Steam explosion

Price developments of the last months showed that the markets for agricultural products are very volatile. The causing effect for this is founded on the rapid growth of food and animal feed demand in particular caused by changing food pattern in developing countries. On the other hand industrial production is putting strong emphasis on renewable resources as raw material for various industrial chemicals and energy generation. Raw materials with stark and sugar as major components can be processed easily and are therefore prominent sources for industrial use with strong inference with food production. However arable land is limited and therefore alternatives are requested to secure the required raw materials. Lignocellulosic material is one of the most abundant biomass and worldwide research and development activities focus on the use of these raw materials as they are low cost by-products with marginal applications as raw materials in chemical production today. An Austrian research group, consisting of staff members of the Technical University of Graz, the paper factory Steyrermühl as well as the plant engineer Voestalpine was prominent in the end of the eighties in the area of enzymatic hydrolysis of straw. Success in technology development was demonstrated in pilot scale and the results are summarized in Steinmüller (1991). As a consequence of low oil prices in the early nineties research and development activities were cancelled. In 2007 a new approach was set up in a project and the first results are very promising that now the enzymatic hydrolysis with subsequent ethanol production can be developed in pilot scale and further research and development for the production of biogas, organic acids, solvents and pure lignin within an integrated and closed process network can be conducted. The planned project is based on current as well as former results and allows the development of a competitive technology to process the raw material straw to bioethanol, biogas, organic acids and solvents. Key technological steps within the integrated concept are the pre-treatment of the chopped straw by steam explosion followed by enzymatic hydrolysis with self grown cellulase and subsequent enthanol fermentation (Simultanious Saccharification & Fermentation Process). The down stream processing of the fermentation broth is done by a novel membrane filtration process and all by-products are substrates for biogas generation which will be optimised in batch fermentation trials to reach energy self-sufficiency of the biorefinery process concept. Besides this investigations of vapour condensates of the pre-treatment step as well as comprehensive characterisation of the sulphur-free lignin will accomplish research and development activities within the project. The developed process network will be tested in the pilot plant scale at a full equipped facility of the project partner SüdChemie AG, therefore a strong economic driver is integrated in the team. Extensive literature review in preparation for the project resulted that there is currently worldwide no comparable technology concept operating.