What technical steps can be taken to reduce ethanol production costs?
Answers
|
08/10/2007
|
A:
|
Katharina Harlander, Vogelbusch, hak@vienna.vogelbusch.com
Bioethanol is a price-sensitive product that has to compete with gasoline. Consequently, the industry is keen to bring down production cost. There are a number of technology trends focusing on the main impacts on production cost: the raw material and the energy cost.
One evident target is the broadening of the raw material basis. Additional grain types like rye and barley as well as waste starch and residues from gluten extraction are taken into account and research advances are made for the use of cellulosic materials as a carbohydrate source in a number of pilot applications around the globe.
Further improvements include process simplification by integration of process steps (e.g. integration of saccharification and fermentation) and combining bioethanol production with processes for further byproducts from grains (e.g. gluten from wheat).
A reduction of energy cost can be gained by process optimisation and circulation of process streams (stillage recirculation and increase of alcohol concentration in fermentation). On the engineering side, a considerable reduction of thermal energy consumption can be obtained from thermal (heat) integration on the level of single process steps and on the plant as a whole, including:
• Multi-effect evaporation units for stillage concentration
• Evaporation units with mechanical vapour compression
• Thermal integration of distillation and dehydration
thermal integration of distillation and evaporation
• Multi-pressure systems with split mash and rectification column
• Thermal integration of stillage drying with evaporation.
Other aspects of process development include:
• More complex distillation systems for separation of fermentation byproducts owing to high quality criteria, especially in Europe
• Alternative methods for stillage processing, such as incineration and anaerobic gasification
• Waste water reduction by using stillage recirculation and the use of treated waste water in utilities (cooling towers) and even process purposes.......
|