Malek Alkasrawi, Mats Galbe, Johanna Söderström Anders Wingren
and Guido Zacchi*

Dept. of Chemical Engineering

Lund University

Box 124

SE-221 00 Lund

Phone: +46 46 222 82 50

E-mail: Guido.Zacchi@chemeng.lth.se

Ethanol production from softwood comprises the following main steps: hydrolysis of hemicellulose, hydrolysis of cellulose, fermentation, separation of lignin, recovery and concentration of ethanol and wastewater handling. In Sweden, several comprehensive studies have been performed based on acid as well as enzymatic hydrolysis. The enzymatic study was investigated using a Process Development Unit (PDU) at Lund University comprising all the necessary steps. The objective of the PDU is to provide reliable data for technical design of a future pilot plant. Such a pilot comprising the possibility to run both acid hydrolysis and enzymatic hydrolysis, with a capacity of 2 ton raw material per day, is now being constructed in the north of Sweden by Etek – Ethanol Technology Corp.

In the enzymatic process high yield of ethanol, about 80% of theoretical based on the raw material, has so far been obtained in the PDU using a two-stage steam-pretreatment and impregnation with SO₂ followed by simultaneous saccharification and fermentation (SSF). More complex process integration, in the form of recirculation of process streams, which is desirable in an industrial process, was also investigated using the PDU. The ethanol production cost was estimated to be around 3.5-4 SEK/liter ethanol assuming a yearly capacity of 200,000 ton raw material (dry matter).

Results from the ongoing experimental study, using the PDU, and from the techno-economic evaluation will be presented.