Stepper motors are inherently inefficient. They use more or less constant power (I^2R loss) whether spinning or holding, and the only way not to is to turn the whole thing off.

The clock is driven by the ubiquitous 28BYJ-48 stepper motors that can be found on eBay for a few bucks. They don’t have much torque, but all they have to do here is turn a cardboard disk. It ...

Here's a simple algorithm that uses conventional microcontroller blocks to control commercially available H-bridges to properly commutate a bipolar stepper motor through a microstepping profile.