It is necessary to distinguish between temperature of reaction and reactor temperature. The latter is much higher due to the need for a temperature gradient to effect heat transfer. For fast pyrolysis the lower limit on wood decomposition is approximately 435 *C for obtaining acceptable liquid yields of at least 50% with low reaction times.

The effect of temperature is well understood in terms of total product yield with a maximum at typically 500-520’C for most forms of woody biomass. Other crops may have maxima at different temperatures. The effect of temperature is less well understood in terms of product fuel quality. Work by the University of Waterloo has demonstrated the effects of ash, DP, heating rate and reactor temperature on chemical yields (9). As progress is made in defining bio-oil quality better in fuel terms, the secondary gas/vapour phase history may be more important. At prolonged residence times (> 1 s), the lignin derived fraction may be further depolymerised to produce a more homogeneous liquids. This is also influenced by the reactor configuration. Work done by McKinley (1) has demonstrated that liquid produced in an ablative pyrolysis reactor has a much lower molecular weight average due to depolymerisation and cracking of the liquids on the metal surface prior to vaporisation.