According to conventional method by which the tested material (CPCAR) is usually regarded as equivalent amount of pure water for calculating the total heat consumption for hydrothermal treatment, 17.2 t steam (0.172 t steam·(t CPCAR)−1) is needed for HTPT of 100 t CPCAR. The actually consumed steam was found to be 15.3 t steam (0.153 t steam·(t CPCAR)−1) according to the data obtained from the pilot test. The difference (0.019 t steam·(t CPCAR)−1) between estimated and experimental data indeed represents the effect of the solid matters contained in the CPCAR which have smaller specific heat capacities than pure water. In the pilot test treating 1.0 t CPCAR only 0.008 t steam was supplied to maintain the material in the reactor at the constant HTPT temperature of 120 °C for 0.5 h. This suggested an ignorable heat loss from the pilot system and a low energy requirement for hydrolysis of the solid matters. The energy difference of 0.019 t steam·(t CPCAR)−1 was usually ignored in the experimental study of HTPT for dewatering sludge (Neyens et al., 2003), but it is surely considerable for industrial plant.