The methods of PFC energy saving:

Power factor correction reduces the reactive power, power consumption and thus power costs drop in proportion.  investment return in 6 to 24 months through lower power costs.

Effective installation use, an improved power factor means that an electrical installation works of higher effective power for the same apparent power.

Improved voltage quality like harmonics reducing.

Reduce voltage fluctuations included transient overvoltage, up and down voltage fluctuations flicker, voltage drops.

Optimum cable dimensioning, cable cross-section can be reduced with improvement of power factor (less current). In existing installations for instance, extra or higher power can be transmitted.

Smaller transmission losses, the power transmission and switching devices carry less current, ie only the effective power , meaning that the ohmic losses in the leads are reduced.