Figure 3. Ethanol production cost as a function of water-insoluble solids (WIS) in
the SSF step (expressed as weight-% of total material) for production of ethanol
from spruce, based on a production capacity of 200 000 DM raw material per year.
Broken line: use of meachanical vapour recompression in evaporation (1
SEK = $0.13). This figure clearly shows the importance of working at high WIS.