively. From the result of the eco-efficiency analysis, ordinance and accessory manufacturing (0.719) was found to have the highest and iron and steel mills manufacturing and agricultural chemical manufacturing (0.130) were found to have the least eco-efficiency scores. It was also critical to address that a significant negative correlation was observed between the eco-efficiency and the ton-km transportation trends.