How materials, energy, transport, and capital contribute to emissions along the supply chain of Material Handling Equipment: The Path Extraction Method applied to USEEIO

The importance of machinery and equipment (ME) to the use of materials and thus to the circular economy and their contribution to climate change mitigation has only recently been recognized. Previous analyses based on EXIOBASE distinguished only five types of ME, giving a coarse picture that is not satisfactory to pinpoint opportunities for mitigation. Here we utilize the US benchmark input-output tables, which represent the production and use of 65 types of ME. We use Hypothetical Extraction Method (HEM) to identify the part of the carbon footprint that can be attributed to the input of materials and energy as well as the use of transport and capital equipment. We use Structural Path Analysis (SPA) to identify those suppliers important for contributing to the carbon footprint of the product of interest through using materials, energy, transport, capital, or direct emissions. We illustrate the application of this path extraction (PEX) to the greenhouse gas emissions (GHGE) of the production of material handling equipment. Cut-off criteria need to be set to less than 0.5% of total impacts to consider more than the first tear of suppliers to each of the investigated production processes.