Greenhouse gasses emissions and energy balances of a non-vertically integrated sugar and ethanol supply chain: A case study in Argentina

In order to address society's concerns regarding the sustainability of sugar and ethanol production and use, this paper calculates the energy and greenhouse gasses (GHG) emissions' balances of a non-vertically integrated sugarcane industry in Tucuman-Argentina. The essential operations involved in the sugar/ethanol production cycle were taken into account. Results show that this industry generated an energy balance of 3.4:1. GHG emissions during sugarcane production were 1824 and 2231 kg CO2eq. ha−1 year−1 for low and middle to high farms' technological levels, respectively. The mill process emitted 1187 kg CO2eq. ha−1 year−1. The main factors influencing these balances were gas-oil and nitrogen fertilizers used in the agricultural stage, natural gas consumed by the sugar mill, and sugarcane burning (only for GHG balance). The impact of ethanol use in reducing GHG emissions under the current production scheme (6.8 Mg ha−1 of sugar + 380.9 kg ha−1 of ethanol), in final blends of 95% gasoline and 5% ethanol in vehicles, is negligible. A sensitivity analysis indicates that switching to 100% bagasse used as fuel in mill's boilers, ethanol being produced directly from sugarcane juice, and a final blend of 90% gasoline and 10% ethanol, an amount of 1746 kg CO2eq. ha−1 year−1 of GHG emissions could be avoided.

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