Mathematical Modelling of Acid Hydrolysis and Fermentation in a Wood-To-Ethanol Process
THE PROBLEM
The world's dependence on fossil fuels is very big. This is particularly true in the transport sector, where fossil fuels are dominant and the consumption is ever increasing with more vehicles and an increased amount of transport of goods. In combination with reduced oil supplies and threatening climate changes caused by combustions of fossil carbon dioxide, this means that there is a great need for alternative fuels. One alternative fuel well suited for today’s engine constructions that also fits well into today’s infrastructure regarding fuel distribution is ethanol. Ethanol can be produced from renewable bio mass by fermentation of sugar, thereby also reducing the combustions of fossil carbon dioxide.Today ethanol is produced by fermentation of sugar or hydrolysed starch, called first generation ethanol. There is still room for expansion of the ethanol production based on agromaterials, primarily sugar canes, but the supply of these resources will constitute a limitation. The production potential would be dramatically increased if sugar could be produced through hydrolysis of the cellulose fraction of plants and rest products. This hydrolysis can be performed both chemically by acid and bio chemically by enzymes. The hydrolysis is a complex process which demands further development, but is still only one of several steps in the even more complex total process from raw material to ethanol. Since the different process blocks are strongly correlated and affect each other it is important that the whole process is studied simultaneously. One of the prerequisites for large scale production of cellulose based ethanol is a process with high availability where the side streams are also processed to useful products. Sekab in Örnsköldsvik works with development and up scaling of techniques for ethanol from lignocellulose, primarily wood based materials. The pilot plant comprising all the process blocks from raw materials to distilled ethanol has been built with support primarily from the Swedish Energy Agency and regional EU funds. The plant has been flexibly designed to make it possible to study different integrated process solutions. The plant generates realistic data from continuous operation to be used as foundation for further up scaling of the technique to full scale commercial production plants.
HOW CAN THE PROJECT CONTRIBUTE TO A SOLUTION TO THE PROBLEM?
Since the production of ethanol from lignocellulose consists of several process blocks, strongly correlated to each other, it is important to study the whole system to avoid sub optimisations of single blocks. By developing a mathematical model, based on results from e.g. the ethanol pilot, where the relations between the process blocks are included different process solutions can be studied. The models are valuable for evaluation and systematisation of performed tests as well as identification of new questions and design of new test cases in the pilot plant. All done with the purpose of designing a suitable production process for a full scale plant.WHO WILL BENEFIT FROM THE RESULTS?
Engineers and scientists working with development and up scaling of integrated processes for production of ethanol from lignocellulose are direct consumers. From a prolonged point of view the project will contribute to a society with sustainable fuel production based on a renewable resource available in all plants containing cellulose or from huge amounts of rest products.
