As the gyrodines are powered by electricity, they reduce the amount of attitude control propellant needed by the Mir base block's control thrusters--they do, however, use a great deal of electricity.
As the gyrodines were powered by electricity, they also reduced significantly the amount of attitude control propellant needed by the Mir base block's control thrusters--15 tons up until 1989. They did, however, use a great deal of electricity.