3.2. Ginning vs cutting/shredding
The most employed automatized ginning technologies are basically: saw ginning(55%), double roller ginning(35%), rotary knife roller gin(5%) and single roller(5%)(Bajaj and Sharma 2012). These methods comprise the use electricity with consumption reported values ranging from 0.20 to 0.95 MJkg-1 with lint yields from 32 to 43% (see Table 3). Scarce LCA data has been obtained from the literature regarding ginning operations, mainly due to the commoninclusion of ginning impacts inside the general frame of cotton cultivation. The impacts of ginning have been quantified as GWP from 0.128 to 0.173 kg co2 eq, AP from 0.0014 to 0,0016kg SO2 eq, and the unique value found for EP was 0.0000612 kg PO43- eq. Thus, environmental impacts caused by ginning appear minimal when they are compared to those obtained for cotton cultivation. Moreover, these operations are the same, independently of the kind of cultivation practices, whether organic or not, employed for the production of virgin cotton.
In the case of Recover fibres, no ginning of cotton is required, but a cutting and shredding of recycled clothes must be performed previous to the spinning step, Thus, this cutting/shredding process has been compared to ginning one in terms of environmental impacts. LCA data for cutting/shredding step is also summarized in Table 3. Energy consumption was estimated in 1.31 Mjkg-1 of cotton treated, which doubles those values obtained for ginning procedures, due to the intensity of the process. As it can be seen, GWP(o.214 kg co2) eq and EP(o. ooo21 kg PO43- eq) categories were slightly increased, by moving from ginning of virgin cotton, to cutting and shredding of the recovered one. Nevertheless, a high efficiency of the method was obtained with a production yield of 96% fibres. Wastes have been characterized as short fibres with a potential utility for the production of building isolation materials, thus providing a new life for these residues.