The existing compressor motors (xx, xx, and xx hp) are standard efficiency (85% efficient or less). They are original equipment with the plant and may have been rewound one or more times since they were new. A motor becomes less efficient each time it is rewound.
Replace the existing motors with high efficiency motors (HEMs). HEMs are typically 2% to 8% more efficient than a standard efficiency motor, which becomes quite significant in motors of this size.