Estimation of the CO₂ Emission for the Clothing Cleaning Process

Abstract

Objective. The most common professional cleaning services available today are professional dry cleaning, laundry, and wet cleaning. Many of the organic solvents used in dry-cleaning have been identified as factors contributing to global warming, destruction of the ozone layer, and groundwater contamination, among other problems, and are subject to legal restrictions and controls. Dry-cleaning remains an essential process, since it causes less damage to clothing than water-based cleaning. Requirements for clothing cleaning have grown increasingly restrictive as exemplified by the launch of the Carbon Footprint Pilot Project. Given these circumstances, this study seeks to estimate greenhouse gas emissions (in terms of GWP₁₀₀) based on LCI analysis of each step of the cleaning processes and discusses methods for reducing emissions. Cleaning is an essential aspect of the usage stage of clothing and its life cycle. To help create a system for establishing carbon footprints for clothing products, this study also examines a wide range of public information sources related to CO₂ emissions, based on cleaning site data collected in fiscal 2009.
Results and Discussion. In the dry cleaning process, the electric power consumed by the various activities at cleaning agencies, the steam required for solvent recovery, steam required for pressing, and packing materials, including hangers and carrier bags, contribute significantly to overall CO₂ emissions. At 0.369 kg-CO₂eq per clothing, the CO₂ emissions associated with the steam required for tetrachloroethylene recovery accounts for the highest fraction of CO₂ generated. The results suggest CO₂ emissions generated by tetrachloroethylene which used as the dry-cleaning solvent exceed those of petroleum-derived solvents. The results also show CO₂ emissions from solvents can be suppressed by reducing the solvent consumption rate to 4% or 20%, which also reduces the generation of photochemical oxidants. In laundry processes, steam for pressing and drying in the finishing processes contributes significantly to CO₂ emissions, followed by heating boilers, detergents, and cardboard use.
Conclusions. The CO₂ emissions generated by the dry cleaning process depend significantly on the types of solvents used. The steam required for solvent recovery contributes a large portion of these emissions, followed by the steam used in finishing processes. Improving boiler efficiency is a key factor in reducing CO₂ emissions in both dry cleaning and ordinary laundry processes. This paper also proposes a flexible method for estimating cleaning-related CO₂ emissions per clothing, based on a conversion proportional to weight, by accounting for differences in washing methods, finishing processes, and solvents.