Ellegaard:
Motor will only be running 2 x 45 seconds per day. I don't think heat will be an issue.
Steppers are hot all the time, they consume power just as much when stationary. If you power
them down, they can lose position.
If you don't care about losing position you'll need some high-side switch to power down the
driver when the motor is idle, if you do care about position you have to keep it powered up and
you will have an issue with heat.