The biorefinery has been the subject of much discussion in the past few years. Biorefinery technologies are divided into biochemical and thermochemical processes. In the biochemical route, wood chips are pre-treated to extract acetic acid and hemicellulose. The separated hemicellulose is then fermented to ethanol and/or converted into specialty products. Identifying products that can be economically produced is a critical step in the biorefinery process. The thermochemical process is based on gasification/pyrolysis of the spent liquor. There are a small number of mills in the USA and Canada that have biorefinery projects (biomass or black liquor gasification). A sulphite mill in Canada has been converting its spent cooking liquor (by fermentation of sugars) into ethanol and specialty chemicals for some years. The mill has also recently started anaerobic biogas production.

In this competitive world, where pulp and paper can be produced much cheaper elsewhere, the biorefinery could provide a much needed edge for the North American industry. However, the biorefinery solution requires careful study of technical and economic issues to have a positive outcome.