Liquid biofuels from wastes and biomass - towards demonstration

VTT is developing integrated fast pyrolysis, where production of bio-oil is coupled to a fluidized-bed boiler plant. The arrangement has lower capital and operation cost compared to stand-alone pyrolysis facilities. This paper presents some of the experimental results obtained during the work. The current challenge is to find an industrial site, where operation at larger scale may be verified. For the applications, experimental data was generated related to the specific feedstock and taking into consideration liquid product properties. Industrial wood waste, forest residues, wheat straw, reed canary grass, timothy hay, eucalyptus chips, and pine sawdust (a reference material) were pyrolysed. High yields of organic liquid were received from wood feedstock with relatively low ash content, whereas annual crops with high ash content yield considerable lower amounts of organics. However, due to the integration of pyrolysis to a boiler, the overall economics of the system developed is much less sensitive to reduced yields of organics than stand-alone pyrolysis plants. The reason for this is that material not converted to bio-oil will be replacing fuel in the main boiler. Economic assessments generated in the project have been attractive, and further development of the concept is being pursued. This may take place at an existing fluidized-bed boiler, where enough space is available to locate the pyrolysis reactor close to the main boiler, or at a new boiler site.