Several innovative technologies for the thermochemical or biochemical conversion of woody biomass into useful bioenergy products are presently under development, although few of these have reached commercialization, as discussed below. A com­plete list of lignocellulose processing facilities for bioenergy production, including types of feedstocks used, processing scale and operational status, is available at http://www. bioenergy2020.eu/flles/publications/pdf/2010-bericht-demoplants. pdf.

Combustion: Systems that employ direct combustion to convert biomass and charcoal into energy for heat, power, and CHP (Combined heat & Power) are widely utilized and commercially available for small-, medium — and large-scale applications. Large scale co-flring of bio-oil has been carried out at Manitowac and Red Arrow, but few other cases of application exist.

Pyrolysis: Different pyrolytic technologies, including torrefaction (Brownsort 2009), pressurized pyrolytic reactor processing (Antal and Gr0nli 2003), slow pyrolysis (Brownsort 2009), vacuum pyrolysis (Bridgwater and Peacocke 2000) and fast pyrolysis (Dahmen et al. 2012; Bridgwater and Peacocke 2000) are all considered to be mature technologies. Slow pyrolysis technologies for charcoal and biochar production are commercially available (Bioenergy Ltd., Yury Yudkevitch, Biogreen Energy, Enecon, Pty Ltd, ICM Inc., Pacific Pyrolysis (formerly BEST Energies)), while fast pyrolysis is on the verge of commercialisation (Dynamotive, Ensyn, BTG, Biomass Eng., KIT/Lurgi, Pytec, ARBI-Tech, ROI, Agri-Therm, Anhui Yineng, Metso Consortium).

Gasification-synthesis: Biomass gasification technologies have been sufficiently developed to be considered as a significant contributor to global sustainable energy production. Nevertheless, there are still some issues with biomass processing (pre­treatment, gas cleaning, reforming efficiency, etc.) to be addressed before successful large-scale commercial introduction of biomass gasification takes place (Bridgwater et al. 2002; Tijmensen et al. 2002). Commercial-scale technology for Fischer — Tropsch synthesis using syngas has been in operation for several decades in South Africa, Malaysia and elsewhere.

Direct liquefaction: Commercialisation of hydrothermal technologies suffers from difficulties that arise with the conversion of batch reactors to continuously processing systems, as it is difficult to pump fluids at high pressures and low flow rates (Peterson and Haase 2009). Nevertheless, the supercritical water gasification process appears to be a suitable technique for hydrogen production from biomass at the commercial scale (Calzavara et al. 2005).

Alcoholic fermentation from lignocellulose: The biochemical conversion of lig — nocellulose into cellulosic ethanol by fermentation has been substantially developed in the past few decades, comparatively more than thermochemical technologies for liquid transportation fuel production (Anex et al. 2010). The first commercial projects for cellulosic ethanol production using woody biomass and/or forest residues as feedstocks are presently under development, including several efforts by Borregaard Industries (Norway), Mascoma Corp (USA), KL Energy Corporation (USA) and SEKAB (Sweden). Butanol fermentation from lignocellulose requires further development prior to commercialisation.

Anaerobic digestion of lignocellulose: Anaerobic digestion (AD) for the pro­duction of biogas is a well-established commercial technology. However, the limitations in terms of conversion efficiency and productivity of lignocellulose conversion requires either the co-digestion of limited amounts of lignocellulose with readily digestible, high-nitrogen content substrates (such as sewage sludge) or alternatively further development of pretreatments applied to lignocellulose to improve digestibility. Pretreatment development needs to facilitate a greater degree of pure lignocellulose digestion as well as higher tolerance of AD to inhibitors formed by sugar degradation during pretreatment.