A case study of ethanol water demand during industrial phase in Brazil
Abstract
Thayse A. D. Hernandesb, Fábio V. Scarparea, Marjorie M. Guarenghib, Tássia P. Pereirab, Marcelo V. Galdosa a Laboratório Nacional de Ciência e Tecnologia do Bioetanol - CTBE/CNPEM, Caixa Postal 6170, 13083-970 Campinas, São Paulo, Brazil, E-mail: fabio.scarpare@bioetanol.org.br b Faculdade de Engenharia Mecânica, Unicamp, Cidade Universitária "Zeferino Vaz", CEP 13083-860, Campinas, SP, Brazil In São Paulo State, the water resources have being used by sugarcane industry responsibly, through high reuse rates that may reach 95% during industrial process. The average amount of catchment water stays around 2.0 m3 Mg 1 of industrial sugarcane stalk. However, in some modern mills which use higher technical level of closed water circuit, the standard goal for sugarcane industry, 1.0 m3 Mg 1 can be reached. In some regions where the uptake water for industrial segment is high as in São Paulo State, water use assessment is desired for sustainable ethanol production. Thus, two regions in São Paulo State with two plants each were taken as a case study aiming to assess ethanol water demand during the industrial phase. Araraquara was the first study region where the water demand was classified as in critical condition in 2010 according to the Water and Electrical Energy Department of São Paulo State (DAEE). The industrial activities were responsible for 50% of the water catchment. Araçatuba was the second study region where water demand was classified as being of concern (DAEE) due to high percentage of catchment water for industrial activities, around 90%. Data regarding the amount of millable cane processed, days of the plant operation, ratio of cane used for ethanol production in 2010/2011 season were used for direct water demand estimation considering different water catchment scenarios of 2.0, 1.0 and 0.7 (technological development prediction scenario) m3 Mg-1 of millable cane. For indirect water demand estimation, data regarding installed capacity of each unit and ethanol production efficiency (number of liters per millable ton of cane) were used considering the same water catchment scenarios. In terms of absolute values, mills in Araçatuba showed higher water consumption than in Araraquara (0.24 and 0.17 m3 s-1 respectively) for water catchment scenarios of 2.0 m3 Mg-1. Regarding the water use per ethanol produced (liter of water use per liter of ethanol produced), mills in Araçatuba also showed higher values, 0.035 than in Araraquara, 0.014 around 60%. Considering all scenarios, the industrial water demand for ethanol production was always the double for Araçatuba due a higher amount of collected water in that region. In the current water uptake scenario (2.0 m3 Mg-1), the mills involvement in industrial water demand was 22% in Araçatuba and 10% in Araraquara. Taking into account the total water demand in both regions, the amount of water demand for ethanol production was 21% and 5% respectively for Araçatuba and Araraquara. In the future, when the water uptake scenario will reach 0.7 m3 Mg-1 it will provide a 65% saving of water in both regions. Our results suggest that the ethanol industry did not represent high pressure on water resources in those analyzed regions.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2012
- Bibcode:
- 2012AGUFM.H53H1617H
- Keywords:
-
- 1804 HYDROLOGY / Catchment;
- 1880 HYDROLOGY / Water management