All the these systems would probably have batteries (except the fuel cells?) just to store the energy. Having battery technology on this list almost doesn't make sense because batteries don't generate power, as the other technologies do, and batteries may still end up on the devices even if the power is generated on the device.
What the battery category implies is that the power for these small devices is not generated on the device itself but elsewhere. Looks like more engineers are thinking power won't be generated on the device itself at all. I wonder why. Remember those calculators with the light harvesting or solar panels on them. You covered the panel and the calculator turned off.
Drones are, in essence, flying autonomous vehicles. Pros and cons surrounding drones today might well foreshadow the debate over the development of self-driving cars. In the context of a strongly regulated aviation industry, "self-flying" drones pose a fresh challenge. How safe is it to fly drones in different environments? Should drones be required for visual line of sight – as are piloted airplanes? Join EE Times' Junko Yoshida as she moderates a panel of drone experts.