Production of bioethanol from lignocelluloses using steam explosion

Status

ongoing

Summary

Bioethanol production from renewable primary products will play a big role in the solution of the CO₂ reduction problem. Conventional petrol engines can be run with bioethanol after minor modifications. In Brazil, bioethanol is produced on the basis of sugar canes whereas in the US and Europe production is based on starch (cereal and corn). Not only is there not enough cultivable land, but other energy carriers such as biogas, vegetable oils and the methyl ester or rapeseed oil will compete for the available cultivable land. Renewable primary products containing lignocelluloses such as wood and hay also have the potential to produce alcohol based on their raw material cellulose.

In order to ferment cellulose, it must first be broken down into sugars using enzymes - the cellulases. The sugars can then be fermented to alcohol like in lots of other procedures. However, the process of biological and enzymatic sugar production from wood is a naturally very slowly occurring process. This process can be sped up via the "steam explosion" procedure. During this procedure, hay is heated up to 180°C under pressure. Subsequently, the pressure is suddenly relaxed which leads to a disruption of the cellulose filaments. This procedure was already developed in the 1980s and will be established and optimised within this project.

Due to the sudden relaxation, the cellulose filaments become available for enzymatic hydrolysis into basic sugar subunits. Enzymes that are suitable for this hydrolysis will be examined or rather the enzymes will be produced on the pre-treated filaments by a mutant yeast strain.

The hydrolyzed cellulose will then be fermented to bioethanol, just as in conventional bioethanol production plants. This fermentation process will be optimized and then adapted to the substrate.

Methods for downstream processing of the produced alcohol will be determined in order to generate a cost effectiveness study for a second generation integrated, decentralized bioethanol production plant.

In summary, a new process for the second generation of bioethanol production will be developed that consists of the following steps: pre-treatment (steam explosion), enzyme production, enzymatic hydrolysis, alcohol fermentation and down-stream processing.

Project management

DI Dr. Horst Steinmüller
Energieinstitut an der Johannes Kepler Universität Linz GmbH

Project or cooperation partner

• FH OÖ Forschungs & Entwicklungs GmbH
• Institut für Biotechnologie und Bioprozesstechnik, TU Graz
• Technologie- und Dienstleistungszentrum Ennstal GmbH

Energieinstitut an der Johannes Kepler Universität Linz GmbH
DI Dr. Horst Steinmüller
HF-Gebäude, 3. Stock, Altenberger Str. 69
4040 Linz
E-Mail: office@energieinstitut-linz.at
Tel.: +43 (70) 2468 5656