Robotic Nation Evidence

The idea of powering robot joints with fuel rather than electric motors is interesting, at least in the short term. Precision seems unlikely, but the power would be nice in some applications.

Center for Intelligent Mechatronics: Exoskeleton: "The power supply most often used for untethered robots is battery power. Although battery power is effective in its own right, it generally contains insufficient mass specific energy density to perform human-scale work for extended periods of time. For example, one of the more advanced current mobile robots - Honda's P-3 Humanoid Robot - has an operation time of only 15-25 minutes, depending on its workload. Operation times of this magnitude or smaller are not uncommon and represent one major technological roadblock for designing mobile robots that can operate remotely for extended periods of time.
The Center for Intelligent Mechatronics is currently working with UC Berkeley under DARPA funding to develop liquid fueled robot actuators that provide an order of magnitude greater energy and power density than typical battery-powered geared DC motors,"