Hi Ranger1.
interesting read from everyone.
Short answer shut everything down during peak load period by power supply company, generally between 6.00pm and 10.00 pm, not always easy with a meat processing plant. But most things like tunnels and holding chillers will not creep temperature too much if closed up, then run hard out at cheaper supply rates. Your client can negotiate a better off peak rate if they adopt the shut down scenario during peak load timing. Talk with power supply company, they are always talkative to keep their network peak loading spike periods and penalties down.
Had a client that adopted that policy and started night shift later,, did the cleaning defrost what ever in that time frame, saved $50K per week.