Optimization and analysis of a bioethanol agro-industrial system from sweet sorghum

The use of non-food crops for bioethanol production represents an important trend for renewable energy in China. In this paper, a bioethanol agro-industrial system with distributed fermentation plants from sweet sorghum is presented. The system consists of the following processes: sweet sorghum cultivation, crude ethanol production, ethanol refining and by-product utilization. The plant capacities of crude ethanol and pure ethanol, in different fractions of useful land, are optimized. Assuming a minimum cost of investment, transport, operation and so on, the optimum capacity of the pure ethanol factory is 50,000 tonnes/year. Moreover, this bioethanol system, which requires ca. 13,300 ha (hectares) of non-cultivated land to supply the raw materials, can provide 26,000 jobs for rural workers. The income from the sale of the crops is approximately 71 million RMB Yuan and the ethanol production income is approximately 94 million RMB Yuan. The potential savings in CO2 emissions are ca. 423,000 tonnes/year and clear economic, social and environmental benefits can be realized.