Carbon dioxide and ethanol from sugarcane biorefinery as renewable feedstocks to environment-oriented integrated chemical plants.

Abstract

The chemical industry share of environmental impacts derives predominantly from the use of non-renewable feedstocks and inefficient use of mass and energy, resulting in atmospheric emissions, especially carbon dioxide, which is the main cause of global warming and climate change and expressive generation of wastes. Rather than treating carbon dioxide as waste, it can be regarded as an alternative chemical feedstock for synthesis of fuels and chemicals. Using carbon dioxide as a renewable and environment-friendly source of carbon is one of the most attractive solutions to reduce our dependence on petrochemicals. This work evaluates the utilization of carbon dioxide as feedstock to the production of chemicals arranged in an industrial eco-pole to reduce environmental impacts of a sugarcane biorefinery. This environment-oriented chemical complex, the Eco-Pole, aims to increase the sustainability of the sugarcane bioethanol industry located nearby the complex using carbon dioxide produced in the sugarcane fermentation and bioethanol itself as feedstocks. The Eco-Pole benefits from the nearly pure carbon dioxide to produce chemicals traditionally derived from fossil raw materials, namely methanol, propylene, ethylene, ethylene oxide, propylene oxide, ethylene carbonate, propylene carbonate and dimethyl carbonate. Process simulation using Aspen HYSYS® is used to compute mass and energy balances to support the calculation of quantitative performance indexes (e.g., net carbon dioxide emissions, energy intensity and water intensity) to compare efficiency of individual process and arranged in the Eco-Pole. The propylene oxide plant shows best individual performance, while the worst performance occurs for the ethylene plant. A multi-criteria analysis ranking sustainability performance points to the dimethyl carbonate plant as the most sustainable and the propylene plant as the poorest performer. The Eco-Pole cash flow presents a deficient economic performance, but with a tendency to profitability. Nevertheless, Eco-Pole shows satisfactory performance regarding the raw material and energy consumption indexes. Moreover, the carbon dioxide emission per Eco-Pole products is relatively low.