Since the robot will be using battery power to function conserving and recapturing energy is of high importance. Conserving is about efficiency of each movement and using only necessary movements. Recapturing energy is about retaining some percentage of original cost of a movement within the robot system. For example, one recapture method could be pressure sensitive pads on the feet for a quadruped robot. Each time the robot steps on a foot, the pressure generates a tiny amount of electricity which is used to extend the time before recharging is necessary. Vibration energy recapture is another method we should look at. Below is an article about a different energy recapture system. Hope you enjoy!