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Ecoproposal for jean manufacture
In this paper a new proposal for the process of dyeing of jean fabrics is studied. Three different scenarios are analyzed. The environmental impact of these three scenarios is done following the life cycle assessment (LCA) methodology based on energy and resources consumption during the material extraction, elements manufacturing, use and dismantle phases. The Ecoinvent 9 database is used to compile a comprehensive and comparable inventory. The definitions of the three scenarios are: *1st scenario: 100% using hydrosulfite. Conventional process. In order to keep indigo dye in its reduced form an excess of hydrosulfite is added at a relation of 2 moles of hydosulfite per 1 mol of Indigo dye (1,5 g of hydrosulfite per 1g of Indio). In this scenario is considered the consumption of energy and materials associated to the production and consumption of hydrosulfite. *2nd scenario: mixt of Hydrosulfite and electric process. In this scenario hydrosulfite is added at stoichiometric relation in order to promote the initial reduction of Indigo dye (0,77 g of hydrosulfite per 1 g of Indigo). The excess of hydrosulfite is substituted by the use of an electrochemical cell which maintain the indigo dye in its reduced form. *3rd scenario: 100% using electric process. The addition of hidrosulfite is completely substituted by the application of an electrochemical process. The energy is directly taken from the electricity grid. For this case, any modification of electricity grid is considered. This study case considers the environmental impact to generate and bring electricity to the process. This includes the different voltage transformations (high/medium– medium/ low) and the distribution losses of the electricity grid in these different stages. The "100% electric" scenario is more environmentally friendly with Spanish electric energy mix than the other two scenarios. Additionally, regarding Europe electric energy mix, we need to evaluate case by case in order to decide if the total or partial substitution of the hydrosulfite is made, so as not to increase the impact, as is the case of Germany. Norway is a case to be followed and we see that clean energies must be promoted in order to reduce the use of chemicals in the process. One possibility would be the installation of renewable energies in the plant where the production process is carried out.