Environmental analysis of a cotton yarn supply chain

This study compares the environmental impacts related to the production of cotton yarn from cultivation to washing and drying, when cotton is supplied by four companies located in four different countries (Egypt, China, India and the USA). Interesting results have been obtained from cultivation scenarios where the productivity influences the value of the environmental impact associated to each country. The highest greenhouse effect is produced by the Indian company, with 0.89 kg of CO2 equivalent (per 1 kg of cotton). Fuel consumption and Ammonium nitrate are the first items of greenhouse effect in all companies because of their extensive use and the lack of rotation with other unprofitable crops. In Chinese and Egyptian companies the irrigation sources are severely threatened and it is necessary to switch from a flood irrigation to a drip irrigation system. The production phase of cotton yarn provides an impact equal to 2.81 CO2 kg-equivalent. The most critical impacts of cotton yarn production are due to Dyeing (1.24 CO2 kg-eq.) and Spinning (0.64 CO2 kg-eq.) phases and they are essentially connected to reactive reagents and pigments, electrical and thermal energy. Regarding thermal energy consumptions some improvements in dyeing plants (recover cooling water, return steam condensate to boilers or reuse different process waters) may allow the company to decrease in CO2 emission by 41.7%. Moreover a reduction in CO2 emission by 34.6% can be achieved in the spinning phase using an optimized suction tube in conjunction with adjustable inverter control. (C) 2014 Elsevier Ltd. All rights reserved.