| Summary: |
Factory-level industrial metabolism (IM) was applied to a case study of carbon flows in an alcohol fermentation factory. A static material flow model and the indicators derived from factory-level IM were used to analyze carbon utilization efficiencies of the system and of each process and to study ways to improve the carbon metabolic level of the system. Among the six processes in alcohol production, the carbon utilization level of the fermentation process was the lowest. The maximum loss of starch carbon in the system was through carbon dioxide generated in the fermentation process, accounting for 19.8% of the system’s total carbon inputs (TCIs). In addition, most of the non-starch carbon, accounting for 35.0% of the TCIs, was not utilized for al-cohol production. Only part of the non-starch carbon was incorporated into the products and by-products, accounting for approximately 14.6% of the TCIs. For the whole system, 39.1% of the TCIs were transformed into products and 19.1% of the TCIs were transformed into by-products. There appears to be considerable potential, therefore, to in-crease carbon utilization efficiency of the system still further by improving the starch carbon utilization level of each process and the resource utilization of the non-starch carbon. |