The energy-saving characteristic of silica gel regeneration with power ultrasonic was analyzed by introducing the conception of specific energy consumption. For the purpose, the experiments of silica gel regeneration with 21-kHz power ultrasound were performed under different drying air temperatures (i.e., 35, 45, 55 and 65 degrees C) combined with different acoustic power levels (i.e., 0, 20, 40 and 60 W). And the energy saving ratios of the ultrasonic-assisted regeneration were studied by the method of ANOVA (Analysis of Variance) and compared among different conditions. The influences of acoustic power and drying air temperature as well as the target moisture ratio (at which the regeneration process ended) on the total specific energy consumption (TSEC) and the excess specific energy consumption (ESEC) were also discussed. The results indicate that all the factors (drying temperature, ultrasonic power level and the interaction between the drying temperature and the power level) have a significant (P < 0.05) influence on the energy saving ratio, among which the influence of drying temperature is the most significant (P < 0.05). According to the analysis of specific energy consumption, the optimal drying conditions aiming at the minimum energy use can be obtained. For the present experimental conditions, the condition of 55 degrees C (drying temperature) and 60W (acoustic power level) can achieve the lowest TSEC and ESEC. In addition, different thresholds of power level are required to achieve the energy-saving effect due to the application of ultrasonic in the regeneration. The method of specific energy consumption can be also used for the energy analysis of the new regeneration technology in the scale-up study. (c) 2011 Elsevier Ltd. All rights reserved.