Demirbas and Arin have summarised the characteristics of each form of pyrolysis commonly used.54 Slow or conventional pyrolysis is characterised by relatively low temperatures, slow heating rates and high residence times. The methodology has been used for the production of charcoal for centuries. The methodology is based on using large solid pieces of feedstock (since heating the solid can be performed slowly and there is no requirement for rapid heat transfer) and heating in situ to a set temperature for a period of time.55 Heating rates are of the order of 1°C/min and residence rates around a few seconds or longer. Higher temperatures are around 600-700°C. Typical yields are around an equal division as solid, gas and liquid.54-56