Comparison of different pretreatment methods for straw for lignocellulosic bioethanol production

In order to reduce carbon dioxide emissions from the combustion of fossil fuels, the production of biofuels from lignocellulosic agricultural residues is the focus of industrial and scientific interest. The feedstocks of the second generation used for bioethanol production are lignocellulose-containing raw materials like different types of straw, or other plants like miscanthus x giganteus. In all these plants, the cellulose in the lignocellulose is not accessible to enzymes. Therefore, lignin and/or hemicelluloses have to be removed by a specific pretreatment in order to make enzymatic degradation of cellulose possible. We examined and compared the pretreatment of wheat straw by means of steam treatment and steam explosion treatment. After hydrolysis, glucose concentrations up to 300 g kg-1 were reached both for steam- pretreated straw and steam-exploded straw. After fermentation, ethanol concentrations ranging from 120–140 g kg-1 were achieved. Results suggest that the explosion process slightly favors the solubilisation of sugars and, therefore, enhances ethanol production. Only at higher temperature and longer incubation time does the explosion process not seem to be necessary. In addition to this, we examined most of the lignocellulosic residuals in Austria available for bioethanol production. As a result, we can show that even in a country not focused on agricultural production all the bioethanol needed for E10 can easily be provided.